Nasa chiefs are thrilled with detailed images and data from Mars Reconnaissance Orbiter, now circling the Red Planet.
One of MRO’s first targets in early October was a valley where water is known to have been present for a long time.
Principle investigator Dr Scott Murchie said the clay-rich areas showed some of the best evidence for conditions favourable for life on ancient Mars.
A European orbiter, Mars Express, previously spotted ancient deposits of clay there which could only have formed in the presence of water.
Now MRO has scanned the area, Mawrth Vallis, in detail and its spectrometer instrument examined its differing clay mineral content in detail.
Upper layers of the valley have been eroded away, revealing an underlying layer that formed in wet conditions a few billion years ago. Scientists say the results will also help them to learn how the martian climate has changed over time.
Another vast valley, Chasma Boreale, which juts into the north polar ice cap, revealed layers with varying amounts of ice in the soil.
Dr Murchie, of Johns Hopkins University, Maryland, said: “You see more-ice-rich and less-ice-rich layers, which tells you that conditions changed from the time one layer was deposited to the time another layer was deposited. These layers are geologically young – on the order of thousands or millions of years – and may hold clues about climate cycles.”
MRO’s high-resolution camera is powerful enough to spot detail the size of a person. It has already photographed the Nasa rover Opportunity and its tracks as it perches on the edge of a half-mile wide crater.
The camera’s principal investigator, Dr Alfred McEwen of the University of Arizona, Tucson, said: “These images are truly beautiful, and since they resolve features the size of people, you can visualize yourself hiking around in these diverse terrains.”
The image shows a region south of Mawrth Vallis and is a combination of infrared, red, and blue-green images. It has been enhanced to accentuate the colour differences. The bright material may be rich in clays and date back to a time when Mars had a wetter environment. Credit: NASA/JPL/University of Arizona.