Voyager milestone sparks awe

Voyager 1 is close enough to a one-light-day distance from Earth that a radio signal now needs about 23 hours and 31 minutes to get here. (science.nasa.gov) (theskylive.com) NASA said this week that Voyager 1 is “closing in on one light-day later this year,” while its mission-status table is being recalibrated to match the latest data. The spacecraft is still operating in interstellar space nearly 49 years after its 1977 launch. (science.nasa.gov 1) (science.nasa.gov 2) A light-day is the distance light covers in 24 hours: about 25.9 billion kilometers, or 16.1 billion miles. Voyager 1 is the farthest human-made object from Earth, and NASA says it is moving away from the solar system at about 3.5 astronomical units a year. (science.nasa.gov) (example.com)) (example.com)) Voyager 1 and Voyager 2 are the only spacecraft operating beyond the heliosphere, the Sun’s bubble of particles and magnetic fields. NASA says Voyager 1 crossed into interstellar space in 2012, and Voyager 2 followed in 2018. (science.nasa.gov) The milestone lands as NASA is trimming the spacecraft to keep it alive. Engineers at the Jet Propulsion Laboratory shut off Voyager 1’s Low-Energy Charged Particles instrument on April 17, 2026, leaving two science instruments still running. (science.nasa.gov 1) (science.nasa.gov 2) The power problem is simple and old-fashioned: each probe runs on a radioisotope thermoelectric generator, which turns heat from decaying plutonium into electricity. NASA says each Voyager loses about 4 watts of power a year, forcing the team to shut down heaters and instruments in a planned order. (science.nasa.gov 1) (science.nasa.gov 2) The spacecraft’s computers are also relics by modern standards. NASA says Voyager’s onboard computers process about 8,000 instructions per second, compared with more than 14 billion instructions per second for a modern smartphone. (science.nasa.gov) That combination of age, distance, and delay helps explain why the one-light-day mark has escaped the science pages and spread through social feeds. Every command sent now takes nearly a full day to arrive, and any reply takes nearly another day to come back. (science.nasa.gov) (theskylive.com) Voyager 1 has been traveling since the Jimmy Carter presidency, past Jupiter and Saturn, into a region no other active mission has reached. Nearing a one-light-day signal time does not change its course, but it puts a number on just how far that journey has carried it. (science.nasa.gov)