Signal from ‘lost’ craft 19.7 billion kilometres away

A botched command misaligned the probe’s antenna, which it uses to communicate with Earth.

An artist’s impression of Voyager. Both probes were launched in 1977. Picture: NASA

NASA scientists have breathed a sigh of relief upon hearing from a 46-year-old probe, Voyager 2, after a botched command sent from Earth severed communi­cations with one of its most distant spacecraft.

The agency said it had picked up a “heartbeat signal”, having lost contact on July 21 after engineers “inadvertently” sent a series of commands that caused its antenna, on which it relies to communicate, to be misaligned by about two degrees.

The new signal “buoyed our spirits”, a NASA official told the Associated Press news agency. Flight controllers at the Jet Propulsion Laboratory, in California, will now try to ask Voyager 2 to turn the antenna back towards Earth. If that effort fails, NASA will have to wait until October 15, when the spacecraft should automatically reset its communi­cations equipment.

“That is a long time to wait so we’ll try sending up commands several times,” NASA said.

A large dish in Canberra is listening for signals.

Voyager 2 left Earth, along with the identical Voyager 1, in 1977. Its computer, once top of the range, has as much memory as a car key fob. Voyager 1 is more than 24 billion kilometres from Earth, making it the most distant spacecraft. Communications with it remain uninterrupted.

Voyager 2 trails its twin, but is still nearly 20 billion kilometres away. At that distance, it takes more than 18 hours for a signal to travel one way.

They are the only spacecraft to leave the heliosphere, the region in which solar winds blow, considered by some as the edge of the solar system.

Each probe carries a “golden record”, which includes recordings of traditional music, greetings in 59 languages, pictures of life on Earth and a message from Jimmy Carter, the American president at the time of their launch, saying: “We are attempting to survive our time so we may live into yours. We hope some day, having solved the problems we face, to join a community of galactic civilisations.”

The Times