NASA’s long-standing interstellar probe is experiencing a gradual loss of power, necessitating the shutdown of one of its scientific instruments to preserve its remaining energy.
Launched in 1977, NASA’s Voyager 2 mission has been exploring the far reaches of the solar system and is currently situated 12.8 billion miles (20.5 billion kilometers) from Earth. The extensive duration of its mission has imposed significant strain on the probe, and NASA is employing all possible measures to prolong Voyager 2’s operational life.
On Tuesday, NASA announced that mission engineers have deactivated the plasma science instrument aboard Voyager 2 due to its declining electrical power supply. Despite this, the spacecraft still retains four operational scientific instruments to analyze various elements of interstellar space. However, it will no longer be capable of measuring the amount of plasma (electrically charged atoms) and its directional flow.
This action was deemed a last resort for NASA. The Voyager probes, Voyager 1 and 2, are powered by decaying plutonium, resulting in a loss of approximately 4 watts of electrical power per year. Throughout its journey to interstellar space, Voyager 2 conducted flybys of Jupiter in 1979, Saturn in 1981, Uranus in 1986, and Neptune in 1989. The Neptune encounter directed the probe below the ecliptic plane, leading it to cross into interstellar space in 2018.
Following the completion of its giant planets tour in the 1980s, the mission team deactivated several scientific instruments deemed unnecessary for interstellar exploration. This helped conserve power; however, the ongoing decay of its power generators is now impacting Voyager 2.
Last year, NASA implemented a strategic workaround that allowed Voyager 2 to utilize a small amount of backup power reserved for an onboard safety mechanism designed to safeguard the craft from damaging voltage spikes. Nevertheless, switching off a scientific instrument eventually became unavoidable.
On September 26, NASA engineers sent the command to deactivate the plasma instrument, which took 19 hours to reach the distant probe and an additional 19 hours to receive a confirmation signal. NASA confirmed that the shutdown command was executed successfully, and the spacecraft is functioning normally post-execution.
The plasma instrument consists of four cups, three oriented toward the Sun to observe the solar wind, and the fourth angled to study the plasma in planetary magnetospheres, the heliosphere, and interstellar space. This instrument played a critical role in determining that Voyager 2 had exited the heliosphere—a vast bubble surrounding the Sun and its planets—and entered interstellar space by detecting changes in atoms, particles, and magnetic fields.
NASA decided to deactivate the plasma science instrument due to its diminished utility in interstellar space. After Voyager 2 left the heliosphere, plasma measurements from the three Sun-facing cups significantly decreased, while the fourth cup gathered limited data due to its position relative to the interstellar plasma flow.
Voyager 1 and 2 continue their interstellar missions despite enduring the harsh environment of space for decades. NASA projects that Voyager 2 has sufficient power to operate with at least one scientific instrument until the 2030s, indicating that the agency will have to progressively deactivate the spacecraft’s instruments until its mission concludes.
