If NASA’s $5 billion Europa Clipper mission launches next month, it will be embarking on a historic scientific objective. The enormous space probe, with solar arrays over one hundred feet long, is designed to travel all the way to Jupiter, where it will examine one of the gas giant’s largest moons, Europa.
Underneath its icy exterior, the Galilean moon is believed to harbor a deep ocean which contains twice as much seawater as Earth. Once it arrives in 2030, the Europa Clipper will perform dozens of flybys to assess if the water-world is capable of supporting life.
But, as The New York Times documents, in May — just months before the launch date — the mission scientists at NASA discovered a disastrous flaw in the craft.
As lead scientist Curt Niebur was informed by an urgent email, recent tests revealed that essential transistors in the Europa Clipper would be destroyed by Jupiter’s intense radiation. Simply put, it would be game over.
“You open that email right away,” Niebur told the NYT. “You read it, and then you reply, ‘Thank you for sharing,’ and then you bury your face in a pillow and you howl in terror.”
One of the biggest hurdles to exploring Jupiter is that it’s shielded by a monstrous magnetosphere. The magnetic field it contains captures charged particles and accelerates them to ridiculous velocities, forming bands of intense radiation that wreak havoc on electronics.
The transistors, which are known as MOSFETS — that stands for “metal-oxide-semiconductor field-effect” — were supposed to be able to withstand this challenge, but tests suddenly revealed they were failing in intense radiation environments.
All of a sudden, the scientists’ backs were against a wall. There were around 1,500 of these transistors used throughout the craft, and exactly where was difficult to determine. According to the NYT, they fretted that replacing them could cost up to one billion dollars and take years.
And if the Clipper didn’t launch in its 21-day window in October, the mission could be catastrophically delayed.
But there’s another side to the radiation’s effects: annealing. As subsequent experiments showed, the heat from the radiation would eventually cause lightly damaged transistor’s atoms to spread out and return to their original arrangement. In effect, they would partially “heal themselves,” Joe Stehly, the mission’s Project System Engineer, told the NYT.
With that in mind, if they could pare down the Europa Clipper’s flybys and sparingly use its electronic instruments, then maybe the mission could be salvaged. This approach, however, would still be filled with uncertainties, not to mention dramatically diminish the space probe’s scientific objectives.
But why settle for less? Jeff Srinivasan, the flight systems manager, proposed taking samples of each type of MOSFET and packing them into a “canary box” attached to the spacecraft. These would serve as early warning systems alerting scientists to when they should shut off certain electronics to avoid radiation damage.
“It was one of those that’s so-crazy-it-might-work moments,” Stehly told the NYT.
Though engineers would ideally have years to make such a system, they put it together in a month. And after rigorous assessments, it appears it’ll work even better than expected. Now, the mission — seemingly against all odds — is slated to continue unaltered and launch next month.
And as it travels to Jupiter, no doubt scientists and engineers throughout NASA will be crossing their fingers that the spacecraft’s systems will survive.
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