Nasa starts shutting down Voyager after 50 years

Nasa starts shutting down Voyager after 50 years

Nasa has begun turning off the spacecraft Voyager’s systems, signalling the beginning of the end of the probe’s 50-year career.

Voyager 1 and Voyager 2 – two identical probes – were launched in 1977 and travelled across interstellar space to the edge of the solar system, giving humanity its closest look at the moons of Jupiter and Saturn.

Now, however, Nasa must start limiting the Voyagers’ processes in order to keep them operating until 2030.

“We’re at 44 and a half years,” says Ralph McNutt, a physicist at the Johns Hopkins University Applied Physics Laboratory, told Scientific American. “So we’ve done 10 times the warranty on the darn things.”

The first Voyager craft has four remaining functioning instruments, while Voyager 2 has five, all of which are powered by converting decaying plutonium into electricity. This battery has had its output decreasing by approximately four watts every year, leading to Nasa making some tough choices about what to disable; in 2019, engineers had to turn off the heater for the cosmic-ray detector, a key piece of equipment for detecting when Voyager 2 exited the heliosphere- the magnetosphere, astrosphere and outermost atmospheric layer of the Sun.

The final instruments Nasa will disable are likely to be the magnetometer and the plasma science instrument, which are contained in the body of the spacecraft. These are warmed by the excess heat of the computers, while the others are suspended on a 13 metre fiberglass boom, meaning that they are likely to take the longest to get cold.

Both craft remain so far from Earth that it takes a radio signal almost 22 hours to reach Voyager 1 and just over 18 for Voyager 2 – even when travelling at the speed of light.

For every day that the craft move further, it adds another three to four light-seconds to that time. It also makes it harder for Earth to hear communications coming from the Voyagers. “Earth is a noisy place,” says Glen Nagle, outreach and communications manager at the Deep Space Network’s facility in Canberra, Australia. “Radios, televisions, cell phones—everything makes noise. And so it gets harder and harder to hear these tiny whispers from the spacecraft.”

Nevertheless, the usefulness of the craft have far exceeded the expectations of astronomers – expected to reach interstellar space very soon, although will take another 300 years before making it to the edge of the solar system.

“The amount of software on these instruments is slim to none. There are no microprocessors—they didn’t exist!” said Stamatios Krimigis, emeritus head of the space department at Johns Hopkins APL and designer of the Low-Energy Charged Particle [LECP] detector system on the craft.

“On the whole,” Mr Krimigis continues, “I think the mission lasted so long because almost everything was hardwired. Today’s engineers don’t know how to do this. I don’t know if it’s even possible to build such a simple spacecraft [now]. Voyager is the last of its kind.”