Thursday, May 28, 1998 Published at 16:41 GMT 17:41 UK
More clues to life on Mars
Mars - the red colour comes from iron oxide
The Mars Global Surveyor spacecraft currently in Martian orbit has found a large deposit of the mineral hematite. Our science correspondent David Whitehouse explains its significance:
Hematite is a heavy and hard mineral composed of iron and oxygen. Finding it on Mars is not all that surprising. Mars has a red colour that is due to iron oxide on its surface.
The significance of hematite is how it may have been formed. It is usually laid down at the bottom of warm seas. Finding hematite on Mars is another line of evidence that points to Mars being wetter and warmer in the distant past.
Professor Phil Christensen of Arizona State University says that the coarse-grained hematite found on Mars originates from geothermal activity or from bodies of water.
"Even more intriguing is the possibility that the hematite may have come from a large body of water. This is one of the best places to look for evidence of life on Mars."
Geologists may be able to examine the hematite deposit at close quarters in 2001 when a lander touches down on the planet. The landing site has yet to be determined.
"The existence and location of these deposits will provide a positive indication that hot water once existed near the Martian surface. It will aid the selection of future landing sites for exploration," Mr Christensen said.