December 19, 2003. Copyright 2002. Graphic News. All rights reserved.

Six Mars probes in search for life

LONDON, December 19, Graphic News: An international armada is heading for the planet Mars to determine if life exists or ever existed there.

By early 2004, six spacecraft will be in orbit or exploring the surface of Mars. The European Space AgencyÕs Mars Express -- EuropeÕs first mission to another planet -- will join NASAÕs Mars Global Surveyor and Mars Odyssey, already in orbit around the planet.

A British-built robot, Beagle 2, which is due to land on Christmas day will be joined by NASAÕs exploration rovers Spirit, on January 4, and its identical twin Opportunity on January 25. A seventh craft, JapanÕs first interplanetary explorer, Nozomi (ÒHopeÓ), which has taken five years to reach the planet, was hopelessly crippled by solar flares earlier this year.

Of the previous 31 missions to the Red Planet since 1960, two out of three have ended in failure. Scientists had to wait until 1964 for their first success, when Mariner 4 made the first fly-by, snapping 21 blurred and grainy pictures.

Mars Express carries instruments for probing the planetÕs atmosphere and surface, including the first radar capable of returning data from below the Martian surface, where large layers of ice are believed to exist.

In 2002, Mars Odyssey made one of the most important discoveries, finding evidence of vast quantities of water-ice -- enough to cover the planet in an ocean at least 500 metres (1,640 feet) deep -- just below the surface across great swathes of the planet.

Cadging a lift on the back of Mars Express is Beagle 2, a probe that will land on Isidis Planitia, a theoretical wet spot where traces of life may have been preserved.

Beagle-2 is the first lander since NASAÕs two Viking probes in the 1970s to look specifically for evidence of past or present life on Mars. It is equipped with a robot sampling arm and a small ÒmoleÓ capable of sub-surface sampling. The lander also carries instruments for gas chromatography and mass spectroscopy, a microscope, panoramic and wide-angle cameras.

The two American landers, Spirit and Opportunity, are the first missions designed to land, search out the most promising areas to study, and then trundle over to study them. NASA has chosen two scientifically compelling landing sites: The Gusev Crater, a giant impact crater that appears to have once held a lake; and Terra Meridiani, a broad outcropping of hematite, an iron oxide mineral that usually forms in the presence of liquid water.

Many astrobiologists say these are the places to look for evidence of life because the presence of water is believed to be a prerequisite for life, either past or present.

ÒMeridiani and Gusev both show powerful evidence of past liquid water, but in very different ways,Ó said Dr. Steve Squyres, a geologist at Cornell University. ÒMeridiani has a chemical signature of past water. Gray hematite is usually, but not always, produced in an environment where there is liquid water. At Gusev, youÕve got a big hole in the ground with a dry riverbed going right into it. There had to have been a lake in Gusev Crater at some point. They are fabulous sites, and they complement each other because theyÕre so different.Ó
/ENDS

Sources: NASA, Jet Propulsion Laboratory, European Space Agency