Plate Nº 65 · recorded November 3, 2026
Space & AstronomyReported finding
Voyager 1 Reaches One Light-Day From Earth as Engineers Fight to Keep It Alive
On November 18, Voyager 1 becomes the first human-made object one light-day from Earth — as engineers save power and puzzle over a 48-hour blackout.
By Priya Raman4 min read703 words
In brief
- Voyager 1 reaches one light-day from Earth — 16.09 billion miles (25.89 billion km) — on November 18, 2026
- Each Voyager probe loses about 4 watts of power per year from plutonium-decay generators
- A 48-hour communication blackout began October 18; contact returned October 20
- The 'Big Bang' upgrade in September replaced three power-hungry devices and could prevent an instrument shutdown slated for summer 2027
- Round-trip communication with the spacecraft now takes 48 hours at the speed of light
On November 18, 2026, NASA's Voyager 1 will become the first human-made object to reach a distance of one light-day from Earth — 16.09 billion miles, or 25.89 billion kilometers, so far away that a radio signal needs a full 24 hours to arrive, and an answer needs another day to come back.
Nearly 50 years after its 1977 launch, the spacecraft arrives at this threshold while engineers work to keep its fading systems running. In September, they completed a delicate energy-saving maneuver. Then, on October 18 and 19, Voyager 1 fell silent for a mysterious 48 hours before its signal unexpectedly returned on October 20.
How did engineers stretch the remaining power?
In early September, the Voyager team replaced three devices aboard the spacecraft with alternatives that consume less electricity. The operation, nicknamed the "Big Bang," took months to prepare and required all three swaps to happen simultaneously. Engineers had carried out an identical procedure on Voyager 2 roughly six weeks earlier.
The six devices involved regulate temperatures inside the spacecraft against the extreme cold of space. Replacing three at once was the only way to cut electricity use while preserving an even distribution of heat.
Both Voyagers run on radioisotope thermoelectric generators — systems that convert heat from the radioactive decay of plutonium into electricity. That decay is relentless: each probe loses about 4 watts of generating capacity every year. After almost five decades, NASA has progressively shut down equipment that is no longer essential.
Power limits have already forced the agency to deactivate two of Voyager 1's scientific instruments in recent years. Of the 10 research instruments carried at launch, several were switched off after the outer-planet encounters, while others kept working to study the outer heliosphere (the vast region of particles and magnetic fields produced by the Sun). Both probes have since crossed beyond that boundary, making them the only spacecraft ever to sample interstellar space directly.
No other mission can currently collect measurements from that region. Without the Big Bang upgrade, NASA would have faced shutting down another Voyager 1 instrument as early as summer 2027.
What happened during the 48-hour blackout?
NASA temporarily lost contact on October 18 and 19, when the agency's Deep Space Network — an array of large radio antennas at three sites worldwide — failed to receive Voyager 1's signal during two scheduled attempts 24 hours apart. At the time, the spacecraft was about 16 billion miles (24 billion kilometers) from Earth.
After two unsuccessful attempts, the signal returned on October 20, roughly 48 hours after the interruption began. Communication has held steady since, and engineers have sent commands to investigate.
The exact cause remains undetermined. Engineers did find that one set of thrusters had stopped operating and that the spacecraft had automatically activated its backup thrusters — the work of fault protection, a built-in safety system that lets onboard computers switch to spare hardware, place the craft in a stable configuration, and suspend normal activities while controllers on Earth decide how to respond.
"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," said Kareem Badaruddin, Voyager mission manager at NASA's Jet Propulsion Laboratory in Southern California. "We're relieved to be back in contact with Voyager 1 and are eager to understand what happened."
What does one light-day actually mean?
Voyager 1 is traveling through interstellar space at roughly 38,000 mph (61,155 kph). Crossing the one-light-day mark changes nothing physically; the spacecraft will continue through the same environment, unaware of the milestone.
The number matters instead as a measure of distance — and of delay. Every command from Earth takes a day to arrive; every response takes another day to return.
"If you want to say 'hello' to Voyager, you send your message and then you go home and you wait two days before you finally get a response," said Suzanne Dodd, Voyager project manager at JPL.
Despite fading power, aging equipment, and unexplained glitches, Voyager 1 keeps moving farther from Earth than anything humans have ever built.
via science.nasa.gov (Original)
More from Priya Raman
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Senior reporter covering people, launches and day-to-day practice in general science news at SciBeat.
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