[meteorite-list] DS1 Flyby Images Will Remake Comet Science, Help Deep Impact Mission

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:49:02 2004
Message-ID: <200109242010.NAA20849_at_zagami.jpl.nasa.gov>

http://www.space.com/scienceastronomy/solarsystem/ds1_scipreview_010924.html

Fly-By Images Will Remake Comet Science, Help 'Deep Impact' Mission
By Robert Roy Britt
space.com
24 September 2001

Images of a comet taken by the Deep Space 1 spacecraft, along with other
data NASA will release Tuesday, will remake what scientists know about the
Sun-orbiting ice balls and help planners for an upcoming comet-smashing
mission.

The future mission, Deep Impact, will attempt to ram a probe into a comet at
high speed, and the manager of that mission now has greater confidence that
his team can actually hit the target as planned.

Some 30 black-and-white pictures of comet Borrelly's nucleus were produced
when Deep Space 1 flew past the comet Saturday in a maneuver that mission
managers did not expect to succeed. The beleaguered but determined craft
also made infrared images and recorded data of magnetic fields and other
emissions from the comet.

"The images and other data we collected from comet Borrelly are going to
make great contributions to scientists' efforts to learn more about these
intriguing members of the solar system family," said mission manager Marc
Rayman.

The new images and other data will come close to remaking what is known
about comets for years to come, Rayman said.

"I think we're going to gain a lot of completely new and absolutely
fascinating insights into comets and perhaps into the origin and evolution
of Earth," he said.

NASA has set a news conference to reveal the fly-by results for Tuesday,
Sept. 25, at 1 p.m. ET.

The black-and-white photographs snapped on Saturday were well centered in
the camera's viewfinder and sharp, said Donald Yeomans, a Jet Propulsion
Laboratory (JPL) comet and asteroid researcher who was in the control room
when early versions of the images first arrived.

Other researchers, who wished not to be quoted because NASA is keeping a
tight lid on the fly-by data, agreed that the images and data would be
extremely important to the study of comets, about which little is known.

Astronomers have so little data on comets, especially on their internal
composition, that there is a wide range of possibilities regarding what they
are made of. Among the most well studied comets is 1999 S4 LINEAR, which
broke apart during the summer of 2000 in view of several space- and
Earth-based telescopes.

Comet LINEAR was found to contain far less water than researchers expected,
a result which, if supported by similar findings, could alter scientists'
view of the role comets played in supplying Earth's water and making the
planet habitable.

But with little to compare it to, scientists could not say whether LINEAR is
typical or a special case. Now, with detailed data on two comets, it's
possible that scientists will be able to draw broader conclusions.

Next up: Crash into a comet

A handful of other firmly planned missions from both NASA and the European
Space Agency will explore comets in greater detail in the next four years.
One of the greatest challenges in studying comets from space is that mission
planners don't know much about their target, hence they are challenged to
program the spacecraft to know what it should be looking for.

This can affect everything from whether the spacecraft actually finds its
target to how successfully it pulls off its imaging tasks and other aspects
of the mission.

The success of Deep Space 1 has significantly boosted confidence in NASA's
Deep Impact mission, which will slam a small probe into comet Tempel 1 on
Independence Day 2005 so that researchers can study the material ejected
from the comet's nucleus. If it succeeds, Deep Impact will likely provide
the true look at the pristine, billions-year-old material inside a comet.

That material is thought to hold secrets of the solar systems formation.

"The images from Deep Space 1 will play a crucial role in refining our
predictions of the targeting environment for Deep Impact," said Michael
A'Hearn, a University of Maryland astronomer who will manage Deep Impact.

A'Hearn, who was at JPL for Saturday's flyby, said via e-mail that the
accomplishment gives Deep Impact some momentum and provides a measure of
confidence for the mission, which is due to launch in January 2004.

"My preliminary look at the data from Deep Space 1 suggests that our
predictions for Borrelly were not far off and that, therefore, we can rely
on our nominal predictions for Tempel 1, rather than our worst case models,
and that we should not have a problem hitting the nucleus," he said.

Deep Space 1 managed to wiggle its way inside the coma of comet Borrelly, a
shroud of gas and dust that NASA had feared might have destroyed the craft
before it got a chance to take pictures. The probe was not designed for such
a flyby and, because it was travelling at 36,900 mph (16.5 kilometers per
second), it was defenseless against the powerful impact of even a small bit
of dust.

"The fact that DS1 survived the encounter despite having no shielding
against the dust in the coma gives us confidence that our flyby, which is
shielded against dust, also will not be destroyed by the dust in the coma,"
A'Hearn said.
Received on Mon 24 Sep 2001 04:10:11 PM PDT