[Galileo image of fragment W collision]


Galileo is en route to Jupiter and will be about 1.5 AU (230 million km) from Jupiter at the time of the impact. At this range, Jupiter will be ~60 pixels across in the solid state imaging camera, a resolution of ~2400 km/pixel. Galileo will have a direct view of the impact sites, with an elevation of approximately 23 degrees above the horizon as seen from the impact point. The unavailability of the main antenna, forcing use of the low-gain antenna for data transmission, severely limits the imaging options available to Galileo. The low-gain antenna will be able to transmit to Earth at 10 bits/sec, so real-time transmission of imaging will not be possible. The Galileo tape recorder can store ~125 full-frame equivalents. On-board data compression and mosaicking may allow up to 64 images per frame to be stored, but playback of the recorded images must be completed by January, 1995 when Galileo reaches Jupiter. This will only allow transmission of ~5 full-frame equivalents, or approximately 320 images. There will be the capability for limited on-board editing and the images can be chosen after the impacts have occured, so the impact timing will be well known, but the imaging times must be scheduled weeks before the impacts. Each image requires 2.33 seconds, so a full frame of 64 images will cover ~2.5 minutes, and consist of ~2400 kilobits. A new mosaic can be started in ~6 seconds. The camera has a number of filters from violet through near-infrared and requires 5 to 10 seconds to change filters. In addition to imaging data, Galileo has a high time resolution photopolarimeter radiometer, near-infrared mapping spectrometer, radio reciever, and ultraviolet spectrometer which can be used to study the collisions. The limited storage capacity and low transmission rate of Galileo make the timing of all the impact observations critical. A memorandum from Clark Chapman gives details of the imaging schedule for Galileo. The latest Galileo status report for 1 September 1994 is also available.

Galileo SSI Images of the collisions

Dr. Edwin V. Bell, II
Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771

NASA Official: Dr. David R. Williams
Last Updated: 05 August 2008, EVB II