Deep impact spacecraft successfully flies by comet Hartley 2

The University of Maryland-led EPOXI mission successfully flew by comet Hartley 2 at 10 a.m. EDT Nov. 3, 2010, and the spacecraft has begun returning images. Hartley 2 is the fifth comet nucleus visited by any spacecraft and the second one visited by the Deep Impact spacecraft.

Scientists and mission controllers are studying never-before-seen images of Hartley 2 appearing on their computer terminal screens. See images at: http://epoxi.umd.edu/

"We are all holding our breath to see what discoveries await us in the observations near closest approach," said University of Maryland astronomer Michael A'Hearn, one of the originators of science team leader for both the Deep Impact mission and its follow on mission EPOXI.

At approximately 10 a.m. EDT, the spacecraft passed within 700 kilometers (435 miles) of the comet. Minutes after closest approach, the spacecraft's High-Gain Antenna was pointed at Earth and began downlinking vital spacecraft health and other engineering data stored aboard the spacecraft's onboard computer during the encounter. Twenty minutes later, the first images of the encounter made the 37 million kilometer (23 million mile) trip from the spacecraft to NASA's Deep Space Network antenna, appearing moments later on the mission's computer screens.

"The mission team and scientists have worked for this day," said Tim Larson, EPOXI project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It's good to see Hartley 2 up close."

A Deeper Impact on Planetary Science

With the latest EPOXI mission data on Hartley 2, the Deep Impact spacecraft is adding to an already extensive scientific legacy. Launched in January 2005, the spacecraft made scientific history and world-wide headlines when it smashed a probe into comet Tempel 1 on July 4th of that year. Following the conclusion of that mission, a Maryland-led team of scientists won approval from NASA to fly the Deep Impact spacecraft to a second comet.

The name EPOXI itself is a combination of the names for the two extended mission components: the extrasolar planet observations, called Extrasolar Planet Observations and Characterization (EPOCh), and the flyby of comet Hartley 2, called the Deep Impact Extended Investigation (DIXI). During the EPOCh phase of EPOXI, the Deep Impact spacecraft provided information on possible extrasolar planets and was one of three spacecraft to find for the first time clear evidence of water on Moon. A study accepted for publication in The Astrophysical Journal and just released by NASA, provides "colorful" findings on Earth and other planets in our solar system that someday may help identify earthlike worlds around other stars.

The overall objective of the flyby of Hartley 2 is the same as that for the Deep Impact mission's trip to Tempel 1: to learn more about the origin and history of our solar system by learning more about the composition and diversity of comets. Comets contain material from the early days of the solar system before the planets formed. "If we understand the comets really well it will tell us how the planets got made," explained A'Hearn. "That's why we choose comets to study."

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the EPOXI mission for NASA's Science Mission Directorate, Washington. The University of Maryland, College Park, is home to the mission's principal investigator, Michael A'Hearn and eight other members of the EPOXI science team. Drake Deming of NASA's Goddard Space Flight Center, Greenbelt, Md., is the science lead for the mission's extrasolar planet observations. The spacecraft was built for NASA by Ball Aerospace & Technologies Corp., Boulder, Colo.