[Federal Register Volume 88, Number 185 (Tuesday, September 26, 2023)]
[Proposed Rules]
[Pages 65835-65865]
[FR Doc No: 2023-20531]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 401, 404, 415, 417, 431, 435, 437, 450, and 453

[Docket No.: FAA-2023-1858; Notice No. 23-13]
RIN 2120-AK81

Mitigation Methods for Launch Vehicle Upper Stages on the
Creation of Orbital Debris

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: To limit the growth of orbital debris, the FAA proposes to
require that upper stages of commercial launch vehicles and other
components resulting from launch or reentry be removed from orbit
within 25 years after launch, either through atmospheric disposal or
maneuver to an acceptable disposal orbit. Any artificial object left in
orbit around the Earth which no longer serves a useful purpose can
become a debris hazard in space. Orbital debris is all such human-
generated debris in Earth orbit that is greater than 5 millimeters (mm)
in any dimension. Collisions between and with orbital debris are a
growing concern because prior to the establishment of the Inter-Agency
Space Debris Coordination Committee (IADC) practices allowed these
objects to accumulate in Earth orbit. Additionally, an increasing
number of launch operators are launching assets into space at greater
rates. If left unchecked, this accumulation can clutter useful orbits
and present a hazard to operations on-orbit. This proposed rule would
reduce the amount of additional debris created, as well as limit
potential collisions with functional spacecraft and other debris
already on-orbit.

DATES: Send comments on or before December 26, 2023.

ADDRESSES: Send comments identified by docket number FAA-2023-1858
using any of the following methods:
     Federal eRulemaking Portal: Go to www.regulations.gov and
follow the online instructions for sending your comments
electronically.
     Mail: Send comments to Docket Operations, M-30; U.S.
Department of Transportation, 1200 New Jersey Avenue SE, Room W12-140,
West Building Ground Floor, Washington, DC 20590-0001.
     Hand Delivery or Courier: Take comments to Docket
Operations in

Room W12-140 of the West Building Ground Floor at 1200 New Jersey
Avenue SE, Washington, DC 20590-0001 between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
     Fax: Fax comments to Docket Operations at<PHONE_NUMBER>.
    Privacy: In accordance with 5 U.S.C. 533(c), DOT solicits comments
from the public to better inform its rulemaking process. DOT posts
these comments, without edit, including any personal information the
commenter provides, to www.regulations.gov, as described in the system
of records notice (DOT/ALL-14 FDMS), which can be viewed at
www.dot.gov/privacy.
    Docket: Background documents or comments received may be read at
www.regulations.gov at any time. Follow the online instructions for
accessing the docket or go to the Docket Operations in Room W12-140 of
the West Building Ground Floor at 1200 New Jersey Avenue SE,
Washington, DC 20590-0001, between 9 a.m. and 5 p.m., Monday through
Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Brenda Robeson, Office of Commercial
Space Transportation, Federal Aviation Administration, 800 Independence
Avenue SW, Washington, DC 20591;<PHONE_NUMBER>;
[email protected].

SUPPLEMENTARY INFORMATION:

Authority for This Rulemaking

    The Commercial Space Launch Act of 1984, as codified and amended at
51 U.S.C.--Commercial Space Transportation, ch. 509, Commercial Space
Launch Activities, 51 U.S.C. 50901-50923 (the Act), authorizes the
Department of Transportation and thus the FAA, through delegations, to
oversee, license, and regulate commercial launch and reentry
activities, and the operation of launch and reentry sites as carried
out by United States (U.S.) citizens or within the United States.
Section 50905 directs the FAA to exercise this responsibility
consistent with public health and safety, safety of property, and the
national security and foreign policy interests of the United States.
Pursuant to Sec.  50903, the FAA is also responsible for encouraging,
facilitating, and promoting commercial space launches by the private
sector.

List of Definitions and Acronyms Frequently Used In This Document

    Disposal (storage) orbit--an orbit intended for post-mission long-
term storage where atmospheric effects and solar radiation will not
move the disposed object into a protected orbit for at least 100 years.
    ISS--International Space Station.
    NASA--National Aeronautics and Space Administration.
    Spacecraft--vehicles, payloads, and other manmade objects that are
designed to for placement or operation in outer space. For example,
spacecraft include satellites, inhabitable space stations, inhabitable
capsules, and cargo vehicles.
    Transfer orbit--a temporary orbit on which an object travels to
move from one orbit to another.
    Upper stage--a segment of a launch vehicle that reaches orbit.

I. Overview of Proposed Rule

    This proposed rule would require an operator licensed or permitted
under this chapter to perform a launch or reentry with a planned
altitude greater than 150 kilometers (km) to limit or dispose of debris
at the end of a launch or reentry to maintain a sustainable space
environment. The FAA proposes to require that operators licensed or
permitted under parts 415, 417, 431, 435, 437, or 450, to perform a
launch or reentry with a planned altitude greater than 150 km submit an
Orbital Debris Assessment Plan (ODAP)--including physical evidence,
test results, and analyses to demonstrate removal activities--prior to
each operation. This notice proposes that if debris--including spent
upper stages and other components--is released during launch or
reentry, during on-orbit aspects of launch or reentry, or during
disposal operations, any pieces greater than 5 mm in size must be
removed from highly-used regions within 25 years. The FAA proposes to
allow operators to meet this criterion by performing one of five
disposal options. Operators may choose to dispose of the debris within
30 days of mission completion through (1) controlled disposal; (2)
maneuver to a disposal orbit; or (3) Earth-escape orbit. Alternatively,
an operator could elect to (4) retrieve the debris within 5 years of
mission completion; or (5) perform atmospheric uncontrolled disposal or
natural decay within 25 years, if the debris disposal meets the risk
criteria.
    The FAA notes that many launches, as they are currently conducted,
would already be in compliance with the operational requirements of the
proposed regulation. The FAA also proposes to amend the reporting
requirements governing debris creation. The FAA would require the
reporting of a non-nominal launch or a debris-creating anomaly to the
FAA.

II. Background

A. Statement of the Problem

    Orbital debris is made up of fragmented material (resulting from
anti-satellite tests, upper stage explosions, accidental collisions,
etc.), nonfunctional spacecraft, rocket bodies, and mission-related
items (explosive bolts, vehicle shrouds, etc.),\1\ but excludes
naturally-occurring debris such as meteoroids. As more and more
spacefaring nations launch objects into Earth orbit, space is becoming
increasingly crowded with orbital debris.\2\ If left unchecked, orbital
debris can diminish the usefulness of certain orbits and present a
hazard to operations on-orbit. Current international modeling indicates
that even if there were no further space launches, collisions between
objects already in space will eventually become the major source of
debris.\3\ This threat could soon escalate dramatically with the
deployment of large constellations of small satellites in the already-
congested Low Earth Orbit (LEO) region.
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    \1\ Belk, C.A., J.H. Robinson, M.B. Alexander, W.J. Cooke, and
S.D. Pavelitz. (1997). Meteoroids and Orbital Debris: Effects on
Spacecraft. NASA Reference Publication 1408, Marshall Space Flight
Center, AL.
    \2\ Inter-Agency Space Debris Coordination Committee. (April
2013). Space Debris IADC Assessment Report for 2010.
    \3\ Inter-Agency Space Debris Coordination Committee. (January
2013). Stability of the Future LEO Environment.
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    As of 2021, the number of orbital objects sized 10 centimeters (cm)
or greater is estimated to be over 23,000. Recent debris projections
estimate a total of half a million objects sized between 1 and 10 cm on
orbit, and over 100 million objects larger than 1 mm.\4\
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    \4\ The NASA Orbital Debris Program Office. (Retrieved April 28,
2020). Frequently Asked Questions. orbitaldebris.jsc.nasa.gov/faq/#
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    Each Earth orbit has a specific usefulness and needs to be
protected from accumulated orbital debris. LEO is commonly used for
Earth observation, communications, and scientific experiments. LEO is
also the region where most human spaceflight activities take place.
Medium Earth Orbit (MEO) contains space navigation satellites and some
communications missions covering the North and South poles. Space
objects in Geostationary Earth Orbit (GEO) typically support
communications and weather missions. A transfer orbit is a temporary
orbit that a launch vehicle uses to move from one orbit into another. A
common transfer orbit is the GEO transfer orbit used to place
spacecraft into GEO. The upper stage often remains in the GEO transfer
orbit with an apogee near the GEO

region and the perigee in LEO. Spacecraft typically occupy LEO, MEO, or
GEO, but can operate in other less congested orbits. The areas outside
LEO, MEO, and GEO have been known as acceptable disposal orbits for
upper stages and discarded satellites because they are not frequently
used by active satellites. Figure 1 illustrates the various levels of
Earth orbit including disposal orbit regions.
[GRAPHIC] [TIFF OMITTED] TP26SE23.027

BILLING CODE 4910-13-C
    Debris in space travels at hypervelocities. On average, collisions
in LEO occur at a closure rate, or combined velocity at impact, over 10
km per second.\5\ This is more than 11 times faster than a bullet. At
those speeds, an impact to a typical operational spacecraft by debris 5
mm and larger will most likely cause damage to critical systems that
ends the mission of the spacecraft.\6\ As seen in Figure 2, the main
threat to operational spacecraft (abbreviated to ``S/C'' in Figure 2)
in LEO is the debris in the range of 5 mm to 1 cm, primarily due to the
sheer number of objects in this range. However, large objects greater
than 1 meter, including discarded upper stages, are the main driver for
debris growth.
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    \5\ Portree, D.S.F. and Loftus, J.P. (January 1999.) Orbital
Debris: A Chronology. NASA/TP-1999-208856.
    \6\ Squire, M., et al. (2015). Joint Polar Satellite System
(JPSS) Micrometeoroid and Orbital Debris (MMOD) Assessment, NASA/TM-
2015-218780.

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    In addition to causing catastrophic breakups, orbital debris
impacts on functioning satellites or spacecraft can also degrade
performance, pit or crack windows, mar surfaces of solar panels, damage
optics, and degrade surface coatings.8 9 In 1984, a piece of
orbital debris damaged the windshield of the Space Shuttle Challenger.
A 4 mm diameter crater was made by a fleck of white paint approximately
0.2 mm in diameter, traveling 3-6 km/sec.\10\
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    \7\ Liou, J. C. (2011). Engineering and Technology Challenges
for Active Debris Removal. Figure 4, page 8. Presented at the 4th
European Conference for Aerospace Sciences. Ibid.
    \8\ Williamson, M. (2006). Space: The Fragile Frontier, American
Institute of Aeronautics and Astronautics, Inc.
    \9\ The NASA Orbital Debris Program Office. (April 2009).
Satellite Collision Leaves Significant Debris Clouds. NASA JSC
Orbital Debris Quarterly News, 13(2), page 1-2.
    \10\ Center for Orbital and Reentry Debris Studies, Aerospace
Corporation. (December 2004). Space Debris Basics: What Are the
Risks?
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    As of 2021, approximately 95 percent of the total mass of human-
generated objects in orbit is rocket bodies (i.e. upper stages) \11\
and spacecraft. The remainder is mission-related debris and
fragmentation debris.\12\ The more mass an object has, the more debris
it will create in the event of an explosion or collision.
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    \11\ Only some of the upper stages on-orbit result from U.S.
commercially licensed launches.
    \12\ The NASA Orbital Debris Program Office. (May 2019). Monthly
Mass of Objects in Earth Orbit by Object Type. NASA JSC Orbital
Debris Quarterly News, 23(1 & 2), page 13.
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    The U.S. Government, for launches it conducts, has taken steps to
mitigate orbital debris generation. Similarly, other countries are
taking steps to mitigate debris generation during operations they
oversee. This proposed rule would align U.S. commercial orbital debris
mitigation practices for U.S. commercial launch operations with orbital
debris mitigation practices accepted by the U.S. Government and certain
other countries. For example, the European Space Agency (ESA) is
implementing a Zero Debris Approach to stop the growth of orbital
debris from their operations by 2030. ESA's policy acknowledges that if
the status quo of orbital debris generation continues, future on-orbit
operations will be hindered unless actions like remediation (active
debris removal) are enacted.\13\
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    \13\ European Space Agency. (Accessed on April 4, 2023). Short
Introduction to ESA's Zero Debris Approach, blogs.esa.int/
cleanspace/2023/01/12/short-introduction-to-esas-zero-debris-
approach/
#:~:text=The%20ESA%20Zero%20Debris%20Approach%20is%20the%20Agency%E2%
80%99s,the%20catastrophic%20degradation%20of%20the%20Low-
Earth%20Orbit%20environment.
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    If no mitigation measures are implemented, the projected growth of
orbital debris is expected to rapidly increase, as Figure 3 shows. The
growth rate, as estimated in 2011, assumed a steady launch rate based
on annual launch rates and did not address the increase in satellite
constellations. SpaceX alone has launched over 1,500 satellites in its
Starlink constellation as of August 2021. Several more companies have
launched their own small satellite constellations. These small
satellites are expected to have relatively short lifetimes, on the
order of 5 years. Even though many operators are following current best
practices, those practices allow multiple generations of spent
satellites to co-exist on-orbit. The graph in Figure 3 is based on
trackable debris. Current technology tracks objects 10 cm and larger,
though debris between 5 mm and 10 cm pose risks. The shaded areas
around the solid lines are the 1-sigma uncertainty from 100 Monte Carlo
runs of the growth model.

[GRAPHIC] [TIFF OMITTED] TP26SE23.029

    A launch vehicle is made up of a first stage and usually one or
more upper stages. When a vehicle is launched into space, the first
stage typically propels the vehicle through the bulk of the atmosphere,
but does not reach orbit. The first stage falls back to Earth shortly
after launch. The upper stage then ignites to put the payload into LEO
or a transfer orbit. Typically, the upper stage deploys the payload in
LEO, if that is the final payload destination; otherwise, it usually
deploys the payload in the transfer orbit for payload destinations
higher than LEO.
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    \14\ Liou, J.-C. (2011). Engineering and Technology Challenges
for Active Debris Removal. Presented at the 4th European Conference
for Aerospace Sciences.
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    Historically, the largest contributor to orbital debris was the
explosion of upper stages.\15\ Defunct upper stages with charged
batteries or partially fueled tanks would often experience catastrophic
failures attributed to stored energy. Current regulations adequately
address this issue by requiring launch operators to ensure that stored
energy is removed from all launch vehicle stages or components.\16\
However, now the greatest risk regarding the growth of orbital debris
population is collision between objects including upper stages on
orbit. The strength of upper stage structures, along with their mass
and size, pose a risk of catastrophic collisions that would create
substantial amounts of orbital debris. The threat of fracturing such a
large object can be mitigated by removing it from populated orbits.
With this proposed rule, the FAA intends to ensure upper stages are
properly disposed of at the end of launch to limit the growing orbital
debris population.
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    \15\ Anz-Meader, P.D., Johnson, N., Cizek, E., and Portman, S.
(July 31, 2001). History of On-Orbit Satellite Fragmentation, 12th
ed. NASA Lyndon B. Johnson Space Center Orbital Debris Program
Office, Houston, TX, JSC29517.
    \16\ 14 CFR 417.129(b) and (c) and Sec.  450.171.(a)(2)-(3).
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    The impact of even one collision has a significant effect on the
growth of orbital debris. Figure 4, generated by the NASA Orbital
Debris Program Office,\17\ shows the predicted growth rate of orbital
debris in LEO, as estimated in 2022. This growth rate is based on the
population of objects greater than or equal to 10 cm, which is
primarily fragmented material. This figure portrays the growth of the
orbital debris environment. The figure highlights collisions and
intentional destruction of spacecraft as the largest contributors to
the debris environment. The figure also highlights the recent and rapid
growth of operational spacecraft as large constellations continue to
proliferate.
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    \17\ Liou, J.-C. (8 Feb 2022). U.S. Space Debris Environment and
Activity Updates. 59th Session of the Scientific and Technical
Subcommittee, Committee on the Peaceful Uses of Outer Space, United
Nations.

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    The Iridium 33/Cosmos 2251 collision and the Chinese Fengyun-1C
anti-satellite test have been the worst debris creating events ever
recorded. These two events contributed approximately 5,900 catalogued
objects to the environment. Launch vehicle upper stages are
significantly more massive than any of the objects involved in these
events and a catastrophic collision involving an upper stage would
produce many more times the debris created in these events.
    Debris imposes a cost on active satellites. Maneuvering an active
spacecraft to avoid collision with space debris will mitigate the
immediate threat of collision, but doing so uses up valuable resources.
It takes time and effort to plan a maneuver; and, in some cases, the
fuel expended on the maneuver will lead to a shortened mission life for
the spacecraft. Most importantly, only active spacecraft are capable of
maneuvering, whereas upper stages have no maneuverability after the
end-of-launch. Removing upper stages from congested orbits would lessen
the likelihood of debris-on-debris collisions and would reduce the
probability of active satellites maneuvering to avoid a collision.
    The first accidental hypervelocity collision between two intact
spacecraft occurred in February 2009. The operational U.S. Iridium 33
communications satellite and the defunct Russian Cosmos 2251
communications satellite collided at a speed of 11.7 km/sec (26,172.2
mph), above northern Siberia.\18\ The collision destroyed both
satellites and produced more than 2,300 pieces of trackable debris.
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    \18\ The NASA Orbital Debris Program Office. (April 2009).
Satellite Collision Leaves Significant Debris Clouds. NASA JSC
Orbital Debris Quarterly News, 13(2), page 1-2.
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    The Chinese anti-satellite test and the Iridium/Cosmos collision
were not the only orbital debris events to occur. In July 1996, a
collision occurred between a French Cerise satellite and a briefcase-
sized piece of debris left in orbit from an exploded Ariane third
stage. The impact tore off a 4.2 m section of the Cerise's gravity-
gradient stabilization boom.\19\
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    \19\ C.A. Belk, J.H. Robinson, M.B. Alexander, W.J. Cooke, and
S.D. Pavelitz. (August 1997). Meteoroids and Orbital Debris: Effects
on Spacecraft. NASA Reference Publication 1408, Marshall Space
Flight Center, AL.
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    An example of orbital debris colliding with other orbital debris
occurred on January 17, 2005, when a 31-year-old U.S. rocket body and a
Thor-Burner 2A collided with a fragment from an exploded third stage of
a Chinese CZ-4 launch vehicle. The collision occurred at an altitude of
885 km above the South Polar Region.\20\
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    \20\ Williamsen, J., Blacklock, K., Evans, H.J., and Guay, T.D.
(1999). Quantifying and Reducing International Space Station
Vulnerability Following Orbital Debris Penetration. Journal of
Spacecraft, 36(1), page 1333-141.
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    If the amount of debris is not curtailed, the risk of future
collisions between spacecraft and orbital debris will increase at a
greater rate which will create more debris and degrade the usefulness
of popular orbits. Fragments generated from one breakup can be large
enough to catastrophically break up another target mass of the same
size, continuing the cycle to create more debris. This cycle is
referred to as the ``Kessler Syndrome.'' \21\
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    \21\ Kessler, D.J., Johnson, N., Liou, J.-C., and Matney, M.,
``The Kessler Syndrome: Implications to Future Space Operations'',
Presented at the 33rd Annual AAS Guidance and Control Conference,
Paper AAS 10-016, Breckenridge, CO, February 6-10, 2010, Published
in Vol. 137 of the Advances in the Astronautical Sciences Series.
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    Figure 5 shows the projected accidental collision activity in LEO
as determined using 100 Monte Carlo runs in NASA's LEGEND model from
2010. An average of 8 to 9 collisions were expected to occur over the
next 40 years (approximately 1 collision every 5 years).\22\ The
uppermost line shows the increasing number of collisions based on a
non-mitigation scenario. The middle line shows the effects if 90
percent of all launchers worldwide \23\ followed the proposed orbital
debris mitigation standards. However, this model did not account for
the large constellations that have now started to populate LEO.
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    \22\ NASA JSC Orbital Debris Quarterly News 14(1), page 7-8.
    \23\ In 2021, there were 135 successful worldwide orbital
launches of which 39 were FAA licensed.

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[GRAPHIC] [TIFF OMITTED] TP26SE23.031

    Figure 6 shows the updated collision expectation taking into
account large constellations. With an addition of 8,300 spacecraft in
constellations, the number of on-orbit collisions are expected to range
from 1 every 2.2 years, up to more than 1 collision per year. The
variance depends on the post-mission disposal (PMD) rate of the
spacecraft in constellations, which is the probability that the
spacecraft will be removed from LEO after its mission is complete. This
study assumed that the constellations were refreshed with new
satellites every 20 years, so the large constellations were renewed and
remained on orbit, just swapping out individual satellites. After 200
years, for a PMD rate of 90 percent, a total of 260 catastrophic
collisions are estimated to have occurred in LEO. With the accumulation
of large constellations in LEO, it is imperative that large mass upper
stages are removed from orbit so as to prevent collisions between upper
stages and constellation spacecraft that could create large amounts of
debris in already crowded orbital regions.
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    \24\ NASA JSC Orbital Debris Quarterly News 14(1), page 7-8.

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    Orbital debris also poses a high risk to safety for the
International Space Station (ISS). The ISS is a high-value asset
occupied by a constant human presence; therefore, it requires more
protection than that provided by its protective shielding. Through
shielding, the U.S. modules of the ISS are protected against impacts
from debris ranging from 1 mm to 1 cm in size. During the first 8 years
of ISS operations between 1999 and 2007, 6 successful maneuvers were
conducted to avoid debris. However, since the Chinese anti-satellite
test and the Iridium/Cosmos collision, the ISS has on average made an
evasive maneuver twice a year due to debris from those events. Each
maneuver costs millions of dollars in fuel usage and to perform the
risk calculations to determine whether to move the station or shelter
the crew.\26\ Collision events and their risk to the ISS, and other on-
orbit human activity, highlight the need to remove upper stages and
prevent more debris creation.
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    \25\ J.-C. Liou, M. Matney, A. Vavrin, A. Manis, and D. Gates.
(September 2018). NASA ODPO's Large Constellation Study. Orbital
Debris Quarterly News, 22(3), pages 4-7.
    \26\ Discussion with NASA VIPER office, January 2012.
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    Orbital debris mitigation is crucial to stem the increase of
accumulation of large objects in orbit. Projections indicate that
orbital debris in the LEO environment will increase approximately 75
percent in the next 200 years, even if 90 percent of spacecraft and
upper stages reenter the Earth's atmosphere within 25 years of the end
of the mission.\27\ This projection was done before the proliferation
of large constellations and the increased launch rate seen in the past
few years. Launch and reentry operators' compliance with the U.S.
Government Orbital Debris Mitigation Standard Practices (USGODMSP) \28\
and any action to remove a number of large objects from orbit would
help prevent this increase.\29\ This proposed rule reflects the best
practices agreed to in the USGODMSP and is reflective of international
consensus for orbital debris mitigation. Currently, research efforts
are underway to develop the technology necessary to economically remove
the critical debris pieces; however, there are no operational systems
and the costs are expected to be high, approximately $30 million to $50
million per large object \30\ (large objects are objects weighing
roughly over 5,000 kilograms). These large objects are primarily rocket
body upper stages. A recent paper \31\ introduced at the 2020
International Astronautical Congress identified the 50 most dangerous
pieces of orbital debris. The paper identified 39 of the 50 objects as
upper stages capable of producing large amounts of space debris were
they to collide.
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    \27\ NASA JSC Orbital Debris Quarterly News 14(1), page 7-8.
    \28\ The USGODMSP apply to all U.S. government space launches.
    \29\ D.J. Kessler, N. Johnson, J.-C. Liou, and M. Matney.
(February 6-10, 2010). The Kessler Syndrome: Implications to Future
Space Operations; Paper AAS 10-016. Advances in the Astronautical
Sciences Series, 137. Presented at the 33rd Annual AAS Guidance and
Control Conference, Breckenridge, CO.
    \30\ Braun, V., Schulz, E., and Wiedemann, C. (August 2014).
Cost Estimation for the Active Debris Removal of Multiple Priority
Targets. Presented at the 40th COSPAR Scientific Assembly.
    \31\ McKnight, D., et al. (April 2021). Identifying the 50
statistically-most-concerning derelict objects in LEO. Acta
Astronautica, 181, page 282-291.
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    With this proposal, the FAA also seeks to mitigate the risk to the
public posed by uncontrolled disposals. Uncontrolled disposals of large
upper stages, such as the Chinese Long March stage that reentered on
May 9, 2021, and the Falcon 9 upper stage that reentered as an
uncontrolled atmospheric disposal over the Pacific Northwest in March
2021, pose a significant risk to people on the ground due to their mass
and the uncertainty of where they will land. Such disposals occur
frequently, from upper stages, defunct spacecraft, and other debris.
Per NASA, ``During the past 50 years an average of one cataloged, or
tracked, piece of debris fell back to Earth each day.'' \32\ Large
upper stages carry the most risk to people on the ground; risk that is
above the common acceptable risk limit of 1 x

10-4. This is the same risk limit codified in 14
CFR 450.101 for purposeful reentries, in International Standard (ISO)
24113, and in the USGODMSP, and the risk limit has been in common
practice in the launch safety industry for more than 20 years. Although
there are currently no documented cases of reentering debris causing
casualties, uncontrolled disposal of large upper stages presents a
significant safety risk to persons and property on the ground, or
aircraft in flight. That risk can be mitigated by the operator
performing a controlled disposal into an unpopulated area shortly after
the end of launch, and providing advance notice to aircraft and vessels
in the area. Uncontrolled disposals would not be permitted under the
proposed orbital debris mitigation rule unless the operator can
demonstrate that the effective casualty area, in total spread over the
entire projected path, for the sum of all surviving debris will be less
than 7 square meters or the expected average number of casualties will
be less than 1 x 10-4.
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    \32\ Frequently Asked Questions: Orbital Debris, www.nasa.gov/news/debris_faq.html.
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B. History

    There have been many national and international efforts to protect
against the effects of orbital debris. Early spaceflight operated under
the theory that, because space was large, collisions were unlikely.
Recent events discussed previously have demonstrated that to continue
to operate under this theory is dangerous.
    On February 11, 1988, President Reagan issued a Presidential
Directive \33\ on national space policy which included a requirement to
limit the accumulation of orbital debris. This directive was the
foundation for a coordinated effort among U.S. agencies and other
nations to increase the understanding of the hazards caused by orbital
debris and to establish effective techniques to manage the orbital
debris environment. The National Security Council produced a Report on
Orbital Debris \34\ in 1989 outlining the problem and recommended more
study of the orbital debris situation. An updated Interagency Report on
Orbital Debris \35\ by the new National Science and Technology Council
was released in 1995, directing government agencies to develop a
coordinated orbital debris work plan, to consult with U.S. industry,
and to continue efforts to achieve international consensus on dealing
with the orbital debris problem.
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    \33\ The White House. (February 11, 1988). Presidential
Directive on National Space Policy, spp.fas.org/military/docops/
national/
policy88.htm#:~:text=The%20directive%20states%20that%20the%20national
%20security%20space%20sector%20will,Space%20Control
    \34\ National Security Council. (February 1989). Report on
Orbital Debris by Interagency Group (Space), ntrs.nasa.gov/citations/19900003319.
    \35\ The National Science and Technology Council Committee on
Transportation Research and Development. (November 1995).
Interagency Report on Orbital Debris, www.hsdl.org/?view&did=722496.
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    In response, NASA and the Department of Defense, coordinating with
other space-related Federal agencies, developed a draft set of
USGODMSP, derived in large measure from NASA Safety Standard
1740.14.\36\ These standard practices, applicable to launches by the
U.S. Government, were adopted by the U.S. Government in February 2001
and mandated by the National Space Policy of 2006.\37\ The Department
of Defense and its service and defense agencies issued their own
detailed orbital debris mitigation requirements to meet the USGODMSP
standard.
---------------------------------------------------------------------------

    \36\ NASA. (August 1995). NSS 1740.14, NASA Safety Standard:
Guidelines and Assessments for Limiting Orbital Debris.
    \37\ The White House. (August 31, 2006). U.S. National Space
Policy.
---------------------------------------------------------------------------

    U.S. regulatory agencies, particularly the FAA, the National
Oceanic and Atmospheric Administration (NOAA), and the Federal
Communications Commission (FCC), have also addressed orbital debris
mitigation by establishing requirements for space activities that they
regulate. In a final rule published September 19, 2000,\38\ the FAA
adopted some, but not all, debris mitigation practices that were widely
accepted by NASA and the commercial space industry at the time, such as
the removal of stored energy sources that could generate debris.\39\
The only collision mitigation measure the FAA established was to
require avoiding any unplanned contact between the launch vehicle and
the payload after payload separation.\40\ At that time, the FAA aimed
to align with then-current international practice without negatively
affecting U.S. launch competition in the international market.
---------------------------------------------------------------------------

    \38\ Commercial Space Transportation Reusable Launch Vehicle and
Reentry Licensing Regulations, 65 FR 182 (September 19, 2000).
    \39\ 64 FR 19586, 19608 (``The FAA has elected to adopt only
selected debris mitigation practices that are of almost universal
applicability.'')
    \40\ 14 CFR 417.129(a).
---------------------------------------------------------------------------

    Since then, there has been considerable progress in addressing
requirements to reduce orbital debris. Most notably, the FCC adopted a
comprehensive set of regulations that apply to U.S. satellites and to
satellites that provide communications services to the United
States.\41\ The FCC regulations closely reflect the USGODMSP.
---------------------------------------------------------------------------

    \41\ Mitigation of Orbital Debris, 69 FR 54581 (September 9,
2004).
---------------------------------------------------------------------------

    The international community is also adopting practices that reduce
orbital debris generation. The Inter-Agency Space Debris Coordination
Committee (IADC), in which NASA represents the U.S., issued Space
Debris Mitigation Guidelines in 2002. The IADC coordinates activities
related to orbital debris issues and is comprised of representatives
from space agencies around the world. Member States are encouraged to
use the consensus-based IADC guidelines. These include implementing a
mitigation plan for each launch that details how the operator will
limit debris from normal operations, minimize the potential of
unplanned breakup, and dispose of spacecraft and stages post-
mission.\42\ The USGODMSP, which apply to U.S. Government launches, are
consistent with, and in parts surpass, the IADC guidelines. The FAA's
current regulations do not meet all the USGODMSP or the IADC
guidelines. The FAA currently only requires passivation at the end of
launch and prevention of collisions between the payload and upper
stage. The current FAA regulations do not otherwise address debris
mitigations or post-mission disposal, and do not restrict uncontrolled
reentries based on the risk posed to public safety.
---------------------------------------------------------------------------

    \42\ IADC. (October 2002). IADC Space Debris Mitigation
Guidelines; IADC-02-01.
---------------------------------------------------------------------------

    In 2010, the National Space Policy specifically encouraged the
development and adoption of industry standards for the purpose of
minimizing debris and preserving the space environment for the
responsible, peaceful, and safe use of all users.\43\ Subsequent
policies have retained similar language.
---------------------------------------------------------------------------

    \43\ The White House. (June 28, 2010). National Space Policy of
the United States of America.
---------------------------------------------------------------------------

    In 2011, the National Research Council recommended incorporating
orbital debris mitigation practices into regulations:

    NASA should continue to engage relevant federal agencies as to
the desirability and appropriateness of formalizing NASA's Orbital
Debris Mitigation Standard Practices, including the ``25-year
rule,'' \44\ and NASA Procedural Requirements for Limiting Orbital
Debris as legal rules that could be applicable

to U.S. non-NASA missions and private activities.\45\
---------------------------------------------------------------------------

    \44\ NASA requires that ``[a]ll debris released during the
deployment, operation, and disposal phases shall be limited to a
maximum orbital lifetime of 25 years from date of release
(Requirement 56398).'' NASA-STD-8719.14A, 2012-05-25.
    \45\ The National Academy of Sciences. (September 2011).
Limiting Future Collision Risk to Spacecraft: An Assessment of
NASA's Meteoroid and Orbital Debris Programs.

    In response, NASA engaged with relevant agencies: NOAA, regarding
implementing orbital debris mitigation standard practices as part of
NOAA's commercial remote sensing licensing program; FCC, regarding
licensing of communications spacecraft; and the FAA, regarding launch
vehicles.
    In 2019, in response to the National Space Council's Space Policy
Directive 3,\46\ the U.S. Government released an updated version of the
USGODMSP \47\ to address the effects of large constellations and small
satellites. The updates consist of a quantitative limit on debris
released during normal operations, a probability limit on accidental
explosions, probability limits on accidental collisions with large and
small debris, and a reliability threshold for successful post-mission
disposal. The new standard practices updated disposal options and
incorporated new sections to clarify and address operating practices
for large constellations, rendezvous and proximity operations, small
satellites, satellite servicing, and other classes of space operations.
---------------------------------------------------------------------------

    \46\ The White House. (June 18, 2018). Space Policy Directive-3,
National Space Traffic Management Policy.
trumpwhitehouse.archives.gov/presidential-actions/space-policy-directive-3-national-space-traffic-management-policy/.
    \47\ United States Government. (November 2019) U.S. Government
Orbital Debris Mitigation Standard Practices, November 2019 Update.
orbitaldebris.jsc.nasa.gov/library/usg_orbital_debris_mitigation_standard_practices_november_2019.pdf.3.

---------------------------------------------------------------------------

    For this proposed rulemaking, the FAA considered the orbital debris
requirements of NASA, FCC, NOAA, and the IADC, in an effort to align
commercial standards and government standards and to address the
persistent risks associated with heavy upper stages abandoned in orbit.
The FAA focused on NASA because it has the most detailed orbital debris
requirements and guidance, and is an internationally recognized leader
in orbital debris and space exploration whose expertise in space and
mission planning is a benchmark for the FAA's rulemaking efforts. The
effort to establish common standards is consistent with the U.S. Space
Transportation Policy, which states the Secretary of Transportation
shall execute exclusive authority, consistent with existing statutes
and executive orders, to address orbital debris mitigation practices
for U.S.-licensed commercial launches, to include launch vehicle
components such as upper stages, through its licensing procedures.\48\
---------------------------------------------------------------------------

    \48\ The White House. (November 21, 2013). National Space
Transportation Policy of the United States of America. www.nasa.gov/sites/default/files/files/national_space_transportation_policy_11212013.pdf.
---------------------------------------------------------------------------

    The FAA believes the proposed regulations would not hinder U.S.
companies from competing in the international launch market because
regulations of foreign countries are also expected to comply with IADC
guidelines, and some countries' regulations are stricter than the
requirements proposed in this rule. For example, the French space
agency, Centre National d'[Eacute]tudes Spatiales (CNES), issued
technical regulations in 2009 that extend beyond the requirements of
the IADC guidelines and spell out the acceptable reentry risk from
orbital debris for those with French space operation licenses. The IADC
guidelines are a consensus document originally based on the USGODMSP.
Due to the consensus nature of the IADC guidelines, an agreed-upon
document between 13 different space agencies, the guidelines are not as
thorough and specific as the USGODMSP. Several of the IADC's 13
participating space agencies are currently working to implement
regulations that align with the IADC guidelines; however, not all IADC
participants have launch capability.

III. Discussion of the Proposal

    The FAA proposes several new requirements for limiting the lifetime
of debris in LEO and in GEO. First, the FAA proposes to amend the
definition of ``disposal'' in Sec.  401.7 to include each of the
disposal options proposed for part 453. The existing definition
describes controlled atmospheric disposal, and would exclude the other
four options proposed in Sec. Sec.  453.14 through 453.18 for the
disposal of spent upper stages and launch or reentry vehicle
components. The FAA therefore proposes to define ``disposal'' as the
execution or attempt to execute ``controlled atmospheric disposal,
heliocentric disposal, uncontrolled atmospheric disposal, disposal
orbit, or direct retrieval of launch vehicle stages or components of
launch or reentry vehicles under part 453 of this chapter.''
    The FAA also proposes to add definitions to Sec.  401.7 for ``Low
Earth Orbit (LEO),'' ``Medium Earth Orbit (MEO),'' ``Geostationary
Earth Orbit (GEO),'' ``the geosynchronous region,'' and ``orbital
debris.'' ``LEO'' would be defined as any Earth orbit with both apogee
and perigee below 2,000 km altitude. ``MEO'' would be defined as any
Earth orbit in which an object's apogee and perigee both remain between
LEO and GEO. ``GEO'' would be defined as any Earth orbit where the
orbiting object orbits at the same angular velocity as the Earth and
the object appears stationary from the ground. The altitude of this
zero-inclination, zero-eccentricity orbit is 35,786 km. ``The
geosynchronous region'' would be defined as the band of orbital space
surrounding GEO. It is bound by altitude limits of 35,786 km +/- 200 km
altitude and +/- 15 degrees latitude.
    The IADC defines Space Debris as ``all man-made objects including
fragments and elements thereof, in Earth orbit or re-entering the
atmosphere, that are non-functional.'' \49\ The FAA agrees with the
IADC definition of space debris and refines the debris issue further by
establishing the size of debris applicable for regulation. ``Orbital
debris'' would be defined as all human-generated debris in Earth orbit
that is greater than 5 mm in any dimension. This includes, but is not
limited to, payloads that can no longer serve a useful purpose, rocket
bodies and other hardware (e.g., bolt fragments and covers) left in
orbit as a result of normal launch and operational activities, and
fragmentation debris produced by failure or collision. The FAA proposes
to expressly exclude released gases and liquids from the definition of
orbital debris. The release of gases and liquids is often deliberate
for the purpose of maneuvering or to evacuate excess gases and liquids
at the end of launch. The FAA does not believe addressing the release
of gases and liquids is necessary at this time because the risk is low.
One of the debris mitigation actions at the end of launch is the
release of pressurized gases and propellants because the risks of
accidental explosion outweigh the risks of released gases and liquids.
Based upon this understanding, the FAA finds that it is unnecessary to
regulate released gases and liquids at this time.
---------------------------------------------------------------------------

    \49\ IADC Space Debris Mitigation Guidelines, IADC-02-0,
Revision 2, Mar 2020.
---------------------------------------------------------------------------

    The FAA proposes 5 mm as the threshold size because an object of
that size, traveling at 10 km per second, a speed typical of objects on
orbit, can incapacitate a functioning satellite, which in turn may
contribute to the creation of more debris. Most active satellites on
orbit are protected against small pieces of debris and micrometeoroids
less than 5 mm in size with shielding or thermal blankets. However,
pieces as small as 5 mm can do significant damage to satellite
operations. The kinetic energy that a 5

mm cube of titanium (4.43 g/cm\3\ density) has, while traveling 10 km
per second in LEO, is 27,700 Joules. Comparably, the energy of a .30-06
rifle bullet (11.7 grams) when exiting a gun muzzle is only 3,700
Joules.
    Spacecraft vary in design and material composition, so it is hard
to identify an exact threshold size of debris that could significantly
damage a spacecraft. Nevertheless, the National Research Council found
in its 2011 report on orbital debris that typical spacecraft are not
well shielded from small debris, and that objects 5 mm and larger can
cause substantial damage.\50\ For this reason, the FAA proposes to use
5 mm as the size threshold for orbital debris. However, the FAA
requests comments on further lowering the size threshold to below 5 mm.
---------------------------------------------------------------------------

    \50\ The National Academy of Sciences. (September 2011).
Limiting Future Collision Risk to Spacecraft: An Assessment of
NASA's Meteoroid and Orbital Debris Programs.
---------------------------------------------------------------------------

    The FAA recognizes that a launch operator cannot prevent the
release of all small debris fragments, such as paint flakes and solid
rocket motor (SRM) slag. SRMs--used to boost satellites into higher
orbits--are potentially a significant source of numerous pieces of
aluminum oxide slag up to 5 cm in diameter. Likewise, flaking paint is
a debris hazard, albeit of very small size. Debris of this size usually
will not disable a spacecraft, but it does pose a hazard to
spacewalkers, and over time it causes erosion damage and more debris.
The FAA is not, however, proposing to regulate debris smaller than 5
mm, paint flakes, or solid rocket motor slag of any size, due to the
current impracticality of tracking and mitigating the propagation of
such small items. At this time, the only practical mitigation for
debris smaller than 5 mm is to harden spacecraft to make them less
susceptible to small debris.
    Proposed Sec.  453.1 would provide the scope of part 453: the
requirements of a launch or reentry operator for orbital debris
mitigation, including collision avoidance analysis, prior to launch or
reentry operations licensed or permitted under this chapter with a
planned altitude greater than 150 km. The FAA proposes to require in
Sec.  453.1(b) that for each licensed or permitted launch or reentry
with a planned altitude greater than 150 km, an operator must submit
(1) an ODAP containing the information required by this part, not less
than 60 days before the licensed or permitted launch or reentry, unless
the Administrator agrees to a different time frame in accordance with
Sec.  404.15; and (2) a Collision Avoidance Analysis Worksheet in
accordance with Sec.  453.11(f). The submittals must be emailed to the
address provided in proposed Sec.  453.1(c) or otherwise submitted as
agreed to by the Administrator in the license or permit. The FAA
proposes to require that operators submit their ODAP no later than 60
days prior to the launch or reentry subject to part 453 to be
consistent with the timeframes in part 450 and in the legacy
regulations. The FAA proposes no change to the timeline for submitting
the Collision Avoidance Analysis Worksheet, which is currently required
by Sec.  450.169 and would be moved to Sec.  453.11(f).
    Proposed Sec.  453.3 would state that part 453 applies to launches
and reentries licensed or permitted under this chapter with a stage or
other component with a planned altitude greater than 150 km. Few
satellites operate below the altitude of 150 km, hence mitigation of
orbital debris below 150 km is not necessary.

A. Limitations on Orbital Lifetime of Debris Released During Normal
Operations

    Current Sec. Sec.  417.129 and 450.171 do not address the planned
release of debris during normal operations, such as the deliberate
planned release of payload spacers, retaining rings, or tension rods.
To reduce the amount of debris in orbit, the FAA proposes to require
that launch operators ensure that no vehicle stages or components
release orbital debris during normal operations that will remain in
orbit for more than 25 years. Proposed Sec.  453.5(a) would require a
launch operator to ensure that no vehicle stages or components that
reach Earth orbit release orbital debris into LEO that would remain in
orbit for more than 25 years. The 25-year rule is a common standard
recommended by the IADC and a requirement for U.S. Government launches
under the USGODMSP.
    For the lowest region of LEO--orbits with perigee altitudes below
600 km--debris typically has an orbital lifetime of less than 25 years,
and smaller pieces of debris here may reasonably be expected to burn up
on reentry into Earth's atmosphere within the allowable time limit.
This proposed requirement would have a greater impact on operations
releasing debris above 700 km, where debris may remain on-orbit for
hundreds of years. The most efficient and practical approach to comply
with the proposed requirements would be to avoid creating any debris in
the upper portions of LEO and higher altitudes. For example, if a
launch operator cannot demonstrate that it will remove all debris
larger than 5 mm from orbit within 25 years, as required by Sec.
453.5, then the launch operator must prevent such objects from
separating from the launch vehicle. A launch operator could do so by
redesigning the separation system (a common source of debris) or by
using lanyards or other means to prevent debris release.
    Given that most current launch vehicles have been designed to
minimize or eliminate normal operations debris release, the FAA
anticipates that this proposed requirement would impose no more than a
minimal burden on operators for compliance. Operators usually meet this
requirement because they want to minimize the release of debris and the
possibility of damage to their deployed payloads. Since commercial
launches are deploying increasing numbers of payloads, which could
result in additional debris release, the FAA finds it appropriate to
require that all operators limit their release of debris.
    The FAA also proposes to require in Sec.  453.5(a) that the total
object-time product for all debris planned to be released into LEO
shall not exceed 100 object-years per licensed or permitted launch.
Object-time is a unit of measure used by NASA. It means the number of
objects multiplied by the unit of time, typically years. A higher
object-time means more objects on orbit for a higher cumulative amount
of time. Limiting the object-time reduces the number of objects in
orbit. The more objects released, the less time they can spend in orbit
to meet the object-time requirement. For example, if an operator plans
to release 5 debris objects, none of those objects can remain in Earth
orbit longer than 25 years, and the total orbital lifetime of all 5
debris objects cannot exceed 100 years. The regulation would specify
that the total object-time product in LEO is the sum of the orbit dwell
time in LEO for all planned released objects, excluding the upper stage
and any released payloads. The requirement would target debris released
into LEO since, as discussed above, this small spatial area is heavily
used and currently contains the most debris. This requirement is
consistent with the USGODMSP guidelines and is necessary to limit the
number of released objects per launch. The FAA supports the USGODMPS
object-time standard and notes the standard is particularly relevant to
space launch activities that use payload deployment devices.
    The FAA notes that the 100 object-years limit would apply to debris
that the operator plans to release during launch activities, and would
not include debris released due to non-nominal

conditions or launch or reentry activity outside the 3-sigma trajectory
provided for collision avoidance. However, an operator would be
required to immediately notify the FAA and provide the information
required by Sec.  453.20 at the detection of a debris-creating event or
any launch or reentry outside the 3-sigma trajectory provided for
collision avoidance.
    The FAA solicits comments on its proposal to limit the total
object-time product of all debris released by a single launch into LEO
to 100 object-years. Although, as noted above, this standard derives
from the USGODMSP, the FAA recognizes that this standard is new, and
the commercial space industry has not had an opportunity to weigh in on
the effectiveness or operational implications of this requirement. As a
result, FAA seeks insight into stakeholders' opinions on limiting the
total object-time product of all debris released by a single launch
into LEO to 100 object-years, and whether a smaller object-time should
be imposed.
    The FAA would also require that debris released into the
geosynchronous region be removed within 25 years after release.
Proposed Sec.  453.5(b) would require a launch operator to ensure that
any orbital debris released into the geosynchronous region enters an
orbit with an apogee that would not remain within the geosynchronous
region within 25 years of the release. Operators would need to submit
analysis showing that the debris will stay below the geosynchronous
region 25 years after release, and that it will not enter the
operational geosynchronous region again. Released debris can only move
into lower orbits. Debris released above GEO would eventually return to
the GEO protected region.
    The FAA solicits public comments on its proposal to require that
debris be removed within 25 years, as opposed to a shorter deadline.
While the FAA recognizes the current IADC and USGODMSP guidelines,
which limit post-mission lifetimes in LEO to 25 years, the FAA
recognizes that increases in the numbers and kinds of activities in
Earth orbit may render the 25-year timeframe inadequate to prevent the
growth of orbital debris. Given that the entire mission lifetime of
upper stages and their components is quite short, and spent upper
stages pose a significant risk of debris propagation the longer they
are in orbit, it may be appropriate to have a shorter disposal timeline
of 5 years or another time period less than 25 years. Shortening the
removal deadline would decrease the risk of orbital debris causing
damage to spacecraft, which could create more debris, shorten another
spacecraft's mission, or endanger the lives of human spaceflight
participants. The FAA requests comments on the degree to which a
shorter timeline for removal from LEO or GEO within 5 years or another
period shorter than 25 years would further encourage the minimization
of released debris, as well as the relative impact of a shorter
timeframe on operational capabilities.
    Proposed Sec.  453.5(c) would specify the information that must be
included in an ODAP to demonstrate compliance with Sec.  453.5(a) and
(b). Specifically, the ODAP must include (1) a demonstration through
environmental qualification and acceptance testing that the system is
designed to limit the release of orbital debris; and (2) a statistical
analysis, including inputs and assumptions, demonstrating that any
orbital debris released will be disposed of within 25 years and satisfy
the 100 object-year requirement. The environmental qualification and
acceptance testing could include vibration, shock, vacuum, or any other
appropriate testing to demonstrate that debris will not be released
from the upper stage. Operators should provide the FAA specific
verifiable analysis or test results that demonstrate the mitigation
measures the launch operator would take to prevent release of debris
greater than 5 mm in size or to ensure that it departs LEO or GEO
within 25 years. Results of hardware and software tests, if performed
on the separation system, would fulfill the requirement to demonstrate
the effectiveness of debris prevention measures. The testing should
apply to the entire lifetime of the system. If debris will be released,
an orbital lifetime analysis using the methods described in ISO 27852
\51\ or NASA's Debris Assessment Software (DAS) or similar software
would be acceptable. The inputs and assumptions referenced in Sec.
453.5(c)(2) would include the initial orbit, the altitude of the
release, and information about the debris objects planned to be
released, such as their mass, area, and estimated orbital lifetime. The
FAA seeks public comments on the proposed demonstration through
specific analysis and testing of debris release prevention.
---------------------------------------------------------------------------

    \51\ International Organization for Standardization. (September
7, 2010). ISO 27852:2010(E), ``Space Systems--Estimation of orbit
lifetime.''
---------------------------------------------------------------------------

B. Collision Mitigation Between Launched Objects

    The current FAA regulations in parts 415, 417, 431, 435, and 450
require that launch operators prevent the unplanned physical contact
between a launch vehicle and each payload after payload separation. The
FAA proposes to move these current requirements for safety at the end
of launch to Sec.  453.9(a). The FAA proposes to add a requirement in
Sec.  453.9(b) to limit the probability of collision with orbital
objects greater than 10 cm to less than 1 in 1,000 over the orbital
lifetime of the upper stage. This proposal matches the standard in
USGODMSP and is necessary to lower the risk of debris impacts with the
upper stage and its components. The probability of collision during
orbital lifetime can be reduced by removing the upper stage and
components from orbit, as discussed in the next section, and by
operating the upper stage in an orbit with a low density of orbital
objects.
    Proposed Sec.  453.9(c) would require launch operators to include
in their ODAP for each launch or reentry a procedure for preventing
vehicle and payload collision after payload separation. The end-of-life
activities, including any propellant depletion burns and compressed gas
releases, could increase or decrease the probability of subsequent
collisions; therefore, the launch operator should explain in the ODAP
how these activities will affect potential collision risks. The ODAP
must also include the results of a probability of collision analysis
between the upper stage and its components and orbital objects. The
analysis must use commonly accepted engineering and probability
assessment methods, such as those available in NASA's DAS tool.

C. Post-Mission Disposal

    In the current debris environment, the greatest risk to operational
orbits is collision between objects having considerable mass. Spent
upper stages are large, strong structures that contribute to the debris
threat because their size increases the chance of a collision, and
because their mass provides an ample source of fragmentation debris in
the event of a collision. As noted above, the amount of orbital debris
is projected to rapidly increase based on the current population of
objects greater than 10 cm.\52\
---------------------------------------------------------------------------

    \52\ See Figures 3 and 4 in the Statement of the Problem.
---------------------------------------------------------------------------

    Disposal, either through reentry or another form of disposal, is
necessary to mitigate the propagation of orbital debris because it
removes upper stages and other vehicle components from the most
populated orbits. If proper disposal is not implemented, spacecraft
operators would need to employ increased shielding of payloads, along

with additional on-orbit collision avoidance, in order to continue to
utilize the most populated orbits. However, neither of these options
would mitigate the volume of dormant upper stages in orbit, and
therefore, the growth of orbital debris. The only option in the future
for these upper stages would be remediation--dedicated missions to
remove them from orbit. This kind of remediation is forecasted to be
expensive and has not yet been shown to be a viable operation. Research
and development is still on-going into debris removal techniques.\53\
---------------------------------------------------------------------------

    \53\ Zhao, et.al. (2020) Science China Technological Sciences,
Survey on research and development of on-orbit active debris removal
methods.
---------------------------------------------------------------------------

    Given that disposal is at this time the only viable means of
mitigating the threat of orbital debris in populated orbits, the FAA is
proposing to require in Sec.  453.13 that launch operators dispose of
all launch vehicle stages or jettisoned components using one of five
methods: (1) controlled atmospheric disposal, (2) Heliocentric, Earth-
escape disposal, (3) direct retrieval, (4) uncontrolled atmospheric
disposal, or (5) maneuver to a disposal orbit. The proposed
requirements for each disposal method are set forth in Sec. Sec.
453.14 through 453.18, respectively. A launch or reentry subject to
part 453 must identify the chosen disposal method in the ODAP and
satisfy the regulatory requirements applicable to that disposal method.
Table 1 provides a list of disposal options derived from the USGODMSP.
Options that promptly remove the upper stage and its components from
orbit are the preferred disposal options according to the USGODMSP, as
they significantly reduce both long term collision and debris
generation risks. Delayed disposals through either direct retrieval or
uncontrolled atmospheric disposal impose some risks to other on-orbit
spacecraft until removal. Disposal orbits may become overly populated
in the future which would preclude the future use of them for disposal.
The FAA notes that while the USGODMSP identifies disposal methods in
order of preference in the following table, the proposed rules do not
allocate preference or distinguish between disposal methods in order to
provide flexibility to operators to perform any of these valid methods
of debris disposal. However, the FAA expects that as space continues to
become more congested, orbital debris requirements will tighten in
response, such that delayed disposal options that pose some additional
risk to on-orbit spacecraft (i.e. uncontrolled atmospheric disposal,
highly eccentric long-term disposal, or use of a disposal orbit) may be
restricted or eliminated. FAA requests comments on whether the prompt
and safest disposal options (controlled atmospheric, heliocentric, and
direct retrieval) should be the preferred disposal methods based upon
expected growing orbital congestion. Additionally, the FAA seeks
comment on whether it should impose a requirement to use the prompt
disposal options unless shown to be impracticable.

                        Table 1--Disposal Options
------------------------------------------------------------------------
       Disposal method             453 section           Time frame
------------------------------------------------------------------------
Controlled Atmospheric        453.14..............  Within 30 days of
 Disposal.                                           mission completion.
Heliocentric (Earth-escape).  453.15..............  Within 30 days of
                                                     mission completion.
Direct Retrieval............  453.16..............  Not to exceed 5
                                                     years post mission
                                                     completion.
Uncontrolled Atmospheric      453.17(b)...........  Not to exceed 25
 Disposal.                                           years after launch.
Highly Eccentric Long-Term    453.17(c)...........  Not to exceed 200
 Disposal.                                           years after mission
                                                     completion.
Disposal Orbit..............  453.18..............  Within 30 days of
                                                     mission completion
                                                     into a perpetual
                                                     disposal orbit.
------------------------------------------------------------------------

a. Controlled Atmospheric Disposal
    Upper stage-controlled reentry is the most effective method of
orbital debris prevention and the safest reentry method. Controlled
reentry eliminates the upper stage as a piece of orbital debris and
therefore mitigates the risk of future debris creation through
collision because the reentry would occur shortly after the end of
launch. The FAA proposes to allow operators to perform controlled
disposal by reentering Earth's atmosphere if they meet the requirements
of Sec.  453.14. The requirements of Sec.  453.14 would only apply if
the operator elects controlled disposal for its disposal method, as
required by Sec.  453.13.
    A controlled disposal means a planned burn of the upper stage
engine to aim for a low-risk area on the surface of the Earth. The FAA
acknowledges that the upper stage is not ``controlled'' during the
entire atmospheric disposal. Variations in the engine burn, the
atmospheric density, and other factors beyond the operator's control
can affect the actual disposal location. Therefore, those uncertainties
must be accounted for in the disposal risk assessment or in the
determination of the disposal ellipse in a broad ocean area, in
accordance with Sec.  453.14(d).
    In order to perform controlled disposal, proposed Sec.  453.14(b)
would require a launch operator to ensure the return of the upper stage
and each of its components to the Earth's surface within 30 days after
mission completion in a controlled manner that ensures the effective
casualty area of any surviving debris is less than 7 square meters,
targets a broad ocean area, or meets the risk criteria set forth in
Sec.  450.101(d)(1)(iii)(A) through (C). This proposal would
effectively require launch and reentry operators to consider disposal
risks in their vehicle and mission designs--for instance, by designing
components that demise when heated by atmospheric reentry or by
reentering in remote locations.
    The FAA's proposal to allow operators to target a broad ocean area
or meet the risk criteria set forth in Sec.  450.101(d)(1)(iii)(A)
through (C) is substantively equivalent to the current text of Sec.
450.101(d), which requires that all disposals--currently defined as
controlled atmospheric disposal in Sec.  401.7--either target a broad
ocean area or meet the risk criteria in Sec.  450.101(b). As discussed
later in this preamble, the FAA proposes to amend Sec.  450.101(d) to
specify the risk criteria applicable to atmospheric disposals, rather
than relying on the reentry risk criteria in Sec.  450.101(b), since
disposal is distinct from reentry. The FAA therefore proposes to extend
the safety criteria applicable to licenses under part 450 to all
launches or reentries covered by part 453, including experimental
permits. The FAA is proposing that all launches or reentries authorized
by the FAA that

exceed 150 km be required to meet the risk criteria in Sec.
450.101(d)(1)(iii)(A) through (C), target a broad ocean area, or have
an effective casualty area less than 7 square meters for the following
reasons.
    Disposal into a broad ocean area would reduce the risk of
casualties to near zero. The FAA considers an area 370 km (200 nm) from
land to be ``broad ocean area,'' as used in Sec.  450.101(d) and
proposed part 453. Two hundred nautical miles is also the recognized
limit of exclusive economic zones (EEZ), which are zones prescribed by
the United Nations Convention on the Law of the Sea \54\ over which the
owning State has exclusive exploitation rights over all natural
resources. Deorbiting beyond an EEZ further reduces the chance of
disrupting economic operations such as commercial fishing.
---------------------------------------------------------------------------

    \54\ United Nations Convention on the Law of the Sea, Dec. 10,
1982, 1833 U.N.T.S. 397.
---------------------------------------------------------------------------

    For massive objects reentering the atmosphere, a controlled
disposal into the broad ocean area may be necessary for safety because
it would ensure that the casualty expectation of reentry could be kept
below 1 in 10,000. Because the broad ocean area has a population
density of nearly zero, objects that survive reentry in this area can
be fairly large without inordinate risk of human casualties.
Alternatively, the operator could show that the 1 x
10-4 collective risk and 1 x
10-6 individual risk limits are met for the
controlled disposal in another area. The expectation of casualty
alternative might allow for controlled disposal into areas near islands
or coast lines with low populations. The operator could also choose to
demonstrate that the cumulative effective casualty area of surviving
debris will be less than 7 square meters. That small casualty area
ensures that the expectation of casualty will be met without requiring
a full expectation of casualty calculation.
    The effective casualty area for inert debris is the region
associated with a fragment's impact location where it is assumed a
person would become a casualty. Debris from atmospheric reentry of an
upper stage is usually made up of multiple pieces, as the upper stage
breaks up due to heating and friction. The total effective casualty
area is determined by adding up the casualty area of each of those
pieces.
    An expectation of casualty calculation requires determination of
the effective casualty area along with analysis of the expected
trajectory and exposed populations to determine how many people could
become a casualty due to the uncontrolled disposal of the upper stage.
Due to uncertainty and growth in population, that calculation can be
difficult to complete for disposals that are expected on long
timeframes like 25 years. As a result, FAA is proposing to allow an
operator to demonstrate that the effective casualty area of surviving
debris will be less than 7 square meters.
    The FAA proposes to require in Sec.  453.14(c) that operators
performing controlled disposal notify the public of any region of land,
sea, or air that contains, with 97 percent probability of containment,
all debris resulting from normal flight events capable of causing a
casualty. The FAA currently imposes this requirement on operators
performing disposal operations under a part 450 license, and would
extend the part 450 requirement to proposed Sec.  453.14(c). The FAA
finds that all operations required to comply with part 453 should
provide this degree of notification to the public. These measures could
include arrangements with the FAA or U.S. Coast Guard to provide Notice
to Air Mission (NOTAM) and Notice to Mariners (NOTMAR).
    The FAA proposes that an operator would be required to implement a
controlled reentry within 30 days after the completion of the mission,
which is also how long a launch operator must have insurance coverage
under Sec.  440.11. The FAA further proposes to require that operators
accomplish any actions necessary to end a launch and commence
controlled disposal within the insurance coverage timeframe. As
discussed later in this preamble, the FAA proposes to apply the 30-day
deadline to the Earth-escape and orbit disposal options as well.
    Additionally, the FAA finds that 30 days would almost always
provide sufficient time to assess the possible consequences of a launch
anomaly, such as delivery to a wrong orbit or failure of a payload to
separate from the vehicle's upper stage. Current technologies and
practices are adequate to require the following within 30 days (1)
perform final maneuvers to direct controlled disposal, (2) relocate to
a lower orbit where the upper stage will decay within 25 years, or (3)
relocate to a disposal orbit.
    Another reason for the proposed requirement to implement a disposal
option within 30 days is the short time frame an upper stage would have
to maneuver. Typically, most upper stages have limited electrical power
supplied by flight batteries, and, by design, must maneuver
expeditiously after payload separation. In order to mitigate the
possibility of an explosion occurring, the FAA requires a launch
operator to power down its batteries at the end of launch. Accordingly,
an affirmative act such as controlled reentry, placement to ensure
reentry within 25 years, or maneuvering to a disposal orbit would have
to occur within that time frame. Upper stages in orbits with an
expected lifetime below 25 years would have no additional required
actions to meet the post-mission 25-year rule. However, these upper
stages may be required to move to disposal orbits if they cannot be
safely deorbited due to excessive risk in uncontrolled reentries.
    The FAA proposes to require in Sec.  453.14(d) that operators
submit a description of the controlled disposal in the ODAP prior to
each launch or reentry pursuant to Sec.  453.1(b). The ODAP must
include verification through hardware and software testing or analysis
that the system has at least a 90 percent probability of successfully
executing the controlled atmospheric disposal as planned. The FAA
proposes to require a probability of success of at least 90 percent.
The FAA is adopting a 90 percent probability of success criteria that
is consistent with the IADC Guidelines, ISO Standard 16126 \55\ and
USGODMSP guidelines. ISO Standards represent a consensus international
standard for specialized space activities. The testing and analysis can
include engine re-light qualification tests or reliability analysis or
similar. The ODAP must also include a description of how the system
will achieve controlled atmospheric disposal under nominal and off-
nominal conditions, such as a partial burn failure or off-trajectory
scenario. Lastly, unless the operator is targeting a broad ocean area,
the ODAP must include the calculated total collective and individual
casualty expectations for the proposed operation or the effective
casualty area of any surviving debris, pursuant to Sec.  453.14(d)(3).
---------------------------------------------------------------------------

    \55\ International Organization for Standardization. (April 1,
2014). ISO 16126:2014, ``Space systems--Assessment of survivability
of unmanned spacecraft against space debris and meteoroid impacts to
ensure successful post-mission disposal.''
---------------------------------------------------------------------------

b. Heliocentric, Earth-Escape Disposal
    The FAA proposes to allow operators to perform heliocentric, Earth-
escape disposal if they meet the performance-based requirements of
Sec.  453.15. The requirements of proposed Sec.  453.15 would only
apply if the operator elects heliocentric, Earth-escape disposal as its
disposal method under Sec.  453.13. Proposed Sec.  453.15(b) would
require that the operator ensure, within 30 days after mission
completion, that the upper stage and each of its components is placed
in a hyperbolic trajectory that no longer orbits Earth. This option
would

remove the upper stage from orbit completely and also result in zero
risk to the people of Earth. The upper stage and its components would
travel into an orbit around the Sun rather than remain as debris in
Earth orbit. The FAA recognizes that this disposal option is
prohibitively costly for operators not already planning inter-planetary
missions, as the energy needed to fully escape Earth orbit is greater
than the energy needed for other disposal options. Operators without
the available fuel will not be able to execute this option.
    Operators who elect to perform heliocentric, Earth-escape disposal
would be required under proposed Sec.  453.15(c) to include a
description of the Earth-escape disposal in the ODAP submitted prior to
each launch or reentry. The description must include (1) verification
through hardware and software testing or analysis that the system has
at least a 90 percent probability of successfully executing the planned
heliocentric, Earth-escape disposal, and (2) a description of how the
system will achieve a controlled disposal under nominal and off-nominal
conditions, such as a partial burn failure or off-trajectory scenario.
The testing and analysis could include engine re-light qualification
tests, reliability analyses, or similar tests.
c. Direct Retrieval
    Another means by which an operator could dispose of the upper stage
of a vehicle, or any other orbital debris released, would be direct
retrieval, also called Active Debris Removal or remediation, in which
an operator retrieves the upper stage and removes it from orbit via a
controlled disposal or maneuver into a disposal orbit. Direct retrieval
would require the launch of a device or spacecraft that attaches to or
otherwise affects the upper stage and causes it to deorbit in a
controlled manner or move to a disposal orbit. Current research and
economic feasibility studies performed by commercial operators and
international space agencies suggest this option could be commercially
viable within a few years.\56\ Demonstrations of this capability have
already been conducted.\57\ For this reason, the FAA proposes to
include as Sec.  453.16 the option for operators to perform direct
retrieval if they meet the requirements of Sec.  453.16. The
requirements of Sec.  453.16 would only apply if the operator elects
direct retrieval as its disposal method under Sec.  453.13.
---------------------------------------------------------------------------

    \56\ Yamamoto, et.al (2017) 7th European Conference on Space
Debris, Cost analysis of active debris removal scenarios and system
architectures.
    \57\ On August 25, 2021, a Japanese spacecraft successfully
captured a simulated piece of space debris as a first step to
demonstrate technology to remove orbital debris. On October 24,
2021, China launched a mission with the stated aim of testing space
debris removal technologies.
---------------------------------------------------------------------------

    Proposed Sec.  453.16 would require that operators retrieve the
upper stage by either removing it from orbit in a controlled manner or
maneuvering it to a disposal orbit no more than 5 years after
completion of the mission. The FAA proposes to allow operators up to 5
years from mission completion to perform the direct retrieval as a
means of balancing the burden on operators to carry out the subsequent
retrieval mission against the compelling need to remove the spent upper
stage and its components from orbit. A 5-year timeline is consistent
with USGODMSP recommendations and would require operators to
demonstrate that they are capable of performing the direct retrieval
based on actual technical capabilities, rather than hypothetical future
capabilities. Operators will have 5 years to perform the direct
retrieval, however, removal should occur as soon as possible to reduce
the risk of creating more debris. Under proposed Sec.  453.16(b), if
the result of the direct retrieval is a controlled disposal of the
upper stage into a planned disposal area, then the retrieval would be
required to meet the disposal safety requirements in Sec.  453.14(b)
and (c). Conversely, if the result of the direct retrieval is a
maneuver into a disposal orbit, then the retrieval would need to meet
the disposal orbit lifetimes and analysis requirements of Sec.  453.18.
    Under proposed Sec.  453.16(c), an operator would be required to
describe its plan for direct retrieval in its ODAP, and demonstrate a
probability of successful disposal of at least 90 percent. The
description must include verification through hardware and software
testing or analysis that the system has at least a 90 percent
probability of successfully executing the planned direct retrieval. If
the planned retrieval will result in a controlled disposal, then the
operator must include in its ODAP (i) a description of how the system
will achieve a disposal under nominal and off-nominal conditions; and
(ii) the total collective and individual casualty expectations for the
proposed operation or the effective casualty area of any surviving
debris, if the operator will not dispose of the debris into a broad
ocean area. The operator should identify the intended disposal location
so that the FAA can discern whether the operator will target a broad
ocean area or verify the expectation of casualty from disposal into
that location. Alternatively, if the operator intends to retrieve and
maneuver the debris to a disposal orbit, under proposed Sec.
453.16(c)(3), the operator would need to include in their ODAP (i) a
description of how the system will achieve and maintain the planned
disposal orbit for the required time limit as specified in Sec.
453.18(b) through (d); and (ii) a statistical analysis demonstrating
that the probability of collision with operational spacecraft and
debris is within the lifetime limit of Sec.  453.18(e). The testing and
analysis performed in accordance with Sec.  453.16(c) should include
qualification tests, reliability analyses, or similar tests.
d. Uncontrolled Atmospheric Disposal
    The FAA proposes to allow launch or reentry operators to perform
uncontrolled atmospheric disposal to meet the requirement of Sec.
453.13 by using one of two methods. Under proposed Sec.  453.17, an
operator could either dispose of debris from LEO through natural decay
by leaving the upper stage and its components in an orbit where the
debris will gradually lower until it falls to Earth, or from MEO or
higher orbit by maneuvering the debris to a highly elliptical orbit for
long-term atmospheric disposal. The requirements of proposed Sec.
453.17 would only apply if the operator elects to perform uncontrolled
atmospheric disposal to meet the disposal requirement of Sec.  453.13.
    In order to dispose of debris from LEO--an orbit below 2,000 km--an
operator would be required in Sec.  453.17(b)(1) to leave an upper
stage and its components in an orbit where, accounting for the mean
projections for solar activity and atmospheric drag, the orbital
lifetime is as short as practicable, but does not exceed 25 years after
launch. Instead of reentering immediately, the orbit of the upper stage
and its components would gradually lower over months or years until the
debris falls to Earth. The disposal would be considered uncontrolled in
the sense that the operator would not initiate the disposal at a
particular time, and the disposal could occur anywhere on Earth under
its orbital path.
    The 25-year rule, which the FAA also proposes to implement in Sec.
453.5, is a common standard recommended by the IADC and a requirement
for U.S. Government launches under the USGODMSP. The IADC's Support to
the IADC Space Debris Mitigation Guidelines, Oct 2004 Working Group
Report states that a 25-year post-mission lifetime appears to be a good
compromise between an immediate (or

very short lifetime) de-orbit policy which is very effective but much
more expensive to implement, and a 50 or 100 year lifetime de-orbit
policy which is less costly to implement but can lead to higher
collision risks in the long-term.\58\ Greater depth of technical
analysis is available in the IADC working group report.
---------------------------------------------------------------------------

    \58\ Inter-Agency Space Debris Coordination Committee. (October
2004). Support to the IADC Space Debris Mitigation Guidelines. Oct
2004 Working Group Report, section 5.3.2.
---------------------------------------------------------------------------

    While the FAA concurs with the current IADC and USGODMSP
guidelines, which limit post-mission lifetimes in LEO to 25 years, the
FAA recognizes that increases in the numbers and kinds of activities in
Earth orbit may necessitate reevaluation of the adequacy of a 25-year
post-mission lifetime in the future. The FAA seeks public comment on
whether a shorter deadline should be imposed. The FAA notes that upper
stages of launch vehicles become debris as soon as the payloads are
released; upper stages in orbits with perigee altitudes below 350 km
typically have orbital lifetimes less than 5 years. Given that the
entire mission lifetime of upper stages and their components is quite
short, and spent upper stages pose a significant risk of debris
propagation the longer they are in orbit, it may be appropriate to have
a shorter disposal timeline of 5 years. A shorter deadline of 5 years
that removes the highest-mass objects from orbit would vastly reduce
the risk of creating more debris and would make U.S. commercial space a
leader in orbital debris mitigation.
    Uncertainties in modeling should be accounted for in evaluation of
the orbital lifetime of an object. The use of publicly available
software such as NASA's DAS and the French Space Agency's STELA (Semi-
analytic Tool for End of Life Analysis) regularly update model inputs
for atmospheric density, which is responsible for the largest
uncertainty, could be used to estimate orbital lifetime prior to
launch.
    In addition to meeting the 25-year requirement of Sec.
453.17(b)(1), the FAA would require in Sec.  453.17(b)(2) that
operators performing uncontrolled atmospheric disposal from LEO satisfy
either an expected casualty (EC) of 1 x
10-4, or an equivalent effective casualty area of
7 square meters. The FAA proposes to delay the effective date of Sec.
453.17(b)(2) until 1 year after the effective date of the rule, so as
to avoid interference with current planned launches and provide
operators additional time to come into compliance with the requirement.
The FAA proposes to regulate uncontrolled atmospheric disposal in this
manner due to the inherent risks posed to people and property on Earth
whenever upper stages reenter the Earth's atmosphere in either a
controlled or uncontrolled manner. Upper stages are designed to be
robust systems capable of withstanding the stresses and temperatures of
launch. Therefore, most upper stages are composed of heat-resistant
material that does not burn-up upon reentry and can be expected to
survive reentry to impact the ground. Although tracking and analysis
can be done to help narrow down where an uncontrolled reentry may
occur, and the appropriate civil authorities can be notified, there are
no means to stop or move the impact location of reentering debris.
Furthermore, the science of predicting impact points for uncontrolled
disposals is limited. Re-entry Assessment is difficult. It is virtually
impossible to precisely predict where and when space debris will
impact. This is due to limitations in the U.S. tracking system as well
as environmental factors that impact on the debris.\59\
---------------------------------------------------------------------------

    \59\ United States Space Command. (Retrieved on August 26,
2021). Reentry Assessment--US Space Command Fact Sheet. SpaceRef.
www.spaceref.com/news/viewpr.html?pid=4008.
---------------------------------------------------------------------------

    National U.S. policy guidelines cited above, as well as those of
NASA,\60\ Department of Defense,\61\ and the FCC,\62\ along with a
growing international consensus, recommend that the risk to the public
on the ground not exceed 1 EC in 10,000 events or 1 x
10-4. This applies to reentries of orbital
debris, whether they are a deliberate controlled disposal or an
uncontrolled disposal through natural decay. The EC should
be calculated to one-significant figure unless an uncertainty analysis
justifies a more precise estimate of risk.
---------------------------------------------------------------------------

    \60\ NPR 8715.6B, NASA Procedural Requirements for Limiting
Orbital Debris and Evaluating the Meteoroid and Orbital Debris
Environments.
    \61\ Department of Defense Instruction 3100.12 and Air Force
Instruction 91-202.
    \62\ FCC Statute 25.114 Applications for Space Authorizations.
---------------------------------------------------------------------------

    The EC can vary greatly due to factors outside of the
launch vehicle designer's control. Growing world populations and
various orbital inclination choices have direct correlations to the
EC rating for reentries. The FAA realizes that the
EC prediction can be difficult to calculate; therefore, the
FAA sought an alternative method in addition to EC.
    As alternatives to a launch operator's calculating and satisfying
of an EC of 1 x 10-4, the FAA is also
proposing to allow an operator to demonstrate that it can limit the
casualty area during disposal by natural decay. Some companies may find
the debris casualty area determination to be a more simplified
analysis, and this analysis relies only on vehicle design and
operation. Both analyses, EC and debris casualty area, would
be adequate to protect the public from disposal risk. Therefore, the
FAA proposes disposal to be acceptable if a size limit is satisfied or
if the EC limit is met.
    The FAA would permit uncontrolled reentry as an acceptable form of
disposal if the surviving debris casualty area measured 7 square meters
or less. This proposed casualty area matches that stated in the
USGODMSP, guideline 4-1(e).\63\ The casualty area is derived from the
acceptance of a risk criteria of 1 x 10-4.
Applying the 1 x 10-4 expectation of casualty to
uncontrolled disposal, NASA calculated the risk to account for the 2019
population of the world that could be affected and the size of the
debris that could impact the ground. On average, analysis showed that a
casualty area of 7 square meters of surviving debris would produce a 1
x 10-4 expectation of casualty. The debris
casualty area takes into account that the force of impact of the debris
is at least 11 ft-lb, the threshold for injury on an unsheltered
person.\64\ Specifying an acceptable casualty area as an alternative to
a risk criterion eliminates the uncertainty inherent in risk
calculations, including such variables as population counts and event
probability assumptions.
---------------------------------------------------------------------------

    \63\ United States Government. (November 2019) U.S. Government
Orbital Debris Mitigation Standard Practices, November 2019 Update.
orbitaldebris.jsc.nasa.gov/library/usg_orbital_debris_mitigation_standard_practices_november_2019.pdf.
    \64\ SANDIA National Laboratories. (April 1997). Hazards of
Falling Debris to People, Aircraft, and Watercraft.
---------------------------------------------------------------------------

    The total effective casualty area is determined by adding up the
casualty area of each piece of debris that impacts Earth. The upper
stage will not land intact, but is expected to breakup in the
atmosphere during reentry. The total casualty area of all pieces added
together would be required to be less than 7 square meters.
    The second option for performing an uncontrolled atmospheric
disposal under proposed Sec.  453.17 would be to maneuver the debris to
a highly elliptical orbit for long-term atmospheric disposal. Under
proposed Sec.  453.17(c), an operator would maneuver the upper stage
and its components from semi-synchronous Molniya orbits, synchronous
Tundra orbits, and other elliptical orbits, to a long-term disposal
orbit where orbital

resonances will increase the eccentricity for long[hyphen]term
atmospheric disposal of the upper stage. This proposal of up to a 200-
year disposal matches the USGODMSP guidelines to allow the upper stage
to be maneuvered to a disposal where orbital resonances keep increasing
the eccentricity and eventually decrease the perigee for an
uncontrolled atmospheric disposal. During the development of the
USGODMSP, the FAA, NASA, and the Department of Defense reviewed various
timeframes for highly elliptical orbit disposals. Objects in highly
elliptical orbits are affected by gravitational forces from the Earth,
the Moon, and the Sun. These forces, over time, alter the object's
orbit and eventually cause the object to reenter Earth's atmosphere.
The FAA foresees that very few commercial operations would fall within
this scenario, because it is rarely used by commercial operators.
    If an operator maneuvers the debris to a highly elliptical orbit in
accordance with Sec.  453.17(c), the orbital lifetime must be as short
as practicable, but must not exceed 200 years after mission completion.
The responsible behavior is to remove debris objects from orbit as soon
as practical. Highly elliptical objects have very high apogees;
therefore, atmospheric drag only affects them during a small portion of
their orbit. Drag is a major factor in atmospheric disposal, so these
disposals take a long time to occur. These objects spend a smaller
portion of time within congested orbits, so over a 200-year timeframe,
the time in congested orbits equals that of objects that are in LEO for
25 years. The probability of collision with operational spacecraft and
debris 10 cm and larger should also be limited to less than 0.001 for
the entire lifetime. The FAA proposes to delay the effective date of
the risk requirement so as not to interfere with current planned
launches. The FAA finds that delaying the effective date of this
requirement by 1 year will allow operators sufficient time to implement
disposal options that meet the risk criteria, without jeopardizing
public safety. After 1 year, the launch operator must show that when
the upper stage reenters, the risk will meet the criteria of 1 x
10-4 or that the effective casualty area will be
less than 7 square meters.
    Proposed Sec.  453.17(d) would identify the information that an
operator must include in its ODAP prior to each launch or reentry in
order to perform uncontrolled atmospheric disposal in accordance with
this section. The ODAP must include (1) verification through hardware
and software testing or analysis that the system has at least a 90
percent probability of successfully executing the planned disposal
option; (2) an estimate of the EC or the effective casualty
area for any surviving debris; and (3) a statistical analysis
demonstrating compliance with the requirements of Sec.  453.17(b) or
(c) to dispose of the debris within the prescribed time limit. The
testing and analysis could include an analysis using NASA's DAS or
similar material that demonstrates compliance with the 25-year rule in
the case of natural decay from LEO, or the 200-year rule for highly
elliptical orbits. Alternatively, an analysis should be provided
showing that the upper stage can meet the casualty area limit or
expectation of casualty limit.
e. Maneuver to a Disposal Orbit
    The FAA proposes to give launch or reentry operators the option in
Sec.  453.18 of disposing of debris by maneuvering it to a disposal
orbit. In this scenario, the operator would move the upper stage and
its components into a less-populated disposal orbit. Disposal or
storage orbits are orbits intended for post-mission long-term storage,
where atmospheric effects and solar radiation will not move disposed
objects into a protected orbit for at least 100 years. Disposal orbits
protect LEO, a narrow band in MEO bounded by 20,182 km plus or minus
300 km, and the GEO region. The band in MEO is used by Global
Positioning System (GPS) spacecraft and other global positioning
constellations. On-orbit disposal is not a permanent solution, and some
of these storage orbits may be used for future space operations. Even
spacecraft orbiting beyond GEO will eventually degrade and reenter
populated orbits. While use of disposal orbits fails to remove debris
from orbit and therefore reduce the chance of debris-making collisions,
on-orbit disposal remains an effective alternative to atmospheric
disposal in today's environment and is preferable to clogging LEO and
intersecting GEO with spent upper stages. This option is consistent
with the USGODMSP. In addition, for some operators, all other methods
of disposal would be costly. The FAA therefore proposes to allow
operators to maneuver orbital debris to a disposal orbit in order to
meet the disposal requirement of Sec.  453.13. Disposal orbits still
impose some risk for future space programs and interplanetary missions.
The FAA seeks comments on whether disposal orbit options should be
phased out. And, if so, what an appropriate timeframe for phasing out
should be.
    The requirements of Sec.  453.18 would only apply if the operator
elects to maneuver to a disposal orbit as its disposal method under
Sec.  453.13. To comply with Sec.  453.18, the operator would move the
upper stage and its components into a less-populated orbit within 30
days after mission completion. To prevent interference with active
spacecraft for a significant length of time, the FAA proposes as
disposal orbits those identified in the USGODMSP. If an operator elects
to use a disposal orbit between LEO and GEO, then the operator would be
required to place the upper stage and its components into either (1) an
eccentric orbit where the perigee altitude remains above 2,000 km, the
apogee altitude remains below the geosynchronous region for at least
100 years, and the time spent by the upper stage between 20,182 plus or
minus 300 km is limited to 25 years or less over 200 years; \65\ or (2)
a near-circular disposal orbit that avoids altitudes 20,182 plus or
minus 300 km, the geosynchronous region, and altitudes less than 2,000
km, for at least 100 years. Under proposed Sec.  453.18(c)(1)(iii), an
orbit that remains completely within the region bounded by 20,182 km
plus or minus 300 km would not qualify as a disposal orbit. The orbital
lifetime of any debris placed within this region would therefore be
limited to 25 years or less over 200 years. If an operator elects to
use a disposal orbit above GEO, the FAA proposes to require in Sec.
453.18(d) that the operator place the upper stage and its components
into an orbit with a perigee altitude above 36,100 km for a period of
at least 100 years after disposal.
---------------------------------------------------------------------------

    \65\ All figures match the guidelines in the USGODMSP. A 200-
year timeline ensures that the upper stage will avoid the altitude
range commonly used by global navigation satellite systems.
---------------------------------------------------------------------------

    In addition to implementing the disposal orbits identified by the
USGODMSP, the FAA proposes to require in Sec.  453.18(e) that operators
limit the probability of collisions with operational spacecraft and
debris 10 cm and larger to less than 0.001 for 100 years after
disposal. This requirement would be consistent with USGODMSP
recommendations, as well as the requirement in proposed Sec.  453.9(b)
to limit the probability of collision between launched objects after
the end of launch.
    Proposed Sec.  453.18(f) would prescribe the information that an
operator must include in its ODAP to maneuver debris to a disposal
orbit in accordance with Sec.  453.18. Under proposed Sec.  453.18(f),
the ODAP must include: (1) verification through hardware and software
testing or analysis that the system has at least

a 90 percent probability of successfully executing the planned maneuver
to the disposal orbit; (2) a description of how the system will achieve
and maintain the planned disposal orbit for the required time limit;
and (3) statistical analysis demonstrating compliance with the
probability of collision lifetime limit with operational spacecraft and
debris. ISO Standard 16126 \66\ provides an acceptable method for
conducting the post-mission disposal probability of success analysis of
Sec.  453.18(f)(1). The testing and analysis can include engine re-
light qualification tests or reliability analysis or similar.
---------------------------------------------------------------------------

    \66\ International Organization for Standardization. (April 1,
2014) ISO 16126:2014.
---------------------------------------------------------------------------

D. Explosion Mitigation

    The FAA proposes minor changes to its current requirement that a
launch operator prevent fragmentation or explosion of its upper
stage.\67\ Currently, under Sec. Sec.  417.129(c) and 450.171(a)(3), a
launch operator must ensure the removal of stored energy from an upper
stage by depleting residual fuel and leaving fuel lines open.\68\
---------------------------------------------------------------------------

    \67\ See proposed Sec.  417.129(b) and (c).
    \68\ See Sec.  417.129(c).
---------------------------------------------------------------------------

    Proposed Sec.  453.7(a) would require that, except for energy
sources that are safety critical on-orbit or during reentry, a launch
operator must ensure: (1) the integrated probability of debris-
generating explosions or other fragmentation from the conversion of
energy sources (i.e. chemical, pressure, kinetic) of each upper stage
is less than 0.001 (1 in 1,000) during operations; and (2) stored
energy is removed by depleting residual propellants, venting any
pressurized system, leaving all batteries in a permanent discharge
state, and removing any remaining source of stored energy. The proposed
rule would replace Sec. Sec.  417.129(c) and 450.171(a)(3), and would
not contain a specific requirement to leave valves open. After
promulgation of its original debris requirements, the FAA has found on
several occasions, through the licensing process, that leaving the
valves open long enough for all fuels and oxidizers to vent and then
permitting them to close, has provided a level of safety equivalent to
leaving the valves open. Either approach removes the source of
explosion risk--namely, the fuels and oxidizers. The FAA proposes a
probability limit of 0.001, which matches the limit in the USGODMSP, in
order to provide operators a quantitative requirement.
    Proposed Sec.  453.7(b) would identify the information that an
operator would need to include in its ODAP to demonstrate compliance
with Sec.  453.7(a), specifically: (1) analysis, using commonly
accepted engineering and probability assessment methods, showing how
the operation meets paragraph (a)(1); and (2) test results or analysis,
with 95 percent confidence levels,\69\ of the planned end-of-mission
passivation procedure that verifies dissipation of all energy sources
to levels that will prevent explosion of any launch vehicle component.
The test results or analysis submitted in accordance with Sec.
453.7(b)(2) would be required to show that all residual propellants
contained in the system can be purged or passivated to an acceptable
level at the end of the launch, all pressurized systems can be purged
or passivated, and all energy storage systems have sufficient
structural design to prevent rupture and subsequent explosion. This
proposal marks a departure from current requirements, which only ask
for a demonstration, without specifying that the demonstration be made
with analysis and verification. The FAA now considers the latter
necessary because operators have historically only stated that they
would comply without providing the test or analysis to show how they
would comply. The FAA seeks to clarify in regulation that asserting
compliance is not a demonstration of compliance that satisfies this
requirement. The FAA seeks feedback on the proposed analysis and
testing requirements.
---------------------------------------------------------------------------

    \69\ In statistics, a confidence interval is the range of values
that includes the true value at a specified confidence level. A
confidence level of 95 percent is commonly used which means that
there is a 95 percent chance that the true value is encompassed in
the interval.
---------------------------------------------------------------------------

E. Collision Mitigation Between Launched Objects

    The FAA proposes minor changes to its current requirements that a
launch operator prevent unplanned physical contact between the launch
vehicle and payload. Currently Sec. Sec.  417.129(a) and 450.171(a)(1)
require a launch operator to ensure that there is no unplanned physical
contact between the launch vehicle and its components and the payload.
Proposed Sec.  453.9(a) would require a launch operator to prevent
unplanned physical contact between a launch vehicle or any of its
components and each payload after payload separation, and would replace
the requirements in Sec. Sec.  417.129 and 450.171.
    The FAA proposes to add a requirement in Sec.  453.9(b) to take
into account the probability of collision with orbital objects 10 cm
and larger when designing the mission profile of an upper stage. The
operator should ensure that the probability of collision is less than
0.001 (1 in 1,000) after the end of launch. Upper stages are the
highest mass of orbital debris by far. It is important to prevent
breakups of massive upper stages due to collisions with large debris.
The proposed requirement also matches ODMSP Objective 3-1.
    Proposed Sec.  453.9(c)(1) would specify the information that an
operator must include in its ODAP to demonstrate compliance with Sec.
453.9: (1) the operator's procedure for preventing vehicle and payload
collision after payload separation, including any propellant depletion
burns and compressed gas releases that minimize the probability of
subsequent collisions; and (2) the results of a probability of
collision analysis, using commonly accepted engineering and probability
assessment methods, meeting paragraph (b) of this section. This marks a
departure from current requirements, which only require a
demonstration, without specifying that the demonstration must consist
of a written procedure. The FAA has received non-actionable
demonstrations in previous applications and now proposes requiring
complete procedures in the ODAP. The FAA now considers the latter
necessary for purposes of clarification as to what the FAA seeks. The
analysis should use commonly accepted engineering and probability
assessment methods.

F. Launch and Reentry Collision Avoidance.

    The FAA proposes to move the collision avoidance analysis
requirements from Sec.  450.169, which are currently applicable to all
orbital launches and reentries authorized by the FAA that exceed 150 km
to Sec.  453.11. The FAA would replace the current text in Sec.
450.169 with a reference to Sec.  453.11, and replace all references to
Sec.  450.169 outside of part 450 with a reference to new Sec.  453.11,
which would be called ``Collision Avoidance with Orbital Objects.''
Proposed Sec.  453.11 is substantially similar to the existing
requirements in Sec.  450.169, but would differ from the existing
regulation in the following respects.
    First, the FAA would omit from proposed Sec.  453.11 the exclusion
provided in Sec.  450.169(d), which states that collision avoidance
analysis is not required if the maximum planned altitude for any
launched object is less than 150 km. This exclusion is necessary under
current Sec.  450.169 because part 450 is not limited to

launch or reentry activity above 150 km. Since the FAA would relocate
the collision avoidance analysis requirements to part 453, which would
only apply to launch or reentry activity that exceeds 150 km, the
exclusion found in Sec.  450.169(d) is no longer necessary. As such,
the FAA would exclude the phrase ``except as provided in paragraph
(d),'' which appears in Sec.  450.169(a) from proposed Sec.  453.11(a).
    The text of proposed Sec.  453.11(a)(1) would match current Sec.
450.169(a)(1).
    The FAA proposes to refer to ``active payloads'' in Sec.
453.11(a)(2), instead of ``objects that are neither orbital debris nor
inhabitable'' as used in current Sec.  450.169(a)(2). The updated
language clearly states the intent of this section and is consistent
with U.S. Space Force terminology and current practice. Active payloads
do not include inhabitable objects like the ISS, which require more
stringent screening.
    In Sec.  453.11(a)(2), the FAA proposes to retain the probability
of collision and spherical separation distance options from Sec.
450.169(a)(2)(i) and (ii), but add a third option for operators to
screen against active payloads: ellipsoidal screening. The FAA would
accept an ellipsoidal separation distance of 25 km in-track and 7 km
cross-and-radial-track ellipsoidal separation from active payloads for
collision avoidance analyses. The FAA looked at collision risk
associated with the radial component greater than 7 km and found that
it posed a risk less than 1 x 10-5. These
ellipsoidal distances also match current practice identified by the
Range Commanders Council. Operators would therefore have three options
for screening against active payloads: probability of collision (Sec.
453.11(a)(2)(i)), ellipsoidal screening (Sec.  453.11(a)(2)(ii)), and
spherical screening (Sec.  453.11(a)(2)(iii)).
    The FAA proposes to add a requirement in Sec.  453.11(a)(3) to
perform launch and reentry collision avoidance analysis against small
objects with a radar cross section greater than 0.04 m\2\. Currently,
Sec.  450.169(a)(3) only requires operators to screen against large
objects with radar cross section greater than 1 m\2\ and medium objects
with radar cross section 0.1 m\2\ to 1 m\2\. However, small objects,
including CubeSat-sized objects, can cause vehicle breakups and orbital
debris if a collision were to occur between the object and a launching
or reentering vehicle. The FAA did not include small debris in its
recent Streamlined Launch and Reentry License Requirements rulemaking,
as the FAA was still investigating the implications of the increase of
small objects in the debris catalog due to the addition of the
Department of Defense Space Fence. It is current practice at the
Federal ranges to screen against all objects in the debris catalog,
including small objects with a radar cross section greater than 0.04
m\2\. Therefore, the FAA proposes to add launch and reentry collision
avoidance analysis screening against those small objects. The FAA would
retain under Sec.  453.11(a)(3) the screening options provided in Sec.
450.169(a)(3): an operator would be required to ensure either (i) that
the probability of collision between the launching or reentering
objects and any known orbital debris does not exceed 1 x
10-5; or (ii) that the launching or reentering
objects maintain a spherical separation distance of 2.5 km. Window
closures that meet these requirements will ensure that launch and
reentry vehicles do not collide with known objects during launch or
reentry operations. Note that probability of collision is different
than probability of casualty used elsewhere for public risk.
Probability of collision is only the odds that two objects will occupy
the same location at the same time. Probability of casualty factors in
the odds of collision plus the vulnerability of a person. Thus, there
are separate risk measures.
    The FAA proposes to move the screening time requirements of Sec.
450.169(b) to Sec.  453.11(b), with several modifications. First, to
enhance clarity the FAA would refer to ``150 kilometers altitude'' in
Sec.  453.11(b)(1) and (2), instead of ``150 km,'' which appears in
Sec.  450.169(b)(1) and (2). The text of proposed Sec.  453.11(b)(3)
would match current Sec.  450.169(b)(3). Second, to accommodate the
additional disposal options proposed in part 453, the FAA proposes to
specify appropriate screening times for controlled atmospheric disposal
and maneuver to a storage orbit, rather than refer to ``disposal''
generally, as done in current Sec.  450.169(b)(4). Under proposed Sec.
453.11(b)(4), an operator performing controlled atmospheric disposal
would need to screen during descent from initial disposal burn to 150
km altitude. To maneuver to a disposal orbit, under Sec.  453.11(b)(5),
an operator would need to screen during initial disposal operation
until removal from LEO or GEO.
    The FAA proposes to move Sec.  450.169(c) to Sec.  453.11(c)
without any changes. Since the FAA would not include the exclusion in
Sec.  450.169(d) because it is redundant of proposed part 453, the
Analysis requirements found in Sec.  450.169(e) would appear under
paragraph (d) of proposed Sec.  453.11.
    The FAA proposes to move the language currently found in Sec.
450.169(e) to Sec.  453.11(d), with two revisions. First, to enhance
clarity, the FAA proposes to revise the first sentence of Sec.
453.11(d) to use the active voice (``An operator must obtain a
collision avoidance analysis . . .''). Second, the FAA proposes to
identify in Sec.  453.11(d)(2) the uncertainties that should be
included in the vehicle trajectory and covariance calculation used in
the collision avoidance analysis. Specifically, the FAA proposes to
require that collision avoidance analyses account for uncertainties,
``including launch or reentry vehicle performance and timing,
atmospheric changes, variations in drag, and any other factors that
affect position and timing of the launch or reentry vehicle.'' It is
important for a scientific and complete analysis to include these
uncertainties because at the velocities of the objects in orbit, small
variations or uncertainties can affect the collision prediction. By
revising this provision, the FAA emphasizes the use of uncertainty at
the beginning of collision analysis, whereas the previous language in
Sec.  450.169(e)(2) directed that uncertainties be used to modify the
final analysis results.
    The FAA proposes to move Sec.  450.169(f) to Sec.  453.11(e)
without any substantive changes.
    The FAA proposes to move part 450 Appendix A, the Collision
Avoidance Analysis Worksheet, to Sec.  453.11(f), with several
revisions. First, the FAA proposes in Sec.  453.11(f)(1) to update the
launch and reentry information that must be included in the Collision
Avoidance Analysis Worksheet. The FAA proposes to combine the ``Segment
Number'' and ``Orbiting objects to evaluate,'' currently found in
paragraphs (a)(5) and (a)(7) of Appendix A, into one requirement, Sec.
453.11(f)(1)(v). These current requirements are redundant, and the
updated requirement uses plain language to describe the objects that
should be evaluated in the analysis: all free-flying launch vehicle
stages, payloads, and components that reach orbit. The FAA also
proposes to more clearly convey in Sec.  453.11(f)(1)(vi) the orbital
parameters of each free-flying launch vehicle stage, payload, or
component achieving orbit that must be identified. The FAA would also
refer to both launch and reentry in Sec.  453.11(f)(1)(ii) and (iv),
unlike the existing Appendix A, which inconsistently addresses launch
and reentry. This is a correction, as all parts of the Collision
Avoidance Analysis Worksheet are applicable to both launch and reentry.

G. Real-Time Reporting of Orbital Safety Hazards

    The FAA proposes to add a requirement in Sec.  453.20 that would
require a launch or reentry operator to submit certain information to
the FAA and, if applicable, to other requesting Federal agencies, at
the detection of any launch or reentry activity outside the 3-sigma
trajectory provided for collision avoidance or any debris-creating
event. Orbital safety is implemented through the pre-launch or reentry
assessment of planned trajectories. If either an operator or Federal
tracking capabilities detect activity outside the 3-sigma planned
trajectory or a debris-generating event, the operator should contact
the FAA to provide as much information as possible on the
characteristics (size and mass), last known orbital or trajectory
information, and other details determined necessary by the FAA to
locate and categorize orbital objects. This should be done by phone or
email as soon as the event is detected. The United States Strategic
Command (USSTRATCOM) would be the Federal agency most likely to detect
an event covered by Sec.  453.20(a) and request information from the
operator. This information may provide critical warning time to
inhabited and active payloads on orbit, and allow USSTRATCOM to update
its models and recalculate projected orbits. If a launch does not go as
planned, and the vehicle ends up in a different orbit than expected,
the original Collision Avoidance Analysis Worksheet would be moot. The
FAA would need to reassess the collision probability against the new
trajectory.
    Specifically, proposed Sec.  453.20(a) would require an operator to
immediately submit the information identified in Sec.  453.20(b) to the
FAA and, if applicable, a requesting Federal agency, at the detection
of any launch or reentry activity outside the 3-sigma trajectory
provided for collision avoidance or any debris-creating event. If an
operator identifies such an event, or is notified by a Federal agency
(such as U.S. Space Force and NASA), then the operator would need to
report to the FAA and, if applicable, the requesting Federal agency:
(1) the size and mass of the affected objects; (2) the last known
orbital or trajectory information; and (3) any other details determined
necessary by the FAA to locate and categorize orbital objects, such as
the vehicle orientation, whether it is tumbling, or the operator's
ability to control the object.

H. Revisions to Existing Regulations

    The FAA's proposal to consolidate existing requirements for orbital
debris mitigation and end-of-launch safety under part 453 necessitates
the following revisions to current regulations.
    Under part 404, the FAA proposes to replace the reference to Sec.
450.169 in Table A404.1 with a reference to Sec.  453.11.
    Under part 415, the FAA proposes to revise Sec.  415.2(b) to
reference part 450 as well as part 453. The proposed revision would
make clear that operations licensed under part 415 must comply with the
critical asset protection requirements in Sec.  450.101(a)(4) and
(b)(4) and, for launches with a planned altitude greater than 150 km,
the launch collision avoidance requirements in Sec.  453.11. The FAA
also proposes to revise Sec.  415.35(d) to require that launch vehicles
be operated ``in a manner that ensures that flight risks meet the
criteria of paragraph (a) of this section and in accordance with
collision avoidance requirements in Sec.  453.11 and critical asset
protection requirements in Sec.  450.101(a)(4) and (b)(4).''
    The FAA also proposes to revise Sec.  415.39 by revising the
heading to read, ``Demonstration of Orbital Debris Mitigation,''
instead of ``Safety at End of Launch,'' and by replacing the reference
to Sec.  417.129 with a reference to the sections of proposed part 453
under which those end of launch requirements would appear: Sec. Sec.
453.7 and 453.9. Similarly, the FAA proposes to revise Sec.  415.133 by
revising the heading to read, ``Orbital Debris Mitigation,'' and by
replacing the reference to Sec.  417.129 with a reference to the
sections of proposed part 453 under which those end of launch
requirements would appear: Sec. Sec.  453.7 and 453.9. These revisions
would direct readers to the Code of Federal Regulations (CFR) part
under which the FAA's safety at end of launch requirements would be
relocated under this proposal, and affirm that any FAA-licensed
launches exceeding 150 km would be required to comply with part 453.
Lastly, the FAA would revise Appendix B to part 415 to reflect the
revised heading of Sec.  415.133 (Orbital Debris Mitigation).
    Under part 417, the FAA proposes to revise Sec.  417.113(c)(1) to
reference the collision avoidance analysis requirements of proposed
Sec.  453.11, instead of Sec.  450.169. The FAA proposes to replace the
requirements in Sec.  417.129 for safety at end of launch with a
reference to the sections of proposed part 453 under which those end of
launch requirements would appear: Sec. Sec.  453.7 and 453.9. This
revision would direct readers to the CFR part under which the FAA's
safety at end of launch requirements would be relocated under this
proposal, and affirm that any FAA-licensed launches exceeding 150 km
would be required to comply with part 453. As discussed above, the FAA
proposes changes to the end of launch requirements under part 453,
consistent with USGODMSP guidelines.
    The FAA proposes to revise Sec. Sec.  431.2(b) and 435.2(b) to
reference part 450 and part 453. The proposed revisions would make
clear that operations licensed under part 431 and 435 must comply with
the critical asset protection requirements in Sec.  450.101(a)(4) and
(b)(4) and, for launches with a planned altitude greater than 150 km,
the launch collision avoidance requirements in Sec.  453.11. The FAA
proposes to revise Sec.  431.43(a)(1) to reference Sec.  453.11 instead
of Sec.  450.169. The FAA also proposes to replace the reference to
Sec.  450.169 in Sec.  431.43(c)(3) with a reference to the sections of
proposed part 453 under which those end of launch requirements will
appear: Sec. Sec.  453.7 and 453.9. As discussed above, the FAA
proposes to change the end of launch requirements consistent with
USGODMSP guidelines. This revision would direct readers to the CFR part
under which the FAA's safety at end of launch requirements would be
relocated under this proposal, and affirm that any FAA-licensed
launches or reentries exceeding 150 km would be required to comply with
part 453.
    Under part 437, the FAA proposes to replace the reference to Sec.
450.169 in Sec.  437.65 with a reference to Sec.  453.11. The FAA also
proposes to remove the word, ``maximum'' from Sec.  437.65 because it
is an unnecessary modifier to the phrase, ``permitted flight with a
planned altitude greater than 150 km.''
    Under part 450, the FAA proposes to revise Sec.  450.101(d), titled
Disposal Safety Criteria, to specify the risk criteria applicable to
controlled and uncontrolled atmospheric disposals. As discussed earlier
in this preamble, the current definition of ``disposal'' in Sec.  401.7
includes only controlled atmospheric disposal. As a result, the
disposal safety criteria currently identified in Sec.  450.101(d) only
apply to controlled atmospheric disposal. Since the FAA is proposing to
amend the ``disposal'' definition to include all five disposal options
proposed in Sec. Sec.  453.14 through 453.18, and the disposal risk
criteria currently identified in Sec.  450.101(d) would not apply to
all five disposal methods, the FAA must therefore revise Sec.
450.101(d) to identify the risk criteria applicable to each