Satcom 3 was lost after launch in 1979 and wound up in a non-geosynchronous orbit. On a tour of the satellite manufacturer, RCA Astro, years after the loss, we

Satcom 3 was lost after launch in 1979 and wound up in a non-geosynchronous orbit. On a tour of the satellite manufacturer, RCA Astro, years after the loss, we heard this story: during the transfer of control from NASA to RCA Astro contact was lost and not re-established. Eventually the U.S. military was asked, "Errrh, did you see where Satcom 3 went?". The answer came back "Yup, looks like isn't in the geosynchronous orbit you expected". The thought was that during the handover a command to fire the apogee motor was inadvertently sent and obeyed! The fix for FUTURE launches was a protocol of checksummed commands. Beyond that, the new, more cautious sequence, became: 1. uplink dangerous command. 2. spacecraft verifies checksum and downlinks a copy of the proposed dangerous command 3. a keylock on the RCA command console is turned on and the "execute that dangerous command" instruction is uplinked. 4. upon verifying the execute command's checksum, the dangerous command is executed. No further launches suffered a failure similar to Satcom 3. Satcom 3's hulk is still in orbit. See: https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1979-101A https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id... https://space.skyrocket.de/doc_sdat/satcom-1.htm#:~:text=Satcom%203 https://space.skyrocket.de/doc_sdat/satcom-1.htm#:~:text=Sat...