NASA’s Voyager probes are still out there, exploring interstellar space 42 years after they left our planet. To keep them running all these years with generators that are 40 percent less powerful than they were decades ago — and which are producing less and less energy over time — the agency had to sacrifice some of their parts and components. In fact, the mission managers have recently switched off the heater for Voyager 2’s cosmic ray subsystem instrument (CRS) as part of their new power management plan.
The probe’s cosmic ray system played a key role in confirming that Voyager 2 left the heliosphere in November, and it remains useful to this day. Since it was designed to detect fast moving particles both from the sun and from sources outside our solar system, it continued sending back data even after it entered interstellar space.