Category: Voyager

Voyager, 1, humanity's most distant spacecraft, is back in contact after briefly losing touch with Earth last month.

The spacecraft stopped phoning home for about 48 hours between Oct. 18 and 20 due to a communications glitch that Voyager 1 resolved on its own, before engineers could send the long-running spacecraft a remote fix.

"This is the first time we've seen the spacecraft do something like this, but we are also at a point in the mission where we have to expect the unexpected," Kareem Badaruddin, Voyager mission manager at NASA's Jet Propulsion Laboratory (JPL), said in an agency statement about the incident on Oct. 29.

Voyager 1 is almost one light-day from Earth, meaning that a command takes nearly a day to reach the spacecraft and a response takes another day to come back to our planet. The spacecraft will reach the light-day milestone on Nov. 18, at 16.09 billion miles (25.89 billion kilometers) from Earth.

NASA's Deep Space Network of three antennas does check-ins to make sure the spacecraft is doing well. On Oct. 18 and 19, Voyager 1 did not respond. Its signal fortunately reappeared on Oct. 20.

"Engineers still are investigating what caused the communication loss," JPL added in the statement, but said it appears Voyager 1 went into a sort of safe mode. "The team has so far determined that one group of thrusters went offline and their backups turned on. Such a swap is programmed to occur automatically if the spacecraft computers detect something amiss with the active thrusters."

Voyager 1 and its still-operational twin, Voyager 2, both launched in 1977 on an initial mission to explore planets in the solar system. The two spacecraft took advantage of a rare alignment that allowed them to swing from Jupiter to Saturn to Uranus and Neptune using a minimum of fuel, although funding to explore the more distant planets and moons was not guaranteed at launch.

The spacecraft duly swung by Jupiter's and Saturn's systems (some months apart from each other) to great acclaim before parting pathways. Voyager 1's close-up view of Saturn's rings as well as the moon Titan — which may have prebiotic or pre-life chemistry — altered the spacecraft's trajectory to put it high above the plane of the solar system. Meanwhile, Voyager 2 flew on to Uranus and Neptune in 1986 and 1989, respectively, providing the only up-close view of these planetary systems to date.

Running on nuclear power, and continuing to deliver valuable science from deep space, the Voyagers saw their missions extended repeatedly. Both crossed into interstellar space a few years ago, and are still operational.

But with age comes a cost: the plutonium power sources on both spacecraft are diminishing, requiring engineers to periodically shut off instruments or come up with other clever ways of saving power. Voyager 1 just underwent one of those power adjustments, nicknamed the "Big Bang" because it reconfigured a number of spacecraft instruments.

"In early September, engineers successfully turned off three devices on the Voyager 1 spacecraft and substituted them with three lower-power alternatives," JPL wrote of the effort, noting that Voyager 2 also had a "Big Bang" about six weeks previous to that.

JPL did not provide an estimate for how long the missions could keep running, but noted each spacecraft loses four watts of power a year — each launched with 470 watts — and that the spacecraft could continue operating science instruments "longer than previously anticipated" due to the Big Bang. On Voyager 1, for example, the falling power would have otherwise meant switching off another instrument possibly as soon as next summer.

In 2022, Suzanne Dodd, project manager for Voyager at JPL, stated the hope was the mission would continue to operate into the 2030s.

NASA just made an interstellar tweak to the Voyager 2 spacecraft, known as the "Big Bang", to keep its remaining 50-year-old science instruments running a little longer.

Voyager 2 and its twin launched in 1977, called Voyager 1, rely on a form of nuclear battery known as a radioisotope thermoelectric generator that uses the heat produced by the decay of plutonium. But the supply of plutonium on each probe drops at about four watts a year on each spacecraft.

To keep the probe running on this dwindling power supply, engineers recently reduced Voyager 2's power requirements by turning off a few non-science devices and using "lower-power alternatives" that are still effective enough to keep the spacecraft warm while it's so far from the sun, NASA officials said in a statement. "The spacecraft power margins have grown razor thin, requiring the team to conserve energy by shutting off non-essential devices and systems," NASA officials wrote of the mission, which is managed by the agency's Jet Propulsion Laboratory.

The drop in power is having a measurable science impact on both spacecraft — each has turned off two of their science instruments since 2024 alone. While some of these instruments were shut off after the spacecraft finished their historic planetary flybys decades ago, others were turned off due to power requirements.

Each spacecraft initially launched with 10 instruments, and Voyager 2 is now down to only three instruments. At first it looked as though Voyager 2 would have to shut down another of these instruments later this year, but luckily, the new power shifts will allow all three to operate "for at least another year," NASA said.

Voyager 1 will be tasked to do the same "Big Bang" power change "in the coming months." A signal to each spacecraft takes nearly 24 hours (or one light-day) to make a one-way journey, and officials noted Voyager 1 is further from Earth than its twin. (Voyager 2 is at about 142 astronomical units or sun-Earth distances, while Voyager 1 is nearing 171 AU.)

The two spacecraft initially launched to take advantage of a rare alignment between the outer solar system gas giant planets, which in order of distance from the sun are Jupiter, Saturn, Uranus and Neptune. Each Voyager spacecraft first flew past Jupiter and Saturn, taking unprecedented imagery of the planets and their moons.

Next, Voyager 1 was directed to fly above the plane of the solar system (also known as the ecliptic) while Voyager 2 continued flying past Uranus and Neptune, becoming the first spacecraft to see these worlds and their moons. Voyager 2's last planetary flyby was in 1989.

The two spacecraft continue to send scientific data from interstellar space; Voyager 1 passed into that region in 2012, while Voyager 2 did so in 2018. Voyager 1 is Earth's most distant spacecraft, currently around 15.9 billion miles (25.5 billion kilometers) away from us, according to NASA.