NASA's Voyager 1 is about to become humanity's first object to reach one light-day from Earth as it pushes ever deeper into interstellar space. At more than 16 billion miles (26 billion kilometers), the spacecraft launched 49 years ago will reach the milestone on Wednesday, when its radio signals take precisely 24 hours at the speed of light to reach Earth.
Project manager Suzanne Dodd described Voyager 1 as Earth's ambassador hurtling between stars, providing a "sense of wonder" on the home front. "It's a national treasure," she told The Associated Press. "Really extraordinary." To mark the moment, NASA is urging people to use phones or flashlights after sunset Tuesday to flash the letters V-G-R, Voyager's call sign, in Morse code into the night sky.S1S2
Voyager 1 and its twin Voyager 2 continue to send back science and engineering data despite sporadic problems typical of old age, as they move toward different points in space at 38,000 mph (61,000 kph). Voyager 2, launched two weeks before its sibling in 1977, will not reach the one-light-day mark until 2035. NASA estimates another 18,000 years before Voyager 1 reaches a full light-year, and more than twice that before it comes near another star.S1S2
Voyager 1 passed Jupiter and Saturn in 1979 and 1980 before exiting the solar system, reaching interstellar space, the expansive region between star systems, in 2012. Voyager 2 visited those planets plus Uranus and Neptune, sending back striking photos, before entering interstellar space in 2018. Almost daily, the Voyagers transmit data on the strength and direction of the magnetic field, as well as the surrounding pressure, dust and galactic cosmic rays. Dodd, who has worked with the Voyagers since 1984, likens them to weather satellites.S1S2
The flight control team at NASA's Jet Propulsion Laboratory in Pasadena, California, sends commands about once a week, ramping up when problems arise, sometimes with help from retirees who once worked on the project. In September, controllers completed the latest power-conserving effort for the plutonium-powered spacecraft, then in October briefly lost contact with it, and are still trying to determine why communication was disrupted. Dodd credits this expertise and dedication with keeping Voyager 1 going like "the little engine that could," while the craft has earned entries in Guinness World Records. In 1990 it also took the most distant picture of Earth, the "Pale Blue Dot."S1S2
