Voyager 1 and Voyager 2 are the oldest operating spacecraft that NASA has with the spacecraft operating for nearly 42 years. Both spacecraft launched in 1977 and as the years have gone buy they have less and less power to run scientific instruments and heaters to keep the components warm and working in the vastness of space. The challenge for engineers at NASA is in deciding what instruments get power and which don’t over time.
The engineers have to make decisions about what instruments to turn off on Voyager 2 before deciding on Voyager 1 because Voyager 2 has more science instruments collecting data and consumes more power than its sibling. To conserve power, the science team and mission managers recently turned off the heater for the cosmic ray subsystem (CRS) on Voyager 2 as part of the new power management plan.
That instrument played its last critical role in the Voyager 2 mission last November when it verified that the spacecraft had exited the heliosphere and entered interstellar space. Mission team members have confirmed that Voyager 2’s cosmic ray instrument is still returning data despite having no heater and operating at minus 74 degrees Fahrenheit. That is lower than the temperature that the CRS was tested at more than 42 years ago before it launched.
Voyager 2 is continuing to return science data from five instruments as it travels through interstellar space. The cosmic ray instrument that detects fast-moving particles is working as are two instruments for studying plasma and a magnetometer. Voyager 1, which moved into interstellar space in August 2012, continues to collect data from its cosmic ray instrument, the plasma instrument, the magnetometer, and low-energy charged particle instrument.
Voyager 1 and 2 both use power generated from heat produced by three radioisotope thermoelectric generators. Both spacecraft produces about 4 watts less electricity each year. That means they are currently making 40% less power than they were when they launched.