The Voyager Probes Are Dying

The end is nigh.

My Battery Is Low

NASA's Voyager 1 and 2 spacecraft have long left the farthest reaches of the solar system, entering interstellar space in 2012 and 2018 respectively.

The pair were originally intended to study the solar system's outer planets when they launched in 1977. But both have outgrown their original missions, flying through the darkness of space over 15 billion miles away, far beyond those planets they were originally tasked with observing.

Instead of relying on tiny glimpses of sunlight as a power source, the pair are relying on radioisotope thermoelectric generators, which use radioactively decaying plutonium-238 isotopes as a direct source of power.

But decades into their journey, that onboard source of electricity is almost depleted, as Wired reports, forcing scientists to shut down scientific instruments one by one. The power output is dropping around four watts per year, giving the probes a definitive end that's now rapidly approaching.

In other words, Voyager 1 and 2's days are numbered — though scientists are still hopeful the pair will last until their 50th anniversary in space just over two years from now.

It's Getting Dark

Most recently, NASA engineers confirmed last week that they were able to restore communications with Voyager 1 after the spacecraft went dark in October.

Power levels are so low that when scientists switched on one of the heaters to get one of its instruments back online, a safety feature was tripped, as Space.com reports.

The feature in question ensures that non-essential systems are switched off to conserve energy. Fortunately, communications resumed on November 18.

It's far from the first time Voyager 1 has struggled to stay online and on course. In September, engineers managed to switch its ancient probe to a different set of thrusters to keep it going.

In March, the probe returned nonsensical messages back to Earth, forcing scientists to get creative yet again.

Voyager 2 hasn't fared much better, suffering from its own thankfully temporary communication blackout last year.

But despite scientists' best efforts, little can be done about the two probes' dwindling plutonium reserves.

Nonetheless, the team is still appreciative of a groundbreaking, decades-long mission that's even managed to escape the heliopause, the outer boundary of the Sun's heliosphere.

"I think we’re all happy and relieved that the Voyager probes have both operated long enough to make it past this milestone," said Voyager project manager Suzanne Dodd in a November statement. "This is what we’ve all been waiting for. Now we’re looking forward to what we’ll be able to learn from having both probes outside the heliopause."

More on Voyager: Decrepit Voyager 1 Probe Runs Into Trouble Again