Comet Whammy Series Completes Slam of Jupiter Today
Jul. 21, 1994
GREENBELT, Md. (AP) _ A comet train's triple whammy that smashed into the cloud tops of Jupiter was actually a quadruple hit because the first fragment broke into two parts, an astronomer said today.
''The fireballs all overlapped each other,'' said Mordacai-Mark Mac Low, a University of Chicago astronomer. ''They all hit within .2 of a degree, which is within about 100 kilometers (60 miles).''
The University of Chicago operates a telescope in Antarctica, called the South Pole Infrared Explorer, that at this time of year can constantly monitor Jupiter. Images taken by the instrument are expected to be relayed to the United States late today.
Mac Low said the images show that the impact points of fragments Q1, Q2, R and S were joined in ''great big blobs'' of bright infrared, or heat, radiation.
''Each impact dredged up more and more material and made it (the impact point) brighter and brighter,'' he said.
Fragment Q2 hit the giant planet on Wednesday, but struck as two pieces close together. Fragment R slammed Jupiter about 10 hours later, and fragment S completed the sequence by hitting shortly after 11 a.m. EDT.
S became the 17th fragment to hit Jupiter's cloud tops. At least four more were expected, with the last, fragment W, hitting about 4 a.m. EDT Friday.
Astronomers at the news conference said that there may more, unseen, fragments from the comet train that also will hit the giant planet.
Eugene Shoemaker, co-discover of the comet, said the comet fragments have a way of ''turning off'' and becoming invisible. When all of their loose material is blown off, the fragments no longer form the coma, or dust halo, that reflects sunlight and makes them visible.
Astronomers are anxious to study the effects on the impact point of the multiple hits. The heat from the repeated fireballs are expected to create chemical reactions not seen during the single impacts.
Three of the fragments are only slightly smaller than fragment G, the largest of the comet shards. G exploded with a force estimated at about 6 million megatons of TNT, an explosive power far larger than all of the world's nuclear bombs put together. Impact points of earlier comet hits were still glowing with heat on Wednesday.
''We're really interested in seeing what happens when the fragments land almost on top of each other,'' said Lucy McFadden, a University of Maryland astronomer. ''It could be a real boiling pot.''
Steve Maran, a National Aeronautics and Space Administration astronomer, called the triple impact ''the greatest one-two-three punch of all time.''
McFadden said the three fragments will hit the top of Jupiter's cloud cover so close together that their ''footprints,'' or impact marks, will overlap. She said the resulting circular scars should resemble three of the famed Olympic rings.
A mark left by fragment G is larger than the Earth and some experts said it could persist in the Jupiter cloud tops for months.
Roger Yelle of the University of Arizona, an astronomer working at the Space Telescope Science Institute, said chemical reactions in the triple-hit areas are likely to be different than in single-hit areas; but as to what the difference will be, he said: ''I can't make predictions.''
Yelle said researchers already have identified three molecules created by the superheated churning of the comet impacts. Ammonia was found earlier and now the scientists have identified sulfur and hydrogen sulfide.
They are still looking for water, a molecule that was expected to boil up quickly.
Telescopes around the world continue to monitor the comet's shelling of Jupiter, and technical reports are clogging an international computer network.
Anita Cochran, a University of Texas astronomer, said researchers ''were like giddy little kids,'' taking turns watching the comet smash into Jupiter on a telescope at the McDonald Observatory near Fort Stockton, Texas.
David Levy, a co-discoverer of the comet, said dark patches left by the comet hits are now distinctive features on Jupiter's southern face. People with good quality amateur telescopes, in good viewing conditions, should be able to see the marks, he said.