Phoenix (spacecraft) explained

Mission Type:Mars lander
Operator:NASAJPLUniversity of Arizona
Cospar Id:2007-034A
Mission Duration:90 martian sols (planned)
157 martian sols (actual)
1 year, 2 months, 29 days (launch to last contact)
Manufacturer:Lockheed Martin Space Systems
Landing Mass:350kg (770lb)
Launch Mass:670 kg (1,477 lb.)[1]
Power:450W, Solar array / NiH2 battery
Launch Date: 09:26 UTC[2]
Launch Rocket:Delta II 7925
Launch Site:Cape Canaveral SLC-17
Launch Contractor:Lockheed Martin Space Systems
Last Contact:
Declared:May 24, 2010
Arrival Date: 23:53:44 UTC
MSD 47777 01:02 AMT
Location:Green Valley, Vastitas Borealis, Mars
Instruments List:
Link:Phoenix (spacecraft)#Scientific payload
Name1:Robotic arm
Name2:Robotic Arm Camera
Name3:Thermal and Evolved Gas Analyzer
Name4:Mars Descent Imager
Name5:Meteorological station
Name6:Surface Stereo Imager
Name7:Microscopy, Electrochemistry, and Conductivity Analyzer
Insignia Caption:Phoenix Mars Lander mission logo
Insignia Size:145px
Programme:Mars Scout Program
Next Mission:MAVEN

Phoenix was a robotic spacecraft on a space exploration mission on Mars under the Mars Scout Program. The Phoenix lander landed on Mars on May 25, 2008. Mission scientists used instruments aboard the lander to assess the local habitability and to research the history of water there. The total mission cost was about US$386 million, which includes cost of the launch.[3] [4] [5]



Mission overview

The mission had two goals. One was to study the geologic history of water, the key to unlocking the story of past climate change. The second was to evaluate past or potential planetary habitability in the ice-soil boundary. Phoenixs instruments were suitable for uncovering information on the geological and possibly biological history of the Martian Arctic. Phoenix was the first mission to return data from either of the poles, and contributed to NASA's main strategy for Mars exploration, "Follow the water."

The primary mission was anticipated to last 90 sols (Martian days)—just over 92 Earth days. However, the craft exceeded its expected operational lifetime[10] by a little over two months before succumbing to the increasing cold and dark of an advancing Martian winter. Researchers had hoped that the lander would survive into the Martian winter so that it could witness polar ice developing around it – perhaps up to 1 metre of solid carbon dioxide ice could have appeared. Even had it survived some of the winter, the intense cold would have prevented it from lasting all the way through.[11] The mission was chosen to be a fixed lander rather than a rover because:[12]

The 2003–2004 observations of methane gas on Mars were made remotely by three teams working with separate data. If the methane is truly present in the atmosphere of Mars, then something must be producing it on the planet now, because the gas is broken down by radiation on Mars within 300 years,[13] [14] [15] [16] [17] therefore the importance to search for biological potential or habitability of the Martian arctic's soils.[18] Methane could also be the product of a geochemical process or the result of volcanic or hydrothermal activity.[19]





On June 2, 2005, following a critical review of the project's planning progress and preliminary design, NASA approved the mission to proceed as planned.[25] The purpose of the review was to confirm NASA's confidence in the mission.

Scientific payload


During EDL, the Atmospheric Structure Experiment was conducted. This used accelerometer and gyroscope data recorded during the lander's descent through the atmosphere to create a vertical profile of the temperature, pressure, and density of the atmosphere above the landing site, at the that point in time.[27]

Robotic arm and camera


Surface stereo imager


Thermal and evolved gas analyzer

See main article: Thermal and Evolved Gas Analyzer.


On May 29, 2008 (sol), electrical tests indicated an intermittent short circuit in TEGA,[35] resulting from a glitch in one of the two filaments responsible for ionizing volatiles.[36] NASA worked around the problem by configuring the backup filament as the primary and vice versa.[37]


Mars Descent Imager



Microscopy, electrochemistry, and conductivity analyzer

The Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) is an instrument package originally designed for the canceled Mars Surveyor 2001 Lander mission. It consists of a wet chemistry lab (WCL), optical and atomic force microscope, and a thermal and electrical conductivity probe.[41] The Jet Propulsion Laboratory built MECA. A Swiss consortium led by the University of Neuchatel contributed the atomic force microscope.[42]


Sample wheel and translation stage

This instrument presents 6 of 69 sample holders to an opening in the MECA instrument to which the robotic arm delivers the samples and then brings the samples to the optical microscope and the atomic force microscope.[44] Imperial College London provided the microscope sample substrates.[45]

Optical microscope


Atomic force microscope


Wet Chemistry Laboratory (WCL)

The wet chemistry lab (WCL) sensor assembly and leaching solution were designed and built by Thermo Fisher Scientific.[46] The WCL actuator assembly was designed and built by Starsys Research in Boulder, Colorado. Tufts University developed the reagent pellets, barium ISE, ASV electrodes, and performed the preflight characterization of the sensor array.[47]



Thermal and Electrical Conductivity Probe (TECP)

The MECA contains a Thermal and Electrical Conductivity Probe (TECP). The TECP, designed by Decagon Devices, has four probes that made the following measurements: Martian soil temperature, relative humidity, thermal conductivity, electrical conductivity, dielectric permittivity, wind speed, and atmospheric temperature.




Meteorological station







The Phoenix LIDAR laser is a passive Q-switched laser with the dual wavelengths of 1064 nm and 532 nm. It operates at 100 Hz with a pulse width of 10 ns. The scattered light is received by two detectors that operate (green and IR) and the green signal is collected in both analog and photon counting modes.[54] [55]



The laser device discovered snow falling from clouds; this was not known before the mission.[57] It was also determined that cirrus clouds formed in the area.[58]


  • 350kg (770lb)
  • About 5.5m (18feet) long with the solar panels deployed. The science deck by itself is about 1.5m (04.9feet) in diameter. From the ground to the top of the MET mast, the lander measures about 2.2m (07.2feet) tall.
  • Power is generated using two gallium arsenide solar panels (total area 3.1m2) mounted to the cruise stage during cruise, and via two gallium arsenide solar array panels (total area 7m2) deployed from the lander after touchdown on the Martian surface. NiH2 battery with a capacity of 16 A·h.[60]

    Lander systems include a RAD6000 based computer system for commanding the spacecraft and handling data.[61] Other parts of the lander are an electrical system containing solar arrays and batteries, a guidance system to land the spacecraft, eight 1lbf and 5lbf monopropellant hydrazine engines built by Aerojet-Redmond Operations for the cruise phase, twelve 68lbf Aerojet monopropellant hydrazine thrusters to land the Phoenix, mechanical and structural elements, and a heater system to ensure the spacecraft does not get too cold.

    Mission highlights



    A noctilucent cloud was created by the exhaust gas from the Delta II 7925 rocket used to launch Phoenix.[63] The colors in the cloud formed from the prism-like effect of the ice particles present in the exhaust trail.


    The Jet Propulsion Laboratory made adjustments to the orbits of its two active satellites around Mars, Mars Reconnaissance Orbiter and Mars Odyssey, and the European Space Agency similarly adjusted the orbit of its Mars Express spacecraft to be in the right place on May 25, 2008 to observe Phoenix as it entered the atmosphere and then landed on the surface. This information helps designers to improve future landers.[64] The projected landing area was an ellipse 100 km by 20 km covering terrain which has been informally named "Green Valley"[65] and contains the largest concentration of water ice outside the poles.

    Phoenix entered the Martian atmosphere at nearly 21000km (13,000miles) per hour, and within 7 minutes had decreased its speed to 8km/h before touching down on the surface. Confirmation of atmospheric entry was received at 4:46 p.m. PDT (23:46 UTC). Radio signals received at 4:53:44 p.m. PDT[66] confirmed that Phoenix had survived its difficult descent and landed 15 minutes earlier, thus completing a 680 million km (422 million miles) flight from Earth.[67]

    For unknown reasons, the parachute was deployed about 7 seconds later than expected, leading to a landing position some 25–28 km east, near the edge of the predicted 99% landing ellipse.Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) camera photographed Phoenix suspended from its parachute during its descent through the Martian atmosphere. This marked the first time ever one spacecraft photographed another in the act of landing on a planet[68] [69] (the Moon not being a planet, but a satellite). The same camera also imaged Phoenix on the surface with enough resolution to distinguish the lander and its two solar cell arrays. Ground controllers used Doppler tracking data from Odyssey and Mars Reconnaissance Orbiter to determine the lander's precise location as .[70] [71]

    Phoenix landed in the Green Valley of Vastitas Borealis on May 25, 2008,[72] in the late Martian northern hemisphere spring (Ls=76.73), where the Sun shone on its solar panels the whole Martian day.[73] By the Martian northern Summer solstice (June 25, 2008), the Sun appeared at its maximum elevation of 47.0 degrees. Phoenix experienced its first sunset at the start of September 2008.[73]


    Like the 1970s era Viking spacecraft, Phoenix used retrorockets for its final descent.[75] Experiments conducted by Nilton Renno, mission co-investigator from the University of Michigan, and his students have investigated how much surface dust would be kicked up on landing.[76] Researchers at Tufts University, led by co-investigator Sam Kounaves, conducted additional in-depth experiments to identify the extent of the ammonia contamination from the hydrazine propellant and its possible effects on the chemistry experiments. In 2007, a report to the American Astronomical Society by Washington State University professor Dirk Schulze-Makuch, suggested that Mars might harbor peroxide-based life forms which the Viking landers failed to detect because of the unexpected chemistry.[77] The hypothesis was proposed long after any modifications to Phoenix could be made. One of the Phoenix mission investigators, NASA astrobiologist Chris McKay, stated that the report "piqued his interest" and that ways to test the hypothesis with Phoenixs instruments would be sought.

    Surface mission

    Communications from the surface



    The lander's robotic arm touched soil on Mars for the first time on May 31, 2008 (sol). It scooped dirt and started sampling the Martian soil for ice after days of testing its systems.[79]

    Presence of shallow subsurface water ice

    See also: Water on Mars.

    The polygonal cracking at the landing zone had previously been observed from orbit, and is similar to patterns seen in permafrost areas in polar and high altitude regions of Earth.[80] Phoenixs robotic arm camera took an image underneath the lander on sol 5 that shows patches of a smooth bright surface uncovered when thruster exhaust blew off overlying loose soil. It was later shown to be water ice.[81] [82] [83]

    On June 19, 2008 (sol), NASA announced that dice-sized clumps of bright material in the "Dodo-Goldilocks" trench dug by the robotic arm had vaporized over the course of four days, strongly implying that they were composed of water ice which sublimed following exposure. While dry ice also sublimes, under the conditions present it would do so at a rate much faster than observed.[84] [85] [86]

    On July 31, 2008 (sol), NASA announced that Phoenix confirmed the presence of water ice on Mars, as predicted in 2002 by the Mars Odyssey orbiter. During the initial heating cycle of a new sample, TEGA's mass spectrometer detected water vapor when the sample temperature reached 0 °C.[87] Liquid water cannot exist on the surface of Mars with its present low atmospheric pressure, except at the lowest elevations for short periods.[88] [89]

    With Phoenix in good working order, NASA announced operational funding through September 30, 2008 (sol). The science team worked to determine whether the water ice ever thaws enough to be available for life processes and if carbon-containing chemicals and other raw materials for life are present.

    Additionally during 2008 and early 2009 a debate emerged within NASA over the presence of 'blobs' which appeared on photos of the vehicle's landing struts, which have been variously described as being either water droplets or 'clumps of frost'. Due to the lack of consensus within the Phoenix science project, the issue had not been raised in any NASA news conferences.[90]


    Wet chemistry

    On June 24, 2008 (sol), NASA's scientists launched a series of scientific tests. The robotic arm scooped up more soil and delivered it to 3 different on-board analyzers: an oven that baked it and tested the emitted gases, a microscopic imager, and a wet chemistry laboratory (WCL).[91] The lander's robotic arm scoop was positioned over the Wet Chemistry Lab delivery funnel on Sol 29 (the 29th Martian day after landing, i.e. June 24, 2008). The soil was transferred to the instrument on sol (June 25, 2008), and Phoenix performed the first wet chemistry tests. On Sol 31 (June 26, 2008) Phoenix returned the wet chemistry test results with information on the salts in the soil, and its acidity. The wet chemistry lab (WCL) was part of the suite of tools called the Microscopy, Electrochemistry and Conductivity Analyzer (MECA).[92]


    End of the mission

    The solar-powered lander operated two months longer than its three-month prime mission. The lander was designed to last 90 days, and had been running on bonus time since the successful end of its primary mission in August 2008.[10] On October 28, 2008 (sol), the spacecraft went into safe mode due to power constraints based on the insufficient amount of sunlight reaching the lander,[93] as expected at this time of year. It was decided then to shut down the four heaters that keep the equipment warm, and upon bringing the spacecraft back from safe mode, commands were sent to turn off two of the heaters rather than only one as was originally planned for the first step. The heaters involved provide heat to the robotic arm, TEGA instrument and a pyrotechnic unit on the lander that were unused since landing, so these three instruments were also shut down.

    On November 10, Phoenix Mission Control reported the loss of contact with the Phoenix lander; the last signal was received on November 2.[94] Immediately prior, Phoenix sent its final message: "Triumph" in binary code.[95] [96] The demise of the craft occurred as a result of a dust storm that reduced power generation even further.[97] While the spacecraft's work ended, the analysis of data from the instruments was in its earliest stages.

    Communication attempts 2010

    Though it was not designed to survive the frigid Martian winter, the spacecraft's safe mode kept the option open to reestablish communications if the lander could recharge its batteries during the next Martian spring. However, its landing location is in an area that is usually part of the north polar ice cap during the Martian winter, and the lander was seen from orbit to be encased in dry ice. It is estimated that, at its peak, the layer of CO2 ice in the lander's vicinity would total about 30 grams/cm2, which is enough to make a dense slab of dry ice at least NaNinches thick.[98] It was considered unlikely that the spacecraft could endure these conditions, as its fragile solar panels would likely break off under so much weight.[99]

    Scientists attempted to make contact with Phoenix starting January 18, 2010 (sol), but were unsuccessful. Further attempts in February and April also failed to pick up any signal from the lander.[100] [101] [102] [103] Project manager Barry Goldstein announced on May 24, 2010 that the project was being formally ended. Images from the Mars Reconnaissance Orbiter showed that its solar panels were apparently irretrievably damaged by freezing during the Martian winter.[104] [105]

    Results of the mission





    Climate cycles


    Surface chemistry

    Chemistry results showed the surface soil to be moderately alkaline, with a pH of 7.7 ±0.5.[111] [112] The overall level of salinity is modest. TEGA analysis of its first soil sample indicated the presence of bound water and CO2 that were released during the final (highest-temperature, 1,000 °C) heating cycle.[113]

    The elements detected and measured in the samples are chloride, bicarbonate, magnesium, sodium, potassium, calcium, and sulfate.[112] Further data analysis indicated that the soil contains soluble sulfate (SO3) at a minimum of 1.1% and provided a refined formulation of the soil.[112]


    PerchlorateOn August 1, 2008, Aviation Week reported that "The White House has been alerted by NASA about plans to make an announcement soon on major new Phoenix lander discoveries concerning the "potential for life" on Mars, scientists tell Aviation Week & Space Technology."[115] This led to a subdued media speculation on whether some evidence of past or present life had been discovered.[116] [117] [118] To quell the speculation, NASA released the preliminary findings stating that Mars soil contains perchlorate and thus may not be as life-friendly as thought earlier.[119] [120] The presence of almost 0.5% perchlorates in the soil was an unexpected finding with broad implications.[121]

    Laboratory research published in July 2017 demonstrated that when irradiated with a simulated Martian UV flux, perchlorates become bacteriocidal.[122] Two other compounds of the Martian surface, iron oxides and hydrogen peroxide, act in synergy with irradiated perchlorates to cause a 10.8-fold increase in cell death when compared to cells exposed to UV radiation after 60 seconds of exposure.[122] It was also found that abraded silicates (quartz and basalt) lead to the formation of toxic reactive oxygen species.[123] The results leaves the question of the presence of organic compounds open-ended since heating the samples containing perchlorate would have broken down any organics present.[124]

    Perchlorate (ClO4) is a strong oxidizer, so it has the potential of being used for rocket fuel and as a source of oxygen for future missions.[125] Also, when mixed with water, perchlorate can greatly lower freezing point of water, in a manner similar to how salt is applied to roads to melt ice. So, perchlorate may be allowing small amounts of liquid water to form on the surface of Mars today. Gullies, which are common in certain areas of Mars, may have formed from perchlorate melting ice and causing water to erode soil on steep slopes.[126] Perchlorates have also been detected at the landing site of the Curiosity rover, nearer equatorial Mars, and in the martian meteorite EETA79001,[127] suggesting a "global distribution of these salts".[128] Only highly refractory and/or well-protected organic compounds are likely to be preserved in the frozen subsurface.[127] Therefore, the MOMA instrument planned to fly on the 2020 ExoMars rover will employ a method that is unaffected by the presence of perchlorates to detect and measure sub-surface organics.[129]

    Phoenix DVD


    The Phoenix DVD is made of a special silica glass[131] designed to withstand the Martian environment, lasting for hundreds (if not thousands) of years on the surface while it awaits discoverers.

    The text just below the center of the disk reads:

    External links

    LPL, LMSS, JPL and NASA links
    Other links

    Notes and References

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    2. Web site: Nelson . Jon. Phoenix . . February 2, 2014 .
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    7. Forbes
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