Demystifying science | How do I communicate with Voyager?

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It’s a monk’s job that requires the use of the largest telescopes on Earth.

“At this distance, it takes 45 hours for a message to travel to To travel and that the response of To travel returns to Earth, explains Linda Spilker, chief scientist of the Voyager program at NASA. We can only send a few hundred bits per second, so we must choose carefully the composition of the messages. »

Launched in 1977, the two probes To travel left the solar system in 2012 and 2018. The probes Pioneer 10 And Pioneer 11, launched in 1972 and 1973, have also left the solar system, and it has not been possible to communicate with them for more than 20 years. The mission of Voyager 2, which was supposed to last five years, has just been extended until 2026 by eliminating a surge protection system that requires power. That of Voyager 1 should also benefit from this arrangement in 2024, when it will be located too far away for current systems to be sufficiently powered.

“There is an antenna, which receives on one frequency band and transmits on another frequency band,” says M^me Spilker. But it takes several telescopes to receive the data from the probes, because the signal is very weak when it arrives here. »

Last summer, the antenna of Voyager 2 did not reorient as expected. “There was a misalignment of two degrees,” says M.^me Spilker. But this caused the transmission to miss the Earth by a distance equivalent to that between the Sun and Jupiter. Eventually, we identified the probable problem and sent a message to resolve it with the reception band of Voyager 2, which has a wider beam. The probe received the message and realigned the antenna. »

In December, it was the turn of Voyager 1 to have problems, due to poor communication between his unit managing scientific instruments and his communications unit. “We receive the signal from Voyager 1but it’s incomprehensible,” says M^me Spilker.

NASA is now testing optical communications, which use frequencies capable of sending much more data. “For the moment, it is envisaged as far as Mars because the antenna must be very precisely aligned towards the Earth,” says M^me Spilker.

A unit for testing these optical communications is located on the probe Psyche, launched in October, which is to explore a metallic asteroid of the same name in 2026. An optical communication test at a distance of 16 million kilometers was successfully carried out in November.