[Illustration: The most critical period of the Galileo flight will be the Probe entry at Jupiter. The Probe must strike the atmosphere at precisely the correct angle and speed to be slowed down without being destroyed. At a pressure level of about 0.1 bar the rapid deceleration period ends and the heat shield is released. A parachute is deployed to slow the descent further, and the Probe then has a period of nearly an hour to study the atmosphere and clouds of Jupiter. The Probe mission ends when its batteries run down or when it is crushed by the pressure of the Jovian atmosphere near the 20-bar level, whichever comes first. [SL78-545(3)]] GALILEO PROBE SCIENCE INVESTIGATIONS Probe Scientist: L. Collin, NASA Ames Investigation Principal Investigator Primary Objectives Atmospheric structure A. Seiff, NASA Ames Measure temperature, density, pressure, and molecular weight to determine the structure of Jupiter’s atmosphere. Neutral mass H. B. Neimann, NASA Measure the spectrometer Goddard composition of the gases in Jupiter’s atmosphere and the variations at different levels in the atmosphere. Helium abundance U. von Zahn, Bonn U. Measure with high interferometer (Germany) accuracy the ratio of hydrogen to helium in Jupiter’s atmosphere. Nephelometer B. Ragent, NASA Ames Determine the sizes of cloud particles and the location of cloud layers in Jupiter’s atmosphere. Net flux radiometer R. W. Boese, NASA Ames Measure energy being radiated from Jupiter and the Sun, at different levels in Jupiter’s atmosphere. Lightning and radio L. J. Lanzerotti, Measure lightning