WASHINGTON—Scientists are reaching out this month to touch two heavenly bodies that have never before been visited by spaceships from Earth: the core of a passing comet and a moon orbiting a distant planet.
The goal is to learn more about the origin and evolution of the solar system, our homeland in the vastness of the universe.
Meanwhile, the two Mars rovers, Spirit and Opportunity, are completing their first year of prospecting on the Red Planet. To their masters' astonishment and delight, they continue to send back valuable information, nine months after their original mission was supposed to end.
"The rovers are both in amazingly good shape for their age," said Jim Erickson, rover project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The twins sailed through the worst of the Martian winter with flying colors and spring is coming."
Wednesday, the space agency is scheduled to launch its Deep Impact spacecraft from Cape Canaveral on its way to the comet Tempel 1, floating 83 million miles away between the planets Mars and Jupiter.
When it arrives July 4, the spaceship will drop an 820-pound slab of copper, hoping to punch a hole, perhaps as deep as a 10-story building, in the comet's hidden nucleus.
The idea is to find out what's inside those mysterious luminous objects that have fascinated—and frightened—humans for thousands of years. People used to think comets were ill omens of famine, flood or the deaths of kings. Now scientists think they contain the most primitive material left in our patch of the sky.
"Comets are the oldest bodies in the solar system," said Andy Dantzler, the acting director of NASA's solar system division. "They contain the oldest clues to answer fundamental questions: How did the solar system form? How did it evolve? How did life begin?"
Two days later, a European Space Agency lander called Huygens will parachute onto the surface of Saturn's giant moon Titan. The wok-shaped lander will be "the furthest man-made object to land on a remote celestial body," Ian Halliday, the British astronomer in charge of the mission, said in a statement from Edinburgh, Scotland.
Huygens (pronounced HIGH-guns and named after a Dutch astronomer) was released from NASA's Cassini satellite on Christmas Eve, and is drifting above Titan until time for the landing. Cassini began orbiting Saturn, 885 million miles from the sun, last June after a six-year voyage, and has been observing its famous rings and many moons ever since.
Titan, larger than the planets Mercury and Pluto, fascinates scientists because its thick, nitrogen-rich atmosphere resembles conditions on Earth billions of years ago, before living organisms began enriching our air with oxygen.
Stuffed with 12 scientific instruments, Huygens will relay observations during its two-hour descent and for up to half an hour after landing. Scientists aren't sure whether it'll splash into a sea of liquid methane, squelch into frozen mush or crash into solid ground.
Although a spaceship named Stardust collected dust from the tail of another comet a year ago, Deep Impact will be the first to penetrate the nucleus of any comet. Tempel 1, which resembles a giant, dirty snowball, is 6 miles long.
"The best way to find what's inside a comet is to blast a hole in it," said Jay Melosh, a planetary scientist at the University of Arizona in Tucson. "The impact may form a crater about the size of a football field and deep enough to swallow a 10-story building."
Karen Meech, a researcher at the Hawaii Institute for Astronomy, said ground-based telescopes might see a momentary flash of light at the time of the encounter. Space telescopes also will collect data from the impact.
In their year on Mars, the twin rovers have been one of the space agency's greatest success stories. Their Web site has received more than 9 billion hits from interested people around the world.
"It's been the coolest geological field trip in human history," said Steve Squyres, the lead rover scientist, from Cornell University in Ithaca, N.Y. "The rovers are still making remarkable discoveries."
So far, Spirit has trundled 2.5 miles across a broad crater near the Martian equator. It's now climbing to the crest of a range of hills to see what's on the other side.
Opportunity, halfway around the planet, has traveled 1.25 miles and now is investigating its discarded heat shield to see what improvements could be made for future missions. Earlier, Opportunity confirmed that liquid water, a necessity for life, once existed on the Red Planet.
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For information on Deep Impact: www.nasa.gov/mission_pages/deepimpact/main/index.html
For information on Huygens: www.nasa.gov/mission_pages/cassini/main/index.html
For information on Mars rovers: http://marsrovers.jpl.nasa.gov/home/index.html
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(c) 2005, Knight Ridder/Tribune Information Services.
PHOTO (from KRT Photo Service, 202-383-6099): SCI-SPACE
ARCHIVE GRAPHICS on KRT Direct (from KRT Graphics, 202-383-6064): 20040702 CASSINI Titan and 20040608 Saturn Mission
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