November 1, 1994
A preliminary analysis and comparison of data from Galileo's ultraviolet spectrometer, photopolarimeter-radiometer and near- infrared mapping spectrometer on the July impact of Comet Shoemaker-Levy 9's fragment G at Jupiter has allowed the scientists to characterize a comet impact directly for the first time. The ultraviolet instrument and photopolarimeter saw the fireball first, when it was about 7 kilometers (5 miles) across with a temperature of at least 8,000 degrees Kelvin (14,000 Fahrenheit), which is hotter than the sun's surface. Five seconds later the infrared spectrometer detected it and monitored its expansion, rise and cooling for a minute and a half.
Results of the observations by these three instruments plus the imaging system of several Shoemaker-Levy events are being reported at a meeting this week of the American Astronomical Society's Division of Planetary Sciences. Other Shoemaker-Levy data stored on Galileo's on-board tape recorder will be transmitted to Earth through January 1995.
Galileo continues to operate normally, spinning at about 3
rpm and transmitting at 10 bits per second to ground stations of
the NASA/JPL Deep Space Network. The spacecraft is currently 866
million kilometers (538 million miles) from Earth, and 197
million kilometers (122 million miles) from Jupiter. It will
reach Jupiter on December 7, 1995, when its probe will descend
into the Jovian atmosphere and the orbiter spacecraft will begin
two years of observation and measurement of the planet, its moons
and magnetosphere.