From the Project Manager

First of all, all of us on Project Galileo heartily salute our colleagues on the Mars Pathfinder Project for their spectacular success. As we watched them on July 4th, we certainly could directly relate to their anxieties and ecstasy. Seeing signal from the Pathfinder Lander after landing was the perfect analogy to our Galileo Orbiter signaling to us that it was seeing the Atmospheric Probe signal after entry. And comparisons are natural and countless. Upon reflection, I find it particularly striking that the flight time of Mars Pathfinder from Earth to Mars was almost exactly the same seven months as Galileo's first orbital flight around Jupiter: December 7th vs. 4th to June 27th vs. July 4th--and our arrival at Ganymede-1 would have been July 4th (1996), except that our adaptive navigation strategy resulted in the one-week advance in Ganymede arrival.

It reminds us of the vastness of the Jupiter System our Galileo Orbiter is exploring. It is indeed the "miniature" solar system we refer to, consisting of 16 known natural satellites. And our flights from one of the major satellites (the Galileans: Io, Europa, Ganymede, and Callisto) to the next are completely analogous to interplanetary flights in the inner solar system--the gravity-assist at a given satellite "launches" Galileo on its trajectory to the next satellite. Indeed each orbit is a mission in itself. And unlike any other orbital mission to date, every orbit is quite unique. Galileo never repeats its path--it is always in new territory-the ultimate explorer!

On June 25th, we performed the eighth satellite encounter of the primary mission tour--Callisto-9. Save just two days, it was exactly one year from our first encounter--Ganymede-1 on June 27, 1996. All eight encounters--or should I say missions--have been grandly successful. We are eight for eight! Galileo is now in the seminal magnetotail orbit. Second in size only to the seven-month first orbit, this Callisto-9 (C9) Orbit is taking Galileo ten million kilometers into the magnetotail of Jupiter, where no spacecraft has ever been, in order to sample the fields and particles of this unexplored region to help explain the vastness of Jupiter's magnetosphere. This journey into the magnetotail has always been a fundamental element of Galileo's primary mission because it is crucial to one of the three major Galileo objectives, which are to investigate the Jupiter atmosphere, satellites, and magnetosphere.

This C9 orbit introduces a new operating feature. At seven key places around this orbit, we are "Recording During Cruise" (RDC). The orbit duration is long enough that we can play back a section of tape, then record new information on that section, subsequently play it back, and repeat this six times. This is particularly important in order to increase the sampling frequency of the fields and particles instruments at these key points in the magnetosphere. The shorter orbital cruise periods of all the other orbits (and greater Earth-Jupiter communication distance, resulting in lower average telemetry bit rates) warrant that we use all of our playback capability to play back the data from the immediately previous encounter.

The Team continues to do a phenomenal job of designing and executing extremely complex sequences, orchestrating the end-to-end data gathering of 11 separate science instruments with very limited (by today's standards) onboard computing capacity and downlink data rates. All 11 instruments are still providing excellent data even though the Photopolarimeter-Radiometer filter wheel is somewhat impaired, one of the 17 Near-Infrared Mapping Spectrometer detectors is not functioning, and another is problematical. The science bounty of Galileo is already tremendous and growing steadily. The preparations for the Galileo Europa Mission (GEM) that will continue operations through the last day of this millennium are well along. In fact, the planning for the last encounter of the primary mission--Europa-11--has now been made an integral part of the GEM planning, so it's a series of nine consecutive, synergistic Europa encounters we are planning. And more and more, we are adopting our GEM techniques/procedures as we near the completion of the primary mission so the transition from primary to GEM will be quite seamless.

Congratulations to the Galileo Team that holds the undisputed record for perseverance in space missions and has skills and ingenuity second to none!

--Bill O'Neil
Project Manager

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