Mars rover makes most of opportunity

Mars rover makes most of opportunity

Spirit has always been the unluckier of NASA's twin Mars rovers.

Just weeks after landing in a Martian crater in 2004, it went haywire and transmitted gibberish to Earth. Engineers eventually nursed it back to health. As if the near-death experience wasn't enough, Spirit was upstaged early on by its twin, Opportunity, which landed in a geologic gold mine and was the first to determine that the frigid, dusty planet possessed a wetter past.

Bad luck has fallen again on Spirit. As the workhorse rover passed its sixth year on the red planet, it found itself stuck in a sand trap, probably forever. The six-wheel robot geologist has been in jams before, but this one seems to be the finale.

The space agency said last week that it's ending efforts to extricate the robot from the loose soil where it's been trapped since April. Spirit will instead continue to function as a stationary science platform -- if it makes it through the harsh winter months. "Spirit has encountered a golfer's worst nightmare: the sand trap that no matter how many strokes you take, you can't get out of," said Doug McCuistion, director of NASA's Mars Exploration Program.

Fortunately for researchers, what may turn out to be Spirit's final resting spot looks like a scientific bonanza. The sand is rich in sulfate, a mineral that forms in the presence of water, researchers say.

Originally designed to conduct a three-month mission, Spirit and Opportunity have operated past their warranty. Since Spirit landed on Jan. 3, 2004, followed by Opportunity three weeks later, the rovers have driven more than 16 miles, cresting hills and peering into craters. Spirit and Opportunity are also closing in on the record for longest-running Mars surface mission, a mark currently held by the Viking 1 lander, which operated on the planet for six years and 116 days.

-- Associated Press

Study gives nod to those who doze off

So you've just had lunch and are sitting in class or at your office desk. And now you're fighting that overwhelming desire for a little nap. According to new research, a midday snooze would be the right thing to do. It can dramatically restore and even boost your brain power afterward.

Researchers at the University of California at Berkeley took a group of 39 healthy adults and divided them into two groups. All were given a rigorous learning task at noon designed to test their fact-based memories. Both groups performed at comparable levels on that test. Half of the group then took a 90-minute nap -- long enough to go through a full sleep cycle. At 6 p.m. both groups were again given a round of tasks. In this case, the nappers performed significantly better and actually improved in their capacity to learn, according to the study.

Exactly why the nap effect works "is still a mystery," according to Berkeley assistant professor of psychology Matthew Walker, lead investigator of the study. "One theory is that particular types of brain-wave patterns that occur during sleep help change the storage locations of recently stored information from short-term to long-term, such that when you wake up, the short-term capacity for new memory formation is refreshed." He said the findings reinforce the researchers' hypothesis that sleep is needed to clear the brain's short-term memory storage -- the hippocampus -- and make room for new information.

"It's as though the e-mail inbox in your hippocampus is full and, until you sleep and clear out those fact e-mails, you're not going to receive any more mail. It's just going to bounce until you sleep and move it into another folder," Walker said in a statement.

The results build on a previous study by Walker and others that found that staying up all night (to study for an exam, say, or finish a big project at work) has a negative impact, decreasing the ability to recall crammed-in facts by nearly 40 percent, due to a shutdown of brain regions caused by sleep deprivation.

-- Margaret Shapiro