There have been stories in the news lately about NASA switching the Voyager 1 and 2 probes to using backup thrusters to save energy. This is supposed to save 12 watts by allowing the primary thruster heaters to be turned off.
The articles claim that this energy saving will allow extended lifetime of the power supply, which is a radioisotope thermoelectric generator powererd by decay of plutonium 238.
Huh? How does the electrical load on the thermocouples have any effect on the decay of plutonium?
No explanation is offered. Assuming the life extension is correct, my only guess is that it is some strange second-order effect, like maybe the thermocouples have some sort of electromigration failure mode that is sped up at higher currents... or something.
Anyone know the true story?
Best regards,
Bob Masta DAQARTA v6.02 Data AcQuisition And Real-Time Analysis