21 November 2015








































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18 November 2015


















Welcome to the Save the LUT Campaign - http://www.savethelut.org/ (link accessed 19 November 2015)

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What if an Apollo Saturn Rocket Exploded on the Launch Pad? (1965)

An Alternate Station-Shuttle Evolution: The Spirit of '76 (1970)

McDonnell Douglas Phase B Space Station (1970)


14 November 2015


The Skylab Orbital Workshop as seen by the Skylab 4 crew, the last astronauts to live on the station. Image credit: NASA
On 14 May 1973, the last Saturn V rocket to fly, designated SA-513, launched the Skylab Orbital Workshop (OWS) space station into a 435-kilometer-high orbit about the Earth. Flight controllers soon realized that the 85-ton space laboratory was in trouble. Although they did not know it at the time - Skylab climbed rapidly into dense clouds, so could not be imaged during most of its ascent - 63 seconds after liftoff a design flaw caused Skylab's meteoroid shield to rip away. Shield debris jammed one of the workshop's two main electricity-producing solar arrays. The other array remained attached to Skylab's side only at its hinge (forward) end.

Shield debris also pummeled SA-513, tearing at least one hole in the tapered interstage adapter that linked its S-II second stage with the Skylab station. Debris also apparently damaged the system for separating the cylindrical adapter that linked the S-II to the S-IC first stage. The adapter, meant to separate shortly after the spent S-IC, remained stubbornly attached to the S-II all the way to orbit.

Skylab 1 launch, 14 May 1973. Image credit: NASA

Without the protection of the reflective meteoroid shield, temperatures within Skylab's 11,303-cubic-foot pressurized volume soon soared, raising fears that its air would become tainted by outgassing from materials on board, film would be ruined, and food and medicines spoiled. Flight controllers soon found to their dismay that maneuvers designed to cool Skylab's interior tended to starve it of electricity, for they turned away from the Sun the four "windmill" solar arrays on the Apollo Telescope Mount (ATM), the beleaguered space laboratory's only functioning sources of electricity.

NASA immediately began a Skylab salvage effort. Engineers developed deployable sunshields and tools for freeing the stuck main solar array, flight controllers carefully maneuvered Skylab to maximize the amount of electricity the ATM arrays could produce while reducing temperatures on board as much as possible, and the first crew meant to board Skylab (their mission was designated Skylab 2) hurriedly trained to become the world's first orbital repairmen.

Skylab 2 astronauts Joseph Kerwin, Charles "Pete" Conrad, and Paul Weitz. Image credit: NASA

The Skylab 3 crew of Alan Bean, Jack Lousma, and Owen Garriott lifted off on 28 July. During their 6 August spacewalk, Lousma and Garriott deployed an improved sunshield. The lived and worked on board the station for 59 days.

The Skylab 4 crew of Jerry Carr, William Pogue, and Ed Gibson boarded Skylab on 16 November. Carr and Gibson mounted a meteoroid collector on an ATM strut during their spacewalk on 3 February 1974, in the hope that a Space Shuttle crew might retrieve it as early as 1979. When the Skylab 4 crew undocked on 8 February 1974 after a record-breaking 84 days in space, Skylab was expected to remain aloft until 1983, when atmospheric drag would cause it to reenter Earth's atmosphere. They left Skylab's airlock hatch closed but not latched so that it could provide entry for future visitors.

This pre-launch cutaway illustration of Skylab shows the station as it would have appeared if it had reached Earth orbit undamaged. In addition to two large main solar array, it includes the micrometeoroid shield which tore free during Skylab's ascent through the atmosphere. Image credit: NASA
During the solar-minimum years of the mid-1970s, the Sun was more active than had been anticipated at the time of Skylab's launch. Solar activity heated and expanded Earth's upper atmosphere, subjecting the first U.S. space station to more aerodynamic drag than had been expected. In March 1977, the NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama, lead center for the Skylab station, asked NASA Headquarters to grant it permission by mid-1977 to begin work on a mission to raise Skylab's orbital altitude.

On 10 June 1977, former Skylab Deputy Director John Disher, by then NASA's Director of Advanced Programs, requested that MSFC conduct a preliminary in-house study of the feasibility of reusing Skylab in the Space Shuttle era. At about the same time, NASA Headquarters directed NASA Johnson Space Center (JSC), lead center for the Space Shuttle, to study an early Shuttle mission to either boost Skylab to a higher, longer-lived orbit or cause it to safely reenter over an unpopulated area.

In September 1977, JSC informed NASA Headquarters and MSFC that the earliest it could reboost or deboost Skylab was September 1979, as part of the fifth Orbital Flight Test (OFT) Shuttle mission. At the time, NASA envisioned a total of six OFT missions before the Shuttle was declared operational. NASA Headquarters then gave the go-ahead for MSFC and JSC to begin work toward a September 1979 Skylab reboost/deboost mission.

On 16 November 1977, MSFC engineers J. Murphy, B. Chubb, and H. Gierow presented to NASA Associate Administrator for Space Flight John Yardley results of the study they had begun in June. They were speaking to a Skylab expert: before coming to NASA in 1974, Yardley had managed Skylab work at McDonnell Douglas, the prime contractor for the OWS.

The MSFC engineers first described Skylab's condition. They reported that when the Skylab 4 crew returned to Earth, the Orbital Workshop's water system contained 1930 pounds of water (enough to supply three men for 60 days). The water, they said, probably remained potable, but might have developed a bad taste. If it was no longer potable, then it might be used for bathing. In any case, the Skylab water system included resupply points, so a Space Shuttle crew could refill it with fresh water if water transfer equipment were developed.

The oxygen/nitrogen supply remaining on Skylab was probably sufficient to supply three men for 140 days at Skylab's standard operating pressure of five pounds per square inch, the MSFC engineers estimated. The station's ventilation and carbon dioxide-removal systems were almost certainly functional. Even if they were not, their most important components were designed to be replaceable in space.

The MSFC engineers also assessed Skylab's electrical power system. They estimated that the main solar array Conrad and Kerwin had freed could still generate between 1.5 and 2.5 kilowatts of electricity, and that the batteries it had charged, located in Skylab's Airlock Module, were probably still usable. The batteries for the four ATM arrays, located inside the ATM, were, on the other hand, almost certainly frozen. The team recommended that controllers reactivate the main array electrical system from the ground before the first Shuttle visit, and that any effort to revive the ATM electrical system be left for a later time.

More problematic than the electrical system was Skylab's attitude control system, which relied on a trio of Control Moment Gyros (CMGs) to turn Skylab so that, among other things, it could reliably point its solar arrays at the Sun. At the time the Skylab 4 crew departed, one CMG had already failed and another showed signs of impending failure. In addition, Skylab's guidance computer was probably dead after being subjected to "extreme thermal cycling" as Skylab passed between daylight and night. The Orbital Workshop's thruster system, on the other hand, was probably operational with about 30 days of propellant remaining.


The MSFC engineers then proposed a four-phase plan for reactivating and reusing Skylab. The target date for their first Phase I milestone had already passed by the time they briefed Yardley: though it was already mid-November, they made a point of calling for an October 1977 decision on whether Skylab should be reboosted to a higher orbit, extending its orbital lifetime until about 1990, or deboosted so that it could reenter safely over an unpopulated area.

Assuming that NASA decided to reboost Skylab, then a ground-controlled Skylab reactivation test would occur between June 1978 and March 1979. If the test was successful, then the fifth OFT Space Shuttle mission would rendezvous with Skylab. As already mentioned, in September 1977 JSC estimated that the fifth OFT would fly in September 1979. Two months later, when the MSFC team briefed Yardley, the mission had already slipped to February 1980.

Artist concept of Teleoperator spacecraft. Image credit: NASA
The MSFC team anticipated that the Space Shuttle crew would conduct an inspection fly-around of Skylab, then would deploy an unmanned Teleoperator spacecraft from the Shuttle Orbiter's payload bay. Using a control panel on the Orbiter flight deck, the astronauts would guide the Teleoperator, which would carry an Apollo probe-type docking unit, to a docking with the drogue-type docking unit on the front of Skylab's Multiple Docking Adapter. The Teleoperator would fire its thrusters to raise Skylab's orbit; then, its work completed, it would detach, freeing up Skylab's front docking port for Phase II of MSFC's plan.

Astronauts in a nearby Space Shuttle Orbiter stand by as the Teleoperator ignites its thrusters to raise Skylab's orbit and extend its orbital lifetime. Image credit: NASA
Phase II would begin in March 1980, when NASA would initiate development of Skylab refurbishment kits, a 10-foot-long Docking Adapter (DA) module, and a 25-kilowatt Power Module (PM). The DA would include at one end an Apollo-type probe docking unit for attaching it to Skylab's front port and at the other end an Apollo-Soyuz-type androgynous unit with which Shuttle Orbiters and the PM could dock.

The first refurbishment kit and the DA would reach Skylab on board a Shuttle Orbiter in January 1982, almost two years after the reboost mission. During the 1982 mission, spacewalking astronauts would fold two of the four ATM solar arrays out of the way to improve clearance for visiting Orbiters and would retrieve the meteoroid experiment the Skylab 4 astronauts had left on the ATM. As time allowed, this and other Phase II crews would perform unspecified "simple passive experiments" on board Skylab and would collect samples of its structure for engineering analysis on Earth.

The third Shuttle visit to Skylab would not take place until August 1983.The astronauts would install additional refurbishment kits and would tackle the daunting job of repairing Skylab's damaged cooling system.

The refurbished Skylab station after the start of Phase III of the NASA MSFC reactivation program. The Power Module, Docking Adapter, and Shuttle-carried Spacelab are clearly visible. Image credit: Junior Miranda
The MSFC engineers told Yardley that Phase III of the Skylab reactivation program would begin in March 1984 with delivery of the PM and any remaining refurbishment kits. Using the Shuttle's Remote Manipulator System robot arm, astronauts would lift the PM from the Orbiter's payload bay and turn it 180° so that it protruded forward well beyond the Orbiter's nose. They would then dock one of the PM's three androgynous docking units to an identical unit at the front of the Orbiter's payload bay. The Shuttle would use another of the PM's docking units to dock with the DA on Skylab.

Following docking with Skylab, the astronauts would deploy the PM's twin solar arrays and thermal radiators, link the PM to Skylab's systems using cables extended through open hatchways or installed on the hull during spacewalks, and power up the PM's three CMGs to replace Skylab's crippled attitude control system. The Orbiter would then undock from the PM, leaving it attached permanently to Skylab. Shortly thereafter, NASA would declare the revived and expanded Orbital Workshop to be fully habitable.

Phase III would continue with the first in a series of 30-to-90-day missions aboard Skylab. During these, a Shuttle Orbiter carrying a Spacelab module in its cargo bay would remain docked with the Orbital Workshop. The astronauts would work in the Spacelab module, take advantage of Skylab's large pressurized volume to perform "simple experiments" requiring more room than Shuttle and Spacelab could provide (for example, preliminary trials of space construction methods), and begin building up stockpiles of food, film, clothing, and other supplies on the revived station.

Another 30-to-90-day mission would see the astronauts refurbish and use selected Skylab science equipment, install new experiments based on Spacelab experiment designs, and stockpile more supplies. Between these missions, the new and improved Skylab would fly unmanned under control from the ground.

The view from the Sun: all of the solar arrays deployed for Phase III of the Skylab reactivation program are visible in this image by Junior Miranda
The MSFC engineers told Yardley that the volume available to a crew on board a Shuttle Orbiter without a Spacelab module in its payload bay would total only 1110 cubic feet. Adding a Spacelab would increase that to about 5100 cubic feet. This would, however, amount to less than half the pressurized volume of Skylab. For a mission including a Shuttle Orbiter, Spacelab module, and Skylab, the total volume available to the crew would exceed 16,400 cubic feet.

They were not specific about what Skylab would be used for when Phase IV of their program began in mid-1986, though they did offer several intriguing possibilities. Shuttle Orbiters might, for example, attach modified Spacelab modules and experiment pallets to the third docking port on the PM.

A Shuttle External Tank might be joined to Skylab to serve as a strongback for large-scale space construction experiments using a mobile "space crane." These experiments might include construction of a large space solar power module or a multiple beam antenna.


The MSFC engineers did not estimate the cost of Phases I and IV of their plan, though they did provide (perhaps optimistic) cost estimates for Phases II and III. Their estimates did not include Space Shuttle transportation and contractor study costs.

In Fiscal Year (FY) 1980, NASA would spend $2 million each on Phases II and III. This would increase to $5 million for Phase II and $3.4 million for Phase III in FY 1981. FY 1982, their plan's peak funding year, would see $4.5 million spent on Phase II and $10.2 million spent on Phase III. In FY 1983, NASA would spend $2.5 million to close out Phase II and $12 million to continue Phase III. The following year it would spend $9.1 million on Phase III. Phase III closeout in FY 1985 would cost $4.5 million. Phase II would cost a total of $14 million, while the more ambitious Phase III would total $41.2 million.

In November 1977, the month the MSFC engineers briefed Yardley on their study, NASA awarded Martin Marietta Corporation a small ($1.75-million) contract to begin development of the Teleoperator. The remote-controlled spacecraft was envisioned as a small space tug made up of modular components.

No decision was taken at that time as to whether the Teleoperator would reboost Skylab to make it available for possible future use or would deorbit it in a controlled manner; that decision would await assessment of Skylab's condition and additional study of potential applications. McDonnell Douglas and Martin Marietta subsequently commenced more detailed and extensive Skylab reuse studies under supervision of JSC and MSFC, respectively.


Skylab 1 Investigation Report, Hearing Before the Subcommittee on Manned Space Flight of the Committee on Science and Astronautics, US House of Representatives, Ninety-Third Congress, First Session, 1 August 1973

"Skylab Reuse Study Presented to Mr. Yardley by MSFC," 16 November 1977

Living and Working in Space: A History of Skylab, NASA SP-4208, W. David Compton & Charles D. Benson, 1983, pp. 361-372

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Evolution vs. Revolution: The 1970s Battle for NASA's Future


08 November 2015


Skylab liftoff on a two-stage Saturn V rocket, 14 May 1973. Had the ISS Program gone ahead as planned, its four station launches in 1976, 1978, 1981, and 1983 would have closely resembled this one. Image credit: NASA
On 6 April 1971, eight engineers in the Advanced Concepts & Missions Division, NASA Headquarters Office of Advanced Research and Technology (OART), completed a blueprint of NASA's future. Their detailed report was strictly internal and of limited circulation.

Had the OART team's plan become more widely known, it would surely have generated controversy. This was because it proposed to end U.S. lunar exploration with Apollo 15 so that the Saturn V rockets earmarked for missions 16, 17, 18, and 19 could be used to launch into Earth orbit a series of four "interim" space stations, each more capable than the last, between early 1976 and late 1983.

Although the OART plan sounds like an Apollo massacre, it would in fact have deprived the U.S. of two manned moon missions, not four. By the time the OART team proposed its program, NASA had already cancelled three Apollos. First was Apollo 20, nixed in January 1970 so that its Saturn V rocket could launch 85-ton Skylab, a temporary space station, into low-Earth orbit (LEO).

Next to go were Apollo 15 and Apollo 19 in September 1970. NASA Administrator Thomas Paine scrapped the two lunar landing missions - an H-class walking mission and a J-class rover mission, respectively - to free up funds for NASA's hoped-for 12-man permanent Space Station and the fully reusable winged Space Shuttle intended to deliver its crews, supplies, and experiment equipment. NASA subsequently renumbered its remaining Apollo missions, so the cancelled missions are more commonly known today as Apollo 18 and Apollo 19.

The Interim Space Station (ISS) Program would have played much the same role for NASA in the mid-1970s/early 1980s as Gemini played in the 1960s. Soon after President John F. Kennedy's 21 May 1961 call for an American on the moon by the end of the 1960s decade, aerospace engineers realized that they needed an experience-building "bridge" program to link simple Mercury suborbital and LEO missions with complex Apollo lunar orbiter and landing missions. Gemini evolved from Mercury - it was initially called "Mercury Mark II" - to fulfill that role.

The Saturn IB stage served as the Apollo moon rocket's third stage, the Saturn IB rocket's second stage, and the structural basis of the Skylab station. Image credit: NASA
OART's ISS Program was envisioned as an evolutionary extension of the Skylab Program. Skylab A and its backup, Skylab B, employed 22-foot-diameter Saturn S-IVB rocket stages as their basic structure. The S-IVB was the third stage of the three-stage Saturn V moon rocket and the second stage of the two-stage Saturn IB rocket. From top to bottom, the stage comprised the ring-shaped Instrument Unit (the "electronic brain" of the Saturn V or Saturn IB rocket of which the S-IVB stage was part), a large tank for low-density liquid hydrogen fuel, a small tank for higher-density liquid oxygen oxidizer, and a restartable J-2 rocket engine.

Through the addition of metal-grid decks, life-support equipment and consumables, lights and air ducts, a film vault, living quarters, and experiment apparatus, the S-IVB hydrogen tank became the Orbital Workshop (OWS), Skylab A's main habitable volume. The empty S-IVB liquid oxygen tank served as a dumpster, and a radiator replaced its J-2 engine.

The OWS hydrogen tank had bolted to its top the Airlock Module (AM), which in turn linked to the Multiple Docking Adapter (MDA) at Skylab A's front. The AM included a surplus Gemini hatch for spacewalks. The MDA included a main axial (front) docking port and a back-up radial port.

Besides the OWS, MDA, and AM, Skylab A included the Apollo Telescope Mount (ATM), an unpressurized compartment containing instruments for viewing the Sun. The ATM, mounted on a truss attached to the side of the MDA, included four electricity-generating solar arrays arranged in "windmill" fashion. These augmented two large solar-array "wings" on Skylab A's sides.

The Skylab space station as envisioned in 1970. Image credit: NASA
Skylab A was commonly referred to simply as Skylab, since no firm plan existed to actually launch Skylab B. When the OART engineers completed their report, NASA planned to launch Skylab in late 1972; then, over a period of about nine months, the U.S. civilian space agency would launch to the station three crews in Apollo Command and Service Module (CSM) spacecraft atop Saturn IB rockets. The three-man crews would live and work on board Skylab for up to 56 days. While unoccupied - months might pass between one crew's departure and the next crew's arrival - Skylab would operate under ground control.

The OART engineers applied the term "interim" to their eight-and-half-year program because they intended that it should lead from the Skylab Program to a permanent Space Station through "evolutionary, gradual, and step-wise spacecraft systems development." Beginning about three years after the third and final Skylab crew returned to Earth, a new ISS would reach LEO every two and a half years. Each would be staffed continuously for from 360 to 420 days.

NASA planning was in flux at the time the OART team prepared its report, and would remain so even after President Richard Nixon approved development of a semi-reusable Space Shuttle in January 1972. The ISS Program would span most of a decade, and NASA had in its dozen-year history experienced program instability on the scale of months. These factors caused the OART engineers to avoid making assumptions about the nature of NASA's eventual permanent Space Station when they planned their ISS Program.

They went so far as to suggest, in fact, that the Station/Shuttle Program might be delayed or abandoned in favor of some new space goal before the ISS Program ran its course. For planning purposes, however, they adhered to a timeline which saw NASA's permanent Space Station become operational in late 1987, about six years after the date they gave for the Shuttle's maiden flight and a little more than three years after the last ISS crew returned to Earth.

In keeping with the $3.3-billion Fiscal Year 1972 NASA budget Nixon's Office and Management and Budget had sought from Congress in January 1971, the OART engineers optimistically assumed a steady NASA annual funding stream of $3.3 billion throughout the ISS Program. They estimated that each interim station would cost $2 billion, of which about $330 million would be spent on hardware development, $500 million on experiments, and $1.6 billion on spacecraft hardware. Their program would, they calculated, cost on average about $500 million per year, leaving $2.8 billion for other NASA projects, including Station/Shuttle development.

Interestingly, just 13 days after the OART team completed its report, the Soviet Union launched 20-ton Salyut 1, the world's first space station. The Soviets had during the 1969-1970 period made it known publicly - most prominently in an October 1969 speech by Soviet leader Leonid Brezhnev - that they intended to establish Earth-orbiting stations, so it is tempting to suppose that OART's study was at least in part motivated by Soviet statements.

In January 1970, in fact, the U.S. Central Intelligence Agency had completed a report, classified "SECRET," in which it suggested that the Soviets might construct a series of stations, each larger and more capable than the last, culminating, perhaps, in a $5-billion, 150-ton station between 1976 and 1980. The OART engineers did not, however, mention Soviet space plans in their report.

Interim Space Station design. Image credit: NASA
Like Skylab, the interim stations would reach LEO atop two-stage Saturn V rockets. The first station in the series, designated Interim Space Station-A (ISS-A), would be mainly outfitted for biotechnology research. It would operate in a a 245-nautical-mile (nm) orbit inclined 28.5° relative to Earth's equator. The OART team envisioned that ISS-A would be built from Skylab B. Like the other three stations in its series, ISS-A would lack an ATM.

Based on Skylab experience, the OART engineers calculated that ISS-A would at launch weigh at least 57.25 tons. To this would be added during development and assembly some or all of a 30-ton "growth allowance." This meant that ISS-A could weigh as much as 87.25 tons at launch.

NASA would launch the first three-man ISS-A crew - indeed, the first crew of the ISS Program - in a modified CSM within a day or two of the station's launch. No more than 16 hours after they reached LEO, the astronauts would pilot their spacecraft to a docking at one of ISS-A's two MDA docking ports.

The CSMs that delivered astronauts to the interim stations would differ significantly from their Apollo/Skylab predecessors. The most obvious change would be a new-design launch vehicle. The OART engineers considered using either the Saturn IB or the Titan-IIIM to launch ISS CSMs before they settled on a hybrid of the two.

Dubbed the SRM-S-IVB, the new rocket's first stage would comprise a cluster of three 10-foot-diameter, seven-segment Titan-IIIM solid-propellant rocket motors. The Titan-IIIM, never flown, had been meant to launch the U.S. Air Force Manned Orbiting Laboratory, which was cancelled in February 1969. As its name implies, the SRM-S-IVB launch vehicle's second stage would be a lightly modified Saturn S-IVB stage.


The ISS CSM, like its Apollo and Skylab predecessors, would be a two-part spacecraft. The smaller of the two parts was the conical Command Module (CM), a three-man crew capsule with a reentry heat shield on its broad aft end and an active probe docking unit on its nose. It would lower on parachutes to a splashdown at mission's end. The drum-shaped Service Module (SM) had a Service Propulsion System main engine bell protruding from its flat aft end.

The 6.3-ton ISS CM would closely resemble its Apollo and Skylab counterparts. The ISS SM, on the other hand, would undergo many changes. Because it would need to carry only enough propellants for Earth-orbital rendezvous and docking maneuvers plus an end-of-mission de-orbit burn, OART proposed to replace its propellant tanks, which were sized for a voyage to lunar orbit and back, with smaller tanks derived from those in the Apollo Lunar Module. Because the ISS CSM would fly independently for a total of less than a day, rechargeable batteries in the ISS SM would stand in for the Apollo SM's trio of fuel cells and tanks of fuel-cell reactants.

These changes would free up for conversion into cargo holds four of the six 175-cubic-foot bays clustered around the SM's cylindrical core bay. The four bays would transport a total of about 10 tons of supplies and equipment. Minus cargo, the ISS SM would weigh 8.6 tons.

The Apollo Command and Service Module (CSM) spacecraft would undergo considerable modification for the ISS Program. Image credit: NASA
Water, oxygen, and nitrogen stored in tanks in the ISS SM cargo bays would pass through umbilicals to nozzles in the ISS CM. The astronauts would attach hoses to the nozzles to transfer the water, oxygen, and nitrogen to storage tanks inside the ISS.

Solid cargo, on the other hand, could only be transferred from the ISS SM to the ISS by means of spacewalks. The OART team noted that the spacewalking astronauts would have to travel only about 15 feet to reach the ISS SM from the ISS AM.

The astronauts would hinge open panels in the ISS SM's sides and transfer cargo items to the open ISS AM hatch by attaching them to a clothesline-like "endless line" similar, perhaps, to that used on the moon to convey sample boxes and film from the base of the LM ladder to the LM ascent stage hatchway. Cargo items as large as 3.5 feet wide by 12 feet long could be removed from the ISS SM cargo bays and transferred through the Gemini-type hatch into the ISS AM, the OART team estimated.

Because it would be cast off to burn up in Earth's atmosphere after it performed the deorbit burn, the ISS SM could transport only "up" cargo. "Down" cargo - for example, biological samples and exposed film - would need to reach Earth within the relatively small volume of the ISS CM. The OART engineers estimated that, by removing all lunar mission equipment and supplies from the ISS CM, enough room would be freed up to enable it to convey to Earth all experiment cargo a three-man crew was likely to generate during a 90-day stint on board an ISS.

Converting the Apollo CSM into the ISS CSM would cost $100 million, the OART engineers estimated. This price-tag would not include the $80-million cost of developing the SRM-S-IVB launcher.

The Saturn S-IVB rocket stage would form the largest habitable component of Skylab and the ISS stations. Spacious with a Skylab or ISS-A crew of three, it would become increasingly crowded as the ISS Program evolved. Image credit: NASA

OART made biotechnology ISS-A's main research emphasis because its crews would need to demonstrate that astronauts could remain fit and competent throughout a 90-day stay in space. In addition, it would seek to advance medicine on Earth through the study of the human organism in novel conditions. Most of the experiments performed in the ISS series would have a similar dual purpose: that is, to advance the cause of spaceflight and to provide tangible benefits to people on Earth.

ISS-A's mission, the OART team explained, would continue and expand the biomedical research program begun on board Skylab. In addition to copies of Skylab experiment apparatus, experiment equipment launched on board ISS-A would include a 1750-pound "Manned Onboard Centrifuge" - a centrifuge large enough to spin a human - and a 1300-pound Integrated Medical and Behavioral Laboratory Measurement System (IMBLMS). The IMBLMS would be linked to operational control systems throughout ISS-A to monitor crew performance. Centrifuge, IMBLMS, and "peripheral equipment" such as a bicycle ergometer, an experiment airlock, and a sound-proofed work area would together cost $72 million.

Astronauts on board the interim stations would work 10 hours per day, six days per week. At any one time, two-thirds of the crew on an ISS would be focused on its experiment programs, while the rest would maintain systems and perform housekeeping chores. For ISS-A, this meant that, during any particular working day, two of the three astronauts on board would focus on experiments while the third served as space handyman.

Forty-five man-hours per week would be spent on IMBLMS experiments and 55 man-hours per week on centrifuge experiments. Other experiments - for example, assessment of techniques for weightless maintenance of life-support equipment intended for more than a year of continuous use - would require a total of 30 man-hours per week.

The OART team estimated that Skylab's six solar arrays and the batteries it carried for storing electricity for the night part of its orbit would produce about six kilowatts of continuous power and have a total mass of 7.5 tons. The ATM arrays and OWS arrays would each produce about half of Skylab's electricity. The team assumed that ISS-A's arrays and batteries would weigh the same as Skylab's, but would produce between six and 10 kilowatts of continuous electricity.

In the absence of an ATM, the ISS-A solar array configuration would necessarily differ from that of Skylab. Of the stations in its series, ISS-A would most resemble Skylab. Beginning with ISS-B, larger crews and more complex experiment programs would drive evolutionary modifications to the ISS design, though all would retain the basic MDA-AM-OWS layout.

The AM would have undergone little modification from its first flight as part of Skylab to its last as part of ISS-D. Image credit: NASA
The first three-man ISS-B crew would arrive for a 90-day stint beginning in July 1978, one-and-a-half years after ISS-A's last crew returned to Earth. A second three-man crew would reach the station a month later. The resulting six-man crew would work together for 60 days, then the first three-man crew would return to Earth. A third three-man crew would arrive almost immediately to replace them. Thirty days later, the second ISS-B crew would return to Earth and a fourth crew would replace them. The seventh three-man ISS-B crew would return to Earth in July 1979 and not be replaced, and the eighth and last three-man crew would splash down a month later, about 390 days after ISS-B reached LEO.

ISS-B's main mission would be to perform experimental Earth surveys, which the OART team placed into five categories. These were: agriculture/forestry/geography; geology/mineralogy; hydrology/water resources; oceanography; and meteorology. The station would revolve around the Earth in an orbit inclined 50° relative to the equator, so that it would pass over the "most populace [sic] and agriculturally productive areas of the Earth."

ISS-B astronauts would spend 90 man-hours per week testing, calibrating, and modifying a $40-million, 4700-pound suite of 19 experiment sensors covering the spectrum from ultraviolet through visible light to infrared and microwave. They would also continue biotechnology experiments; for example, the OART team allotted 70 man-hours per week to continuation of the IMBLMS program begun on board ISS-A.

ISS-B solar arrays and batteries would produce between seven and 15 kilowatts of continuous electricity for experiments and station operations. As with ISS-A, the OART engineers did not specify ISS-B's solar array configuration, though they implied that it would have a collecting area larger than the ISS-A configuration.

The MDA flown as part of Skylab was more more cluttered than it appears in this NASA cutaway. Skylab crews did not feel comfortable within the MDA because it lacked an obvious "up-down" orientation; no doubt the ISS MDAs would be modified to take this into account. EREP = Earth Resources Experiment Package. ATM = Apollo Telescope Mount
ISS-C, scheduled for launch in January 1981, and ISS-D, scheduled for launch on NASA's last Saturn V rocket in July 1983, would have many similarities. Each would have a crew complement of nine, making NASA's reliance on the three-man ISS CSM for crew rotation and resupply somewhat problematic. Surprisingly, though the OART engineers acknowledged that, based on their own NASA flight schedule, the reusable Space Shuttle would begin flights in late 1981, they elected (for the sake of "simplicity") not to use it for ISS-C and ISS-D crew rotation and resupply.

ISS CSM launches in January, February, and March 1981 would boost ISS-C's population to nine. Only a month after its third crew arrived, its first crew would complete its 90-day stint on board the station and would return to Earth. NASA would immediately launch a fourth crew to replace them.

ISS-C and ISS-D would each receive 12 three-man crews. Each station would support nine men for 360 of the 420 days it was occupied. Flights to ISS-C and ISS-D would bring to 36 the total number of ISS CSMs and SRM-S-IVB boosters required for the program.

ISS-C astronauts would "evaluate in terms of direct Earth economic benefits the use of the space environment for materials processing and manufacture." Taking advantage of weightlessness and nearly pure vacuum, the astronauts would devote 95 man-hours per week to manufacturing large crystals, exotic composite materials, and biological compounds impossible (or at least very difficult) to create under terrestrial conditions. Manufactured materials and compounds would splash down with returning astronauts as "down" cargo in the ISS-C CMs.

The Saturn V S-IC second stage would have served as a counterweight for the ISS-C artificial-gravity experiment. Image credit: NASA
ISS-C would also see a 45-day artificial-gravity experiment that would preempt the space exploitation experiments. The OART engineers provided few details of the experiment, though they did explain that the spent S-II second stage of the Saturn V that launched ISS-C into orbit would serve as an artificial-gravity counterweight. Probably cables would have linked the interim station and the spent stage; as the cables were slowly reeled out, thrusters on ISS-C would have fired to spin the assemblage end-over-end and keep the cables under tension. As the cables reached maximum extension, thrusters would carefully trim the spin rate to ensure the desired acceleration - which the crew would feel as gravity - on board the ISS-C station.

The ISS-C/ISS-D solar array configuration would be identical to that of ISS-B; technological advancements would, however, enable their power systems to provide no less than 15 kilowatts of continuous electricity. The ISS-C and ISS-D astronauts would also evaluate Isotope Brayton nuclear power units for use on NASA's permanent Space Station.

The Isotope Brayton units would not reach space attached to ISS-C and ISS-D; rather, they would be launched separately, possibly atop Titan rockets. The OART engineers did not describe how they would rendezvous and dock with ISS-C and ISS-D. The five-ton ISS-C Isotope Brayton unit would generate six kilowatts of electricity; the more advanced six-and-a-half-ton ISS-D unit would produce 15 kilowatts, doubling that station's electrical supply.

Biotechnology experiments would continue during the ISS-C and ISS-D missions. The ISS-C biotechnology program would, of course, include assessment of the effects of spin-induced artificial gravity. With their nine-person crews, the third and fourth stations of the ISS program would be more crowded than their predecessors, offering an opportunity for study of complex human interactions aboard spacecraft.

ISS-D would include three free-flying astronomy modules in addition to asatronomy instruments on the station. How the free-flyers would reach LEO was not made clear. The $50-million Cosmic Ray Physics Laboratory would weigh in at a whopping 26,700 pounds. The $125-million, 6195-pound Solar Astronomy Module would include "larger versions" of the solar astronomy instruments in the Skylab ATM. The $130-million, 6000-pound Stellar Astronomy Module would carry a telescope with a three-meter mirror. For comparison, the Hubble Space Telescope primary mirror is 2.4 meters across. Astronauts would regularly collect exposed film from the free-flying modules, though how they would reach them was not explained.

The OART engineers estimated that, by the time the last ISS-D crew returned to Earth, NASA would have accrued the equivalent of more than two years of permanent Space Station biomedical data and operations experience from its four interim stations. This would, they concluded, constitute the ISS Program's chief benefit to U.S. spaceflight; specifically, it would



"Intelligence Report: Aims and Costs of the Soviet Space Station Program," SR IR 70-1-S, Directorate of Intelligence, Central Intelligence Agency, January 1970

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Dreaming a Different Apollo, Part One

03 November 2015

Dreaming a Different Apollo, Part Three

Image credit: NASA
Had anyone told him on 4 January 1964 that he'd be standing on the moon on 4 January 1974, he'd probably have punched whoever that was in the nose. That was the day Al burned and they lost the race. They'd stumbled, taken too long to get up again, and so had emboldened their adversary.

The Soviets had taken a different approach to piloted moon-flight; one less costly, safer, and more likely to succeed than the American Apollo plan. They never tired of saying that. They had used their converted R-7 missiles, the same rockets that had launched Sputnik and Laika and Gagarin and Leonov. They had ignored their captured Germans, they said, had gone with native Russian wisdom.

Five launches, five pieces orbiting Earth, with the last one carrying two men. They had chased down the other four, docked with them. Those four payloads turned out to be rocket stages; by the time the next-to-last exhausted its propellants and was cast off, the two cosmonauts were on course for the moon.

No one expected them to land. Everyone thought it was a fly-around circumlunar mission - which would have been bad enough, as far as American prestige was concerned. Yet land they did. 8 October 1968 - the date that men, products of the superior Soviet system, stood for the first time on another world. Even after almost six years, he could not quite believe that it had happened.

The two cosmonauts spent their last rocket stage and most of the propellants in their tiny lander to set down not far from a robot lander launched a month before. They hadn't said much about that lander after they launched it, so everyone thought it had crashed. Suddenly, though, its purpose became clear: besides providing a landing beacon for the manned lander, it was tanker.

After they'd planted and saluted their flag, the first thing they did was drive the tubby tanker, with its eight little wheels, to within hose length of their lander. Then they fastened on the hoses and pumped across the propellants.

The Russians called the place they landed Tranquility Base. Of course it wasn't a real "base" - that came later. They picked up a few rocks and saluted their flag a second time for the camera. Then, five hours after they landed, they blasted off for home.

"Charlie, you daydreaming over there?" The voice from his headphones gave him a start. He cleared his throat. "No, boss. Keepin' an eye on things." He heard Young chuckle, then his commander appeared out of the long shadow Lander-2 cast on the stark gray plain.

Beyond stood three more landers, L-1, L-3, and L-4, scattered off into the distance. L-1 was short, empty, abandoned. L-3 and L-4, with their pointy Earth-Return Vehicles on top, were the tallest things for a hundred miles around.

Native Russian wisdom, Duke thought, snorting. No way the Russians could do what they were about to do, even with the Proton and Salyut rockets they had used to win the second moon race, the race to establish a permanent lunar outpost.

The pressurized rover Endurance was already unloaded from L-1, powered up, and checked out. Argo, its near-twin, still stood atop L-2, its front windows pointed at the sky. Argo's four cleated wheels glinted in stark sunlight; its roof was in shadow, but visible by light reflected from the lunar surface. The wheels were locked onto the ramp Argo would roll down to reach the ground.

Now the ramp and Argo's rounded nose began to tip slowly - ever so slowly - off vertical, toward the rising lunar Sun. "Gene-o," Duke said, "tip start looks good from this side. Do you copy?" Cernan, commander of Endurance, spoke up after a moment. "Yeah, Charlie - looks nice and straight here, too. Over."

"Good resistance on the motors," said Evans, Cernan's pilot. He stood close by L-2, reading the lighted display on the flip-down rover-release control panel. Argo was now tilted about 30 degrees from vertical. "Stand by for the drop," Evans said.

Argo continued to tip, passing horizontal. As its nose began to angle downward, the ladder-like lower ramp slid out and touched the surface in two puffs of dust. "Ramp is locked," Evans reported.

Duke moved forward to watch the wheel locks disengage. "Ready for wheel lock release," said Evans. "Go ahead, Ron," said Young. Duke saw the three locking mechanisms disengage and tip out of the way. On Earth, there'd been three rapid loud bangs - pyros cutting the locks. Here, in lunar vacuum, utter silence.

Argo rolled the last yard to the surface, bounced a little on its suspension and stirred up some dust. As it rolled to a stop, the umbilical linking it to L-2 pulled free and, after a moment, the rover's low-gain antenna tilted and slewed automatically and found Earth.

"Rover boys, this is Houston." That was Ken Mattingly on Capcom. Mission Control shift had changed from White to Maroon. A long, crackling pause. "We are receiving Argo telemetry. Looks good."

"Whew-ee! That's two for two," said Cernan.

"Can't wait to get behind the wheel," said Young as he circled Argo, video recording its exterior for the engineers back on Earth. "Ken - how are we on the timeline? Over."

A pause. "John, you're about 10 minutes behind. Not yet into your PLSS reserve. No one is worried here. Over." "Roger that," said Young, as he stowed his recorder in his hip bag.

Mattingly spoke again after a moment. "Rover control says - he says, 'no racing once you're behind the wheel.' He keeps saying that. He's worried about you hotshots. Over." Young and Cernan both chuckled.

Cernan spoke. "John, Charlie, Ken - Ron and me, we're headed back to Endurance. We're hungry. Over."

"Go ahead, get your dinner," Young said, hopping past Duke, toward their lander. "Charlie and I will return to L-4 in a coupla minutes. That OK, Ken?"

A pause. "Gene, John - you are go to close out EVA-1. Over."

Duke hopped over to Young. He turned, minding his footing, and looked back at Argo, glittering on the surface of the moon, and at the retreating PLSS backpacks of Cernan and Evans, who followed the trail of footprints leading to Endurance. Argo had light blue painted highlights and Endurance had red ones. They matched the red stripes on Cernan's suit and the blue stripes on Young's.

"All right, Charlie, let's get inside," Young said. "Tomorrow we test-drive our new ride. Can you believe it?"

Duke felt a lump in his throat. They had come so far, and now they were ready to make history. The first lunar surface circumnavigation. They'd follow the route the engineers and scientists had so carefully plotted for them using the high-res images from the Apollo 12 and Apollo 14 lunar polar orbiters. They'd cross the north pole and drive south over the high center of Farside, then cross the south pole and drive north. They'd rendezvous with Surveyor-derived cargo landers every couple hundred miles or so to take on supplies and refuel.

If all came off as planned, in two months they'd all be back here, in Sinus Medii, ready to power up L-3 and L-4 and return to Earth. And it would all come off as planned, Duke was sure of it. It was time America scored a victory on the moon.

After that, other astronauts - most likely Jack and Karl doing science, plus Dick and Ken in command - would drive around the moon along its equator. If all went as planned, the second circumnavigation would be under way during the U. S. Bicentennial.

"We're on our way, John," said Duke, as he hopped toward L-4's ladder. "It feels real good."