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Mars rover faces make-or-break weekend
Date: Friday, January 02, 2004 @ 18:26:53 EST

Spirit due to bounce onto Red Planet Saturday night

PASADENA, Calif. - After a journey of seven months and millions of miles, a six-wheeled NASA rover will speed like a bullet Saturday night toward the surface of Mars and, if all goes as planned, stop with a bounce.

The plunge through the Martian atmosphere at 12,300 mph will mark the start of the riskiest portion of the 303-million-mile (485-million-kilometer) voyage. As the unmanned spacecraft Spirit plummets to the rocky surface 80 miles (128 kilometers) below, it will rely on the precisely choreographed use of heatshields, parachutes and rockets to slow its descent. Just eight seconds before hitting the ground, the golfcart-size Spirit should inflate a set of airbags to cushion its impact. The entire harrowing trip down should take just six minutes. An overly strong gust of wind or a single sharp boulder could doom the entire enterprise. “It's going to be six minutes from hell. It's going to be high anxiety,” Ed Weiler, NASA's associate administrator for space science, said Friday at NASA's Jet Propulsion Laboratory. As of late Friday, Spirit was less than 173,750 miles (278,000 kilometers) from Mars, closer than the moon is to Earth. The $820 million project also includes a twin rover, Opportunity, which is set to arrive on Mars late Jan. 24.

An image of Gusev Crater, the landing site for NASA's Spirit rover, is color-coded to show altitude. The projected landing area is indicated by the faint outline of an ellipse. A canyon called Ma'adim Valles is connected to the crater at the bottom of the image. Scientists believe Gusev Crater may have been an ancient lakebed.

Looking for life

The camera- and instrument-laden rovers are designed to spend 90 days analyzing Martian rocks and soil for clues that could reveal whether the Red Planet was ever a warmer, wetter place capable of sustaining life. Spirit is to come down in Gusev Crater, which is thought to have been was an ancient lakebed. A canyon known as Ma'adim Valles is connected to the crater, and scientists have detected evidence of sedimentary deposits.

Opportunity is targeting a geologically complex region called Meridiani Planum, which contains significant deposits of hematite, a mineral that could have been formed through the action of ancient hot springs. On Earth, such springs provide a home for microbial life. If successful, the six-wheeled, 384-pound (175-kilogram) Spirit and its twin would become the fourth and fifth U.S. spacecraft to survive landing on Mars — following the two Viking landers and the Mars Pathfinder lander/rover craft. If neither survives, they will join the ranks of 20 other spacecraft from various nations that failed to successfully reach the planet. The latest entries on the list, apparently, were Japan's Nozomi satellite and Britain's Beagle 2 lander. Nozomi was unable to enter Mars orbit last month. Beagle 2 has been silent since it was to have landed on Christmas Day, although British scientists are still hopeful that Mars Express, a European orbiter that carried Beagle most of the way to Mars, will be able to contact the lander as early as this weekend. NASA officials believe they have done everything possible to ensure the success of the rover missions, and say the rest now depends on Mars. “Some, including myself, call it the ‘death planet,”' said Ed Weiler, NASA's associate administrator for space science.

NASA hopes to learn whether Spirit has landed safely within 10 minutes of its expected 8:35 p.m. PT (11:35 p.m. ET) arrival. If scientists have not heard from Spirit within 22 hours of landing, the likelihood that it survived is very low, project manager Pete Theisinger said.

In 1999, NASA's last attempt at landing on Mars failed when a software glitch sent the Polar Lander crashing to the ground. Its descent took place in a communications blackout, and the lack of data later stymied the investigation into the failure. Spirit, in contrast, is designed to transmit a series of tones to Earth throughout its descent to signal engineers each time onboard computers order a critical action, such as the deployment of the parachute. Even if Spirit crashes, engineers on Earth will be able to reconstruct its last minutes. “Entering into Mars is always very tricky, as everyone knows, and we can fail. But we want to learn from those failures, so next time — of course, we have another rover coming three weeks later, so we do have our own next time — we can learn from the experience so we can correct any problems,” said Polly Estabrook, who is in charge of telecommunications for the landing.

By Andrew Bridges
The Associated Press
Updated: 9:16 p.m. ET Jan. 02, 2004

Source: MSNBC

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