archive: SETI [ASTRO] Chicago Instrument To Get Close Look At Comet During
SETI [ASTRO] Chicago Instrument To Get Close Look At Comet During
Larry Klaes ( lklaes@bbn.com )
Fri, 05 Feb 1999 10:12:26 -0500
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>Date: Wed, 3 Feb 1999 16:54:36 GMT
>From: Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
>To: astro@lists.mindspring.com
>Subject: [ASTRO] Chicago Instrument To Get Close Look At Comet During
STARDUST Mission
>Sender: owner-astro@brickbat12.mindspring.com
>Reply-To: Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>
>
>
>February 2, 1999
>For immediate release
>
>Contact: Steve Koppes
> (773) 702-8366
> s-koppes@uchicago.edu
>
>Chicago instrument to get close look at comet during Stardust mission
>Launch scheduled for Feb. 6
>
>A University of Chicago instrument will be riding shotgun on the first
>spacecraft designed to return a sample of a comet to Earth. NASA plans
>to launch the Stardust spacecraft to Comet Wild-2 as early as Feb. 6.
>
>Stardust will be blasted with a hail of dust particles traveling
>nearly four miles per second as the spacecraft approaches to within 93
>miles of Comet Wild-2 (pronounced "Vilt"-2) in 2004. A special shield
>called the bumper shield will protect the main body of the spacecraft
>as it passes through the glowing gas cloud that surrounds the comet's
>solid nucleus. The detectors for Chicago's Dust Flux Monitor Instrument
>will be mounted on the front of the bumper shield.
>
>"There, they will be exposed to the full force of the dust flux to
>measure the size of the dust particles the spacecraft encounters and
>map their distribution around the comet's nucleus," said Anthony
>Tuzzolino, Senior Scientist at Chicago's Laboratory for Astrophysics &
>Space Research.
>
>The DFMI was not originally part of the Stardust mission. Noel Hinners,
>vice president of spacecraft contractor Lockheed Martin Astronautics,
>suggested its addition to provide rapid measurement of the dust density
>around the comet to help engineers and flight controllers assess the
>health and safety of the spacecraft as it approaches the comet. Ben
>Clark, also of Lockheed Martin, led the effort to find a way to
>integrate the experiment and the spacecraft, the design for which was
>already nearly complete.
>
>"Our instrument performs an important health-hazard function,"
>Tuzzolino said. "Conditions may be far more hazardous than we thought
>as we approach the comet." If so, DFMI data will warn mission
>controllers that it is time to take protective measures for the
>spacecraft.
>
>Scientists also will correlate DFMI's data with the samples that
>Stardust will collect from the comet and return to Earth in 2006.
>Stardust will use a material called aerogel to collect the samples
>without damaging or altering the speeding particles. Aerogel is a
>silica-based solid with a porous, sponge-like structure that consists
>mostly of empty space. "It is so light that it has been called 'solid
>smoke,'" Tuzzolino said.
>
>The other instruments aboard Stardust include a camera to take detailed
>photographs of the comet's surface features, and the Cometary and
>Interstellar Dust Analyzer, which will analyze the composition of the
>comet's dust particles.
>
>The DFMI consists of an electronics box, two detectors mounted on the
>front of the spacecraft's bumper shield and two acoustic sensors,
>measurements from which will be analyzed by a team headed by Professor
>J.A.M. McDonnell of the University of Kent in England.
>
>The detectors consist of a polarized plastic material. "The material is
>similar to Saran wrap," Tuzzolino said. The material generates an
>electrical pulse when hit by small, high-speed particles, even those
>many times smaller than a sand grain.
>
>The two acoustic sensors are embedded between layers of the shield that
>protects the spacecraft from impacting dust particles. "The acoustic
>sensors will be triggered by a large impact particle that hits the
>shield anywhere," said LASR Senior Scientist Bruce McKibben.
>
>Stardust will meet Comet Wild-2 at a distance of 242 million miles from
>Earth, following a flight trajectory that will loop twice around the
>sun. The spacecraft will loop once more around sun after its comet
>encounter on the way back to Earth.
>
>The trajectory will take Stardust close to several meteor streams that
>the DFMI may be able to detect. The first such opportunity will occur
>April 20, 1999 when Stardust comes within 3.5 million miles of the
>Orionid meteor stream. The Orionid meteors, left in the wake of Comet
>Halley, can be seen from Earth each October.
>
>The DFMI may also be able to detect particles of interstellar dust,
>which NASA's Ulysses spacecraft recently discovered streaming into the
>solar system.
>
>"There is a chance that we can identify the trajectory of incoming
>particles that must have come from interstellar space," said John
>Simpson, Arthur Holly Compton Distinguished Service Professor Emeritus
>in Physics. "This is matter that is involved in the origin of the solar
>system itself. It's primordial material."
>
>Stardust will be the 34th space-science mission Simpson and Tuzzolino
>have participated in, starting with Pioneer 2 in 1958. Last November,
>Tuzzolino received the NASA Public Service Medal for his role in the
>development of cosmic ray and dust detectors, including the first to be
>sent to Mercury, the moon, Mars, Jupiter and Saturn. All of their
>experiments have been aimed at understanding the origin of elements and
>matter that formed Earth's galaxy and solar system.
>
>The DFMI is a descendant of Chicago's Dust Counter and Mass Analyzer
>instrument that flew on the Soviet Union's Vega 1 and Vega 2 missions
>to Halley's Comet in 1986. Simpson invented the instrument concept in
>1983, with Tuzzolino playing a key role in its rapid development and
>testing.
>
>On the Vega missions, Chicago scientists discovered to their surprise
>that tiny dust particles streaming from the comet had survived to the
>outer bounds of the comet's coma, the spherical cloud of glowing gas
>that develops around a comet's solid nucleus as it approaches the sun.
>
>"We were able to show that the particles coming off the comet's nucleus
>had to be a conglomerate, probably bound together by an ice glue,"
>Simpson said. "Then, as it carried far out into space, the ice glue
>dissolved, releasing the very small stuff that would have otherwise
>disappeared if it had come directly from the comet."
>
>Two other instruments related to the DFMI are components on NASA's
>current Cassini mission to Saturn and on the Air Force's unclassified
>Advanced Research and Global Observation Satellite.
>
>Simpson and Tuzzolino built Cassini's High Rate Detector, part of the
>larger Cosmic Dust Analyzer from Germany, which will collect and
>analyze dust particles found in interplanetary space and those that
>form the major components of Saturn's rings.
>
>The ARGOS Space Dust instrument, devised by Simpson, Tuzzolino and
>McKibben, will measure the mass, speed and trajectory of cometary dust
>particles and man-made space debris found in low-Earth orbit when
>launched later in February.
>
>The $350,000 DFMI was funded by NASA for Stardust, the fourth mission
>in the space agency's Discovery Program of smaller, faster, cheaper
>missions. The Stardust scientific team is led by University of
>Washington astronomy professor Donald Brownlee.
>
>###
>Editor's Note: An image of the researchers with a model of Stardust and
>a prototype of their detectors is available upon request.
>
>NASA Stardust home page: http://stardust.jpl.nasa.gov
>
>University of Washington Stardust home page:
>http://www.washington.edu/newsroom/stardust/stardust.html
>
>University of Kent Stardust home page:
>http://wwwspace.ukc.ac.uk/stardust.html
>
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>