PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

FOR IMMEDIATE RELEASE                                                March 6, 1991

       The Magellan spacecraft resumed mapping the surface of Venus Tuesday morning after Earth receivers missed three and one-half orbits over 10 hours due to an on-board computer problem.

       It was the second interruption in the signal since Magellan began mapping Venus Sept. 15. The previous incident happened in mid-November last year.

       The interruption, triggered by an unidentified computer problem, lasted for about two and one-half hours beginning at 5:45 p.m. PST Monday evening. Although Deep Space Network receivers acquired a radio signal about 8:20 p.m. adequate for engineering data, the higher data rate for radar telemetry was not regained until later.

       The high-gain antenna was pointed away from Earth by five and one-half degrees. All spacecraft systems including radar mapping continued normally, but mapping data was not received.

       Normal mapping operations resumed at 4 a.m. Tuesday after ground controllers manually corrected spacecraft pointing. Star calibrations indicated pointing was within 0.04 degrees.

       "Our operations team deserves a great deal of credit for getting us back to mapping so soon," said Mission Director Jim Scott.


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3/6/91 JJD
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