13:15 18 May 04 NewScientist.com news service The Mars rover Opportunity has discovered hints of a type of rock never before seen on the planet. Its presence would mean that any watery periods in Mars' past were cold and short-lived.
Opportunity has been perched on the rim of a 130-metre wide crater dubbed Endurance since early May. It has been using its remote sensing instruments to study the rocks exposed in the steep sides of the crater.
A dark layer of rock, one to two metres deep, particularly intrigued mission scientists because it looked so different to the lighter-coloured rocks that Opportunity had studied at its landing site, the smaller Eagle crater. The composition of the latter rocks indicated that water had once washed over them.
Link:
http://www.newscientist.com/news/news.jsp?id=ns99995004 
19th May 2004, 08:50 AM
