|Phoenix Mars Lander
Mars Scout Program - Searching for Signs of Life
After a journey of 423 million miles across the
interplanetary space, the Phoenix Mars Lander touched down on the
surface of the red planet. Its mission: to search for signs of life -
past or present.
Phoenix was a robotic spacecraft on a space exploration mission on Mars under the Mars Scout Program. The Phoenix lander descended on Mars on May 25th, 2008.
Mission scientists used instruments aboard the lander to search for environments suitable for microbial life on Mars, and to research the history of water there.
The multi-agency program was headed by the Lunar and Planetary Laboratory at the University of Arizona, under the direction of NASA's Jet Propulsion Laboratory.
The program was a partnership of universities in the United States, Canada, Switzerland, Denmark, Germany, the United Kingdom, NASA, the Canadian Space Agency, the Finnish Meteorological Institute, Lockheed Martin Space Systems, MacDonald Dettwiler & Associates (MDA) and other aerospace companies.
It was the first mission to Mars led by a public university in NASA history. The mission underscored the value of university-led management. It was led directly from the University of Arizona's campus in Tucson, with project management at the Jet Propulsion Laboratory in Pasadena, Calif., and project development at Lockheed Martin in Denver, Colorado.
The Phoenix Mars Lander surpassed its original three-month mission,
lasting five months in the Martian northern plains, digging up
'firsts' along the way.
The operational funding for the mission extended
through November 10th, 2008. Phoenix is NASA's sixth successful landing out
of seven attempts and is the most recent spacecraft to land
successfully on Mars (as of December 2009) as well as the first
successful landing in a Martian polar region.
The lander completed its
mission in August 2008, and made a last brief communication with Earth
on November 2nd as available solar power dropped with the Martian winter.
The mission was declared concluded on November 10th, 2008, after engineers
were unable to re-contact the craft.
After unsuccessful attempts to
contact the lander by the Mars Odyssey orbiter up to and past the
Martian summer solstice on May 12th, 2010, JPL declared the lander to be
dead. Like the two Mars Exploration Rovers, the program was considered a
success because it exceeded its planned mission length by several
Phoenix Blasting Off to Mars
Phoenix departing planet Earth on the way to Mars
While the proposal for Phoenix was being written, the Mars Odyssey Orbiter used its gamma ray spectrometer and found the distinctive signature of hydrogen on some areas of the Martian surface, and the only plausible source of hydrogen on Mars would be water in the form of ice, frozen below the surface.
The mission was therefore funded on the expectation that Phoenix would find water ice on the arctic plains of Mars. In August 2003 NASA selected the University of Arizona "Phoenix" mission for launch in 2007.
It was hoped this would be the first in a new line of smaller, low-cost, Scout missions in the agency's exploration of Mars program.
The selection was the result of an intense two-year competition with proposals from other institutions. The $325 million NASA award is more than six times larger than any other single research grant in University of Arizona history.
Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory, as Principal Investigator, along with 24 Co-Investigators, were selected to lead the mission. The mission was named after the Phoenix, a mythological bird that is repeatedly reborn from its own ashes.
The Phoenix spacecraft contains several previously built components. The lander used for the 2007–08 mission is the modified Mars Surveyor 2001 Lander (canceled in 2000), along with several of the instruments from both that and the previous unsuccessful Mars Polar Lander mission. Lockheed Martin, which built the lander, had kept the nearly complete lander in an environmentally controlled clean room from 2001 until the mission was funded by the NASA Scout Program.
"The Phoenix spacecraft succeeded in its investigations and exceeded its
planned lifetime," said Fuk Li, manager of the Mars Exploration Program
at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
work is finished, analysis of information from Phoenix's science
activities will continue for some time to come."
The robotic arm's first movement was delayed by one day when, on May 27th, 2008, commands from Earth were not relayed to the Phoenix lander on Mars.
The commands went to NASA's Mars Reconnaissance Orbiter as planned, but the orbiter's Electra UHF radio system for relaying commands to Phoenix temporarily shut off.
Without new commands, the lander instead carried out a set of activity commands sent May 26th as a backup. On May 27th the Mars Reconnaissance Orbiter relayed images and other information from those activities back to Earth.
The Phoenix Mars Lander
Mars is a cold desert planet with no liquid water on its surface. But in
the Martian arctic, water ice lurks just below ground level.
Discoveries made by the Mars Odyssey Orbiter in 2002 show large amounts
of subsurface water ice in the northern arctic plain.
The Phoenix lander
targets this circumpolar region using a robotic arm to dig through the
protective top soil layer to the water ice below and ultimately, to
bring both soil and water ice to the lander platform for sophisticated
The robotic arm was a critical part of the Phoenix Mars mission. On May 28th, scientists leading the mission, sent commands to unstow its robotic arm and take more images of its landing site.
The images revealed that the spacecraft landed where it had access to digging down a polygon across the trough and digging into its the center.
The polygonal cracking in this area had previously been observed from orbit, and is similar to patterns seen in permafrost areas in polar and high altitude regions of Earth. A likely formation mechanism is that permafrost ice contracts when the temperature decreases, creating a polygonal pattern of cracks, which are then filled by loose soil falling in from above.
When the temperature increases and the ice expands back to its former volume, it thus cannot assume its former shape, but is forced to buckle upwards. (On Earth, liquid water would probably enter at times along with soil, creating additional disruption due to ice wedging when the contents of the cracks freeze.)
The Lander's Robotic Arm touched soil on the red planet for the first time on May 31st, 2008. It scooped dirt and started sampling the Martian soil for ice after days of testing. Phoenix's 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 ice. Ray Arvidson of Washington University in St. Louis said: "We could very well be seeing rock, or we could be seeing exposed ice in the retrorocket blast zone."
Phoenix Mars Landing
Nerves and Joy
Animation and mission control video from Mars Phoenix landing day May 25th, 2008.
On June 19th, 2008, NASA announced that die-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 sublimated following exposure.
While dry ice also sublimates, under the conditions present it would do so at a rate much faster than observed. On July 31st, 2008, NASA announced that Phoenix confirmed the presence of water ice on Mars, as predicted on 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. Liquid water cannot exist on the surface of Mars with its present low atmospheric pressure, except at the lowest elevations for short periods.
With Phoenix in good working order, NASA announced operational funding through September 30th, 2008. The science team labored 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'.
Phoenix Mars Mission
The primary mission was anticipated to last 90 sols (Martian days) – just over 92 Earth days. However, the craft exceeded its expected operational lifetime by a little over two months before succumbing to the increasing cold and dark of an advancing Martian winter.
Due to the lack of consensus within the Phoenix science project, the issue had not been raised in any NASA news conferences. One scientist believed that the lander's thrusters splashed a pocket of brine from just below the Martian surface onto the landing strut during the vehicle's landing.
The salts would then have absorbed water vapor from the air, which would have explained how they appeared to grow in size during the first 44 Martian days before slowly evaporating as Mars temperature dropped.
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.
On October 28th, 2008, the spacecraft went into safe mode due to power constraints based on the insufficient amount of sunlight reaching the lander, 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 10th, Phoenix Mission Control reported the loss of contact with the Phoenix lander; the last signal was received on November 2nd.
Immediately prior, Phoenix sent its final message: "Triumph" in binary code. The demise of the craft occurred as a result of a dust storm that reduced power generation even further. While the spacecraft's work ended, the analysis of data from the instruments was in its earliest stages.