Lockheed Martin Phoenix Mars Lander

History

The NASA Phoenix Mars Lander was a stationary robotic spacecraft developed to investigate the ice-rich northern plains of Mars. The mission focused on the history of water, the chemistry and habitability of the Martian arctic soil, and the interaction between the surface and atmosphere. NASA selected Phoenix in 2003 as the first mission in the Mars Scout Program.

Phoenix reused major hardware from the canceled Mars Surveyor 2001 Lander and incorporated instruments derived from Mars Polar Lander and other earlier programs. The University of Arizona's Lunar and Planetary Laboratory led the science mission, NASA's Jet Propulsion Laboratory managed the project and mission design, and Lockheed Martin Space Systems built and tested the spacecraft. The Canadian Space Agency and other international partners supplied additional scientific hardware.

The spacecraft was undergoing assembly and testing as Phoenix by September 2006. It launched from Cape Canaveral on August 4, 2007, reached Mars on May 25, 2008, and operated on the surface for 157 Martian sols. NASA records the mission, its objectives, and principal results on the Mars Phoenix mission page.

Development

Phoenix emerged from NASA's effort to pursue smaller, competed Mars missions while reusing existing flight hardware. The lander structure had originally been prepared for the Mars Surveyor 2001 program, which was canceled after the loss of Mars Polar Lander. The nearly complete lander was preserved by Lockheed Martin and later adapted for Phoenix after NASA selected the University of Arizona proposal in August 2003.

The reuse strategy affected both the spacecraft and its payload. Phoenix carried improved or repurposed versions of instruments associated with Mars Polar Lander and Mars Surveyor 2001, while adding equipment needed to study the shallow ice-soil boundary in the Martian arctic. NASA approved the mission to proceed after a critical design review in June 2005. By September 2006, Phoenix was in assembly and test at Lockheed Martin Space Systems in Denver.

Launch and cruise

Phoenix launched on a Delta II 7925 rocket from Launch Complex 17A at Cape Canaveral Air Force Station, Florida, at 09:26 UTC on August 4, 2007. The launch placed the spacecraft on an interplanetary trajectory toward Mars. The cruise lasted about 295 days and covered approximately 680 million km (422 million miles). Four trajectory corrections refined the approach to the northern polar region.

NASA's Mars Odyssey and Mars Reconnaissance Orbiter, together with the European Space Agency's Mars Express, were positioned to support the landing and communications. A detailed NASA account of the launch, cruise, landing, and surface campaign is available in the NASA mission history.

Design

Phoenix was a fixed, solar-powered lander rather than a rover. Its design concentrated available mass on scientific instruments and a robotic sampling system instead of mobility. The spacecraft consisted of a cruise stage for the interplanetary flight, an aeroshell and parachute system for atmospheric entry and descent, and the lander itself with deployable solar arrays, landing gear, scientific instruments, communications hardware, and hydrazine thrusters.

Structure, power, and communications

The complete launch configuration had a mass of about 670 kg, while the landed spacecraft had a mass of about 350 kg. With its solar arrays deployed, the lander was about 5.5 m across. The science deck was about 1.5 m in diameter, and the top of the meteorological mast stood about 2.2 m above the ground.

Electrical power on the surface came from two deployable gallium-arsenide solar arrays with a combined area of about 7.0 m², supported by a nickel-hydrogen battery. Phoenix used X-band communications during cruise and UHF links on and near Mars, normally relaying data through Mars orbiters. Its command and data system was based on a RAD6000 computer.

Entry, descent, and landing system

Phoenix entered the Martian atmosphere at roughly 21,000 km/h. The aeroshell and heat shield provided initial deceleration, followed by a parachute. After separation from the parachute, the lander used radar and twelve hydrazine landing thrusters to reduce its speed for a controlled soft landing. Unlike the airbag systems used by the Mars Exploration Rovers, Phoenix completed its final descent under rocket power.

Robotic arm and sampling system

The robotic arm could extend about 2.35 m from its base and was designed to dig as deep as about 0.5 m into the soil. Its scoop collected soil and ice for delivery to the lander's analysis instruments. A rasp in the scoop helped cut into hard frozen material. The Robotic Arm Camera was mounted near the scoop to inspect trenches, surfaces, and collected samples at close range.

Scientific instruments

• Surface Stereo Imager (SSI): the primary panoramic stereo camera, used for high-resolution imaging, terrain mapping, atmospheric observations, and selection of digging sites.
• Robotic Arm Camera (RAC): a color close-up camera mounted on the robotic arm for examining soil, ice, trench walls, and samples in the scoop.
• Thermal and Evolved Gas Analyzer (TEGA): eight small ovens combined with a mass spectrometer and thermal-analysis equipment for heating soil and ice samples and identifying released gases and volatile compounds.
• Microscopy, Electrochemistry, and Conductivity Analyzer (MECA): a package containing a wet chemistry laboratory, optical microscope, atomic force microscope, and thermal and electrical conductivity measurements for characterizing soil particles and soluble chemistry.
• Meteorological Station (MET): a weather package with pressure and temperature sensors, a wind indicator, and a lidar for studying dust, clouds, fog, and the vertical structure of the lower atmosphere.
• Mars Descent Imager (MARDI): a descent camera installed on the spacecraft. A pre-launch interface concern created a risk to critical descent data, so mission managers decided not to operate MARDI during landing.

Operational history

Landing and initial operations

Phoenix landed on May 25, 2008, in the Green Valley area of Vastitas Borealis at about 68.2 degrees north latitude, farther north than any previous Mars lander. During the descent, the HiRISE camera aboard Mars Reconnaissance Orbiter photographed Phoenix beneath its parachute, the first time one spacecraft imaged another while it was descending to the surface of another planet.

After touchdown, Phoenix waited about 15 minutes for dust to settle before deploying its two solar arrays. Early images showed flat, patterned terrain with small pebbles and polygonal ground forms similar to terrestrial permafrost regions. The robotic arm made its first test scoop on May 31, 2008.

Water ice and soil analysis

Images taken beneath the lander and inside trenches revealed bright material close to the surface. In June 2008, several bright clumps exposed by the robotic arm disappeared over several days, behavior consistent with water ice sublimating in the thin Martian atmosphere. On July 31, NASA announced that TEGA measurements had directly confirmed water ice in a soil sample.

MECA wet-chemistry measurements found a moderately alkaline soil containing soluble salts. Phoenix also detected perchlorate in the Martian soil. NASA reported that the perchlorate result neither confirmed nor refuted the possibility of life on Mars, while adding important information about the chemistry of the landing site.

Atmospheric observations

The meteorological package returned regular measurements of temperature, pressure, wind, dust, clouds, and the lower atmosphere. The lidar detected falling snow from water-ice clouds. Together with surface imaging and soil measurements, these observations helped characterize how water moves between the atmosphere and the ground in the Martian arctic.

End of mission

The nominal surface mission was planned for 90 sols and was completed in August 2008. NASA then extended operations as Phoenix remained healthy. As northern autumn progressed, falling sunlight and lower temperatures reduced available electrical power. A dust storm in October worsened the power shortage, and the lander entered safe mode on October 28.

Phoenix transmitted its last signal on November 2, 2008, after 157 sols of surface operation. Attempts to reestablish contact during the next Martian spring were unsuccessful. Orbital images indicated substantial winter damage to the spacecraft, including apparent damage to its solar arrays, and NASA formally ended the mission on May 24, 2010.

Operators

• NASA: sponsor of the Mars Scout mission and overall U.S. space agency responsible for Phoenix.
• University of Arizona Lunar and Planetary Laboratory: led the science mission, with Peter H. Smith serving as principal investigator.
• NASA Jet Propulsion Laboratory: managed the project, mission design, spacecraft operations, and mission control.

Specifications (Phoenix Mars Lander)

General characteristics

• Type: stationary robotic Mars lander.
• Manufacturer: Lockheed Martin Space Systems.
• Launch mass: approximately 670 kg.
• Landing mass: approximately 350 kg.
• Deployed width: approximately 5.5 m with solar arrays open.
• Science deck diameter: approximately 1.5 m.
• Height: approximately 2.2 m to the top of the meteorological mast.
• Robotic arm reach: approximately 2.35 m.
• Maximum digging depth: approximately 0.5 m.
• Planned surface mission: 90 Martian sols.
• Actual surface operation: 157 Martian sols, ending with the last contact on November 2, 2008.

Power and communications

• Surface power: two deployable gallium-arsenide solar arrays with about 7.0 m² combined area, supported by a nickel-hydrogen battery.
• Communications: X-band during cruise and UHF relay communications at Mars through compatible orbiters.

Propulsion and landing

• Propellant: hydrazine monopropellant.
• Final landing propulsion: twelve 302 N hydrazine thrusters.
• Launch vehicle: Delta II 7925.
• Launch site: Launch Complex 17A, Cape Canaveral Air Force Station, Florida.

Scientific payload

• Imaging: SSI and RAC, with MARDI installed but not operated during descent.
• Sample analysis: TEGA and MECA.
• Surface sampling: robotic arm and scoop with rasp tool.
• Meteorology: MET package with pressure, temperature, wind, and lidar measurements.