Posted: 11 November, 2008
After more than five months on the Martian surface, NASA’s Phoenix Mars Lander has said its farewells to the Earth as the decline in solar power forces the spacecraft to shut down.
Phoenix last communicated with mission engineers on 2 November but there is still hope the lander will revive itself and phone home. In addition to shorter daylight hours, Phoenix must also contend with a dustier sky, greater cloud coverage and colder temperatures as the northern Mars summer turns to autumn.
One of Phoenix's major acheivements was finding a layer of ice just below the surface. The ice was seen to vapourise before its cameras in just a few Martian days. Image: NASA/JPL-Calech/University of Arizona/Texas A&M University.
Even though the practical side of the spacecraft’s work has concluded, mission scientists say that the analysis of data from the instruments is in its earliest stages. "Phoenix has given us some surprises, and I'm confident we will be pulling more gems from this trove of data for years to come," says Phoenix Principal Investigator Peter Smith of the University of Arizona.
Phoenix already notched up a first by landing farther north than any other spacecraft has dared on the Martian surface. Following its arrival on 25 May 2008, Phoenix has photographed, dug, scooped, baked, tasted and sniffed out the ingredients of the north polar soil, confirming the presence of water-ice in the Martian subsurface early in its mission. Phoenix is the first mission to directly ‘touch’ water-ice on Mars, which it found just a few centimetres below the surface, verifying the remote observations made by Mars Odyssey in 2002. The lander’s cameras returned over 25,000 images from panoramas to atomic level images of soil grains with the first atomic force microscope ever used outside Earth.
"Phoenix not only met the tremendous challenge of landing safely, it accomplished scientific investigations on 149 of its 152 Martian days as a result of dedicated work by a talented team," says Phoenix Project Manager Barry Goldstein at NASA's Jet Propulsion Laboratory. The mission was scheduled to last just three months, but continued for over five months.
During the first 90 Martian days after its May 25, 2008 landing in the north arctic plains of Mars, Phoenix dug several trenches in the workspace reachable with the lander's robotic arm. Image: NASA/JPL-Calech/University of Arizona/Texas A&M University.
One of Phoenix's science goals was to advance our understanding of Mars as a potentially habitable environment, either now or in the past. Supporting findings include documenting a mildly alkaline soil environment unlike any found by earlier Mars missions, finding small concentrations of salts that could be nutrients for life, discovering perchlorate salt, which has implications for ice and soil properties, and detecting calcium carbonate, a marker of effects of liquid water. Many of the minerals detected by both Phoenix and the Mars Exploration Rovers could only have formed in the presence of water, and scientists believe that by finding water, they will find clues to the history of life on Mars, should it ever have existed.
Phoenix also documented the Martian weather for the duration of the mission, observing snow descending from clouds, and providing extensive data on daily temperature, pressure, humidity and wind, as well as direct observations of haze, clouds, frost and dust devils. Coordinated with NASA's Mars Reconnaissance Orbiter, the duo performed simultaneous ground and orbital observations of Martian weather to provide context for both sets of recordings.
"Phoenix provided an important step to spur the hope that we can show Mars was once habitable and possibly supported life," says Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. "Phoenix was supported by orbiting NASA spacecraft providing communications relay while producing their own fascinating science. With the upcoming launch of the Mars Science Laboratory, the Mars Program never sleeps."
Mars Science Laboratory will launch in late 2009 and will be winched down to the Martian surface by a rocket-powered ‘sky-crane’. The landing site has yet to be determined. You can read more about the Mars Science Laboratory in the Astronomy Now 2009 Yearbook, available to buy now.