July 19, 2005
NASA Weighs Encore for Deep Impact Craft
LOS ANGELES -- NASA is considering an encore for its Deep Impact spacecraft, which made history earlier this month when it smashed a hole in a comet to study its frozen primordial core.
While the space agency has not approved a specific future mission, it gave scientists at its Jet Propulsion Laboratory in Pasadena the go-ahead to bring the spacecraft closer to Earth's orbit for a potential mission extension.
Deep Impact planned to fire its thrusters Wednesday to slightly change course in a maneuver that will bring it back to Earth by 2008.
The spacecraft then will switch to safe mode to conserve energy until it receives orders for a possible second mission. If left untouched, the spacecraft will drift farther away.
The original mission called for the mothership to release an 820-pound copper impactor into the path of the onrushing comet Tempel 1, record the collision from a distance and retire as space junk.
But the mothership remained surprisingly healthy despite being bombarded with debris during a close flyby of Tempel 1 minutes after the collision.
Members of the Deep Impact team hope the maneuver will allow the spacecraft to steer toward 85P/Boethin, a comet that was discovered in 1975 and orbits the sun every 11 years.
Since Deep Impact carried only one impactor, any future mission will not cause a cosmic smashup. Instead, scientists hope the scientific instruments aboard Deep Impact will allow them a detailed glimpse of yet another comet.
Mission principal investigator Michael A'Hearn said a possible extended project would cost about $32 million; the Deep Impact mission cost $333 million.
The July 4 collision 83 million miles from Earth gave off two flashes of bright light and carved a crater in the potato-shaped comet. A larger-than-expected debris cloud extended thousands of miles into space, and has prevented scientists from peering into the comet's interior.
The impactor vaporized as it crashed on the comet's sunlit side, but the mothership survived unharmed. It flew within 310 miles of Tempel 1 and took pictures of the comet as it flew away.
Comets are irregular bodies of ice and dust that orbit the sun and were born about 4.5 billion years ago - nearly the same time as the solar system itself. When a cloud of gas and dust condensed to form the sun and planets, comets formed from what was left over. Studying them could shed light on how the solar system formed.
Deep Impact blasted off in January from Florida for a 268-million-mile journey toward Tempel 1, which was discovered in 1867 and moves around the sun in an elliptical orbit between Mars and Jupiter every six or so years.
On the Net:
Deep Impact mission: http://www.nasa.gov/deepimpact