NASA's next Mars-bound spacecraft, the Phoenix Mars Lander, was partway through assembly and testing at Lockheed Martin Space Systems, Denver, in September 2006, progressing toward an August 2007 launch from Florida. In this photograph, spacecraft specialists work on the lander after its fan-like circular solar arrays have been spread open for testing. The arrays will be in this configuration when the spacecraft is active on the surface of Mars.

Image Credit: NASA/JPL/UA/Lockheed Martin

Image Addition Date: 2006-11-29

Launch Date Aug. 4, 2007 | 09:26:34 UT
Launch Site Cape Canaveral, Florida, USA | Pad SLC-17A
Destination Mars
Type Lander
Status Successful
Nation United States
Alternate Names 2007-034A, 32003


Phoenix was sent to Mars to search for evidence of past or present microbial life and to study geology and climate on the icy arctic plains of the Martian north pole. The lander's robotic arm could dig up to half a meter (20 inches) into the Martian soil and return it for analysis to a special bake-and-sniff oven.


Phoenix verified the presence of water-ice in the Martian subsurface, which NASA's Mars Odyssey orbiter first detected remotely in 2002. Phoenix's cameras also returned more than 25,000 pictures from sweeping vistas to near the atomic level using the first atomic force microscope ever used outside Earth. The findings advance the goal of studying whether Mars could ever have been favorable to microbial life.

Key Dates

Aug. 4, 2007 | 09:26:34 UT: Launch

May 25, 2008 | 23:53:44 UT: Mars Landing

Nov. 2, 2008: End of Mission

In Depth

Favorable opportunities to launch missions to Mars come about every 26 months, but the 2007 launch opportunity was the best in several years for sending a surface mission to the northern region on Mars. The Phoenix mission took advantage of this opportunity and launched a lander with a robotic arm to Mars on 4 August 2007 on board a three-stage Delta II launch vehicle.

NASA's Mars Odyssey orbiter found evidence in early 2002 that the northern region on Mars shelters high concentrations of water ice mixed with the soil just beneath the surface. Phoenix was sent with a payload of science instruments particularly appropriate for examining an environment of ice and soil. Phoenix's robotic arm was designed to dig trenches, scoop up soil and water ice samples, and deliver these samples to the Thermal and Evolved Gas Analyzer (TEGA) and the Microscopy, Electrochemistry and Conductivity Analyzer (MECA) instruments for detailed chemical and geological analysis.

Phoenix Lander Self Portrait on Mars, Vertical Projection
This view is a vertical projection that combines hundreds of exposures taken by the Surface Stereo Imager camera on NASA's Mars Phoenix Lander and projects them as if looking down from above. Image Credit: NASA/JPL-Caltech/University Arizona/Texas A&M University

Data from Phoenix suggest liquid water has interacted with the Martian surface throughout the planet's history and into modern times. The research also provides new evidence that volcanic activity has persisted on the Red Planet into geologically recent times, several million years ago.

Phoenix precisely measured isotopes of carbon and oxygen in the carbon dioxide of the Martian atmosphere. Isotopes are variants of the same element with different atomic weights. "Isotopes can be used as a chemical signature that can tell us where something came from, and what kinds of events it has experienced," said Paul Niles, a space scientist at NASA's Johnson Space Center in Houston. This chemical signature suggests that liquid water primarily existed at temperatures near freezing and that hydrothermal systems similar to Yellowstone's hot springs have been rare throughout the planet's past. Measurements concerning carbon dioxide showed Mars is a much more active planet than previously thought. The results imply Mars has replenished its atmospheric carbon dioxide relatively recently through volcanic emissions, and the carbon dioxide has reacted with liquid water present on the surface.

The mission's biggest surprise was finding a multi-talented chemical named perchlorate in the Martian soil. "With perchlorate, for example, we see links to atmospheric humidity, soil moisture, a possible energy source for microbes, even a possible resource for humans" said Michael Hecht of NASA's Jet Propulsion Laboratory, Pasadena, Calif. Perchlorate, which strongly attracts water, makes up a few tenths of a percent of the composition in all three soil samples analyzed by Phoenix's wet chemistry laboratory. Perchlorate could pull humidity from the Martian air. At higher concentrations, it might combine with water as a brine that stays liquid at Martian surface temperatures. Some microbes on Earth use perchlorate as food. Human explorers might find it useful as rocket fuel or for generating oxygen.

Another surprise from Phoenix was finding ice clouds and precipitation more Earth-like than anticipated. The lander's Canadian laser instrument used for studying the atmosphere detected snow falling from clouds.

Phoenix's cameras also returned more than 25,000 pictures from sweeping vistas to near the atomic level using the first atomic force microscope ever used outside Earth.

"Not only did we find water ice, as expected, but the soil chemistry and minerals we observed lead us to believe this site had a wetter and warmer climate in the recent past—the last few million years—and could again in the future," said Phoenix Principal Investigator Peter Smith of the University of Arizona, Tucson.

Phoenix ended communications in November 2008 as the approach of Martian winter depleted energy from the lander's solar panels.


Launch Vehicle: Delta II 7925 (three-stage)

Spacecraft Mass: 1,464 pounds (664 kilograms) total at launch, consisting of 181-pound (82-kilogram) cruise stage, 242-pound (110-kilogram) back shell, 137-pound (62-kilogram) heat
shield, and 904-pound (410-kilogram) lander. That lander mass includes 130 pounds (59 kilograms) of science-instrument payload and 148 pounds (67 kilograms) of fuel.

Power: Solar panels and lithium-ion batteries

Spacecraft Instruments:

59 kilograms (130 pounds) consisting of

  1. Robotic Arm

  2. Robotic Arm Camera

  3. Surface Stereo Imager

  4. Thermal

  5. Evolved-Gas Analyzer

  6. Microscopy, Electro-chemistry and Conductivity Analyzer

  7. Mars Descent Imager

  8. Meteorological Station

Landing site: 68 degrees north latitude, 233 degrees east longitude, in Vastitas Borealis, the arctic plains of Mars

Earth-Mars distance on May 25, 2008: 276 million kilometers (171 million miles)

One-way radio transit time Mars to Earth on May 25, 2008: 15.3 minutes

Total distance traveled, Earth to Mars: About 422 million miles (679 million kilometers)

Primary mission: 90 Martian days, or “sols” (equivalent to 92 Earth days)

Expected near-surface atmospheric temperatures at landing site during primary mission: minus 100 Fahrenheit to minus 28 Fahrenheit (minus 73 Celsius to minus 33 Celsius)

Additional Resources

National Space Science Data Center Master Catalog: Phoenix

Gallery: (all images)

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