Phoenix

NASA's Phoenix landed farther north on Mars than any previous spacecraft to date. The lander verified the presence of water ice in the Martian subsurface, which NASA's Mars Odyssey orbiter first detected remotely in 2002. Phoenix sent back more than 25,000 pictures.

Aug. 4, 2007: Launch

May 25, 2008: Touch down on Mars

Nov. 2, 2008: Mission ends, last signal received from Phoenix

The Mars Phoenix lander was the first under NASA’s new Mars Scout Program to send a series of small, low-cost, low-complexity, and higher-frequency robotic missions to Mars. (The second and last mission in the series was MAVEN launched in 2013. Mars missions were then folded into the Discovery Program where they would compete with missions to other planetary destinations.)

The mission’s science goals included studying the history of water on Mars in all phases, searching for evidence of habitable zones, and assessing the biological potential of the ice-soil boundary.

More broadly, the lander was designed to determine whether life ever existed on Mars, characterize the climate and geology of the Red Planet, and to help prepare for future human exploration of its surface.

The spacecraft was essentially built on the basis of the abandoned and never-launched Mars Surveyor 2001 lander and contained other instruments built to support the unsuccessful Mars Polar Lander mission.

It was the first NASA mission to Mars that was led directly by a public university, the University of Arizona (more specifically its Lunar and Planetary Laboratory). The primary mission was designed to last 90 sols (Mars days) or approximately 92 Earth days.

Phoenix was launched from Cape Canaveral, Florida, at 09:26:34 UT on Aug. 4, 2007. After two burns of the Delta’s second stage, the PAM-D upper stage (with a Star 48 motor) fired at 10:44 UT Aug. 4, to send the spacecraft toward Mars. It conducted course corrections on Aug. 10 and Oct. 30, 2007, and April 10 and May 17, 2008, the latter two directing it toward the northern polar region of Mars.

As it approached Mars, the orbits of three other spacecraft orbiting Mars—Mars Reconnaissance Orbiter (MRO), 2001 Mars Odyssey, and Mars Express—were adjusted so that they could observe Phoenix’s entry into the atmosphere. In addition, MRO’s HiRISE instrument was used to thoroughly scout out the landing area, with some images identifying rocks smaller than the lander itself.

Phoenix entered the Martian atmosphere at nearly 13,000 miles per hour (21,000 kilometers per hour) on May 25, 2008, and touched down safely on the surface at 23:38:38 UT in the Green Valley of Vastitas Borealis.

It was the first successful landing of a stationary soft-lander on Mars since Viking 2 about 32 years earlier.

During its descent, MRO’s HiRISE camera clearly photographed Phoenix suspended from its parachute, the first time one spacecraft photographed another during a planetary landing.

The lander waited 15 minutes for the dust to settle before unfurling its solar panels. The first images showed a flat surface marred by pebbles and troughs, but no large rocks or hills as expected given its northern position.

Within four days, Phoenix had transmitted a complete 360-degree panorama of the cold Martian surface, deployed the nearly 8-foot (2.5-meter) robotic arm, and started returning regular weather reports.

On May 31, the robotic arm scooped up dirt and began sampling Martian soil for ice.

By June 19, mission scientists were able to conclude that clumps of bright material in the “DodoGoldilocks” trench dug by the robotic arm were probably water ice: the material had vaporized four days after the scoop.

On July 31, NASA officially announced that, based on an analysis (by the thermal and evolved gas analyzer instrument, or TEGA) of a sample collected by the lander, there is water on Mars. William Boynton of the University of Arizona noted that such data added to the data from the 2001 Mars Odyssey orbiter.

On Aug. 5, in response to media rumors about the possibility of life on Mars, the Phoenix team announced that they had found perchlorates on the surface of Mars that neither confirmed nor refuted the possibility of life on Mars. The results also led scientists to revisit the data from the Viking landers.

By the end of August, Phoenix had completed its originally planned 90-day mission, which was extended to Sept. 30.

On Sept. 12, the lander scoop delivered a new soil sample to its wet chemistry laboratory that mixed an aqueous solution from Earth to the soil as part of a process to identify soluble nutrients and other chemicals in the soil.

Early results suggested that the soil was alkaline, composed of salts and other chemicals such as perchlorate, sodium, magnesium, chloride, and potassium.

On Oct. 13, Phoenix weathered a dust storm and placed another soil sample, the sixth, in the TEGA instrument. But as the Martian winter was upon the landing site, the lander went into safe mode on Oct. 28, 2008, due to insufficient sunlight and poor weather conditions. During safe mode, activities that weren’t critical were suspended while the spacecraft awaited instructions from mission control.

There was daily communication with the lander from Oct. 30 to Nov. 2 but no signals were received after Nov. 2, 2008.

On Nov. 10, 2008, NASA announced the lander had finished its work on the Red Planet.

On Dec. 1, 2008, the agency announced that NASA “had stopped using its Mars orbiters to hail the lander.”

The loss of the spacecraft was due to a combination of low power and the dust storm.

During the harsh cold winter, CO2 ice – some of it as thick as about 7.5 inches (19 centimeters) – probably built up on the lander, sufficiently heavy to break the fragile solar arrays. Because of this likely damage, subsequent communications attempts with the lander in early 2010, were unsuccessful.

On May 24, 2010, NASA announced that the project was formally ended. Images from MRO conclusively showed that Phoenix’s solar panels were severely damaged by the Martian winter.

Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.