[FPSPACE] Dawn Mission Journal for February 12, 2009

[LARRY KLAES]

February 12, 2009
 
Dear Charles Dawnwins, Dawn continues to close in on Mars, ready for the gravitational slingshot that will help it on its expedition to the asteroid belt and its quest to gain insights into the evolution of the solar system. The ship remains on course, with the latest calculations of its trajectory being very close to those described in the last log. The spacecraft will streak about 549 kilometers (341 miles) above the planet at 4:28 p.m. PST on February 17.  While Dawn and Mars move in their separate orbits around the Sun, they are approaching each other at the stately pace of 2.56 kilometers/second (5720 miles/hour). Gradually, the gravitational pull of the planet will grow as the distance shrinks, and the spacecraft’s path will start to change, beginning the boost we seek. By about noon PST on February 14, the tug from Mars will have grown to be the same as the famously gentle thrust from Dawn’s ion propulsion system. When Dawn is closest to Mars, speeding past it at 5.31 kilometers/second (11,900 miles/hour), the red planet will be exerting 34,000 times greater force than the blue-green xenon beam generates. Full journal entry here:
 
http://dawn.jpl.nasa.gov/mission/journal_2_12_09.asp
 
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