Spectacular new colour view of Mars from Phoenix
BY KEITH COOPER
ASTRONOMY NOW
Posted: May 26, 2008

NASA’s Phoenix spacecraft is spending its first day (or sol, as they say on Mars) on the red planet after safely touching down on the red planet at 12.53am BST (UT +1) this morning. Already, mission scientists are growing excited at the views of the Martian arctic presented in colour images that have been beamed back to Earth from the path-finding probe.

Principle Investigator on the mission, Peter Smith of the University of Arizona, gave Phoenix the thumbs up. “We see the lack of rocks that we expected, we see the polygons that we saw from space, we don’t see ice on the surface, but we think we will see it beneath the surface,” he says. The polygonal marks are similar to patterns of cracks caused by repeated freezing and melting found in icy regions on Earth, strongly hinting at the presence of ice beneath the surface layer of dirt.

One of the first images of Phoenix's surroundings shows a terrain filled with pebbles and dark polygonal patterns, thought to be cracks in the ice just beneath the surface caused by repeated melting and freezing. Image: NASA/JPL-Caltech/University of Arizona.

“We’re so relieved that Phoenix has managed to land safely,” adds Dr Tom Pike of Imperial College London, who is leading the UK team that contributed to some of the instruments on Phoenix. “The descent and landing phase of the mission is one of the most tricky and hazardous. It’s great to have made it down in one piece and now we can get to work uncovering more of the red planet’s surface.”

Notable in the new pictures of that surface is the lack of large boulders, unlike the terrain filled with large rocks that NASA’s Mars rovers, Spirit and Opportunity, regularly come across. Instead, strewn across the surface of the northern arctic plains known as Vastitas Borealis (68 degrees north, 233 degrees east), are lots of small and possibly icy pebbles.

Phoenix’s mission is to dig down into the ground and the permafrost below to, first of all, confirm beyond all doubt that the ice is indeed there. With its digging arm, it will scoop up some of the ice and dirt from as deep as perhaps a metre underground, and analyse this material in the Thermal and Evolved Gas Analyser (TEGA), which Phoenix carries in its onboard laboratory. In the simplest terms, this instrument is a furnace that will bake the Martian ice and dirt, releasing gases that will then pass through a mass spectrometer that will determine what gases they are, and whether any complex organic molecules are present that may be indicative of life, either in the past or the present. In addition, Phoenix’s laboratory also includes an experiment called the Microscopy, Electrochemistry and Conductivity Analyser (MECA), with which it will dissolve samples of dirt and ice in water to determine the abundance of minerals and gases contained within the samples.

The chances of Phoenix directly detecting life on Mars are slim. However, MECA carries the most powerful microscope ever taken to another planet, and could potentially image Martian bacteria larger than ten microns (i.e. ten millionths of a metre). The likelihood though is that Phoenix will just be able to reveal whether the chemistry of the Martian tundra is favourable to the possible existence of life, to prepare for future missions such as NASA’s Mars Science Laboratory (scheduled to launch in 2009) and the European Space Agency’s ExoMars rover (due to launch in 2011). Because life as we know it needs water to survive, the arctic and polar regions of Mars are considered prime spots in which to search for it.

Phoenix is designed to survive for three months on the surface, before the Martian winter really gets a grip. However, that is more than enough time for it to achieve its mission. With the drama and razzamatazz of the landing over, planetary scientists can now concentrate on the science mission.

Stay tuned to www.astronomynow.com, and keep reading the monthlyAstronomy Now magazine, available now from your local newsagent, for future stories about what Phoenix discovers on the red planet.