The farthest-flung human-made objects will be able to take their science-gathering even farther, thanks to these energy-conserving measures.
An artist's concept depicts one of NASA's Voyager probes. The twin spacecraft launched in 1977. NASA/JPL-Caltech Mission engineers at NASA's Jet Propulsion Laboratory in Southern California turned off the cosmic ray subsystem experiment aboard Voyager 1 on Feb. 25 and will shut off Voyager 2's low-energy charged particle instrument on March 24. Three science instruments will continue to operate on each spacecraft. The moves are part of an ongoing effort to manage the gradually diminishing power supply of the twin probes. Launched in 1977, Voyagers 1 and 2 rely on a radioisotope power system that generates electricity from the heat of decaying plutonium. Both lose about 4 watts of power each year. "The Voyagers have been deep space rock stars since launch, and we want to keep it that way as long as possible," said Suzanne Dodd, Voyager project manager at JPL. "But electrical power is running low. If we don't turn off an instrument on each Voyager now, they would probably have only a few more months of power before we would need to declare end of mission." The two spacecraft carry identical sets of 10 science instruments. Some of the instruments, geared toward collecting data during planetary flybys, were turned off after both spacecraft completed their exploration of the solar system's gas giants. The instruments that remained powered on well beyond the last planetary flyby were those the science team considered important for studying the solar system's heliosphere, a protective bubble of solar wind and magnetic fields created by the Sun, and interstellar space, the region outside the heliosphere. Voyager 1 reached the edge of the heliosphere and the beginning of interstellar space in 2012; Voyager 2 reached the boundary in 2018. No other human-made spacecraft has operated in interstellar space. Last October, to conserve energy, the project turned off Voyager 2's plasma science instrument, which measures the amount of plasma — electrically charged atoms —…