NASA wants the Voyagers to move forward gracefully, so it’s time to correct the software – Ars Technica

Forty-six years in deep space have taken their toll on NASA’s twin Voyager spacecraft. Sometimes their old computers do confusing things, their drives wear out, and their fuel lines become clogged. About half of their scientific instruments no longer display data, and their power levels are declining.

However, the meager team of engineers and scientists working on the Voyager program at NASA’s Jet Propulsion Laboratory are taking steps to wring every bit of life from the only two spacecraft flying in interstellar space, the vast amount of diluted gas beyond the influence of the universe. Solar winds of the sun.

“These are measures we’re trying to take to extend the life of the mission,” Susan Dodd, Voyager project manager at JPL, said in an interview with Ars.

Voyager’s instruments study cosmic paths, the magnetic field, and the plasma environment in interstellar space. They don’t take pictures anymore. Both probes traveled beyond the heliosphere, where particles emitted by the Sun stream into the interstellar medium.

“These two spacecraft are still operational, still providing uniquely valuable scientific data, and every additional day we get data is a blessing,” Dodd said.

But spacecraft engineers love redundancy, but they no longer have the luxury of backups aboard Voyager. This means that in any given section of the spacecraft, the failure of one part could bring the mission to a halt.

“Everything on both spacecraft is one chain,” Dodd said. “There’s no longer any backup capabilities left. In some cases, we’ve turned things off to save power, just to keep devices running.”

Solve problems from more than 12 billion miles away

Over the weekend, JPL ground controllers planned to attach a software patch to Voyager 2. It’s a test before the ground team sends the same patch to Voyager 1 to fix a problem with one of its onboard computers. This issue first appeared in 2022, when engineers noticed that the computer responsible for guiding the Voyager 1 spacecraft was sending distorted status reports even though it was operating normally. It turned out that the computer had somehow entered an incorrect mode, According to NASA.

The managers wanted to try the patch on Voyager 2 before sending it to Voyager 1, which is flying away from Earth, in interstellar space. This makes observations of the environment surrounding Voyager 1 even more valuable to scientists.

Meanwhile, engineers devised a new system to operate the thrusters on both Voyager spacecraft. These small rocket motors—launched independently—are essential to keeping the main antenna on each probe pointed toward Earth. There is a buildup of propellant residue in the narrow lines that feed hydrazine fuel to the thrusters. NASA says the buildup “became significant” in some lines, so engineers sent new commands to the spacecraft in the past few weeks to allow the probes to rotate a little more in each direction before firing the thrusters.

This will cause the spacecraft to perform fewer and longer launches, each of which increases residue in the fuel lines. The downside of this change is that science data sent back to Earth can sometimes be lost, but over time, the ground team concluded that the plan would allow the Voyagers to return more data over time, NASA said.

With these steps, engineers expect the fuel inlet tubes will not become completely clogged for at least another five years, and “possibly much longer,” NASA said. There are other things engineers can try to extend the life of thrusters.

“At this point in the mission, the engineering team faces a lot of challenges for which we don’t have a playbook,” Linda Spilker, Voyager project scientist at JPL, said in a statement. “But they keep coming up with creative solutions.”

Dodd told Ars that the propulsion problem is likely the most serious problem facing the Voyager spacecraft. In 2017, engineers began converting Voyager’s probes into a backup set of propulsion devices after their primary jet rockets showed signs of deterioration. Both vehicles are now running on fully redundant propulsion to control their direction, but they have plenty of fuel left over for another 10 to 15 years.

The Voyager probes were launched two weeks apart in 1977 and took different paths outside the solar system. Voyager 1 flew by Jupiter and Saturn, then took a faster path into interstellar space, while Voyager 2 encountered Jupiter, Saturn, Uranus and Neptune on its outer journey.

Both spacecraft are powered by nuclear batteries, which convert heat generated by the decay of plutonium into electricity. They generate slightly less power each year, a decrease of 4 watts per year, according to Dodd, and ultimately won’t produce enough electricity for important spacecraft systems. Late this decade, officials anticipate a scenario in which they will have to decommission Voyager’s science instruments one by one.

But in general, the power situation is stable and predictable. Earlier this year, engineers bypassed Voyager 2’s voltage regulator to allow the spacecraft to draw more power. The decision means ground controllers will not have to deactivate one of Voyager 2’s five remaining science instruments until 2026, after previously expecting one instrument to be deactivated this year. Ground-based teams will do the same with Voyager 1, which has only four active instruments and therefore uses less energy, Dodd said.

If you just look at the power situation, the Voyagers should last until 2030, and maybe a little longer, before the decay of the plutonium power source forces NASA to turn off all of its science instruments.

“The transmitter consumes about 200 watts of power, so once we reach that level of power, that will be the end of the mission,” Dodd said.

Even when they stop working, NASA’s Voyagers will continue to reach the stars.

“A lot of things can break before the power runs out,” she told Ars. “Just as this propulsion issue arose, there are a lot of other issues that could arise and cause the mission to fail.”

Due to their distances, the Voyagers can only communicate through the largest 230-foot (70 m) dish antennas in NASA’s Deep Space Network, or by stringing several smaller antennas together to detect faint signals coming from the spacecraft. Voyager 1 is Currently located It is more than 15 billion miles (24 billion kilometers) from Earth, about four times greater than Pluto’s average distance. Voyager 2 is a few billion miles away.

NASA is still making communications with Voyagers daily, Dodd said. But it’s all done by a small team of about a dozen “full-time equivalent” employees, only about half of whom are fully dedicated to Voyager. Others share their time with other NASA projects.

After 46 years in space, the Voyagers are NASA’s longest-lived mission, and the fact that they have reached such a longevity to explore the outer reaches of the solar system makes their accomplishments even more impressive.

“They overcame a lot of problems, and the engineers were very smart at overcoming those problems,” Dodd said. “I think the focus now is to get to 50 people and have the biggest party possible.”