Tuesday, September 18, 2007

Deep Impact and Stardust Missions Redesignated

On July 3, NASA announced that Deep Impact and Stardust, two successful comet-study spacecraft, would have their useful lives extended. In a coordinated effort, they will make new observations of comets and also characterize extrasolar planets.

Deep Impact Spacecraft Redesignated for “DIXI” and “EPOCh”

The Deep Impact spacecraft will be committed to two science investigations. The first is called the Deep Impact Extended Investigation (DIXI). The second is called Extrasolar Planet Observation and Characterization (EPOCh).

DIXI will involve the flyby of periodic comet 85P/Boethin, which has not been visited previously. This investigation will allow the recovery of some of the science which was lost with the August 2002 failure of the COmet Nucleus TOUR (CONTOUR) mission that was designed to make comparative studies of multiple comets. The Deep Impact spacecraft will be directed to fly by Boethin on December 5, 2008. Boethin was discovered by an amateur astronomer, the Reverend Leo Boethin, on January 4, 1975. Reverend Boethin discovered the comet, and made the first series of observations, from the town of Abra in the Philippines. The comet has a period of 11.225 years and the next perihelion is predicted to occur June 29, 2008. The rest of the orbital elements are as follows: Aphelion distance, 20,7560 AU; Perihelion distance, 1.1143 AU; Semi-major axis, 11.67560 AU; Eccentricity, 0.7777; Inclination, 5.756 degrees.

While en route to Boethin, the spacecraft will be used for the EPOCh investigation to observe several nearby bright stars, watching as known extrasolar giant planets pass in front of their stars 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.

Stardust Spacecraft Redesignated for “NExT”

While DIXI (Deep Impact) heads elsewhere, the Stardust spacecraft is off to visit Deep Impact’s old friend, periodic Comet 9P/Tempel (or Tempel 1). The mission is called New Exploration of Tempel 1 (NExT). This investigation will provide the first look at the changes to a comet nucleus produced after its close approach to the sun. It will also mark the first time a comet has been revisited. NExT will also extend the mapping of Tempel 1, making it the most mapped comet nucleus to date. The mapping will 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 the Deep Impact spacecraft from its encounter with the comet on July 4, 2005. NExT is scheduled to fly by 9P/Tempel 1 on February 14, 2011. Comet 9P/Tempel was discovered April 3, 1867 by German astronomer Ernst Wilhelm Leberecht Tempel, who was working in Marseille. The comet has a period of 5.515 years and the next perihelion is predicted to occur in 2011. The rest of the orbital elements are as follows: Aphelion distance, 4.737 AU; Perihelion distance, 1.506 AU; Semi-major axis, 3.122 AU; Eccentricity, 0.5175; Inclination, 10.5301 degrees.

Background Information

Stardust was launched February 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.

Stardust Mission Home Page:

Deep Impact was launched January 12, 2005. It traveled 268 million miles to Comet Tempel 1. The two-part spacecraft consisted of a larger “flyby” spacecraft carrying a smaller “impactor” spacecraft. The impactor was released July 2 and impacted Tempel 1 at 10:52 pm PDF on July 3 (July 4 EDT). The flyby spacecraft observed the impact and aftermath from 300 miles away, while other spacecraft and ground instruments made observations.

Deep Impact Mission Home Page:

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