Why did the antenna fail to open all the way up?
On April 11, 1991, Galileo began to deploy its High Gain Antenna under computer-sequence control. The antenna, a paraboloid stretched over 18 umbrella-like ribs — had been furled and hiding behind a small sunshade for the almost 18 months since launch, in which the spacecraft came closer to the sun than Earth and briefly closer even than Venus. Communications, including Venus and Earth-moon science data return, had been using the Low Gain Antennas. Within minutes, Galileo’s flight team, watching spacecraft telemetry 37 million miles away on Earth, could see that something was wrong: The motors had stalled, something had stuck, the antenna had opened only part way. Within weeks, a tiger team had thoroughly analyzed the telemetry, begun ground testing and analysis, and presented its first report. They attributed the problem to the sticking of a few antenna ribs due to friction between their standoff pins and their sockets. The first remedial action was taken — turning the spacecraft to
Related Questions
- Rather than going to the trouble of installing a Yagi antenna why not reposition the existing antenna so that it mounts horizontally rather than the present vertical?
- Can I use the PSM-4900 to help align the station antenna? Is an AGC output provided to feed to automatic antenna positioning equipment?
- Why did the antenna fail to open all the way up?
