3 ms·

I also read this a while ago [1]: "The Voyager’s computer system was very impressive as well. Knowing the craft would be on its own much of the time, with the

by isolli 3y ago

I also read this a while ago [1]: "The Voyager’s computer system was very impressive as well. Knowing the craft would be on its own much of the time, with the lag between command and response from Earth growing longer the farther the craft went into space, engineers developed a self-repairing computer system. The computer has multiple modules that compare the data they receive and the output instructions they decide on. If one module differs from the others, it's assumed to be faulty and is eliminated from the system, replaced by one of the backup modules. It was tested shortly after launch, when a delay in boom deployment was misread as a malfunction. The problem was corrected successfully." [1] https://science.howstuffworks.com/voyager.htm https://science.howstuffworks.com/voyager.htm

shagie 3y ago
Some of the fault protection and failover procedures: https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--141029.pdf https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--14... Page 74-75 > 3.7.3 Spacecraft Fault Protection > The CCS has five fault-protection algorithms (FPAs) stored in memory, as summarized in Table 3-9. The two algorithms most directly related to the telecommunications system are named RF Loss and Command Loss [19]. > 3.7.3.1 RF Loss. RF Loss provides a means for the spacecraft to automatically recover from an S- or X-band exciter or power amplifier degradation or failure affecting the unit’s RF output. The CCS monitors the output RF power at four points in the RFS: the S-band exciter and S-band power amplifier and the X- band exciter and X-TWTA. If the output RF power from one or more powered- on units drops below a threshold level, the algorithm will attempt to correct the problem by switching to the redundant unit. > 3.7.3.2 Command Loss. Command Loss provides a means for the spacecraft to automatically respond to an onboard failure resulting in the inability to receive or recognize ground commands. If a period of time set in the flight software goes by without the spacecraft recognizing a valid uplinked command, the Command Loss timer expires. The algorithm responds to the presumed spacecraft failure28 and attempts to correct that failure by systematically switching to redundant hardware elements until a valid command is received. Command Loss will be executed four consecutive times if command reception is not successful. After four unsuccessful executions, the CCS will disable Command Loss and activate a set of sequences of commands named the backup mission load (BML) and described below. > 3.7.3.3 Backup Mission Load. In the event of permanent loss of command reception capability, a BML command sequence stored onboard each spacecraft is programmed to continue controlling the spacecraft and achieving fundamental VIM objectives. The BML will begin execution two weeks after the first execution of Command Loss and continue until the spacecraft stops operating. It will transmit cruise science and engineering telemetry, store science observations on the tape recorder, and downlink playbacks regularly.

by isolli 3y ago

shagie 3y ago

Some of the fault protection and failover procedures: https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--141029.pdf https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--14... Page 74-75 > 3.7.3 Spacecraft Fault Protection > The CCS has five fault-protection algorithms (FPAs) stored in memory, as summarized in Table 3-9. The two algorithms most directly related to the telecommunications system are named RF Loss and Command Loss [19]. > 3.7.3.1 RF Loss. RF Loss provides a means for the spacecraft to automatically recover from an S- or X-band exciter or power amplifier degradation or failure affecting the unit’s RF output. The CCS monitors the output RF power at four points in the RFS: the S-band exciter and S-band power amplifier and the X- band exciter and X-TWTA. If the output RF power from one or more powered- on units drops below a threshold level, the algorithm will attempt to correct the problem by switching to the redundant unit. > 3.7.3.2 Command Loss. Command Loss provides a means for the spacecraft to automatically respond to an onboard failure resulting in the inability to receive or recognize ground commands. If a period of time set in the flight software goes by without the spacecraft recognizing a valid uplinked command, the Command Loss timer expires. The algorithm responds to the presumed spacecraft failure28 and attempts to correct that failure by systematically switching to redundant hardware elements until a valid command is received. Command Loss will be executed four consecutive times if command reception is not successful. After four unsuccessful executions, the CCS will disable Command Loss and activate a set of sequences of commands named the backup mission load (BML) and described below. > 3.7.3.3 Backup Mission Load. In the event of permanent loss of command reception capability, a BML command sequence stored onboard each spacecraft is programmed to continue controlling the spacecraft and achieving fundamental VIM objectives. The BML will begin execution two weeks after the first execution of Command Loss and continue until the spacecraft stops operating. It will transmit cruise science and engineering telemetry, store science observations on the tape recorder, and downlink playbacks regularly.