NASA’s Voyager 1 crosses the one light-day milestone at 5:16 a.m. ET on Wednesday, Nov. 18, sitting more than 16 billion miles away from Earth, Mashable reported.
A radio signal sent from Earth takes a full 24 hours to reach the spacecraft at that distance. Because Voyager 1 keeps moving, that communication lag will only increase over time, Mashable reported.
The spacecraft left Earth in September 1977 to tour the giant outer planets during a rare planetary alignment that occurs once every 176 years, Mashable reported. It left the solar system in August 2012 to enter interstellar space, travelling at about 38,000 miles per hour, according to AOL.
Its twin, Voyager 2, took a different path past Uranus and Neptune and left the solar system in 2018, but it will not reach the one light-day distance until November 2035, Mashable reported.
Dwindling nuclear power affects Voyager probes and communication
Both Voyager probes face dwindling nuclear power sources that convert heat from decaying plutonium into electricity, Mashable reported. The mission team has shut off two science instruments on each spacecraft since 2024 to stretch remaining power supplies, Mashable reported.
“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,” Suzanne Dodd, Voyager project manager, told AOL.
Global Flashlight Tribute
To mark the milestone, NASA invited people worldwide to point a light at the sky after sunset on Tuesday, Nov. 17, to spell out VGR in Morse code, Mashable reported. Participants could use an online flasher built by NASA or tap out short dots and long dashes using a household flashlight, Mashable reported.
Mission leaders and top NASA science officials will meet at noon ET on Thursday, Nov. 19, at JPL to discuss the status of the twins, Mashable reported. The public can watch the retrospective discussion stream on NASA+ or YouTube, Mashable reported.
Why signals take time and how long probes will run
Why does it take a full day for signals to reach Voyager 1?
Radio signals travel at the speed of light, which is approximately 186,000 miles per second. At a distance of more than 16 billion miles, those signals require 24 hours to bridge the void, Mashable reported.
How much longer will Voyager 1 and Voyager 2 operate?
Both probes are nearly tapped out of nuclear power from decaying plutonium. A recent power swap completed this year should keep key instruments running for at least another year, according to AOL.
When did Voyager 1 leave the solar system?
Voyager 1 entered interstellar space in August 2012 after passing Jupiter and Saturn, Mashable reported.
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