From: Jet Propulsion Laboratory
Posted: Friday, August 2, 2002
CONTOUR continues operating nominally in its phasing orbit. Five propulsive burns occured over the last week, all of them executed very well. Three of the burns were performed for changing the pointing of the spin axis. Two of the burns were delta-v maneuvers. So far, there have been a total of sixteen propulsive burns since launch, all of them have been successful. With only two weeks to go before CONTOUR fires its solid rocket motor, the mission operations team will spin up the spacecraft to 60 rotations per minute, or rpm, on Monday, August 5. The reason for spinning the spacecraft up to sixty rotations per minute is to make it gyroscopically 'stiff' to lessen errors caused by thruster misalignments, center-of-mass misalignments, and the resulting nutation.
During ground testing, we spun up the spacecraft to 65 rpm on three separate occassions as part of an effort to balance it and also to confirm that the spacecraft was properly constructed to withstand the centrifugal force generated by the spin. To do this, the spacecraft was placed on a spin balance machine which physically rotated the 2138 pound spacecraft. During electrical testing, the solar array simulator was programmed to provide electrical power into the spacecraft that mimicked a spacecraft spinning at rates upto 120 rpm. We wanted to make sure that the circuits that regulated the power did not create a lot of electrical noise that could possiby disrupt spacecraft operation -- they didn't.
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