<p>Confirming this mineral clue took four years of analysis by several scientists. An outcrop that Spirit examined in late 2005 revealed high concentrations of carbonate, which originates in wet, near-neutral conditions, but dissolves in acid. The ancient water indicated by this find was not acidic.<br /><br />NASA's rovers have found other evidence of formerly wet Martian environments. However the data for those environments indicate conditions that may have been acidic. <br /><br />In other cases, the conditions were definitely acidic, and therefore less favourable as habitats for life. Lab tests helped confirm the carbonate identification. <br /><br />"This is one of the most significant findings by the rovers," said Steve Squyres of Cornell University in Ithaca, New York. <br /><br />Squyres is principal investigator for the Mars twin rovers, Spirit and Opportunity, and a co-author of the new report. <br /><br />"A substantial carbonate deposit in a Mars outcrop tells us that conditions that could have been quite favourable for life were present at one time in that place. "<br /><br />Spirit inspected rock outcrops, including one scientists called Comanche, along the rover's route from the top of Husband Hill to the vicinity of the Home Plate plateau which Spirit has studied since 2006. <br /><br />Magnesium iron carbonate makes up about one-fourth of the measured volume in Comanche. That is a tenfold higher concentration than any previously identified for carbonate in a Martian rock.<br /><br />"We used detective work combining results from three spectrometers to lock this down," said Dick Morris, lead author of the report and a member of a rover science team at NASA's Johnson Space Centre in Houston."<br /><br />The instruments gave us multiple, interlocking ways of confirming the magnesium iron carbonate, with a good handle on how much there is."<br /><br />Massive carbonate deposits on Mars have been sought for years without much success. The ancient, dense Martian atmosphere was probably rich in carbon dioxide, because that gas makes up nearly all the modern, very thin atmosphere.<br /><br />However, mineral-mapping spectrometers on orbiters since then have found evidence of localised carbonate deposits in only one area, plus small amounts distributed globally in Martian dust, says a NASA release.<br /><br />The rovers landed on Mars in January 2004 for missions originally planned to last three months. Spirit has been out of communication since March 22 and is in a low-power hibernation status during Martian winter. <br /><br />Opportunity is making steady progress toward a large crater, Endeavour, which is about seven miles away. The findings were published in the June edition of Science.<br /></p>
<p>Confirming this mineral clue took four years of analysis by several scientists. An outcrop that Spirit examined in late 2005 revealed high concentrations of carbonate, which originates in wet, near-neutral conditions, but dissolves in acid. The ancient water indicated by this find was not acidic.<br /><br />NASA's rovers have found other evidence of formerly wet Martian environments. However the data for those environments indicate conditions that may have been acidic. <br /><br />In other cases, the conditions were definitely acidic, and therefore less favourable as habitats for life. Lab tests helped confirm the carbonate identification. <br /><br />"This is one of the most significant findings by the rovers," said Steve Squyres of Cornell University in Ithaca, New York. <br /><br />Squyres is principal investigator for the Mars twin rovers, Spirit and Opportunity, and a co-author of the new report. <br /><br />"A substantial carbonate deposit in a Mars outcrop tells us that conditions that could have been quite favourable for life were present at one time in that place. "<br /><br />Spirit inspected rock outcrops, including one scientists called Comanche, along the rover's route from the top of Husband Hill to the vicinity of the Home Plate plateau which Spirit has studied since 2006. <br /><br />Magnesium iron carbonate makes up about one-fourth of the measured volume in Comanche. That is a tenfold higher concentration than any previously identified for carbonate in a Martian rock.<br /><br />"We used detective work combining results from three spectrometers to lock this down," said Dick Morris, lead author of the report and a member of a rover science team at NASA's Johnson Space Centre in Houston."<br /><br />The instruments gave us multiple, interlocking ways of confirming the magnesium iron carbonate, with a good handle on how much there is."<br /><br />Massive carbonate deposits on Mars have been sought for years without much success. The ancient, dense Martian atmosphere was probably rich in carbon dioxide, because that gas makes up nearly all the modern, very thin atmosphere.<br /><br />However, mineral-mapping spectrometers on orbiters since then have found evidence of localised carbonate deposits in only one area, plus small amounts distributed globally in Martian dust, says a NASA release.<br /><br />The rovers landed on Mars in January 2004 for missions originally planned to last three months. Spirit has been out of communication since March 22 and is in a low-power hibernation status during Martian winter. <br /><br />Opportunity is making steady progress toward a large crater, Endeavour, which is about seven miles away. The findings were published in the June edition of Science.<br /></p>
