How NASA saved a digital camera from 370 million miles away

The mission workforce of NASA’s Jupiter-orbiting Juno spacecraft executed a deep-space transfer in December 2023 to restore its JunoCam imager to seize photographs of the Jovian moon Io. Outcomes from the long-distance save have been offered throughout a technical session on July 16 on the Institute of Electrical and Electronics Engineers Nuclear & Space Radiation Effects Conference in Nashville.

JunoCam is a shade, visible-light digital camera. The optical unit for the digital camera is situated exterior a titanium-walled radiation vault, which protects delicate digital elements for a lot of of Juno’s engineering and science devices.

It is a difficult location as a result of Juno’s travels carry it by means of essentially the most intense planetary radiation fields within the photo voltaic system. Whereas mission designers have been assured JunoCam may function by means of the primary eight orbits of Jupiter, nobody knew how lengthy the instrument would final after that.

All through Juno’s first 34 orbits (its prime mission), JunoCam operated usually, returning pictures the workforce routinely included into the mission’s science papers. Then, throughout its forty seventh orbit, the imager started exhibiting hints of radiation injury. By orbit 56, almost all the photographs have been corrupted.

Lengthy-distance microscopic restore

Whereas the workforce knew the difficulty may be tied to radiation, pinpointing what was particularly broken inside JunoCam was troublesome from lots of of hundreds of thousands of miles away. Clues pointed to a broken voltage regulator that was very important to JunoCam’s energy provide. With few choices for restoration, the workforce turned to a course of known as annealing, the place a fabric is heated for a specified interval earlier than slowly cooling. Though the method just isn’t nicely understood, the thought is that heating can scale back defects within the materials.

“We knew annealing can generally alter a fabric like silicon at a microscopic degree however did not know if this may repair the injury,” stated JunoCam imaging engineer Jacob Schaffner of Malin House Science Methods in San Diego, which designed and developed JunoCam and is a part of the workforce that operates it. “We commanded JunoCam’s one heater to boost the digital camera’s temperature to 77 levels Fahrenheit—a lot hotter than typical for JunoCam—and waited with bated breath to see the outcomes.”

Quickly after the annealing course of completed, JunoCam started cranking out crisp pictures for the following a number of orbits. However Juno was flying deeper and deeper into the center of Jupiter’s radiation fields with every go. By orbit 55, the imagery had once more begun exhibiting issues.

“After orbit 55, our pictures have been filled with streaks and noise,” stated JunoCam instrument lead Michael Ravine of Malin House Science Methods. “We tried totally different schemes for processing the photographs to enhance the standard, however nothing labored. With the shut encounter of Io bearing down on us in a couple of weeks, it was Hail Mary time: The one factor left we hadn’t tried was to crank JunoCam’s heater all the best way up and see if extra excessive annealing would save us.”

Take a look at pictures despatched again to Earth through the annealing confirmed little enchancment within the first week. Then, with the shut strategy of Io solely days away, the photographs started to enhance dramatically. By the point Juno got here inside 930 miles (1,500 kilometers) of the volcanic moon’s floor on Dec. 30, 2023, the photographs have been virtually pretty much as good because the day the digital camera launched, capturing detailed views of Io’s north polar area that exposed mountain blocks lined in sulfur dioxide frosts rising sharply from the plains and beforehand uncharted volcanoes with in depth circulation fields of lava.

Testing limits

So far, the solar-powered spacecraft has orbited Jupiter 74 instances. Lately, the picture noise returned throughout Juno’s 74th orbit.

Since first experimenting with JunoCam, the Juno workforce has utilized derivations of this annealing approach to a number of Juno devices and engineering subsystems.

“Juno is instructing us learn how to create and preserve spacecraft tolerant to radiation, offering insights that can profit satellites in orbit round Earth,” stated Scott Bolton, Juno’s principal investigator from the Southwest Analysis Institute in San Antonio. “I anticipate the teachings realized from Juno will probably be relevant to each protection and business satellites in addition to different NASA missions.”