for National Geographic News
Spacecraft from three different space missions are drawing closer to Mars. Over the next six weeks, landers and rovers are scheduled to touch down on the red planet's surface. Together with orbiting spacecraft, the probes will poke, scratch, sniff, and image the Martian environment for clues to the existence of past or present life.
Mission scientists will clear a significant hurdle to see their spacecraft simply reach Mars.
"Mars has been a most daunting destination," said Ed Weiler, NASA's associate administrator for space science at a press briefing earlier this month in Washington, D.C. "Some, including myself, call it the 'death planet.'"
Historically, two out of every three missions to Mars have faileda testament to the difficulty of enduring a 300-million-mile (480-million-kilometer) journey from Earth. NASA's Mars Polar Lander and Mars Climate Orbiter were lost upon arrival in 1999.
But space scientists around the world hope the current wave of spacecraft scheduled to reach Mars in the coming weeks, one as early as Sunday, will yield at least a few success stories.
The five spacecraft from three agencies are on unrelated but complementary missions to study the red planet's atmosphere, soil, and rocks for signs that Mars could haveor still doesharbor life.
The first among the current wave of spacecraft to reach Mars is Nozomi, a spacecraft operated by Japan's Institute of Space and Astronautical Science. Nozomi was scheduled to enter Mars' orbit Sunday, but owing to an unresolved electrical problem the agency has adjusted the spacecraft's altitude so that it will shoot past Mars and become an artificial planet in orbit around the sun.
The next chance for success is the European Space Agency's Mars Express mission. The Mars Express probe is expected to release the Beagle 2 lander on December 19 for a Christmas Eve touch down. Mars Express will enter Mars' orbit Christmas Day.
The first of NASA's current Mars Exploration Rovers, Spirit, is scheduled to arrive January 3, 2004. Opportunity will arrive January 24.
As the spacecraft make their way to Mars, mission scientists are striving to ensure a safe arrival and, in the event of problems, avert harm to the Martian environment.
"Everybody knows there's a potential that bad things can happen to good spacecraft. We are trying to avoid that," said John Rummel, a NASA researcher in Washington, D.C., who chairs the Paris-based Committee on Space Research's planetary protection panel.
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