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Sun Sample Return Mission Nears Launch

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Sun Sample Return Mission Nears Launch

The science payload for NASA's Genesis spacecraft, which will collect samples of the solar wind and return them to Earth, is now complete.

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see captionOctober 12, 2000 -- NASA's Genesis spacecraft, the first mission to collect and return samples of the solar wind, is moving closer to launch. Scheduled for liftoff in February 2001, Genesis will help scientists refine our basic understanding of the Sun's characteristics, and understand how the solar nebula, an interstellar cloud of gas and dust, gave rise to our complex solar system billions of years ago.

According to NASA's Jet Propulsion Laboratory, which manages the mission for NASA's Office of Space Science, the spacecraft has just received its final piece of science equipment: a solar wind collector made of bulk metallic glass, similar to materials found in high-tech golf clubs. It and other solar wind collector tiles on the spacecraft will gather the first-ever samples of the solar wind as the spacecraft floats in the oncoming solar stream outside Earth's magnetosphere.

On its return to Earth in 2003, samples collected by Genesis will be retrieved in midair by helicopters and sent to laboratories for detailed analysis.

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Above: The solar wind streams away from the Sun in all directions. NASA's Genesis spacecraft will travel 1.5 million kilometers toward the Sun where it can sample the solar wind from the L1 Lagrangian point.

Because the outer layers of the Sun are composed of nearly the same material as the original solar nebula, samples returned by Genesis will shed new light on the chemical evolution of meteorites, comets, lunar samples, and planetary atmospheres.

The body of the spacecraft contains a canister with collector plates that fold out like blades on a pocket knife to collect solar wind. Most of the collectors are hexagonal silicon wafers, but one is different. Capping the shaft on which the collector plates rotate will be a disk about the size of a coffee cup that is a unique formulation of bulk metallic glass created especially for Genesis.

see captionLeft: The Genesis science canister contains all the sampling equipment for the science of the mission. When traveling to and from the Earth, the canister is completely sealed to prevent contamination. This photo shows the canister in the fully open position that it will assume when it reaches L1. Inside the lid and stacked inside the canister are arrays of hexagonal silicon wafers. The samples of solar wind particles will be returned to Earth embedded inside these wafers.

In an odd mix of science and sports, golfers and Genesis scientists both like bulk metallic glasses, but for different reasons. Premium golf clubs can be made with a kind of bulk metallic glass that is hard but springy. Scientists use a type that absorbs and retains helium and neon, important elements in understanding solar and planetary processes.

The new bulk metallic glass-forming alloy was designed by Dr. Charles C. Hays in the materials science laboratories of Caltech. It is a complex mixture of zirconium, niobium, copper, nickel, and aluminum. The atoms of metallic glasses solidify in a random fashion, unlike metals that have an ordered crystalline structure. This disordered atomic state makes metallic glasses useful in a wide range of applications, from aircraft components to high-tech golf clubs. The Genesis metallic glass was prepared in a collaborative effort by Hays and George Wolter of the Howmet Corporation, Greenwich, Conn., using the same process the company uses for the high-tech Vitreloy-based golf clubs.

see captionThe surfaces of metallic glasses dissolve evenly, allowing the captured ions to be released in equal layers by sophisticated acid etching techniques developed by the University of Zurich, Switzerland. Higher-energy ions blast further into the metal's surface. When samples are back on Earth, special techniques will be used to etch the metal layer by layer, releasing the particles of gas for laboratory study.

Above: The Genesis Mission's bulk metallic glass solar wind collector.

"One exciting thing about bulk metallic glass is that it will enable us to study ions with energies higher than the solar wind. This allows Genesis to test proposals that the higher energy particles differ in composition from the solar wind," said Burnett. This will be the first time the theories about different kinds of solar wind can be tested by bringing back actual samples, he said.

Below: A specially modified helicopter with a boom and winch underneath snags the parafoil chute attached to a model Genesis sample return capsule. The hook on the end of the boom collapses the chute, allowing the helicopter to retrieve the capsule in mid-air. This is necessary to ensure the purity of the solar wind samples inside. This photo was taken during successful trials of this novel capsule recovery technology.

see captionTo bathe in the solar wind, the spacecraft only needs to fly about 1.5 million kilometers (1 million miles) toward the Sun (about 1 percent of the Sun-Earth distance). When it is in the right position -- outside of Earth's magnetic field, between Earth and the Sun where the gravity of both bodies is balanced, called the Lagrange point -- the capsule will open its collector arrays and let ions barrage its panels.

Genesis is managed by JPL for NASA's Office of Space Science, in Washington, DC. It is part of NASA's Discovery Program of low-cost, highly focused science missions. JPL is a division of the California Institute of Technology.

Web LinksNASA's Genesis Mission -- from NASA's Jet Propulsion Laboratory


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