- WASHINGTON (Reuters) - Gusts
of wind or a hard rock could spoil next month's landings of two robots
designed to explore the surface of Mars, NASA said on Tuesday.
-
- But the U.S. space agency, shaken by the deaths of seven
shuttle astronauts in February and the loss of two robotic missions to
Mars in 1999, said it had spared no expense in planning for the latest
rover mission.
-
- If they succeed, the two landers, nicknamed
"Spirit"
and "Opportunity," will help answer questions about how much
water ever existed on the surface of Mars and whether it lingered in
life-sustaining
lakes or rivers.
-
- "This mission is just the beginning of finding the
right place to search for life," Ed Weiler, NASA associate
administrator
for space science, told a news conference.
-
- Mars is a perilous destination. Of 30 space missions
launched by various nations over the years, only 12 have succeeded. Just
three of nine attempts to land have succeeded.
-
- "Landing on Mars is very, very, very
difficult,"
Weiler said. "Mars has been a most daunting destination. Some,
including
myself, call it the "Death Planet."
-
- But he said great care had been taken with the launches
of the two golf cart-sized craft. "I don't know what else humans could
have done to make these two rovers successful," Weiler said.
-
- Funding shortfalls have been blamed for some of the other
failures.
-
- "But Mars will determine whether we succeed,"
Weiler added. "We could land on a rock. We could get a gust of
wind."
-
- The two Mars explorers, worth a combined $800 million,
are wrapped inside a landing craft that will parachute to Mars after a
seven-month, 300-million-mile voyage.
-
- Spirit will land on Jan. 3 and Opportunity follows, on
the opposite side of the planet, on Jan 24.
-
- After nine balloons have deployed, surrounding the
landing
craft like a bunch of grapes, Spirit will bounce for as far as 2 miles
before coming to rest.
-
- WAITING IN THE DARK
-
- NASA will be unable to hear from the rovers for as long
as 24 hours after the Spirit's landing, not knowing how the spacecraft
has fared until it can get its antennas out and send a signal back to
Earth.
Earth will set and be out of transmission range 10 minutes after the craft
hits the surface.
-
- If it gets up and running, Spirit will unfold a camera
that can look around and find interesting rocks to roll over and look at.
Previous missions have shown "lots and lots and lots of water on
Mars,"
Weiler said.
-
- The question is -- what kind of water and how long did
it last?
-
- The rovers can travel about 300 feet an hour on a flat
surface with no obstacles.
-
- The landing spots are two large craters on opposite sides
of the planet.
-
- One, the Gusev Crater, is about 90 miles in diameter,
said Cathy Weitz, Mars Exploration Rover program scientist.
-
- "We estimate it is about 4 billion years old,"
Weitz said.
-
- From photographs, it looks as if water flowed in to fill
it, and then flowed out on the opposite side.
-
- The second site, the Meridiani Planum, contains
hematite.
-
- "We know that hematite usually is formed by the
action of liquid water but there a lot of different ways of doing
that,"
said Steve Squyres, Mars Exploration Rover principal investigator at
Cornell
University in New York.
-
- If the hematite were made by deep standing water or a
hot spring, the potential is good that bacteria or similar life forms could
have evolved, he said.
-
- A drilling tool on the robots will scrape away the
surface
of rocks to see if hematite lies deep -- suggesting pools of water once
existed, Squyres said.
-
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