MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
Contact: Franklin O'Donnell
FOR IMMEDIATE RELEASEFebruary 3, 1999
STARDUST MISSION SET TO BRING BACK A PIECE OF A COMET
NASA's Stardust mission, scheduled for launch Saturday,
February 6, from Cape Canaveral, FL, will send a spacecraft
flying through the cloud of dust that surrounds the nucleus of a
comet - and, for the first time ever, bring cometary material
back to Earth.
Launch is scheduled at 4:06 p.m. Eastern time, with live
coverage on NASA Television beginning at 2:30 p.m. Eastern. A
post-launch briefing is planned to be broadcast on NASA
Television at 6 p.m. Eastern.
Comets, which periodically grace our sky like celestial
bottle rockets, are thought to hold many of the original
ingredients of the recipe that created the planets and brought
plentiful water to Earth. They are also rich in organic
material, which provided our planet with many of the ready-to-mix
molecules that could give rise to life. They may be the oldest,
most primitive bodies in the solar system, a preserved record of
the original nebula that formed the Sun and the planets.
"Scientists have long sought a sample directly from a known
comet because of the unique chemical and physical information
these bodies contain about the earliest history of the solar
system," said Dr. Edward Weiler, NASA's associate administrator
for space science. "Locked within comet molecules and atoms could
be the record of the formation of the planets and the materials
from which they were made."
Stardust is the first U.S. mission dedicated solely to a
comet and will be the first to return extraterrestrial material
from outside the orbit of the Moon. Stardust's main objective is
to capture a sample from a well-preserved comet called Wild-2
The spacecraft will also collect interstellar dust from a
recently discovered flow of particles that passes through our
solar system from interstellar space. As in the proverbial "from
dust to dust," this interstellar dust represents the ultimate in
recycled material; it is the stuff from which all solid objects
in the universe are made, and the state to which everything
eventually returns. Scientists want to discover the composition
of this "stardust" to determine the history, chemistry, physics
and mineralogy of nature's most fundamental building blocks.
Because it would be virtually impossible to equip a
spacecraft with the most sophisticated lab instrumentation needed
to analyze such material in space, the Stardust spacecraft is
more of a robotic lab assistant whose job it is pick up and
deliver a sample to scientists back on Earth. The spacecraft
will, however, radio some on-the-spot analytical observations of
the comet and interstellar dust.
"The samples we will collect are extremely small, less than
a micron, or 1/25,000th of an inch, in size, and can only be
adequately studied in laboratories with sophisticated analytical
instruments," said Dr. Donald C. Brownlee of the University of
Washington, principal investigator for the Stardust mission.
"Even if a ton of sample were returned, the main information
in the solids would still be recorded at the micron level, and
the analyses would still be done a single grain at a time."
Stardust will meet up with Comet Wild-2 on January 2, 2004.
A gravity assist flyby of Earth will put Stardust on a trajectory
that will allow it to capture cometary dust intact at a low
relative speed of 6.1 kilometers per second (about 13,600 miles
per hour). An onboard camera will aid in navigating the
spacecraft as close as about 150 kilometers (100 miles) from the
comet's nucleus, permitting the capture of the freshest samples
from the heart of the comet.
Dressed for survival behind armored shields, Stardust will
document its 10-hour passage through the hailstorm of comet
debris with scientific instruments and the navigation camera. On
approach to the dust cloud, or "coma," the spacecraft will flip
open a tennis-racket-shaped particle catcher filled with a smoke-
colored glass foam called aerogel to capture the comet particles.
Aerogel, the lowest-density material in the world, has enough
"give" in it to slow and stop particles without altering them too
much. After the sample has been collected, the aerogel capturing
device will fold down into a return capsule, which closes like a
clamshell to enclose the sample for its safe delivery to Earth.
In addition, a particle impact mass spectrometer will obtain
in-flight data on the composition of both cometary and
interstellar dust, especially very fine particles. The optical
navigation camera should provide excellent images of the dark
mass of the comet's nucleus. Other equipment will reveal the
distribution in both time and space of coma dust, and could give
an estimate of the comet's mass.
On January 15, 2006, a parachute will set the capsule gently
onto the salt flats of the Utah desert for retrieval. The
scientifically precious samples can be studied for decades into
the future with ever-improving techniques and analysis
technologies, limited only by the number of atoms and molecules
of the sample material available. Many types of analyses now
performed on lunar samples, for example, were not even conceived
at the time of the Apollo missions to the Moon.
Comets are small, irregularly shaped bodies composed of a
mixture of grains of rock, organic molecules and frozen gases.
Most comets are about 50 percent water ice. Typically ranging in
size up to about 10 kilometers (6 miles) in diameter, comets have
highly elliptical orbits that bring them close to the Sun and
then swing them back out into deep space. They spend most of
their existences in a deep freeze beyond the orbit of Pluto - far
beyond the Sun's dwindling influence, which is why so much of
their original material is well-preserved.
When a comet approaches within about 700 million kilometers
(half billion miles) of the Sun, the surface of the nucleus
begins to warm, and material on the comet's nucleus heats and
begins to vaporize. This process, along with the loss of rocky
debris or other particles that fly off the surface, creates the
cloud around the nucleus called the coma. It is the glowing,
fuzzy coma that appears as the head of a comet when one is
observed from Earth. A tail of luminous debris and another, less
apparent, tail of gases flow millions of miles beyond the head in
the direction away from the Sun.
Comet Wild-2 is considered an ideal target for study
because, until recently, it was a long-period comet that rarely
ventured close to the Sun. A fateful pass near Jupiter and its
enormous gravity field in 1974 pulled Comet Wild-2 off-course,
diverting it onto a tighter orbit that brings it past the Sun
more frequently and also closer to Earth's neighborhood. Because
Wild-2 has only recently changed its orbit, it has lost little of
its original material when compared with other short-period
comets, so it offers some of the best-preserved comet samples
that can be obtained.
Stardust was competitively selected in the fall of 1995
under NASA's Discovery Program of low-cost, highly focused
science missions. As a Discovery mission, Stardust has met a
fast development schedule, uses a small Delta launch vehicle, is
cost-capped at less than $200 million, and is the product of a
partnership involving NASA, academia and industry.
Principal investigator Brownlee is well-known for his
discovery of cosmic particles in Earth's stratosphere known as
Brownlee particles. Dr. Peter Tsou of NASA's Jet Propulsion
Laboratory, Pasadena, CA, an innovator in aerogel technology and
maker of aerogel, serves as deputy investigator. JPL, a division
of the California Institute of Technology, manages the Stardust
mission for NASA's Office of Space Science, Washington, DC. Dr.
Kenneth L. Atkins of JPL is project manager. The spacecraft is
designed, built and operated by Lockheed Martin Astronautics,
Denver, CO. JPL provided the spacecraft's optical navigation
camera, and the Max Planck Institute of Germany provided the
real-time dust composition analyzer.
NASA Television is broadcast on the satellite GE-2,
transponder 9C, C band, 85 degrees west longitude, frequency
3880.0 MHz, vertical polarization, audio monaural at 6.8 MHz.