After a nearly 2.9-billion-mile (4.6-billion-kilometer) voyage, NASA’s EPOXI mission spacecraft has survived its risky rendezvous with comet 103P/Hartley 2 and has beamed back the first close-up images of the comet. This montage of five pictures, for example, shows Hartley 2′s nucleus as the craft was flying toward and under the icy body on Thursday. The images progress in time clockwise, starting at top left.
“Early observations of the comet show that, for the first time, we may be able to connect activity to individual features on the nucleus,” Michael A’Hearn, EPOXI’s principal investigator said in a statement. “We certainly have our hands full. The images are full of great cometary data, and that’s what we hoped for.”. The vessel EPOXI, previously called Deep Impact, traveled 2.9 billion miles into space and captured images 435 miles away from the Hartley 2 comet, which was traveling at a speed of 27,000 miles-per-hour. Scientists say the photos of the icy body will provide them with new and useful information about comets.
The comet discovered in 1985 by British astronomer Malcolm Hartley — became only the fifth comet ever to have been photographed by a spacecraft. Comets are collections of dust, rocks and ice that travel through the solar system. The Deep Impact craft is so named because of a previous mission it flew to a comet called Tempel 1. The craft fired a missile into the comet, causing an explosion and creating a crater. Two imaging instruments on Deep Impact are responsible for the pictures NASA now has of Hartley 2; each instrument had its own specific capability and purpose, according to NASA.
“In the center there doesn’t seem to be any jet activity at all, creating a possible natural reservoir.” Sunshine speculates that the smooth region may be filled with fine grains of dust that originated from the active regions near the comet’s poles and were drawn by gravity to the middle. The main computer flying Deep Impact is based on a Rad 750 chip, a radiation-hardened version of a PowerPC processor, according to NASA. The craft’s power comes from a fixed solar array of 7.5 square meters, with a rechargeable 16-amp-hour nickel hydrogen battery that provides power during a solar eclipse. A hydrazine-fueled propulsion system powers its flight through space. NASA is now evaluating the photos, which provide detail about material that has not changed for more than 4 billion years, to determine what it can learn about the solar system.