It's not the end of the world but the beginning of a new space exploration expedition. A proposed NASA mission, codenamed Deep Impact, aims to smash a 500 kilogram copper projectile into a speeding comet.
Deep Impact is one of five proposals under consideration by the space agency. The winner will be launched in 2003. The copper ball will be launched from a space craft and smashed into the P/Temple comet to see what the comet is made of.
"Missions like Deep Impact may enable scientists to discover the origins of life or at least the materials that have gone to make up life and how they evolved in space," said Larry Lemke, chief of the advanced projects branch at NASA's Ames Research Center in Mountain View, California.
But Deep Impact is only one of five proposals vying for funding. Just one, or possibly two, missions will be approved in June 1999.
Other mission proposals selected for evaluation by NASA are: sending a spacecraft to orbit Mercury, returning samples of the two small moons of Mars to Earth, studying the interior of Jupiter, and investigating the middle atmosphere of Venus. Details of these proposals must be submitted to NASA by 31 March 1999.
Comets are thought to be remnants of the primordial dust and ice that gave rise to the solar system. The material lies in the outer reaches of the solar system but is dragged in by the gravitational pull of the planets.
Scientists hope the projectile will hit the comet hard enough to travel 65 feet into its pristine interior of ice and rock.
"Basically the idea is to impact the comet at a speed of up to 750 miles per minute and the kinetic energy generated is greater than that of high explosives," said Lemke. "So when it vaporizes it makes a crater."
NASA hopes to observe the impact from a distance and analyze the blast.
"Actually collecting the material and bringing it back to Earth is better," said Lemke.
Scientists have collected particles from comets before. For example, researchers believe that the particles that form the Leonid meteor shower originated from a comet.
With the Deep Impact mission, they may be able to detect biologically significant material -- such as amino acids.
The Deep Impact team will be led by Michael A'Hearn of the University of Maryland at College Park, and will cost more than US$203 million.
