Two NASA spacecraft now have new assignments after
successfully completing their missions. The duo will make new
observations of comets and characterize extrasolar planets. Stardust
and Deep Impact will use their flight-proven hardware to perform new,
previously unplanned, investigations.
"These mission extensions are as exciting as it gets. They will allow
us to revisit a comet for the first time, add another to the list of
comets explored and make a search for small planets around stars with
known large planets. And by using existing spacecraft in flight, we
can accomplish all of this for only about 15 percent of the cost of
starting a new mission from scratch, " said Alan Stern, associate
administrator for NASA's Science Mission Directorate, Headquarters,
Washington. "These new mission assignments for veteran spacecraft
represent not only creative thinking and planning, but are also a
prime example of getting more from the budget we have."
The EPOXI mission melds two compelling science investigations -- the
Deep Impact Extended Investigation (DIXI) and the Extrasolar Planet
Observation and Characterization (EPOCh). Both investigations will be
performed using the Deep Impact spacecraft, which finished its prime
mission in 2005.
DIXI will involve a flyby of comet Boethin, which has never been
explored. Boethin is a small, short period comet, or one that returns
frequently to the inner solar system, from beyond Jupiter's orbit.
This investigation will allow the recovery of some of the science
lost with the 2002 failure of the COmet Nucleus Tour (CONTOUR)
mission that was designed to make comparative studies of multiple
comets. DIXI will be targeted to fly by comet Boethin December 5,
2008.
The EPOCh investigation also will use the Deep Impact spacecraft to
observe several nearby bright stars, watching as the giant planets
already known to be orbiting the stars pass in front of and then
behind them. The collected data will be used to characterize the
giant planets and to determine whether they possess rings, moons, or
Earth-sized planetary companions. EPOCh's sensitivity will exceed
both current ground and space-based observatory capabilities. EPOCh
also will measure the mid-infrared spectrum of the Earth, providing
comparative data for future efforts to study the atmospheres of
extrasolar planets. This search for extrasolar planets will be made
this year, en route to comet Boethin.
Michael A'Hearn of the University of Maryland, College Park, is
EPOXI's principal investigator and the leader of the DIXI science
team. L. Drake Deming of NASA's Goddard Space Flight Center, in
Greenbelt, Md., is EPOXI's deputy principal investigator and leads
the EPOCh investigation.
John Mather, Chief Scientist for NASA's Science Mission Directorate,
said, "EPOXI is a wonderful opportunity to add to our growing body of
knowledge of exoplanets. Watching planets go behind or in front of
their parent stars can tell us about their atmospheric chemistry."
The other newly selected Discovery mission of opportunity is called
New Exploration of Tempel 1 (NExT). The mission will reuse NASA's
Stardust spacecraft to revisit comet Tempel 1. This investigation
will provide the first look at the changes to a comet nucleus
produced after its close approach to the sun. It will mark the first
time a comet has ever been revisited. NExT also will extend the
mapping of Tempel 1, making it the most mapped comet nucleus to date.
This mapping will help address the major questions of comet nucleus
"geology" raised by images of areas where it appears material might
have flowed like a liquid or powder. The images were returned by Deep
Impact from its encounter with the comet on July 4, 2005. NExt is
scheduled to fly by Tempel 1 on Feb. 14, 2011.
Joseph Veverka of Cornell University, Ithaca, NY, is NExT's principal
investigator.
Stardust launched in Feb. 7, 1999. It traveled over 2 billion miles to
fly within 150 miles of the comet Wild 2 in January 2004 to bring
back samples that may provide new insights into the composition of
comets and how they vary from one another. The container with the
comet samples returned to Earth in January 2006 while the rest of the
spacecraft remained in space.
Created in 1992, NASA's Discovery Program sponsors frequent,
cost-capped solar system exploration missions with highly focused
scientific goals. In 2006, NASA received approximately two dozen
proposals in response to an Announcement of Opportunity for Discovery
missions and Missions of Opportunity. Proposals were evaluated for
scientific merit, technical, management and cost feasibility.
For more information about the Discovery Program, visit:
http://discovery.nasa.gov
US $23.55
