NASA’s Juno autonomous satellite used Wind River software to help get scientists closer than ever to the fifth planet from the sun.
Never before has a functioning spacecraft hurtled through space at this extraordinary speed: : 165,000 miles per hour (275,000 Km/hour). Last Monday night, with the planet Jupiter’s powerful gravity pulling the spacecraft ever closer, it was time to tap the brakes.
Very. Very. Carefully.
After a 5-year, 1.7-billion-mile slingshot across our solar system, NASA’s Juno spacecraft fired its engines for exactly 35 minutes—and successfully slipped into an oblong 53-day polar orbit around gas giant Jupiter, and its 60-some-odd moons.
This is ten times closer to Jupiter than we’ve ever been before, and sets the stage for a raft of discoveries about our solar system’s most massive planet. If Jupiter was the size of a basketball, Juno will be skimming just one-third of an inch above its surface.
Among those celebrating the loudest is the team that designed the software used in Juno.
“It’s a very satisfying feeling that it did go successfully,” said Corey Hutchins by phone in Colorado. He is a veteran aerospace engineer with Wind River—the Intel subsidiary whose team created VxWorks, the software that helped make possible Juno’s bullseye on the 4th of July.
As it made its first dive past Jupiter, Juno was essentially a self-driving satellite. It had to be. A one-way radio command from Earth—traveling at the speed of light—takes fully 48 minutes to reach Jupiter. Humans are uselessly far away.
That’s why—throughout Juno’s journey—Wind River software handled mission-critical stuff like guidance, navigation, data transfers, engine burns, communications, and more.
“The vehicle is completely autonomous,” explained Hutchins, adding that it does depend on communications and instructions from pilots on the ground.
VxWorks is a so-called “real time” operating system specially created for applications that require rapid processing time (tenths of a second or less) and extreme reliability. On planet Earth, VxWorks runs literally billions of devices, from assembly line robots, to farming equipment to home wireless routers.
Out in space, if an on-board hourglass or beach ball had decided to spin in the critical moments as it prepared to fire its orbital engine, poor Juno might have sailed past Jupiter into interstellar space—$1 billion vanishing into the void.
This is why spacecraft software “must work flawlessly,” Hutchins pointed out.
VxWorks is running on a radiation-hardened RAD750 single-board computer, made by BAE and running PowerPC microarchitecture, specially made for satellites and spacecraft. All of Juno’s critical electronics are armored inside a half-inch thick titanium box to shield them from Jupiter’s fierce radiation belt. Over the course of its mission, NASA calculates that Juno will be exposed to the equivalent of 100 million dental x-rays.
And the VxWorks code is remarkably “light.” Windows 10, for example, needs about 20 gigabytes to store the OS on a personal computer. Instead, the entire VxWorks OS consumes 20,000 times less, only about a megabyte of storage—less data than a typical smartphone photo.
After its successful engine burn on Monday, July 11, Juno dropped into an orbit barely above Jupiter’s multi-hued clouds—a witch’s brew of swirling hydrogen, helium, methane, ammonia, hydrogen sulfide, and other nasty stuff.
And when the all-good radio ping arrived from Juno—48 minutes after the fact—flight engineers and scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California burst into cheers, applause, and high-fives, the scene streamed lived online. The people at Wind River, though less in the spotlight, were no less pleased.
It’s a wonder to design a 4-ton high-tech craft and then fling it across the solar system to a perfect on-time rendezvous with another world.
But creating the software to help pull it off? That part is rocket science, too.
Editor’s note: VxWorks was also used in Mars Curiosity and Opportunity missions. After its closest encounter with Jupiter, VxWorks helped Juno speed away on a 53-day elliptical orbit. The New York Times reports that Juno will get close to Jupiter again on Aug 27, when it will turn on the camera and instruments to collect much anticipated scientific data. Engines will fire again on Oct. 19 to initiate a two-week orbit to collect even more valuable data about the gas giant.
Feature image of the Juno spacecraft being assembled in at the NASA Jet Propulsion Lab in California in 2010 is by NASA.