NASA successfully completed a rescue mission in Jupiter orbit in December 2023, using a novel technique to save the JunoCam camera aboard the Juno spacecraft—a mission only recently revealed on July 16 at the Institute of Electrical and Electronics Engineers Nuclear & Space Radiation Effects Conference in Nashville.
The experimental deep-space maneuver could offer a new method for remotely repairing instruments at risk of radiation damage, potentially extending the lifespan of space-based hardware. Thanks to the effort, JunoCam—a visible light color camera—was restored just in time to capture new images ofJupiter’s moon Io, including the first views of some of the moon’s northernmost features.
Juno Mission Vulnerabilities
The Juno spacecraft’s interior components are shielded from space radiation inside a titanium vault. Unfortunately, the JunoCam’s optical unit is located outside this shielding to achieve a clear view of space, leaving it susceptible to the intense radiation fields it encounters.
Designers were confident that the camera had enough durability to withstand the initial eight Jupiter orbits, yet uncertainty lingered about the instruments’ long-term prospects. Luckily, JunoCam’s lifespan proved to be much longer, showing no signs of radiation damage until its 47th orbit, when it began a rapid decline.
Having already outlived its projected resilience, the team suspected radiation was to blame—but pinpointing the issue from hundreds of millions of miles away proved difficult. Ultimately, engineers concluded that a damaged voltage regulator in the camera’s power supply was the most likely cause.
A Plan to Save JunoCam
Running out of options, the team turned to a process known as annealing, where materials are heated and cooled to relieve internal stresses and smooth out microscopic defects. Though the exact physics behind annealing remain partially understood, its effects on silicon components can sometimes repair radiation-induced damage.
“We knew annealing can sometimes alter a material like silicon at a microscopic level but didn’t know if this would fix the damage,” said JunoCam imaging engineer Jacob Schaffner of Malin Space Science Systems in San Diego. “We commanded JunoCam’s one heater to raise the camera’s temperature to 77 degrees Fahrenheit — much warmer than typical for JunoCam — and waited with bated breath to see the results.”
The effort worked. Following the heat treatment, the camera resumed producing sharp images for several orbits. But as Juno’s orbit brought it closer to Jupiter, radiation exposure increased—and the damage returned.
A Second Attempt
“After orbit 55, our images were full of streaks and noise,” said JunoCam instrument lead Michael Ravine of Malin Space Science Systems. “We tried different schemes for processing the images to improve the quality, but nothing worked. With the close encounter of Io bearing down on us in a few weeks, it was Hail Mary time: The only thing left we hadn’t tried was to crank JunoCam’s heater all the way up and see if more extreme annealing would save us.”
Even with a more extreme round of annealing, the subsequent images were still displaying significant corruption in the first week. Yet, at crunch time, with Io only a few days’ journey, image quality experienced a dramatic turnaround. The improvement was so significant that the camera’s image quality was nearly identical to that of launch day. NASA’s solution came just in time to capture plains with sharply rising sulfur dioxide frosts and never-before-seen volcanoes alongside their lava flow fields in Io’s north polar region in December 2023.
The camera’s performance held steady through orbit 74. Since then, the team has used the annealing process to resolve additional issues with Juno’s systems.
“Juno is teaching us how to create and maintain spacecraft tolerant to radiation, providing insights that will benefit satellites in orbit around Earth,” said Scott Bolton, Juno’s principal investigator from the Southwest Research Institute in San Antonio.
“I expect the lessons learned from Juno will be applicable to both defense and commercial satellites as well as other NASA missions,” Bolton added.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.