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NASA Implements Energy Conservation Measures for Voyager Probes

The most distant human-made objects in space are set to extend their scientific missions, aided by strategic energy conservation measures.

Engineers at NASA’s Jet Propulsion Laboratory (JPL) in Southern California have recently taken significant steps to manage the power supply of the Voyager spacecraft. On February 25, they switched off the cosmic ray subsystem experiment on Voyager 1, with plans to deactivate Voyager 2’s low-energy charged particle instrument on March 24. Despite these measures, both spacecraft will continue to operate three scientific instruments each, as part of a larger strategy to navigate their diminishing power resources.

Launched in 1977, the Voyager probes utilize a radioisotope power system that produces electricity from the heat released by decaying plutonium. This system loses approximately 4 watts of power annually, highlighting the urgency of energy management efforts.

“The Voyagers have been pioneers in deep space exploration since their launch, and our goal is to sustain that legacy for as long as possible,” remarked Suzanne Dodd, the Voyager project manager at JPL. “However, the electrical power is dwindling. Without turning off some instruments, we may only have a few months left before we must declare the mission over.”

Both Voyager spacecraft are equipped with identical arrays of 10 scientific instruments. Following their successful exploration of the gas giants, many instruments were deactivated. The remaining operational instruments are focused on studying the solar system’s heliosphere—the protective bubble of solar wind and magnetic fields generated by the Sun—as well as interstellar space. Voyager 1 crossed into interstellar space in 2012, followed by Voyager 2 in 2018, making them the only human-made objects to operate in this realm.

In a previous conservation effort last October, NASA turned off Voyager 2’s plasma science instrument, which had collected limited data due to its alignment relative to interstellar plasma flows. Voyager 1’s similar instrument had been deactivated earlier due to performance degradation.

The recently turned-off cosmic ray subsystem on Voyager 1 consists of three telescopes designed to measure cosmic rays’ energy and flux. Data from these telescopes were pivotal in identifying Voyager 1’s exit from the heliosphere.

Likewise, Voyager 2’s low-energy charged particle instrument, which is set for deactivation later this month, analyzes a range of particles from our solar system and beyond. This instrument employs a dual subsystem setup that allows for comprehensive energy measurements and magentospheric analyses.

These systems are built on a rotating platform powered by a stepper motor, which is designed to operate continuously throughout the mission. By the time it is disconnected, the motor will have successfully completed over 8.5 million steps, a testament to its robust engineering.

“The Voyager spacecraft have far exceeded their initial mission objectives of studying the outer planets,” stated Patrick Koehn, a program scientist at NASA Headquarters. “Every ounce of data they provide now is invaluable, yielding insights into heliophysics, and serving as a tribute to the pioneering engineering efforts initiated almost half a century ago.”

Efforts are being made to postpone further instrument deactivation for as long as possible, as the data from these probes is unparalleled. Following the shutdown of the two instruments, the Voyagers are projected to maintain enough power for approximately another year before additional instruments need to be turned off.

Meanwhile, Voyager 1 will keep its magnetometer and plasma wave subsystem running, while its low-energy charged particle instrument will operate until the end of 2025 before deactivation. Voyager 2 is expected to continue functioning its magnetic field and plasma wave measurements indefinitely, with the cosmic ray subsystem scheduled for shutdown in 2026.

With this power conservation plan, engineers optimistically believe that the Voyager missions could last into the 2030s, although unforeseen challenges may alter that expectation.

At present, Voyager 1 is located over 15 billion miles (approximately 25 billion kilometers) from Earth, while Voyager 2 is more than 13 billion miles (21 billion kilometers) away. Due to the immense distances, it takes over 23 hours for a signal to reach Voyager 1 and about 19.5 hours for Voyager 2.

“Every minute, the Voyagers are diving into unexplored territory,” noted Linda Spilker, a project scientist. “This exploration comes with uncertainty; each day is a new opportunity for discovery or a potential endpoint. We’re committed to maximizing the operational time of Voyagers 1 and 2, as they continue their groundbreaking journey.”

For further details about NASA’s Voyager missions, please visit:
https://science.nasa.gov/mission/voyager

Source
www.nasa.gov