Nancy Neal Jones
NASA Goddard Space Flight Center, Greenbelt, Md.        June 2, 2008
301 286 0039

RELEASE: 08-58

HUNT FOR SUPEREARTH PLANETS UNDERWAY

NASA Goddard Space Flight Center scientist, Dr. Drake Deming, will
present an update on the EPOXI mission on June 2, 2008 at the 212th
American Astronomical Society in St. Louis, MO.

The mission which uses the Deep Impact spacecraft has begun its search
for "super Earth" planets. The EPOXI team has focused its attention on
the star GJ436.  This red dwarf star which is 32 light-years from Earth
has a Neptune-sized planet that transits in front of the star. Spitzer
observations have shown that this Neptune-sized planet has an oval
shaped orbit (eccentric).

"Tidal forces from the star should have made the orbit circular, unless
there is another planet whose gravitational tug pulls the orbit into an
oval shape, said Drake Deming, Deputy Principal Investigator for the
Deep Impact extended mission, EPOXI.  "If that second planet lies in the
same orbital plane as the Neptune-sized planet then we should see it
transit.  The transit would be too shallow to be spotted by ground-based
telescopes, and EPOXI is the only space mission that can look at GJ436
nearly continuously for several weeks."

The orbital period of the "super Earth" is not precisely known, but the
EPOXI team estimates it to be in the range from 20 to 30 days.  EPOXI
has been observing the system from May 5 - May 28. Deming and his team
are in the process of analyzing the results of these data.

In addition to targeting the red dwarf star for study, EPOXI imaged the
Earth over three 24-hour periods. EPOXI measured the Earth's rotational
light curve at visible wavelengths from the ultraviolet to the
near-infrared.  These observations will help to calibrate future
observations of Earth-like exoplanets.  EPOXI obtained a particularly
interesting view of the Earth on May 29, when the Moon passed in front
of the Earth as viewed from the spacecraft.  This "transit" of the Moon
is an event that may also be observed to occur for Earth-like
exoplanets, and it may help us to deduce the nature of their surface
features.

EPOXI is a combination of two separate science investigations. The
investigations consist of the Extrasolar Planet Observations and
Characterization (EPOCh), and the flyby of comet Hartley 2, called the
Deep Impact eXtended Investigation (DIXI) which is lead by Dr. Michael
A'hearn at the University of Maryland.  Deming is the Principal
Investigator on the EPOCh investigations. EPOCh observations began in
January 2008.  Professor A'Hearn is the Principal  Investigator for the
combined EPOXI mission.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages Epoxi for
NASA's Science Mission Directorate, Washington. The University of
Maryland is the Principal Investigator institution. NASA Goddard leads
the mission's exosolar planet observations. The spacecraft was built for
NASA by Ball Aerospace & Technologies Corp., Boulder, Colo.

More information about EPOXI can be found at:
     http://www.nasa.gov/epoxi
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