From: University of Arizona
Posted: Saturday, May 19, 2007
A spacecraft called Phoenix is destined to land on Mars in 2008, seeking to unravel some of the mysteries of the red planet.
Back on Earth, NASA scientist and Phoenix biological interpretation co-investigator Chris McKay will anxiously await results radioed from the red planet for clues about possible organics on Mars. McKay is a scientist who works at NASA Ames Research Center in the heart of California's Silicon Valley.
"What I hope we find is organic material in the ice," said McKay. "We know from Viking that there's very little, maybe no organic materials in the soils. We're hoping that the ice in the polar regions could preserve organics." NASA sent two Viking landers to Mars in 1976, which landed in non-icy zones, but neither found any organics in those areas.
NASA has scheduled the Phoenix lander spacecraft for launch in August 2007. In May 2008, Phoenix is to land in an ice-rich area in the northern polar region of the planet between 65 and 72-north latitude. The lander's robotic arm will dig into the arctic terrain in search of clues about the history of water on Mars, and also for evidence of organics.
"It's got an arm that will dig to reach the ice which is below ground," McKay explained. "At the site where we're landing, we think we have to go down four to eight centimeters, about 1.6 to three inches, down."
Phoenix will deploy its robotic arm that is capable of digging trenches as deep as 1.6 feet (about one half meter) into the soil, or to the top of an ice boundary, during the course of the 90-day mission.
"We can identify organic material, but we won't be able to determine if it is biological," said McKay. The organic material could be biological, or it could be delivered by meteors from space, according to McKay.
To analyze soil samples collected by the robotic arm, Phoenix will carry eight small ovens in a portable laboratory. Selected martian samples will be heated to release volatiles that can be examined for their chemical composition and other characteristics. The instrument that will look for organics is the Thermal and Evolved Gas Analyzer (TEGA.) It will heat samples that the arm has retrieved to temperatures as high as 1,832 degrees Fahrenheit (1,000 degrees Celsius) and will examine the vapors released from the heated samples, according to McKay. Scientists say the samples could be martian dirt and ice.
The University of Arizona, Tucson, is developing TEGA. The TEGA principal investigator is Professor William V. Boynton.
"What I hope will happen is we'll get to the ice and scrape up a little piece of it, put it in the TEGA oven, and we'll find that it is rich in organics," McKay said. "It would mean that the ice is the place to find organics. Phoenix will be the test." The subsurface layers of ice, originally indicated by sensors on the Mars Odyssey spacecraft and recently imaged by the MARSIS radar on the European Space Agency's Mars Express spacecraft, could be an organic-rich, frozen soup, according to McKay.
Speaking about the significance of finding organics in Mars' polar ice, McKay said scientists would not know from the Phoenix mission how the organics were formed. "We'll know that they're there, and that's pretty exciting," he said.
"Finding organics in the ice would mean that the ice in the polar regions is where we might find evidence of past life - frozen and dead in the dirt and ice," McKay said.
"There is no liquid water on the surface, but there is evidence that there was liquid water on the surface in the past," McKay noted. "There is some possibility that there are active water features on Mars today, but it's not certain," McKay added, referring to recent evidence from NASA's Mars Global Surveyor spacecraft that gullies on the planet may have been produced by recent flows of liquid water.
Asked about how proof of organics uncovered by Phoenix in the red planet's ice might influence the future exploration of Mars, McKay said, "It would mean that the poles are where we're going to go next." McKay noted that the Mars Science Laboratory (MSL) rover is designed for operation in zones where ice is not predominant.
"I'm hoping that the next one after the MSL, unofficially named the Astrobiology Field Laboratory - also a rover - would examine a martian region where ice is prevalent," McKay ventured. The Astrobiology Field Laboratory could be designed to cope with icy martian areas, according to McKay.
In addition to looking for organics, scientists will conduct other studies of Mars' polar region using Phoenix, which is not a rover, but instead will remain where it lands. The Phoenix mission is the first mission chosen for NASA's Scout program, designed to produce smaller, lower-cost, competed spacecraft.
The Phoenix mission is derived from two previous missions. Named for the resilient mythological bird, Phoenix will use a lander that was intended for use by 2001's Mars Surveyor program before NASA cancelled the lander portion of that program.
Phoenix also will carry a complex suite of instruments that are improved variations of those that flew on the unsuccessful Mars Polar Lander mission that failed to return a signal to Earth from the red planet's southern polar region in 1999.
Engineers originally designed the martian lander to land in lower, warmer latitudes on Mars, where, presumably, there is softer dirt. Phoenix mission scientists are working to resolve the problem that the spacecraft was designed to work in softer soil. Scientists expect that ice on Mars will be very hard, because the temperature of ice on the red planet is extremely low.
Imaging technology inherited from both the Pathfinder and Mars Exploration Rover missions also will be used in Phoenix's stereo camera, located on its 6.6-foot (2-meter) mast. The camera's two "eyes" will reveal a high-resolution perspective of the landing site's geology, and will also provide range maps that will enable the team to choose ideal digging locations. Multi-spectral capability will enable Phoenix to identify local minerals.
To update our understanding of martian atmospheric processes, Phoenix will probe the martian atmosphere up to 12.4 miles (20 kilometers) in altitude, obtaining data about the formation, duration and movement of clouds, fog and dust plumes. The spacecraft will also carry temperature and pressure sensors.
Principal Investigator Peter H. Smith of the University of Arizona, Tucson, leads the Phoenix mission. Project management is being led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Lockheed Martin Space Systems, located near Denver, Colo., is designing and building the spacecraft and will provide Mars space flight operation for Phoenix. The Canadian Space Agency, the University of Neuchatel (Switzerland), the University of Copenhagen and the Max Planck Institute in Germany provide international contributions for Phoenix. JPL is a division of the California Institute of Technology in Pasadena.
For information about the Phoenix mission visit:
For information about the Viking missions to Mars, visit:
For more information about McKay, please visit:
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