Nasa sees 'Mars quake'
2005-09-21 07:54
Washington - A Nasa orbiter has detected a series of dynamic geological and thermal changes on the surface of the Red Planet, possibly caused by a "Mars quake", mission scientists said on Tuesday.
The Mars Global Surveyor spacecraft found gullies on a sand dune that did not exist in 2002 and fresh tracks left by tumbling boulders. The orbiter also documented more shrinking of deposits of frozen carbon dioxide near the planet's south pole, suggesting a changing climate.
"To see new gullies and other changes in Mars surface features on a time span of a few years presents us with a more active, dynamic planet than many suspected before Mars Global Surveyor got there," said Michael Meyer, chief scientist for the mission.
The two new gullies photographed in April are 900 metres long and about 30 to 40 metres wide.
The new craters that formed since the 1970s suggest that models used to estimate the passage of time on the planet will need to be adjusted, Meyer said.
In images captured by the spacecraft's optical instruments, more than a dozen boulders left tracks after rolling down a hill sometime between November 2003 and December 2004.
"It is possible they were set in motion by strong wind or by a 'Mars quake,'" said Michael Malin, principal investigator for the Mars Orbiter Camera on board the Global Surveyor.
Launched in November 1996, the Global Surveyor entered orbit in 1997 and scientists expect it will continue to relay valuable information for another "five to ten more years", according to Tom Thorpe, project manager for the mission at the Jet Propulsion Laboratory in Pasadena, California.
Two other spacecraft are orbiting the planet: Nasa's Mars Odyssey and the European Space Agency's Mars Express.
Nasa also said on Tuesday it had named a new director of the troubled space shuttle programme, Wayne Hale, who will succeed Bill Parsons.
Hale, a mechanical engineer, has worked for NASA since 1978 and served as flight director for more than 10 years, supervising mission control in Houston for 40 shuttle launches.
- AFP