Europa Clipper Transistors: Will They Work When They Have To?
Keith’s note: NASA posted a blog update on the Europa Clipper mission and put out a tweet. Note the last sentence: “NASA’s Europa Clipper mission remains on track, with a launch period opening on Thursday, Oct. 10. The next major milestone for Clipper is Key Decision Point E on Monday, Sept. 9, in which the agency will decide whether the project is ready to proceed to launch and mission operations. NASA will provide more information at a mission overview and media briefing targeted for that same week. The Europa Clipper mission team recently conducted extensive testing and analysis of transistors that help control the flow of electricity on the spacecraft. Analysis of the results suggests the transistors can support the baseline mission.” Hmmm … “results suggest they’re ready to support our baseline mission”. Um, that’s not the same as “Yes, the transistors have been fully tested and they can fully support the mission we originally planned to do”. There is also another meeting – “Key Decision Point E” – where they give the formal go ahead to launch. I’d ask NASA PAO to clarify the wording – but they won’t respond to me – and if they do respond they will punt and tell me to wait a few weeks for the press event. So stay tuned.
5 responses to “Europa Clipper Transistors: Will They Work When They Have To?”
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As a taxpayer, I find this to be really infuriating. Something like $5 billion ultimately spent on this mission and it sounds like they’re unwilling to invest the funds necessary to make sure that it has components in tiptop shape. Voyager comes to mind – they certainly didn’t use components that were maybe-kinda-sorta-just-good-enough and humanity has reaped the benefits over the intervening decades. ‘Data suggest just good enough for a minimal baseline mission’ should never ever be an acceptable quality standard for a NASA mission, especially one of this magnatude and overall budget. Congress should give them hell for this, and demand that they do whatever repair work is necessary to bring the craft up to snuff.
It is fairly clear that the are-breaking discovery that the FETs used on EC are not as radiation resistant as previously believed has put the project into a higher risk posture than anyone would prefer. However, reworking the spacecraft to replace them with more robust units (if such units exist) would be a major undertaking, involving a launch slip, possibly years in duration given the trajectory requirements. It would not surprise me if the associated costs exceeded $1B, likely resulting in cancellations or delays of other projects as well. So simply insisting that everything has to be ris-free is not realistic.
The challenge is in fairly evaluating those risks and trading them against the impacts of taking more robust corrective actions. That’s what the review process is all about. It is certainly not infallible, bur it is the only thing we’ve got when there is residual risk – and there are always residual risks when we launch.
Removing and replacing these components would be a mission killer. JPL has mitigated the risk somewhat through recent testing of a “canary box”.
Today’s parts problem on a JPL project is particularly ironic. Much more so than in our current “Agile environment” for PM. Monkeying with risk classification of various instruments and subsystems to reverse schedule impacts and cost growth is the main contributing cause to the present mission status. Hindsight being 20-20, it appears many of the actual technical risks the mission now faces were either not addressed or well-understood. -30-
It’s my understanding this has to do with a late discovery – like a few months ago – that the parts in question were taken from a batch/lot that upon further investigation did not meet radiation requirements. This came to NASAs attention not by the typical GIDEP process but from folks in the DoD community learning their parts were suspect. And don’t you know it NASA JPL has these same parts all over the Europa Clipper mission. I think the specific issue is Total radiation dose. So, the question is, can the mission re do its mission ops concepts to avoid extensive radiation exposure while still getting missions science goals ; I believe additional testing was done to confirm the DoD findings. And these parts are everywhere on Europa. Instruments , bus , It would take a long time to tear all the h/w down and replace the parts and that would introduce its own risks and unknown unknown problems
This is classic “Rock, say hello to Hard Space, you are stuck “