This image of the Gale Crater on Mars was created using visible-light information from NASA’s Mars Reconnaissance Orbiter and the European Space Agency’s Mars Express orbiter.
The crater contains rocks that have preserved records of what the environment was like in the early history of the red planet.
Instruments on the orbiters have detected traces of clay minerals and sulfate salts in the crater. The amount of clay is greater in the foreground, and these differences indicate a possible change in Mars’ ancient environment.
The small hills in the picture could provide clues to the water cycle on Mars as varying exposure to sunlight affects ground temperature and hence evaporation rates.
Astronomers believe that as the temperature increases, the water in the sulfate salts on the hillsides evaporates, while the salts absorb water as the temperature drops.
The Mars Reconnaissance Orbiter has also detected surface features that change with the seasons on some hillsides, for example in the Newton Crater.
These could well be flows of salty water, according to new research announced by NASA today.
