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 October
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.
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.
 Left: 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.
 The 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.
 To 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.
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