Gullies spreading like cracks down a once-smooth Martian sand dune are one sign that unexpected forces of change are moving across the planet’s surface, NASA officials said Tuesday.
The change in the dune – over a three year period – was captured by a Colorado-built spacecraft called the Mars Global Surveyor.
NASA is celebrating the orbiter’s eighth birthday this month. On Tuesday, it released new images and data the craft collected.
Mars, scientists said, is more changeable than they realized, with liquid-carved gullies racing down crater edges, polar ice caps melting and boulders tumbling down cliffs, perhaps shaken loose by small earthquakes.
“To see new gullies and other changes … over a time span of a few years presents us with a more active, dynamic planet than many suspected,” said Michael Meyer, NASA’s chief scientist for Mars exploration.
The orbiter has been successful in large part because its longevity has allowed researchers to watch geological events reshape Mars’ surface, Meyer said.
Since 1997, scientists have focused the spacecraft’s instruments on the same spots over and over, often revealing startling changes, said Jack Mustard, a geology professor at Brown University in Providence, R.I.
The images show geological events familiar to Earth-dwellers, he said, describing rockfalls and meandering gullies. “But this is Mars,” Mustard said.
Lockheed Martin Space Systems in Jefferson County built the Mars Global Surveyor.
The mission was designed to cost about $200 million, and the craft was supposed to last only about two Earth years, said Jeff Lewis, a Lockheed engineer.
NASA extended the orbiter’s mission by several years, at the cost of about $9 million a year, Meyer said.
Michael Malin, NASA’s chief scientist on the project and the director of Malin Space Science Systems in San Diego, said the new gullies may have been carved by melting carbon-dioxide snow.
Scientists have also captured longer-term changes by comparing more recent images with those shot during the Viking missions of the 1970s, Malin said.
New craters have pocked Mar’s surface since scientists have been watching, probably the result of small asteroids smashing into the planet, Malin said.
Images from the craft can be seen at mars.jpl.nasa.gov/mgs.
Staff writer Katy Human can be reached at 303-820-1910 or khuman@denverpost.com.
