Voyager 1: NASA regains the signal after a two-day outage and saves power with the “Big Bang” swap

Voyager 1, the most distant human-made object, went two days without a signal to Earth and came back on its own. NASA announced on Thursday, October 29 that communication with the spacecraft was restored on October 20, before engineers could send commands to locate the problem. The same NASA update also reports the completion of a months-long effort to save power aboard the spacecraft.

NASA’s Deep Space Network, three stations with large antennas at different points on the planet that communicate with spacecraft from the Moon and beyond, detected no radio signal from Voyager 1 during two scheduled contact attempts, on Sunday, October 18 and Monday, October 19. The spacecraft is about 16 billion miles (about 25.7 billion km) from Earth. The signal reappeared on Tuesday, October 20, and contact has held since.

The cause is still under investigation

Engineers have found so far that one group of thrusters was switched off and the backup ones were activated. That change is meant to happen automatically when the spacecraft’s computers detect a malfunction in the active thrusters. It is fault protection, which puts the spacecraft in a safe, stable configuration and interrupts normal operation to give time for diagnosis. “This is the first time we’ve seen the spacecraft do something like this, but we’re at a point in the mission where we must expect the unexpected,” said Kareem Badaruddin, Voyager mission manager at NASA’s Jet Propulsion Laboratory (JPL) in California. “We’re relieved to be talking with Voyager 1 again and we want to understand what happened.”

It was not the first such episode. In 2024 the spacecraft stopped sending data when fault protection turned off its main X-band transmitter and switched on the weaker S-band one. NASA announced on November 26, 2024 that normal operation had been restored.

The “Big Bang” power swap

In early September engineers switched off three Voyager 1 devices and replaced them with three lower-power ones. The operation, nicknamed “Big Bang”, was completed about six weeks after the same change on Voyager 2. It was special because the replacements had to be made simultaneously: the six devices keep the spacecraft warm enough to operate in the freezing cold of space, and only by changing all three at once could consumption fall and heat be distributed correctly. Without “Big Bang”, the mission would have had to shut down another Voyager 1 instrument as early as summer 2027.

Power is the basic problem. Both Voyagers draw energy from radioisotope thermoelectric generators, which convert the heat of decaying plutonium into electricity, and each spacecraft loses about 4 watts a year. Voyager 1 launched in 1977 with 10 science instruments. On April 17, 2026 NASA turned off the Low-Energy Charged Particle (LECP) instrument, which had operated almost continuously for nearly 49 years. Two instruments remain active, one for plasma waves and one for the magnetic field, sending data from a region no other human-made spacecraft has explored. Voyager 1 entered interstellar space, outside the heliosphere, in 2012, and Voyager 2 in 2018.

One light-day from Earth

The next milestone is near. Voyager 1 is moving at 38,000 miles per hour (61,155 km/h) and on November 18 will be 16.09 billion miles (25.89 billion km) from Earth, which is one light-day. Radio waves will take 24 hours to reach it and another 24 for the reply to come back. “If you want to say ‘hello’ to Voyager, you send the message, go home and wait two days to finally get an answer,” said Suzanne Dodd, Voyager program manager at JPL. The spacecraft will not notice any change in its environment; the significance of the milestone is symbolic.

NASA has other fronts open in deep space these days: the Psyche spacecraft is heading for its metal asteroid and Lucy has entered the region of Jupiter’s Trojan asteroids.