Mars keeps turning up surprises
5 April 2001It was standing room only for the "Water and life on Mars" session at the European Geophysical Society's General Assembly in Nice last week. "This shows that the life issue is by no means dead. This was a very lively session," commented Agustin Chicarro, Project Scientist for ESA's Mars Express mission.
The latest results from Mars Global Surveyor (MGS), NASA's spacecraft now in orbit around the Red Planet, are revealing that Mars may not be completely dry or geologically inactive. After feeding the latest temperature and topography data into a model, Robert Haberle from NASA Ames found that, even today, conditions could occasionally permit liquid water to surface in a few regions where ancient lakes are thought to have existed.
Nathalie Cabrol, from the SETI Institute at NASA Ames, looked forward to the launch of Mars Express in 2003 because the stereo and global imaging provided by the High Resolution Stereo Camera (HRSC) should be the "best" so far for determining whether layers seen on the surface were deposited as sediments in paleolakes, or by volcanoes. Several of those attending also expressed their eagerness to see results from MARSIS, the ground penetrating radar that will fly on Mars Express, which is the only instrument planned for any mission capable of searching for water and ice down to a few kilometres below ground.
If there's water on Mars, then there could be - or could have been - life. Imre Friedmann from Florida State University presented the latest evidence for ancient life in the form of biogenic magnetite in a Martian meteorite. This evidence was recently published in Proceedings of the National Academy of Sciences and widely reported by the media. However, meteorite studies are no substitute for experiments on the surface of the planet, as the possibility of contamination by biological specimens on Earth can never be entirely eliminated. Beagle 2, the lander element of ESA's Mars Express mission, is the only spacecraft so far planned that will make the search for life on Mars central to its mission. Gvstar Klingelhvfer from Johannes-Gutenberg University in Mainz, reported that the Mvssbauer spectrometer on the lander would be capable of distinguishing biogenic from non-biogenic magnetite. Beagle 2's other instruments will also look for different, chemical signatures of life.
Five sessions in the planetary and solar system sciences section of the Assembly were devoted to the exploration or scientific understanding of Mars. A whole morning of talks and about 20 posters were devoted to Mars Express and its scientific payload. Both the oral presentations and posters attracted large audiences. There were also talks on other missions, including France's plans to send four Netlanders to the Red Planet for seismological and climate studies. Among ideas presented for future missions were a Marskite, under preparation at ESTEC, ESA's technical centre in the Netherlands, and a micromission made out of shape memory alloys and weighing only 20kg, which is under study at the DLR, Germany.
"Every time we go to a more detailed scale, Mars seems to be a new place," commented Chicarro when reflecting on the outcome of the meeting. "After Mariner 6, people saw craters in the southern hemisphere and thought 'oh, the Moon again'. Mariner 9 saw the polar caps, canyons, volcanoes and wind - and Viking saw it all in more detail still. With MGS, we've had a revolution again - we now know that Mars had a magnetic field and there's evidence for huge amounts of water everywhere in the past. It used to be just geologists and geophysicists who were interested in Mars, but now we're building global models with contributions from a wide range of disciplines."