Posted on 12/30/2003 6:52:01 AM PST by rs79bm
If everything works as planned, panoramic cameras will send back extraordinarily clear pictures of the bleak landscapes that give the red planet its name. They'll have three times the resolution of the images beamed back by Mars Pathfinder in 1997.
``These cameras are 20-20 human vision,'' he said, ``so it really will be a walk on Mars.''
Next up: The NASA rovers Spirit and Opportunity, each about the size of a golf cart and designed to roam up to 44 yards a day, snapping pictures and exploring sites that were chosen because they may have once held liquid water -- an essential component for life. They're part of a mission formally known as Mars Exploration Rover.
Spirit is scheduled to land Saturday at Gusev Crater, a large basin that may have once contained a lake. Opportunity will attempt a landing Jan. 24 at Meridiani Planum, or plain, on the opposite side of the planet, where previous missions detected a gray mineral called hematite that usually forms in the presence of liquid water.
Each rover is tucked into a lander and swaddled in air bags so they can bounce onto the planet, just as Mars Pathfinder did six years ago. The landers will boing around like beach balls and roll up to half a mile before coming to a stop, deflating their air bags and opening like the petals of a flower to release the rovers.
For G. Scott Hubbard, director of Ames Research Center, this mission is a milestone. Three years ago, after simple errors led to the embarrassing failures of two Mars missions in a row, Hubbard was named Mars program director for NASA. During the next 15 months he helped reshape the agency's plan for exploring the planet, lining up a string of missions through the end of this decade.
``It's an exciting time,'' he said of the upcoming rover landings. ``Everybody's got their fingers crossed. If this works as planned, we'll have live from Mars for six months.''
Although the National Aeronautics and Space Administration's Jet Propulsion Laboratory in Pasadena is in charge of the rover mission, Ames has played a major role, Hubbard said.
The heat-shield materials for the landers were designed, manufactured and tested at Ames. The tests take place in a facility built for the Apollo moon missions that takes up almost a city block and uses 100 megawatts of power. Most of the air is pumped out of the test chamber, to simulate the thin Martian atmosphere. The remaining air is zapped with arcs of electricity, like artificial lightning bolts, to create a hot plasma like the one faced by a spacecraft streaking through the atmosphere.
Ames also stepped in when the parachutes that were supposed to ease the landers' descent into the Martian atmosphere failed in last-minute tests.
Dropped from a helicopter a few months before the landers were scheduled for launch, ``the parachute just shredded -- it came apart,'' Hubbard said. ``The project was just appalled.''
The designers traced the problem back to some bad calculations and came up with three alternatives. But there was a concern that the traditional helicopter-drop tests might not be good enough to predict how well the chutes would perform.
Then someone suggested that the big wind tunnel at Ames -- the largest in the world -- could give the chute a more realistic workout.
``Our people really jumped in and got going in a very speedy manner,'' Hubbard said. The nylon parachute, 47 feet in diameter, was tested over a four-month period in conditions that simulate the descent. It's designed to open when a lander is five miles above the planet's surface and help slow the craft before it hits the ground.
Complicating matters, since the rovers are landing on opposite sides of the planet, they'll be carrying out their solar-powered forays at different times of the Martian day.
The first panoramic pictures will be beamed back from the rovers within a day or two of landing, along with data that may tell something about the minerals on the surface.
``The first week will be to figure out where we are'' within a few hundred yards, said Nathalie Cabrol, a planetary geologist at Ames and a member of the science team. Only then will the rovers begin their travels.
For her part, she said, she's mostly interested in understanding where the sediments on the surface of Mars are coming from: Were they deposited by water? Wind?
``It's such an amount of data that we never had before,'' she said. ``It's amazing.''
(Excerpt) Read more at mercurynews.com ...
Got my fingers crossed, and it worked great last time the Americans did it. But where do bouncing balls tend to end up on uneven surfaces? In deep holes and crevices. Somebody tell me that NASA has double, triple and quadruple checked that there are none such within miles of where these bouncing landers will be touching down. I'm losing faith in that agency.
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