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and three quarters of the way to the asteroid belt.
The Dawn probe almost never got off the ground following cancellation by Nasa in the cutbacks of 2006. Owing to the project status as unique (this being the first time anyone had sent a rocket to a newly classified 'dwarf planet'), the manufacturer offered to build the rocket at cost.
Even then, delays at the launchpad almost lost the whole mission as the flyby of Mars was restricted to a two month window.
Dawn has another first under its belt, using a secondary boost of onboard Xenon ion thrusters to move onto the second of its planned targets, Ceres. All other deep space probes have used gravity fly-bys to springboard from one object to another, which only allows half an orbit or so for the data to be collected on the way through.
If all goes well Vesta will be orbited as from August 2011 for around nine months. Ceres will be reached in 2015, and depending on the amount of fuel left over, another couple of asteroids are on the books.
The one fly in the ointment however is a lack of fine detail on the total number of asteroids orbiting between Mars and Jupiter. The total number so far discovered is over 100,000, but the smallest ones in the list are some four miles in diameter. Beyond this (and currently unobservable) estimates range from another 250,000 to some four million lumps of rock flying about over 300m in diameter, (and over 30 million smaller than this ) with no detectable trajectory or speed. Anyone of these could demolish the probe without prior warning.
_http://video.google.com/videoplay?docid=4465672384624896677#
The Dawn probe almost never got off the ground following cancellation by Nasa in the cutbacks of 2006. Owing to the project status as unique (this being the first time anyone had sent a rocket to a newly classified 'dwarf planet'), the manufacturer offered to build the rocket at cost.
Even then, delays at the launchpad almost lost the whole mission as the flyby of Mars was restricted to a two month window.
Dawn has another first under its belt, using a secondary boost of onboard Xenon ion thrusters to move onto the second of its planned targets, Ceres. All other deep space probes have used gravity fly-bys to springboard from one object to another, which only allows half an orbit or so for the data to be collected on the way through.
If all goes well Vesta will be orbited as from August 2011 for around nine months. Ceres will be reached in 2015, and depending on the amount of fuel left over, another couple of asteroids are on the books.
The one fly in the ointment however is a lack of fine detail on the total number of asteroids orbiting between Mars and Jupiter. The total number so far discovered is over 100,000, but the smallest ones in the list are some four miles in diameter. Beyond this (and currently unobservable) estimates range from another 250,000 to some four million lumps of rock flying about over 300m in diameter, (and over 30 million smaller than this ) with no detectable trajectory or speed. Anyone of these could demolish the probe without prior warning.
_http://video.google.com/videoplay?docid=4465672384624896677#
