Mars orbiter spots changes on Red planet

The Martian surface has undergone dramatic changes in the last few years with the appearance of new gullies and fresh boulder tracks, new images show.

The photos, taken by the orbiting Mars Global Surveyor spacecraft, suggest the Red Planet is perhaps more active than previously thought.

The spacecraft, in its ninth year in orbit, spotted two fresh gullies on a Martian sand dune that were not present in 2002. Scientists think the gullies might have formed when frozen carbon dioxide trapped by windblown sand vaporised, releasing gas that allowed the sand to flow freely.

The spacecraft also took images of boulder tracks at another site that were not there two years ago.

The tracks were probably caused by dozens of boulders rolling down a slope from strong wind or a quake, scientists said.

Researchers also noted that impact craters forming since the 1970s suggest crater-formation is a slow process, occurring at one-fifth the pace previously thought.

The pace is important because it is used to estimate the age of Martian surfaces, said Michael Malin, principal investigator of the camera aboard the spacecraft.

The planet may be undergoing a climate change, according to images that show a shrinking of carbon dioxide deposits near the south pole. For the last three Martian summers, the deposits have shrunk from the previous year.

The Mars Global Surveyor was launched in 1996 and entered orbit a year later. The project is managed by Nasa’s Jet Propulsion Laboratory.