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Science@NASA
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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