Rover to Roll Off Ahead of Schedule

NASA’s Opportunity rover severed its final link to its lander Friday as it prepared for its first drive onto the Martian surface, two days ahead of schedule.

Controllers planned to signal the craft to begin the roll-off just after midnight Friday and hoped to receive confirmation early this morning.

Meanwhile, repairs are proceeding on Opportunity’s twin rover, Spirit, out of action for more than a week because of a computer malfunction, and the team at NASA’s Jet Propulsion Laboratory in Pasadena expected it to be back to normal operation as soon as tomorrow.

Controllers have been operating the craft in what is called “cripple” mode, in which Spirit’s flash memory is not used.

The flash memory, similar to memory cards in digital cameras, is used for short-term storage of data before it is transmitted to Earth.

The team concluded that the primary reason Spirit stopped sending data to Earth was that the number of files built up in its flash memory had overwhelmed its computer’s ability to manage them. Engineers deleted 1,700 unnecessary files Friday, such as those accumulated during the seven-month cruise to Mars, then re-booted the craft’s computer using the flash memory.

“I am pleased to report it appears to be working just fine,” said Glenn Reeves, chief engineer for the rover’s software. He said the team should be able to declare the craft “fully recovered” by Sunday.

Spirit, which landed on Mars on Jan. 3, has resumed many of its scientific activities at its Gusev Crater landing site, resuming its detailed examination of the rock called Adirondack. The craft sent back its first microscopic image of the surface of the rock, as well as a Mossbauer spectrum revealing its chemical composition.

“This is a really cool spectrum,” said JPL’s Dick Morris. It showed that the rock was composed primarily of olivine-bearing basalt with trace amounts of an iron oxide known as magnetite.

“Together they tell us this is a good volcanic rock,” he said. “On Earth, it’s one of the most common types of rock we find on the surface.”

Over the next two days, the team will use the craft’s arm to brush dust off the surface of the rock, then use the rock abrasion tool, or RAT, to remove any coating so they can test the rock’s interior to see if it is different from the surface.

Spirit will then roll away to a nearby crater called Bonneville. The team has named craters in the region after lakes on Earth.

Opportunity’s early days on Mars have proceeded smoothly, said systems engineer Daniel Limonadi. Overnight Thursday, the craft deployed its rear wheels, freed its middle wheels and stowed its instrument-bearing arm for travel.

The craft, which landed on Mars on Jan. 24, also partially retracted the air bags at its rear, then pushed down on them with one of the lander’s three petals to point the craft’s nose down about 12 degrees.

“We have a very good egress path now,” Limonadi said. “We can get ready to do science.”

The craft has begun using its thermal emission spectrometer, a device the scientists call mini-TES, to examine the surface of Opportunity’s Meridiani Planum landing site, looking for the hematite that Mars orbiters had said was there.

Scientists chose Meridiani as a landing site because of the presence of hematite, an iron oxide that most commonly forms in the presence of water, although it can also be formed by volcanic action.

At a news conference Friday, deputy principal investigator Ray Arvidson of Washington University would not confirm that the team had found the hematite. “Let’s just say that the mini-TES team members all have huge smiles on their faces,” he said.