Word: spacecraft
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Allen, co-founder of Microsoft, owner of the Portland Trail Blazers and the Seattle Seahawks, and one of the developers of the first private spacecraft, has never lacked for ways to stay busy, but in 2001 he joined with the University of California, Berkeley, and the SETI (Search for Extraterrestrial Intelligence) Institute to install a set of 42 dish antennas in Hat Creek, Calif. The so-called Allen Telescope Array (ATA), which was scheduled to go live on Oct. 11, does what conventional radio telescopes do. That is to say, it listens to the faint whisper of radio signals from...
...fuel tank and - once again - left a deep divot in the ship's insulating tiles. It was foam damage that killed the shuttle Columbia in February 2003, when superheated gases generated during reentry entered the ship through a breach in the insulation. Ever since then, astronauts have given their spacecraft a close visual inspection upon reaching orbit to look for any troublesome chips. On Sunday, a 3D laser imager attached to Endeavour's robotic arm revealed what could be a nasty...
...Endeavour has plenty of things going for it. While the temperature in the vicinity of the wheel well grows blistering during reentry - on the order of 2,300 degrees Fahrenheit - that's a fair bit cooler than the 3,000 degrees reached at the spacecraft's nose and wingtips. Even damaged tiles can usually survive the heating at the aft end of the ship. NASA reports that it caught one bit of good luck in that the breach occurred right over a stretch of the aluminum framework of the ship itself - a bit like damaging a sheet-rock wall directly...
Like any other spacecraft, Dawn will have to be muscled off its launchpad by a conventional rocket burning conventional propellant. Once it climbs to near Earth space, however, everything will change. Of all the things that add weight to a spacecraft, fuel presents the most problems. The farther you're going, the more propellant you need, but every pound of it you add means more mass the engine must propel, which requires more fuel still, and on and on. A spacecraft like Dawn, which is designed not just to fly by its two targets but also to settle into orbit...
...secrets of both worlds, Dawn will ease itself into a six-month orbit around Vesta, then climb gradually back out and fly on to Ceres, which it will orbit for about five months. This is the part that would have been simply too fuel intensive for an ordinary spacecraft. Dawn, by contrast, should have enough xenon left over after its Ceres stay that mission planners might even consider sending it on to a third destination...