This Week on Galileo: Four Weeks
17 Jun 2002
(Source: Jet Propulsion Laboratory)
June 17 - July 14, 2002
The Galileo spacecraft has now rounded the corner in its longest looping orbit around Jupiter and is again heading back in towards the giant planet and a close flyby of the tiny moon Amalthea in November.
This past week brought good news about the on-board tape recorder. On April 12, during a routine maintenance activity, the tape appears to have stuck to the record or playback heads. After five preliminary tests to characterize the problem, on Saturday, June 8, the tape was successfully pulled free and we now expect it to be operational. On Tuesday, June 18, the recorder will be commanded back to the beginning of the tape and the tape position counter will be reset. From there we can safely command the tape as we have in the past without worrying that tape-position errors will trip fault protection routines in the spacecraft software. Subsequent activities are still in the planning stage. They may include slowly traversing the entire length of the tape several times, gradually increasing the distance and speed of motion until we are confident the recorder can again be used freely and reliably to record our final set of encounter data in November.
On Friday, June 21, and Monday, July 8, routine maintenance of the propulsion system is performed.
On Monday, July 1, the spacecraft performs a nearly 11 degree turn in place to keep the communications antenna pointed towards Earth. This turn positions the spacecraft to comfortably ride out an upcoming period called solar conjunction. During conjunction, Jupiter and Galileo appear to pass behind the Sun as seen from Earth. With the Sun still relatively near the peak of its 11-year activity cycle, interference from the dynamic solar wind scrambles the radio signal sent from the spacecraft. Between July 9 and July 28, the spacecraft will be within 7 degrees of the Sun, and communications are expected to be completely blocked. We are already seeing occasional degradation of the signal that we think can be attributed to solar activity. On Monday, June 24, we reconfigure the radio signal from the spacecraft to help improve our ability to communicate during this turbulent time.
With the spacecraft well outside the magnetosphere of Jupiter on the sunward side of the planet, continuous data collection by the Magnetometer, the Dust Detector, and the Extreme Ultraviolet Spectrometer instruments provides scientists with information about the interplanetary medium. During the solar conjunction period, the Magnetometer data collection is suspended, but the Dust Detector and Extreme Ultraviolet data will collect in an on-board computer memory buffer to be returned once communication is re-established in late July.
For more information on the Galileo spacecraft and its mission to Jupiter, please visit the Galileo home page.