After a short circuit last month in one of the Mars Lander's test ovens, NASA is moving its most important test to the front of the line in case this next run is the instrument's last.
The eight analysis ovens, which have been dubbed TEGA, heat Martian soil so that any gases emitted can be analyzed. On its first test in mid-June, the oven being used developed a short circuit. National Aeronautics and Space Administration scientists stalled any further TEGA analysis while they were studying the problem. And now they've halted planned tests and moved a test of Martian ice up to the front of the line, according to Ray Arvidson, a co-investigator for the Phoenix Mars Lander's robotic arm team and a professor at Washington University in St. Louis.
"Because of the possibility, even the remote possibility, that TEGA might go belly-up in the next sample, we wanted to go straight to ice," said Arvidson. "We cleared the pathway to get the next sample from the ice. The prudent choice is to go off and get the most important sample."
The Mars Lander, which is on a one-way mission since it can't return to Earth, is expected to gather and analyze samples from the northern pole of Mars for a total of three months. Scientists are looking for the elements that could support life, and determining whether there is water on Mars has been one of the mission's key goals.
Late last month, NASA announced that its initial analysis showed that Martian soil could support life. Saying they were "flabbergasted" by the data they were receiving, scientists pointed out that the minerals in the soil on Mars are typical of soils here on Earth. They even noted that asparagus, green beans and turnips would thrive in the alkaline dirt.
Their mineral analysis was based on two tests from the same trench that the Lander's robotic arm dug in the ground. Researchers received analysis from the wet chemistry laboratory on the Mars Lander and from the microscopic imager that sent back pictures of the trench, named "Wonderland," that contained the tested soil. At the time, NASA scientists were waiting for analysis from the TEGA ovens from the same trench. Running the three tests on the same soil was the ultimate goal.
That, however, has been put off so the oven can be used to test the ice -- just in case the ovens can't be used again.
Barry Goldstein, project manager for this Mars mission, told Computerworld that the problematic circuit apparently shorted out when the Lander was trying to shake some clumpy soil down into the oven. When the robotic arm deposited the soil onto the screen above the oven, none of it would fall through. A rasp attached to the arm vibrated the screen to try to shake some soil down -- seven different times.
Goldstein said the robotic arm had to vibrate the screen four times as much as scientists had ever planned on. And that's when they believe the circuit shorted.
Now, scientists are running a series of tests to see how they can scrape up enough ice and move it to the oven before it vaporizes in the Martian atmosphere. The ice, which is at -135 degrees Fahrenheit and as hard as a sidewalk, has proven tough to scrape up, said Arvidson.
On Monday, the robotic arm tried 50 different scrapes and didn't dig up enough ice to test. Now, scientists are trying the rasp, which is on the back of the scoop. Arvidson said he's quite sure the rasp will be able to scrape up enough ice; the real challenge, he noted, is moving the scrapings into the oven before they disappear.
Because the water vapor in the atmosphere is so low and because the temperature is so cold, liquid water isn't stable on Mars, he explained. The ice, if not kept in shadow and quickly transferred to the analyzer, would simply vaporize.
Scientists are working on calculating how quickly they can scrape up some ice and move it while making sure the Lander and robotic arm stay out of the sun.
Arvidson said it may be a week or more before the test can be run on the ice in TEGA.
Leslie Tamppari, a Phoenix project scientist at the Jet Propulsion Laboratory, said the Lander in the meantime has been busy collecting atmospheric data and taking pictures of the rocks and soil around it.