STARDUST

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STARDUST "Bringing Cosmic History to Earth"
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STARDUST Mission to a Comet
Mission Schedule Launch February
1999 Encounter January 2004 Earth Return
January 2006 The STARDUST spacecraft was
launched into space on February 7, 1999. Its
destination - Comet Wild 2 (pronounced Vilt 2)
its mission, to capture cometary materials before
returning to earth in 2006. STARDUST will
encounter Wild 2 in 2004, while nearly 390
million kilometers (242 million miles) from
earth. En Route to the comet, the spacecraft will
collect interstellar dust particles. These
samples will provide a window into the distant
past, helping scientists around the world to
unravel the mysteries surrounding the birth and
evolution of our Solar System. The spacecraft
was designed and built by Lockheed Martin
Astronautics Operations (LMAO), Denver, Colorado,
for the Jet Propulsion Laboratory (JPL),
California Institute of Technology. JPL manages
the STARDUST mission for the National Aeronautics
and Space a Administration (NASA) under direction
of Principal Investigator, Professor Donald
Brownlee at the University of Washington.
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What instruments are aboard STARDUST?
The Navigation Camera (NC), an engineering
subsystem, will be used to optically navigate the
spacecraft upon approach to the comet. This will
allow the spacecraft to achieve the proper flyby
distance, near enough to the nucleus, to assure
adequate dust collection
The primary objective of the STARDUST mission is
to capture both comet coma samples and
contemporary interstellar grains moving at high
velocity with minimal heating and other effects
of physical alteration.
The CIDA instrument is a mass spectrometer, which
separates ions' masses by comparing differences
in their flight times. The operating principle
ofthe instrument is the following when a dust
particle hits the target of the instrument, ions
are extracted from it by the electrostatic grid.
Depending on the polarity of the target positive
or negative ions can be extracted. The extracted
ions move through the instrument, are reflected
in the reflector, and detected in the detector.
Heavier ions take more time to travel through the
instrument than lighter ones, so the flight times
of the ions are then used to calculate their
masses.
The purpose of the Whipple Shield is to protect
the spacecraft from damage from impacting dust
particles. The Dust Flux Monitor Instrument
(DFMI) is used to monitor the dust particle
impacts and transmit this information directly
back to Earth.
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STARDUST Encounter with a Comet
The spacecraft will encounter Wild 2 at 97.5 days
past perihelion at 1.86 AU from the Sun when Wild
2 is far from its peak active period and
relatively safe for a close flyby. The spacecraft
will approach Wild 2 from above its orbital
plane, then dip slightly below it. The image
shows the geometry of the flyby, which will be at
150 km on the sun side.
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STARDUST There and Back!
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Interstellar Particle Collection
The comet samples will be collected during a 6.1
km/s flyby of Comet Wild 2. At this
extraordinarily low flyby speed, coma dust in the
1 to 100 micron size range will be captured by
impact into ultra-low density aerogel and similar
microporous materials. Particle collection at
this speed has been extensively demonstrated in
laboratory simulations and Shuttle flights and we
have shown that the comet dust collection can be
done with acceptable levels of sample alteration.
Cometary Particle Collection
Although the dust/volatiles ratio varies greatly
from comet to comet, the volatile material is a
significant fraction of the mass of every comet
nucleus. Because the volatile and refractory
components of comets may have condensed in very
different locations and environments, complete
knowledge of the composition of a comet requires
study of both phases. The objectives of the
volatile collection experiment are to determine
the elemental and isotopic compositions of
cometary volatiles. Of special interest are the
biogenic elements (C,H,N,O,P and S) and their
molecules. Some molecular bonds in large
molecules can remain unbroken in a 6 km/s impact,
as shown by laboratory experiment. At the very
least, the obtainable information on gaseous
components will be elemental and Isotopic.
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STARDUST Return to Earth
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Earth Return of Sample Particles
This phase of the STARDUST mission begins two
weeks before Earth re-entry and ends when the SRC
is transferred to its ground-handling team. The
planned landing site is the Utah Test and
Training Range (UTTR) as shown. The Space Return
Capsule (SRC) will be recovered by helicopter or
ground vehicles and transported to a staging area
at UTTR for retrieval of the sample canister. The
canister will then be transported to the
planetary materials curatorial facility at
Johnson Space Center. The Earth Return is divided
into four sub-phases 1) Earth Approach 2)
Entry 3) Terminal 4) Recovery
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STARDUST's "Mystifying Blue Smoke"
The primary objective of the STARDUST mission is
to capture both comet coma samples and
contemporary interstellar grains moving at high
velocity with minimal heating and other effects
of physical alteration. To achieve this a new
intact capture technology has been developed over
the past decade specifically for comet flyby
sample return missions in which hypervelocity
particles are captured by impact into
under-dense, microporous media known as aerogel.
This is not like conventional foams, but is a
rather special porous material that has extreme
microporosity at the micron scale. Aerogel is
composed of individual features only a few
nanometers in size, linked in a highly porous
dendritic-like structure. This exotic material
has many unusual properties, such as uniquely low
thermal conductivity, refractive index, and sound
speed, in addition to its exceptional ability to
capture hypervelocity dust. Aerogel is made by
high temperature and pressure critical point
drying of a gel composed of colloidal silica
structural units filled with solvents. Over the
past several years, aerogel has been made and
flight qualified at the Jet Propulsion
Laboratory. When hypervelocity particles are
captured in aerogel they produce narrow
cone-shaped tracks, that are hollow and can
easily be seen in the highly transparent aerogel
by using a stereo microscope. The cone is largest
at the point of entry, and the particle is
collected intact at the point of the cone.
Aerogel Collector Grid (above)
Dr. Peter Tsou, JPL (above)
A captured particle. Aerogel Magnified 6500x
(above)