Spacecraft Sets Out to Strike a Comet
January 12, 2005 | NASA's Deep Impact spacecraft lifted off from Cape Canaveral at 1:47 p.m. Eastern time today and began its six-month journey to strike a comet. If all goes as planned, Deep Impact will reach 9P/Tempel 1 in July and release a 370-kilogram projectile that will slam into the comet's nucleus at 10 kilometers per second. Instruments aboard the spacecraft, as well as ground-based and Earth-orbiting telescopes, will scrutinize the spray of liberated material. The impact should provide data about the comet's subsurface chemical composition, while the size and shape of the resulting crater will yield valuable insight into the internal structure of the icy body.
One aspect of the Deep Impact mission has been the involvement of amateur astronomers. Backyard observers participating in the Small Telescope Science Program are already monitoring the comet, but activity will swing into high gear at the time of collision on July 4th. Researchers don't know exactly what will happen when the projectile hits, but they say the comet could briefly brighten to 6th magnitude.