Xref: utzoo sci.space:15339 sci.space.shuttle:4001 sci.astro:5648 Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!cs.utexas.edu!usc!henry.jpl.nasa.gov!elroy.jpl.nasa.gov!forsight!jato!mars.jpl.nasa.gov!baalke From: baalke@mars.jpl.nasa.gov (Ron Baalke) Newsgroups: sci.space,sci.space.shuttle,sci.astro Subject: Galileo Update Message-ID: <2106@jato.Jpl.Nasa.Gov> Date: 7 Nov 89 20:17:12 GMT Sender: news@jato.Jpl.Nasa.Gov Reply-To: baalke@mars.jpl.nasa.gov (Ron Baalke) Organization: Jet Propulsion Laboratory, Pasadena, CA. Lines: 59 GALILEO WEEKLY STATUS November 7, 1989 As of 8 a.m. (PST) Tuesday, November 7, 1989, the Galileo spacecraft is 4.16 million miles from Earth, 28.2 million miles along its path to its first gravity assist at Venus. Round-trip light time is almost 45 seconds. Galileo still has 157 million miles to go just to reach Venus; it is reducing that distance at a rate of just over 60,000 mph, increasing slowly as it comes closer to the Sun. Jupiter lies about 2.4 billion miles ahead along the VEEGA trajectory. The spacecraft is spinning at about 3 rpm around an axis pointed a few degrees from the Sun. It is transmitting telemetry at 7.68 kilobits per second; the RTG's are providing about 570 watts of power, 60 watts more than needed at present. The heavy ion counter, an engineering instrument which detects charged particles from the atomic weight of carbon through that of iron, has been seeing at least one every 2/3 second, mostly oxygen. It detected and characterized the recent major solar flare. Last week Galileo's flight team continued checkout, maintenance, and characterization of various elements of the spacecraft. Notable among these was the dual-spin mode, in which a major part of the spacecraft, carrying the scan platform with 4 instruments, the probe and probe relay system and associated electronics, was spun in reverse while the rest of the machine was still spinning at about 3 rpm. This mode, which allows the camera and other remote-sensing instruments to be aimed at planetary targets, was satisfactorily maintained during the 70-minute checkout. The spacecraft was then put back in the all-spin mode for other planned cruise operations. These included sun pointing (moving the spin axis from about 10 down to 1.25 degrees from the Sun line). Before and after this maneuver, the star sensor was given a star map and turned on to determine attitude and spin rate, which it did as planned. An additional propulsion system maintenance sequence was done early Monday. The first trajectory correction maneuver is planned for November 9, 10, and 11; it will change the spacecraft velocity by less than 17 meters per second (about 38 mph). Small axial and lateral thrusters will fire in pulses of about 1-sec duration. Nothing in the mission so far has ruled out the possibility of an asteroid encounter (Gaspra, between the first and second Earth flybys). However, no final decision on asteroid encounters will occur until after the Venus flyby in February, when Galileo's flight team and other project personnel evaluate the post-Venus flight path and the propellant margins at that time. Ron Baalke | (818) 541-2341 x260 Jet Propulsion Lab M/S 301-355 | baalke@mars.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 |