[meteorite-list] Daughters of Deep Impact: Two University of Maryland-Proposed Missions Could Help Clear Suddenly Clouded Comet Picture

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri Apr 21 23:29:52 2006
Message-ID: <200604211656.JAA11702_at_zagami.jpl.nasa.gov>

http://newswire.ascribe.org/cgi-bin/behold.pl?ascribeid=20060420.094212&time=10%2004%20PDT&year=2006&public=0

Daughters of Deep Impact: Two University of Maryland-Proposed
Missions Could Help Clear Suddenly Clouded Comet Picture

       COLLEGE PARK, Md., April 20 (AScribe Newswire) -- Over the past
five years, three space missions -- Deep Impact, Deep Space 1 and
Stardust -- have provided unprecedented information about comets.
However, rather than clearing up the true nature of comets, the
sometimes conflicting data from these missions have scientists
questioning almost everything they thought they knew about these
fascinating -- and potentially dangerous -- objects.

       Now, the University of Maryland-led team that produced the
spectacular Deep Impact mission is proposing two new missions that they
think can help coalesce the cloud of cometary information into solid
ideas about the nature of comets, how they formed, how they have evolved
and what role, if any, they may have played in the emergence of life on
Earth.

       Both missions would build on the highly successful Deep Impact
mission that on July 4th 2005 smashed a probe into Tempel 1 to reveal
that comet's interior, its fluffy structure and weak materials. Deep
Impact was the first large scale experiment ever conducted on a comet.

       The proposed new missions are called DeepR and DIXI. DeepR
(Deep-Rosetta) would clone the Deep Impact mission, building identical
flyby and impactor spacecraft and targeting comet
67P/Churyumov-Gerasimenko (C-G), the destination of the European Space
Agency's currently-in-route Rosetta mission. DIXI, which stands for Deep
Impact eXtended Investigation, would use the surviving Deep Impact
spacecraft and its three working instruments (two color cameras and an
IR spectrometer) for a flyby of Comet Boethin in December 2008.

       Like Deep Impact, DeepR and DIXI would be a partnership between
the University of Maryland, the Jet Propulsion Laboratory (JPL), and
Ball Aerospace & Technologies Corporation.

       "One of the great surprises of comet explorations has been the
wide diversity among the different cometary surfaces imaged to date,"
said Deep Impact leader and University of Maryland astronomer Michael
A'Hearn, who would be principle investigator (PI) for DIXI and deputy PI
for DeepR. "Even on Tempel 1, the comet we've imaged the best, there is
shocking variability in its surface. The comet's different surface types
clearly have undergone different histories."

       "These proposed missions are very cost effective ways to provide
new results that can be directly compared to the landmark Deep Impact
findings as well as with the results of Deep Space 1 and Stardust," said
A'Hearn.

       Jessica Sunshine, an adjunct professor of astronomy at Maryland
who would be the principle investigator for the DeepR mission and deputy
PI for DIXI, said, "By giving us high quality comparable data on two
additional Jupiter class comets, these missions will help us figure out
which characteristics of structure and composition are common among
comets and which are more individual or distinctive characteristics."

       A'Hearn, Sunshine and the other University of Maryland scientists
who would be part of the missions say the data that would be obtained
from these two missions would also will help scientists determine which
characteristics of comet structure and composition are primordial,
reflecting conditions and processes that existed 4.5 billion years ago
when the solar system formed, and which are the result of evolutionary
forces (heating and cooling, impacts, etc.) that have acted on comets
since that time.

       "Data from comets can help us to better understand the origin of
the solar system, as well as what role, if any, comets may have played
in the emergence of life on Earth," said Sunshine, who is a member of
the Deep Impact science team. "However, we first must know which
cometary characteristics are due to evolution and which are primordial."

       Making a Deep-R Impact

       Results from Deep Space 1, Stardust, and the Deep Impact
experiment at comet 9P/Tempel 1 fundamentally challenge the existing
paradigms on cometary formation, composition, and evolution. The DeepR
(Deep Rosetta) mission will fly a build-to-print clone of the highly
successful Deep Impact mission to an encounter with comet
67P/Churyumov-Gerasimenko, which is the current destination of Rosetta,
a mission of the European Space Agency (ESA).

       Employing the experimental approach defined by Deep Impact
mission, the DeepR mission would deliver to comet
67P/Churyumov-Gerasimenko an impactor that would collide with the comet
at some 22,000 miles an hour (10 km/s) on July 29, 2015. The collision
will expose the interior of 67P/ Churyumov-Gerasimenko to examination by
a comprehensive set of instruments from both the DeepR flyby spacecraft
and ESA's flagship-class Rosetta mission. These instruments will monitor
the impact from two complementary viewing directions at high temporal
and spatial resolution, -- including the formation of the crater and its
subsequent evolution -- and provide unprecedented analyses of the
components in the interior comet's nucleus.

       "The DeepR experiment will leverage ESA's more than $1 billion
Rosetta mission, which includes 11 orbiter and 10 lander experiments, to
create the most complete knowledge set to date for any comet," said
Sunshine.

       She explained that the focus of DeepR is to determine if the
variability seen on Tempel 1 extends to the chemistry and physical
properties of other cometary interiors and to understand if findings
from the material excavated from the interior of Tempel 1 are
representative of comets in general. "DeepR would employ the same
experimental approach that we pioneered at Tempel 1," she said. "Since
the only variable will be the cometary target, we will be able to
directly compare the results of both experiments."

       For, DeepR competing for selection by NASA is a two-step process.
The first round is expected in September, 2006. If selected in that
round, the DeepR team will write another larger proposal called a
"concept study report" that NASA will evaluate in the final selection
process.

       DIXI: Deep Impact eXtended Investigation

       The Deep Impact flyby spacecraft made many surprising discoveries
on approach to comet Tempel 1. These include an extremely fluffy
composition that largely insulates the interior from heat experienced by
the surface; frequent, natural outbursts; major differences in the
distribution of carbon dioxide and water; craters and other surprising
geological features; demonstration that the ice below the surface must
be evaporating (subliming) to water vapor, and the first detection of
ice (a very small amount) on a cometary nucleus.

       "There are clearly large differences between Tempel 1 and the
much younger Wild 2 [pronounced Vild 2], visited by the Stardust
mission" said A'Hearn. "Deep Impact's flyby spacecraft and payload are
still healthy. We propose to direct the spacecraft for a flyby of Comet
Boethin in December 2008 in order to investigate whether the results
found at comet Tempel 1 are unique or are found on other comets.
Obtaining data of the same type on a second, similarly evolved comet is
crucial to our understanding."

       "Since half the discoveries at Tempel 1 were from the flyby data
taken before impact, DIXI can return half the science of Deep Impact for
much less than 10 percent of the cost of Deep Impact," he said. "From
the point of view of cost-effective science, an extended mission such as
DIXI is unbeatable."

       NASA's decision to select DIXI or a competing mission proposal is
expected in September, 2006.

       - - - -

       CONTACT: Lee Tune, UM Office of University Communications,
301-405-4679, ltune_at_accmail.umd.edu

      Media Contact: See above.
Received on Fri 21 Apr 2006 12:56:21 PM PDT