A picture of Victoria Crater on Mars taken by the Mars Global Surveyor. The vertical relief, which appears steeper than usual, provides evidence that water once existed on the Red Planet. (Reuters)

Los Angeles, Dec. 6 (AP): A provocative new study of photographs taken from orbit suggests that liquid water flowed on the surface of Mars as recently as several years ago, raising the possibility that the Red Planet could harbour an environment favourable to life.

The crisp images taken by the Mars Global Surveyor do not directly show water. Rather, they show apparently recent changes in surface features that provide the strongest evidence yet that water even now sometimes flows on the dusty, frigid world. Water and a stable heat source are considered keys for life to emerge.

Until now, the question of liquid water has focused on ancient Mars, and on the Martian north pole, where water ice has been detected. Scientists have long noted Martian features that appear to have been scoured by water or look like shorelines.

“This underscores the importance of searching for life on Mars, either present or past,” said Bruce Jakosky, an astrobiologist at the University of Colorado at Boulder, who had no role in the study. “It’s one more reason to think that life could be there.” Oded Aharonson, an assistant professor of planetary science, said that while the interpretation of recent water activity on Mars was “compelling”, it’s just one possible explanation.