[meteorite-list] NASA Swift Satellite Offers a Different View of the Great Comet Collision

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Jul 5 14:09:03 2005
Message-ID: <200507051733.j65HXl514813_at_zagami.jpl.nasa.gov>

http://www.science.psu.edu/alert/Swift-Deep-Impact.htm

NASA Swift Satellite Offers a Different View of the Great Comet Collision
Pennsylvania State University
July 4, 2005

Scientists using the Swift satellite witnessed a tale of
fire and ice today, as NASA's Deep Impact probe slammed into the frozen
comet Tempel 1. The collision briefly lit the dim comet's surface and
exposed, for the first time, a section of ancient and virgin material
from the comet's interior.

Swift is providing the only simultaneous multi-wavelength observation of
this rare event, with a suite of instruments capable of detecting
optical light, ultraviolet, X-rays and gamma rays. Different wavelengths
reveal different secrets about the comet.

So far, after a set of eight observations each lasting about 50 minutes,
Swift scientists have seen a quick and dramatic rise in ultraviolet
light, evidence that the Deep Impact probe struck a hard surface, as
opposed to a softer, snowy surface. A movie of the ultraviolet
observations is available at this web site
<http://www.science.psu.edu/alert/Swift-Deep-Impact.htm> (left) and at
the Swift Mission Operations Center
<http://www.swift.psu.edu/swift.php?src=whatsNew.html> .

More observations and analysis are expected in the coming days from
teams at NASA and Penn State and in Italy and the United Kingdom.

"We have now observed this comet before, during, and after the
collision," said Dr. Sally Hunsberger of the Swift Mission Operation
Center at Penn State. "The comparison of observations at different times
-- that is, what was seen, when and at what wavelength -- should prove
to be quite interesting."

Most of the debris observed in ultraviolet light likely came from
once-icy surface material heated to 2,000 degrees by the impact. X-rays
have not been detected yet but analysis will continue throughout the
week. X-rays are expected to be emitted from newly liberated sub-surface
material lifted into the comet's coma, which is then illuminated by the
high-energy solar wind from the Sun. It takes about a day, however, for
the material to reach the coma.

"Some called it fireworks today, but it really was more like
'iceworks,'" said Prof. Keith Mason, Director of Mullard Space Science
Laboratory at University College London, who organized the Swift
observations. "Much of the comet is ice. It's the other stuff deep
inside we're most interested in -- pristine material from the formation
of the solar system locked safely below the comet's frozen
surface. We don't know exactly what we kicked up yet."

Swift's "day job" is detecting distant, natural explosions called
gamma-ray bursts and creating a map of X-ray sources in the universe,
far more energetic "fireworks." Indeed, since beginning this Deep Impact
campaign on July 1 -- in addition to seeing comet Tempel 1 -- Swift has
seen a gamma-ray burst and a supernova and has discovered a black hole
in the Milky Way galaxy. The satellite's speed and agility, however,
provides an important complement to the dozens of other world-class
observatories in space and on Earth observing the Deep Impact
experiment. Swift will continue to monitor the comet this week.

Comets are small astronomical objects usually in highly elliptical
orbits around the sun. They are made primarily of frozen water, methane
and carbon dioxide with a small amount of minerals. They likely
originate in the Oort Cloud in the outskirts of the solar system. Comet
Tempel 1 is about the size of Washington, D.C. Some scientists say that
comets crashing into Earth billions of years ago brought water to our
planet.

A comet becomes visible when radiation from the Sun evaporates its outer
layers, creating a coma, the thin atmosphere. Solar wind impacts the
coma to form the comet's tail of dust and gas, which always points away
from the Sun. Comets are best visible when they enter the inner solar
system, closer to the Sun.

"The Deep Impact collision was the most watched astronomical event of
the year," said Dr. Neil Gehrels, Swift Principal Investigator at NASA
Goddard Space Flight Center in Greenbelt, Md. "All the 'big-guns'
observatories tracked it. In the next few days, as material continues to
fly off the comet from newly created vents, we will see whether Swift
can offer new insight into comets by virtue of the high-energy light we
are seeing."

Prof. Mason and Prof. Alan Wells of the University of Leicester in
England are at the Swift Mission Operation Center to help with the
observation.

The Deep Impact mission is managed by NASA's Jet Propulsion Laboratory,
Pasadena, California. Swift is a medium-class NASA explorer mission in
partnership with the Italian Space Agency and the Particle Physics and
Astronomy Research Council in the United Kingdom, and is managed by NASA
Goddard. Penn State controls science and flight operations from the
Mission Operations Center in University Park, Pennsylvania. The
spacecraft was built in collaboration with national laboratories,
universities and international partners, including Penn State
University; Los Alamos National Laboratory, New Mexico; Sonoma State
University, Rohnert Park, Calif.; Mullard Space Science Laboratory in
Dorking, Surrey, England; the University of Leicester, England; Brera
Observatory in Milan; and ASI Science Data Center in Frascati, Italy.

IMAGES AND VIDEOS:
High-resolution images and videos are available on the web at
http://www.science.psu.edu/alert/Swift-Deep-Impact.htm

MORE INFORMATION:
http://swift.gsfc.nasa.gov
http://www.science.psu.edu/alert/SwiftPressReleases.html
and
http://swift.sonoma.edu/

CONTACTS:
Margaret Chester: chester_at_astro.psu.edu, 814-8685-7746
Sally Hunsberger, sdh_at_astro.psu.edu, 814-865-7748
Neil Gehrels: gehrels_at_gsfc.nasa.gov, 301-286-6546
Lynn Cominsky: llynnc_at_universe.sonoma.edu, 707-664-2655
Barbara K. Kennedy (PIO), science_at_psu.edu, 814-863-4682
Received on Tue 05 Jul 2005 01:33:45 PM PDT