Daughters of Deep Impact: U.Maryland Proposed Missions Could ClearClouded Comet Picture (Forwarded)

Office of University Communications
University of Maryland

Contacts:
Lee Tune, 301 405 4679

For Immediate Release: April 20, 2006

Daughters of Deep Impact: UM Proposed Missions Could Clear Clouded Comet
Picture

COLLEGE PARK, Md. -- 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 the
University of Maryland, NASA's 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, a scientist 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.