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Phoenix Set To Land On Mars Tonight

Posted on: Sunday, 25 May 2008, 06:05 CDT

There's no turning back now.

The UA-led Phoenix Mars Lander is in the gravitational grip of the red planet this morning, with only a few hours and a hundred thousand more miles to travel before shooting through the planet's atmosphere and touching down on the arctic surface.

"There's no second chance," said Peter Smith, the University of Arizona researcher who is the principal investigator on the mission.

"We're going straight in, and that's our fate," he said.

Saturday, with the mission's tricky landing roughly a day away, engineers at Lockheed Martin and NASA's Jet Propulsion Laboratory had an opportunity to adjust the spacecraft's course but opted not to do so, saying Phoenix was still on target.

If necessary, mission planners will have a final chance to correct the lander's course today, just hours before it enters Mars' atmosphere.

Engineers running the mission are shooting for a small site below Mars' north pole, but there are a lot of variables that could alter the final target.

Because of the uncertainty, mission planners have given themselves ample wiggle room on where Phoenix can land. It's a strip several miles wide and about as long as the distance between San Francisco and San Jose, Calif., said Joe Guinn, JPL's Phoenix mission manager, during a news conference from Pasadena, Calif.

By late Saturday afternoon, the lander was about 182,000 miles from Mars and speeding up as it entered the planet's gravitational field, expecting to hit 12,500 mph before entry.

If the complex landing goes off as planned, Phoenix should be greeted with clear skies and warm weather -- by Mars' standards -- of roughly minus 50 degrees Fahrenheit.

The area should be clear of large rocks, as satellites orbiting Mars have used high-resolution cameras to determine that the landing site is nearly boulder-free.

There might be a little dust in the air, though, which could be kicked up as Phoenix touches down or left over from a dust storm that recently moved through the landing site.

All in all, it looks like beautiful weather for a first day on Mars, said Barry Goldstein, JPL's Phoenix project manager.

"The storm has cleared out, and it looks like it's going to be a very clear day when we're landing," he said.

Should there be an abrupt change, which Goldstein called unlikely, the crew has the ability to reprogram the lander today for the weather.

"All the way up until three hours before entry, if a dust storm builds up or something else happens, we can adjust," he said.

If all goes according to plan, mission scientists will hear from the lander at 4:53 p.m. after it sends a signal via satellites orbiting Mars.

The lander is expected to send another set of data back to mission planners two hours after that. That signal could contain some of the first images of the planet's surface.

Phoenix Mars Lander parachutes to the surface. Credit: NASA

The spacecraft will jettison its heat shield and extend its three legs. Credit: NASA

Phoenix sets down on the surface and unfurls its solar panels. Credit: NASA

The data from the lander will have to travel millions of miles before reaching Earth, meaning there will be a 15-minute delay between the lander's actions and the time mission planners learn of the activity.

Planetary factors such as weather don't concern Goldstein as much as what has to happen during Phoenix's final descent to Mars.

The lander must perform so many complex events, and "all of them have to work, and you don't have another chance," Goldstein said.

But the spacecraft has undergone extensive testing. For example, to test the radar, which sits on the underside of the lander and judges the distance to the ground, engineers dropped a test model out of a helicopter to make sure it worked.

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Related Articles:

http://www.redorbit.com/news/space/1399096/mars_phoenix_spacecraft_healthy_upon_approach/index.html

http://www.redorbit.com/news/space/1400187/mars_lander_will_be_copiloted_by_univ_of_arizona_scientists/index.html

http://www.redorbit.com/news/space/1398318/mars_express_to_provide_support_for_phoenix_landing/index.html

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On the Net:

redOrbit's Mars Phoenix Section

University of Arizona's Mars Phoenix Site

Source: The Arizona Daily Star

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