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Status Report: NASA MESSENGER Passes the Billion-Mile Mark!

Wednesday, March 29, 2006

On March 23 MESSENGER reached the one-billion mile mark, placing the spacecraft about one-fifth of the way toward its destination to orbit Mercury. On that same day, in the early morning hours (UTC), the spacecraft's distance from the Sun was about the same as the Earth's distance to the Sun. "One billion miles and the team and spacecraft are doing well," says Mission Operations Manager Mark Holdridge of the Johns Hopkins Applied Physics Laboratory (APL), where the spacecraft is operated and where it was designed and built.

The MESSENGER spacecraft performed its final "flop" maneuver for the mission on March 8, pointing the back side of the spacecraft to the Sun until June 2006. This rotation about the X-axis is performed whenever the solar distance increases beyond approximately 0.95 astronomical units (AU), nearly the distance between the Earth and the Sun. At this distance, the solar arrays do not generate enough power to operate all spacecraft components simultaneously, including instruments and heaters. The "flop" is performed to heat the back side of the spacecraft with the Sun. A "flip" maneuver reverses the effect of the "flop" maneuver by pointing the sunshade toward the Sun. This solar heating reduces the need for multiple onboard heaters, providing the necessary power until the spacecraft is closer to the Sun again. Previous flip, flop, and flip maneuvers were performed on March 8, 2005, June 14, 2005, and September 7, 2005. The spacecraft is scheduled to flip back toward the Sun on June 21.

Even though the MESSENGER spacecraft is years away from entering its final destination of orbiting Mercury, the mission Science Team is already very busy collecting scientific data and sharing it with the larger scientific community. Those plans and results are now available on the team's new Web site: http://messenger.jhuapl.edu/soc/index.html.

For a complete look at MESSENGER's journey through the inner solar system, visit the Mission Design section of the Web site at http://messenger.jhuapl.edu/the_mission/mission_design.html.

To see where MESSENGER is now, visit http://messenger.jhuapl.edu/whereis/index.php.

More: NASA -Status Report on MESSENGER

NASA Reinstates the Dawn Mission

Wednesday, March 29, 2006

NASA senior management announced a decision Monday to reinstate the Dawn mission, a robotic exploration of two major asteroids. Dawn had been canceled because of technical problems and cost overruns.

The mission, named because it was designed to study objects dating from the dawn of the solar system, would travel to Vesta and Ceres, two of the largest asteroids orbiting the sun between Mars and Jupiter. Dawn will use an electric ion propulsion system and orbit multiple objects.

The mission originally was approved in December 2001 and was set for launch in June 2006. Technical problems and other difficulties delayed the projected launch date to July 2007 and pushed the cost from its original estimate of $373 million to $446 million. The decision to cancel Dawn was made March 2, 2006, after about $257 million already had been spent. An additional expenditure of about $14 million would have been required to terminate the project.

The reinstatement resulted from a review process that is part of new management procedures established by NASA Administrator Michael Griffin. The process is intended to help ensure open debate and thorough evaluation of major decisions regarding space exploration and agency operations.

"We revisited a number of technical and financial challenges and the work being done to address them," said NASA Associate Administrator Rex Geveden, who chaired the review panel. "Our review determined the project team has made substantive progress on many of this mission's technical issues, and, in the end, we have confidence the mission will succeed."

The Dawn decision document will be available on the Web at:http://www.nasa.gov/formedia

Story Credit: NASA-Erica Hupp/Dean Acosta