Mars Lander Stymied by Ice; Like "Scraping a Sidewalk"
for National Geographic News
|July 11, 2008|
The Mars Phoenix lander is having a difficult time digging through the tough ice at the planet's north pole to collect a usable ice sample for analysis, mission scientists say.
In fact, they compared the digging to scraping a sidewalk.
But the researchers say they expected the icy landscape to be extremely solid and that the lander is equipped for the job.
The team is now delving deeper into the spacecraft's toolbox to gather the icy sample for delivery into the craft's Thermal and Evolved Gas Analyzer (TEGA).
Analysis from this "bake and sniff" oven will help the scientists further their primary goals—investigating the planet's water ice, soil, and potential for life.
But troubleshooting can be difficult at a remove of 200 million miles (320 million kilometers), and the team is treating each attempt at analyzing the Martian surface as potentially its last.
Bill Farrand, of the Boulder, Colorado-based Space Science Institute, is a veteran of interplanetary robotics. He's part of the Mars Exploration Rovers Mission that has been piloting Spirit and Opportunity around the red planet for more than four years.
"Anytime you work with robots in a different kind of environment, there are going to end up being surprises you have to be wary of," he said. "That's part of the process of exploration."
Quest for Ice
During tests earlier this week two scrapers on Phoenix's robotic backhoe succeeded in creating piles of soil and ice particles in the bottom of the trench nicknamed "Snow White."
But the fragments were too small to be collected by the lander's scoop—an operation that NASA engineer Richard Volpe likened in a press statement to "trying to pick up dust with a dustpan but without a broom."
Now the team is preparing to use a drill-like rasp to grind up ice and kick it into the scoop for delivery to the TEGA.
"We knew it was going to be really tough. We put [the drill] into the design on the assumption that we'd need it, and as it turns out, we do," said Barry Goldstein, project manager for the Phoenix Mars Mission.
Goldstein also stressed that the rasp can work quickly, digging and delivering a sample to the oven in about an hour.
"That's important, because if it has water ice in it, we want to avoid [that ice] disappearing between the time we acquire it and we deposit it in the TEGA."
Ahead of Schedule
Digging is not the only thing that has proven difficult. TEGA itself has encountered some snags—including a short circuit that may threaten its operation.
The short likely occurred when the first Martian soil sample was placed in the TEGA. Because the soil was clumpier than expected, the spacecraft had to vibrate for several days to sift a sample into the oven.
Principal investigator Peter Smith, of the University of Arizona, has said that the oven could short circuit again at any time, so his team is working under the assumption that the next sample delivered to the oven is "possibly our last."
Project manager Goldstein added that the Phoenix team has worked hard to identify and preemptively address potential problems but that they are taking things one day at a time.
He added that he's been pleased with Phoenix's successes so far.
"With the exception of the issue we've had with the TEGA, [the mission] has been a lot more benign than I expected," he said.
Phoenix had a smooth landing and found itself in what scientists called "dream" terrain—a relief, because a number of high-profile Mars missions have failed to touchdown safely.
The spacecraft then delivered the first definitive evidence of water ice on Mars on June 19.
A week later scientists were surprised by their finding that Martian soil is surprisingly rich in nutrients—reminiscent of what is used on Earth to grow asparagus. The soil find adds to evidence that liquid water existed on Mars sometime in its past.
Goldstein noted that Phoenix has completed nearly all of its milestones for full mission success in only about half of its 90-day mission period.
But he's not anticipating an early end to the mission, which is slated for around the time the lander's power is completely drained.
"Of course, [if we complete the mission early] we'll have time to do more science," he said.
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