On April 17, Eastern Time, the National Aeronautics and Space Administration's (NASA) Jet Propulsion Laboratory engineering team in Southern California sent an instruction to the deep space probe "Voyager 1" to shut down a scientific instrument called the "Low Energy Charged Particle Experiment" (LECP) on board to extend the working life of humanity's first interstellar probe as the power of the probe becomes increasingly tight.
LECP has been operating almost continuously since the launch of Voyager 1 in 1977. It has been nearly 49 years. It has obtained a large amount of scientific data by observing low-energy charged particles from the solar system and the Milky Way, including ions, electrons and cosmic rays. This instrument helps scientists map the structure of the interstellar medium beyond the heliosphere and detect the distribution of different particle densities and pressure frontier areas in interstellar space. Currently, only the Voyager binary detector is far enough away from the earth to provide relevant information in this unique space environment.
Like Voyager 2, Voyager 1 relies on a radioisotope thermoelectric generator, a device that generates electricity from the heat released by the decay of plutonium, but both probes lose about 4 watts of available power per year. After nearly half a century of flight, electrical redundancy was stretched to its limits, and the mission team had to conserve energy by sequentially turning off heaters and some scientific instruments while ensuring that the probe did not become too cold and cause fuel lines to freeze.
On February 27 this year, Voyager 1 performed an attitude roll maneuver as planned, but its power level unexpectedly dropped during the process. Engineers realized that if the power supply dropped again, the aircraft's undervoltage fault protection system might be triggered, automatically shutting down some components to protect itself. This would then require a complex and time-consuming recovery operation by the ground team, and this process itself was also risky. Therefore, the team chose to take proactive measures.
"No one wants to shut down a scientific instrument, but under the current conditions, this is the best choice we can make." said Karim Badaruddin, Voyager project manager at Jet Propulsion Laboratory. He pointed out that Voyager 1 still has two scientific instruments that are functioning normally - one for "listening" to plasma fluctuations and the other for measuring magnetic fields. These two devices continue to send back data from deep space areas that humans have never personally visited. The team's goal is to maintain the operation of the two Voyager probes as long as possible.
In fact, the decision to close LECP this time was not a temporary decision, but a "long-range plan" that had already been written into the mission. A few years ago, the science and engineering teams reached a consensus on the order in which various equipment would be gradually shut down in the future, so as to maintain the scientific value of the mission as much as possible while the power continues to decline. Each probe was initially equipped with 10 sets of the same scientific instruments, 7 of which have been shut down successively. Now it is the turn of the LECP on Voyager 1 to be shut down, while the similar instruments on Voyager 2 will be shut down in March 2025.
Since Voyager 1 is currently more than 15 billion miles (approximately 25 billion kilometers) away from Earth, it takes about 23 hours for instructions from the ground to reach the detector, and the shutdown process itself lasts about 3 hours and 15 minutes. It is worth noting that a small motor in the LECP system that is used to rotate the sensor to scan the entire sky will continue to work. It only consumes about 0.5 watts of power. Retaining this component will help preserve the possibility of reactivating the instrument if a little more power can be "squeezed out" in the future.
Engineers estimate that shutting down LECP this time will give Voyager 1 about a year of "breathing space." The team plans to use this time to plan and implement a more ambitious energy-saving plan for the two detectors, which is called "Big Bang" internally. The idea of this approach is to adjust an entire group of electrical equipment at once, by shutting down some devices and replacing some functions with low-power components to maintain the internal temperature of the detector while continuing to support scientific observations.
According to the plan, the "Big Bang" plan will first be implemented on Voyager 2, which has slightly more power and is closer to the earth, as a relatively safe test subject. Relevant tests are currently scheduled to be conducted from May to June 2026. If all goes well, the team will try the same operation on Voyager 1 as early as July. If everything works as expected, there is still hope that the LECP on Voyager 1 can be restarted in the future.