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Archive for Monday, July 30, 2001

Solar explorer to catch some rays

July 30, 2001

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— NASA is going after its first extraterrestrial samples since the Apollo moon landings. This time, instead of lunar rocks, the prize will be atoms from the sun blasted into space on the solar wind.

The robotic sun catcher, a spacecraft named Genesis, is due to be launched on its three-year, 20 million-mile, round-trip mission Tuesday afternoon at the earliest. Liftoff had been scheduled for today but was delayed Sunday night because of concern over a power-supply device in the spacecraft's navigation system.


"It's obviously a big deal. We're extremely happy to be here. But it's only the first step," said the chief scientist, Don Burnett of the California Institute of Technology.

"The next step is to get this stuff back and then, over the next few years, actually do the things we want to do with it. That's when I'll really be excited," he said Sunday.

Burnett and other scientists hope the captured atoms that are brought back to Earth will help explain the origin of the solar system 4 1/2 billion years ago.

Genesis will travel beyond Earth's magnetic field to a spot 1 million miles away from the planet and 92 million miles from the sun. It will spend about 2 1/2 years circling that imaginary point, gathering bits of solar material hurtling by at more than 1 million mph.

A capsule containing the solar samples is due to return to Earth on Sept. 8, 2004, descending by parachute and then parafoil before being caught by a helicopter above the Utah desert.

Burnett hopes for a yield that's equivalent, if all the desirable particles were piled up, to perhaps 10 grains of salt.

"There's another way to look at it, which is more the way we look at it. It's a billion-billion atoms," Burnett said with a smile. "Take a billion somethings and you make a billion piles of a billion somethings. That's how many atoms we've got and that's a lot."

Genesis will be the first U.S. spacecraft since Apollo 17 in 1972 to return samples from outer space. Apollo 17, in fact, brought back more than moon rocks; it and all five previous manned moon landings brought back samples of solar wind material captured on sheets of aluminum foil that had been placed on the lunar surface.

NASA hopes to capture all 83 naturally occurring elements on Genesis' collector panels. Each panel has rows of hexagon-shaped wafers made of ultra-pure silicon, diamond, sapphire, gold, aluminum or germanium. As the solar wind streams by, the atoms will become embedded in the materials.

These elements are the same material as the original solar nebula, the disk of gas and dust from which the planets and other objects in the solar system formed.

The solar particles will be stored, like the moon rocks, at Johnson Space Center in Houston.

Burnett, a geochemist, expects the scientific results of Genesis to exceed those of the Apollo moon rocks. He studied the lunar rocks and has been planning a solar sample mission since 1983.

"If we can pull this off, even if there's nothing that really makes the press, if everything comes out as we predict, that's going to be very important because you're talking about a fundamental set of data that's going to be useful," he said.

The $259 million Genesis mission is managed by the Jet Propulsion Laboratory in Pasadena, Calif., and is part of NASA's Discovery program featuring low-cost robotic explorers.

Stardust, also a Discovery mission, was launched in 1999 to collect and return comet dust. The comet dust is due back in January 2006.

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