NASA's $5 billion Europa Clipper mission may not be able to handle Jupiter's radiation

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Europa Clipper's transistors aren't as radiation resistant as expected.

A spacecraft seen over a red-streaked world. Jupiter, a striped and swirly looking world, is in the background, offscreen.
An illustration of NASA's Europa Clipper spacecraft soaring over the icy Jovian ocean moon Europa. (Image credit: NASA)

A highly anticipated NASA astrobiology mission is troubleshooting a serious issue just months before its planned liftoff.

The Europa Clipper spacecraft is scheduled to launch this October atop a SpaceX Falcon Heavy rocket. The robotic explorer will embark upon a $5 billion mission to assess the potential of Europa, an ice-covered ocean moon of Jupiter, to support life as we know it.

But that launch date, and the probe's ability to carry out its ambitious mission, may now be in peril: Mission team members have discovered a problem with Clipper's transistors, devices that control the flow of electricity on the probe.

"The issue with the transistors came to light in May when the mission team was advised that similar parts were failing at lower radiation doses than expected," NASA officials wrote in an update on Thursday (July 11).

That's of serious concern, because Clipper is headed into a radiation gauntlet. 

"The Jupiter system is particularly harmful to spacecraft, as its enormous magnetic field — 20,000 times stronger than Earth's magnetic field — traps charged particles and accelerates them to very high energies, creating intense radiation that bombards Europa and other inner moons," NASA officials wrote in the update.

Europa Clipper is scheduled to arrive in the Jupiter system in 2030. The probe will orbit the gas giant, not Europa, but it will spend a fair bit of time in the moon's neighborhood: Clipper will make about 50 flybys of Europa over the course of its 3.5-year science mission.

Related: Why NASA's Europa Clipper mission to Jupiter's icy moon is such a big deal

This artist's concept shows a simulated view from the surface of Jupiter's moon Europa. (Image credit: NASA/JPL-Caltech)

This past May, the mission team was told that parts similar to Europa Clipper's transistors "were failing at lower radiation doses than expected," NASA officials wrote in the Thursday update. Transistor testing is now underway at NASA's Jet Propulsion Laboratory in Southern California, which leads the mission, as well as the Johns Hopkins Applied Physics Laboratory and NASA's Goddard Space Flight Center, both of which are in Maryland.

The results aren't exactly promising.

"Testing data obtained so far indicates some transistors are likely to fail in the high-radiation environment near Jupiter and its moon Europa because the parts are not as radiation-resistant as expected," NASA officials wrote.

"The team is working to determine how many transistors may be susceptible and how they will perform in flight," they added. "NASA is evaluating options for maximizing the transistors' longevity in the Jupiter system. A preliminary analysis is expected to be complete in late July."

NASA's Europa Clipper spacecraft being assembled at the agency's Jet Propulsion Laboratory in Southern California. (Image credit: NASA)
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— Watch this Jupiter moon lander handle harsh terrain it may face on Europa (video)

The devices in question are called metal-oxide-semiconductor field-effect transistors, or MOSFETs, and they were manufactured by a company called Infineon Technologies, according to the journal Science. The discovery of their vulnerability at this late stage makes it very difficult to deal with.

"The transistors cannot simply be replaced," Science's Paul Voosen wrote. "Clipper's aluminum-zinc electronics vault, meant to provide a measure of radiation resistance, was sealed in October 2023. Barring an indication that the faulty MOSFETs will cause catastrophic failure, the agency will likely seek to continue with the launch — although backup windows are available the next 2 years." 

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Mike Wall
Mike Wall
Senior Space Writer

Michael Wall is a Senior Space Writer with Space.com and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.

6 Comments Comment from the forums
  • George²
    Space technology is becoming more and more expensive and of poorer quality. This proves that universities and facilities are unable to produce and improve the knowledge and expertise of quality scientists and engineers. It's good that they celebrate and are proud of their diplomas and where they work, and yet nothing becomes of them, they are useless.
    Reply
  • newtons_laws
    Quite concerning. From the linked Science report https://www.science.org/content/article/vulnerable-transistors-threaten-upend-europa-clipper-mission
    Some years ago, Infineon changed its manufacturing process for its radiation-hard MOSFETs, which it designs to meet U.S. military specifications—the same radiation-resistance standards used by the Clipper team. After this change, the company’s classified customers found that several lots of the transistors failed at lower than expected radiation levels, Fitzpatrick said. The company has already corrected the mistake, but Infineon did not report the flaw to NASA because the company did not know what the transistors would be used for, Fitzpatrick said. “They did not realize it was going to affect us.” Infineon did not respond to a request for comment.
    “This is concerning,” said Deborah Woods, a planetary scientist at the Massachusetts Institute of Technology’s Lincoln Laboratory, at the PSAC meeting. “It’s fortunate that you happened to talk to people at the conference and learn of this issue. It’s troubling that this was the only way this was uncovered.”

    The transistors cannot simply be replaced. Clipper’s aluminum-zinc electronics vault, meant to provide a measure of radiation resistance, was sealed in October 2023. Barring an indication that the faulty MOSFETs will cause catastrophic failure, the agency will likely seek to continue with the launch—although backup windows are available the next 2 years.
    NASA engineers, working closely with Infineon, are now studying how many of the defective transistors are onboard Clipper, where in the hardware they are deployed, and which ones would most threaten the mission if they failed. They are also looking at possible ways to mitigate the problem, such as turning off certain switches for parts of the spacecraft’s lifetime, or naturally healing the vulnerable transistors, potentially by raising temperatures, a process called annealing.

    It seems to me that contractually the MOSFETs supplied by Infineon failed to meet the order radiation resistance specifications, potentially putting at risk a $5Billion mission, yet they didn't inform NASA. Infineon's excuse that they didn't know what the transistors would be used for doesn't wash. Once they knew goods supplied didn't meet the order specifications then they had an obligation to inform the customer regardless of who the customer was. Not good at all. :rage:
    Reply
  • AceExplorer
    George² said:
    Space technology is becoming more and more expensive and of poorer quality. This proves that universities and facilities are unable to produce and improve the knowledge and expertise of quality scientists and engineers. It's good that they celebrate and are proud of their diplomas and where they work, and yet nothing becomes of them, they are useless.
    Human error is always a risk. On education - we are having similar quality problems with degreed hires in non-space technology sectors. We must attract, train, and hire only the best and brightest - the same as our foreign competitors continue to do. It is becoming more evident that we are losing ground. And I hesitate to say that I know one of the prime recent causes. There is little room in space technology for compromise at any level. Period. "Play silly games, win silly prizes."
    newtons_laws said:
    Quite concerning. From the linked Science report https://www.science.org/content/article/vulnerable-transistors-threaten-upend-europa-clipper-mission
    Some years ago, Infineon changed its manufacturing process for its radiation-hard MOSFETs, which it designs to meet U.S. military specifications—the same radiation-resistance standards used by the Clipper team. After this change, the company’s classified customers found that several lots of the transistors failed at lower than expected radiation levels, Fitzpatrick said. The company has already corrected the mistake, but Infineon did not report the flaw to NASA because the company did not know what the transistors would be used for, Fitzpatrick said. “They did not realize it was going to affect us.” Infineon did not respond to a request for comment.
    “This is concerning,” said Deborah Woods, a planetary scientist at the Massachusetts Institute of Technology’s Lincoln Laboratory, at the PSAC meeting. “It’s fortunate that you happened to talk to people at the conference and learn of this issue. It’s troubling that this was the only way this was uncovered.”

    The transistors cannot simply be replaced. Clipper’s aluminum-zinc electronics vault, meant to provide a measure of radiation resistance, was sealed in October 2023. Barring an indication that the faulty MOSFETs will cause catastrophic failure, the agency will likely seek to continue with the launch—although backup windows are available the next 2 years.
    NASA engineers, working closely with Infineon, are now studying how many of the defective transistors are onboard Clipper, where in the hardware they are deployed, and which ones would most threaten the mission if they failed. They are also looking at possible ways to mitigate the problem, such as turning off certain switches for parts of the spacecraft’s lifetime, or naturally healing the vulnerable transistors, potentially by raising temperatures, a process called annealing.

    It seems to me that contractually the MOSFETs supplied by Infineon failed to meet the order radiation resistance specifications, potentially putting at risk a $5Billion mission, yet they didn't inform NASA. Infineon's excuse that they didn't know what the transistors would be used for doesn't wash. Once they knew goods supplied didn't meet the order specifications then they had an obligation to inform the customer regardless of who the customer was. Not good at all. :rage:
    Nice comment, with helpful additional information. Mission managers have a tough situation on their hands. I would be surprised if they do keep the current launch target knowing this issue is present. I'm very interested in how they will resolve this, if at all.
    Reply
  • Torbjorn Larsson
    It is of course hard to say what happened and what will be the outcome, but the general radiation problem with MOSFETs is interface traps between the gate and the silicon that can be charged and change the threshold voltage. In the worst case the transistor starts conducting without having any applied gate voltage. (Theoretically it can be worse still if the transistors can't be turned off at all, but in practice the problem should be zero voltage on states.)

    Those traps are of two types around the gate insulator oxide, shallow traps in the silicon and deep radiation induced traps in the oxide. If the production process has been compromised there will be more pre-existing traps and they will more easily appear during the transistor lifetime. Typically annealing is used to suppress traps, before or after they are induced. But that can take time for a low temperature anneal of assembled circuit boards or an entire assembly such as here.

    Time is the essential problem in all of this. Electronic components fail along a bath tub curve, but verifying the quality takes time, even when accelerated by elevating the operational temperatures. Since electrical properties correlate with process quality, manufacturers sort out "best of breed" components to sell as more expensive 'radiation hardened' (whether or not the manufacturing process hardens further). But it is not a panacea.
    Reply
  • Torbjorn Larsson
    newtons_laws said:
    It seems to me that contractually the MOSFETs supplied by Infineon failed to meet the order radiation resistance specifications, potentially putting at risk a $5Billion mission, yet they didn't inform NASA.
    Transistors are used for all sorts of purposes, and "radiation hardened" selections are actually components that are selected from the tail end of good manufacturing outcome and can be used for e.g. low noise amplifiers.

    NASA has already stated:
    is a phenomenon that the industry wasn’t aware of and represents a newly identified gap in the industry standard radiation qualification of transistor wafer lots.
    Reply
  • Torbjorn Larsson
    George² said:
    Space technology is becoming more and more expensive and of poorer quality. This proves that universities and facilities are unable to produce and improve the knowledge and expertise of quality scientists and engineers.
    The quantified outcome says the reverse on space industry. It is the decreasing costs and more reliable launchers that has increased the market so that kore satellites are launched today than previously.

    But even if the specific NASA problems would be used as a proxy for the industry, there is no evidence that those problems are caused by scientists and engineers. Like the space industry, science and engineering are growing markets.

    NASAs problems can be multifactorial. But from a non-US citizen's view NASA is an odd construction with a presumed "independent agency" where obviously political meddling (inviting micromanagement or corruption), is front and center. Say, the expensive SLS, which is used to pull votes from all states by laying out production to them.

    Instead of having a clean separation between an independent state administration and political control of its regulatory structure.
    Reply