NASA’s Voyager is in Hostile Territory. It’s All About Dodging Bullets.

NASA’s Voyager probe has gone where no other human machine has gone – into the space between the stars. But that comes with costs.

At about 15 to 12 billion miles away, Voyager 1 and 2 are beyond the Sun’s protective bubble called the heliosphere. Out in this region of interstellar space, the nearly 50-year-old probes have a higher chance of being damaged by hostile high-speed particles called galactic cosmic rays, as larger numbers of particles fly in every second.

“We’re dodging the bullets out there,” Alan Cummings, a cosmic ray physicist at Caltech — the research university that manages NASA’s Jet Propulsion Laboratory — told Mashable. Cummings began working on the Voyager mission 51 years ago.

But direct hits are inevitable. In 2010, while Voyager 2 was at the edge of our solar system’s heliosphere, it unexpectedly began sending gibberish back to Earth. Cummings suspects that a passing galactic cosmic ray destroyed some of a computer’s memory – although NASA was eventually able to fix the problem. Most recently, Voyager 1 failed to send back readable data five months, a particularly worrying incident that may also have been triggered by cosmic radiation. Something damaged a computer chip.

“We don’t know everything,” Cummings explained, citing the difficulty of perfectly diagnosing such deeply distant mishaps. “But I think galactic cosmic rays are responsible for most of these problems here.”

“We’re dodging the bullets out there.”

Galactic cosmic rays are merciless because they are extremely small, charged particles that travel at incredible speeds – almost the speed of light. “The galaxy is permeated by galactic cosmic rays,” Cummings marveled. Astronomers believe that violently exploding stars – supernovae – are responsible for the creation of these particles, as the event’s colossal shock wave accelerates the particles. These atomic particles, stripped of their outer shell, race through space as mere atomic nuclei.

The heavier atoms, like iron atoms converted into galactic cosmic rays, can cause more damage than the lighter, more abundant atoms. (It’s a bit like being hit by a bowling ball at 50 miles per hour, as opposed to a golf ball.) They can rip right through a computer chip and change its code—or even lodge themselves there, creating an even larger one Can deal a blow by dealing permanent damage.

Destructible speed of light

Of course, NASA spacecraft like Voyager are equipped with radiation-resistant parts and shielding, including the sheathing of critical cables. These layers can keep out some particles – but not all. “You can protect yourself to a certain extent, but a high enough energy particle will penetrate your defenses,” Cummings explained. At the start of the Voyager mission, space agency engineers worried that the spacecraft might fly past Jupiter, a planet that produces intense radiation. A person hypothetically aboard Voyager would have been hit with a radiation dose 1,000 times the lethal dose. “It was pretty hostile,” Cummings recalled. He said a few detectors on his instrument for measuring galactic radiation (the Cosmic Ray Subsystem).) were wounded, but overall both the instrument and the entire spacecraft survived and produced new scientific results, including vivid, unprecedented images.

But out in the deeper cosmos, Voyager faces a different threat. The spacecraft around the gas giant Jupiter were sprayed with charged particles, but these had lower energy. Now spacecraft in interstellar space are more frequently exposed to these high-energy particles. Any location in space – whether in our solar system or beyond – may be at risk from harmful galactic cosmic radiation. But in the interstellar region the chances are greater.

“Explorers encounter problems when they enter new territory.”

When could another hit like this come? “Right now it’s just a random chance,” Cummings said.

However, billions of miles away on Earth, in sunny Pasadena, California, the spacecraft have a guardian. Or a legion of Guardians. Engineers at NASA and Caltech have spent decades developing ways to keep the aging, radiation-plagued spacecraft alive. They communicate with vintage computers on board the nearly half-century-old probes. Talking to an interstellar spacecraft is not like sending a text message: it takes almost two days to send and then receive a message. Most recently, in April, NASA engineers struggled with a permanently damaged computer chip on Voyager 1. By sending messages to the spacecraft over 15 billion miles away, they were able to successfully store the defective chip’s unique code in other chips, as “No Single.” The location is large enough to accommodate the entire code section,” the agency said. The ship is communicating again about its health status, but is not yet providing any scientific data.

“You have to praise the engineers,” emphasized Cummings.

They were definitely busy. And in hostile space, where high-speed particles whiz past incessantly, they will probably continue to do so. Space probes are running low on nuclear fuel but – if left undamaged – could send unprecedented readings from unexplored space by the mid-2030s.

“Explorers encounter problems when they enter new territory” Cummings said. “Lewis and Clark didn’t have it easy either.”