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Unmanned Spaceflight.com _ Jupiter _ Europa Clipper Development
Posted by: nprev Sep 8 2018, 07:14 AM
The spacecraft has entered its preliminary design review phase, so I think it's time to begin discussion of what promises to be a fascinating journey to one of the most interesting destinations in the Solar System. Dr. Robert Pappalardo, the mission's chief scientist, delivered an overview of Europa as well as a top-level description of instrumentation and objectives during a talk tonight at the Griffith Observatory as part of their monthly "All Space Considered" series, so that serves as a good starting point. His presentation starts at 29:35.
As a reminder, please carefully review rule 1.3 before commenting. In fact, please review all of them. 
Thanks!
https://www.youtube.com/watch?v=_aInKr1cn5I
Posted by: vjkane Sep 8 2018, 02:56 PM
https://www.youtube.com/watch?v=_aInKr1cn5I
I listened to the talk given yesterday by Bob Pappalardo, project scientist for the Clipper mission, at the Griffith Observatory. In general, the talk was aimed at the general public and did not go into many details. There were some tidbits that were new to me:
He stated that the project is keeping the spacecraft compatible with launch by the Delta IV Heavy, Falcon Heavy, and SLS. The former two would result in cruises of nearly 8 years, the latter 2 years.
He stated that the mission will do a number of Callisto and Ganymede flybys when they flip the orbit to go from flybys on the anti-Jovian hemisphere to the pro-Jovian hemisphere. (I've also read that there will be several flybys of these moons early in the mission as they crank down the orbit for to shorten the period and lower the periapsis to Europa's orbit.)
He also stated that the likely limiting factor for the mission would be the decay of power from the solar cells as they are degraded by the radiation. (Which brings up the idea to me that at some point they could raise the periapsis of the orbit out of the intense radiation field and become a Jovian system observatory for some period. ESA's JUICE mission will orbit Ganymede and do a number of Callisto flybys. Don't know the science return for additional flybys of these moons by the Clipper spacecraft late in its mission.)
The current disposal plan is to dump the spacecraft into Jupiter, although crashing the craft onto Ganymede or Callisto remains a possibility. (From a previous public lecture, another Clipper manager said his favorite idea was to crash into Io, collecting data on the way in. Don't know if that remains a feasible option.)
Posted by: nprev Sep 9 2018, 02:36 AM
One thing that really caught my notice is that they're expecting 0.5m resolution of Europa at selected times/passes. He used the phrase "HiRISE-quality". Was rather surprised by that; I'm assuming that means that at least some of the flyby relative velocities are fairly low.
Characterization of surface roughness at that scale will be enormously helpful for future lander mission planning, of course. I wonder if they'll be able to achieve something similar during the Ganymede & Callisto flybys?
Posted by: antipode Mar 5 2019, 09:33 PM
Oh dear, according to the latest PEN newsletter, the ICEMAG Europa interior characterisation instrument has been terminated due to cost overruns.
P
Posted by: nprev Mar 5 2019, 09:45 PM
Do you have a link to that, Antipode? Didn't find anything via a quick Google.
Posted by: antipode Mar 5 2019, 10:47 PM
PLANETARY EXPLORATION NEWSLETTER
Volume 13, Number 10 (March 5, 2019)
PEN Website: http://planetarynews.org
P
Posted by: nprev Mar 6 2019, 04:03 AM
Thank you.
Bad news indeed. However, it does seem that the mission will likely still include a magnetometer albeit a less complex (and capable) instrument, perhaps a flight spare of some sort from another project.
This is not without precedent; seems to happen more often than not for most missions, actually. Hopefully the legendary ingenuity of NASA will find a way forward.
Posted by: Explorer1 Mar 6 2019, 05:17 AM
Too bad; luckily, JUICE will definitely carry a magnetometer too (called J-MAG).
Posted by: MahFL Mar 6 2019, 06:07 AM
Volume 13, Number 10 (March 5, 2019)
PEN Website: http://planetarynews.org
P
300% cost increase...
Posted by: Bjorn Jonsson Mar 6 2019, 09:05 PM
I noticed that according to the PEN newsletter, a simpler, less complex magnetometer will be included on Europa Clipper if possible. Hopefully this is possible since including a magnetometer is really important for exploring Europa properly (the subsurface ocean in particular).
Posted by: JRehling Mar 7 2019, 07:28 AM
Since JUICE and EC will run concurrently, it would be particularly nice to have them both operating at the same time, in the event that both of them might make a close Europa pass at the same time. A magnetic field inside another magnetic field is a complex beast, and getting measurements along two trajectories at once would be a bonus.
JUICE won't make that many passes by Europa, so it can't possibly replace the science value that a magnetometer on EC would offer.
I'm still smarting over the fact that Dawn had its magnetometer downscoped away.
Posted by: Steve5304 Mar 7 2019, 03:57 PM
This isn't Clipper. That's the Euro mission.
And it looks like the Russian's and Chinese may very well send their own vessel also. So possible 3 missions to Europa, Ganymede during the 2030's.
Posted by: JRehling Jun 6 2019, 04:51 AM
The latest review of Europa Clipper and Europa Lander paints a less-than-rosy picture of the status of each.
https://www.sciencemag.org/news/2019/05/without-champion-europa-lander-falls-nasa-s-back-burner
(This article is more about the Lander than the Clipper, so the match with this forum is ~40%.)
These sagas go back and forth as we all know, but it seems like postponement is a solid possibility for the Clipper and more than likely for the Lander.
Posted by: vjkane Jun 8 2019, 03:01 AM
A friend of mine in the professional space community pointed out to me that these reports often document problems well known to the development teams. Often by the time the reports are published, project management is well toward solving the problem
Posted by: Jaro_in_Montreal Aug 20 2019, 01:01 AM
Yaay !!
https://www.nasa.gov/feature/europa-clippers-mission-to-jupiter-s-icy-moon-confirmed
Posted by: Jaro_in_Montreal Aug 20 2019, 04:31 PM
BTW, I remember reading a detailed Europa Clipper mission proposal somewhere, but now I can't find it in my files.
Anybody here remember where it was posted?
A quick Google search came up empty.
Thnx
Posted by: JRehling Aug 21 2019, 02:41 AM
Maybe this is the one you were thinking of?
https://smd-prod.s3.amazonaws.com/science-red/s3fs-public/atoms/files/Europa-PSS_Sept_2016.pdf
One thing that catches my eye is that virtually all of Europa would be mapped at better than 30m per pixel with a median of about 9m per pixel. Due to orbital mechanics that are easy to visualize (flybys just inside or outside of Europa's orbit), there is a rough 180° periodicity in the coverage with the sub-jovian and anti-jovian regions imaged with the best resolution and the leading and trailing regions imaged with the worst resolution. This is approximately 10 times higher resolution than Viking coverage of Mars.
Posted by: nprev Oct 23 2019, 06:23 AM
Panel discussion tomorrow (23 Oct 19) about Clipper featuring Bob Pappalardo and TPS CEO Bill Nye, 1030 US Pacific Daylight Time, 1730 GMT. https://www.nasa.gov/multimedia/nasatv/index.html#public.
Posted by: Explorer1 Apr 22 2021, 08:33 PM
I didn't want to start a new topic in the book subforum, but I wanted to let everyone know about 'The Mission' by David Brown; a fantastic book about the long history of Europa missions that recently released and everything that led up to the Europa Clipper's development so far. I'm only in chapter 4 of the audio version, but it's filled with all sorts of details on JIMO and previous proposals, as well as the nitty-gritty scientists, bureaucrats, politicians, (as well as some some cameos by posters on this very forum)! I had never known the origin of OPAG and MEPAG, the various rivalries, and the constant competition for scarce dollars.
The author has done quite a bit of science writing on space missions, and the prose is a good mix of details that will interest both experts and amateurs. It really emphasizes the long slog before even the first physical part of a probe destined for space is machined. I think there will be plenty new even to the users of UMSF.
Posted by: mcaplinger Apr 22 2021, 08:53 PM
Since I was on a number of teams for the 3 or 4 precursor missions and on a losing team for Clipper itself, I found that the book omitted all of the interesting details about those competitions (few of which, I expect, will ever be public). Not a surprise, since history is written by the winners...
Posted by: JRehling Apr 23 2021, 12:12 AM
Richard Greenberg's books about the science of Europa are extremely lively, documenting some passionate disagreements, to put it mildly. I suspect that the rivalries in engineering a Europa mission are mainly about different issues, not necessarily scientific ones, but it seems like there has to be some aspect of the thin-ice vs thick-ice theories coming into play, at least during the ~2002-2014 era. But I am only on the outside looking in.
Posted by: scalbers May 24 2021, 07:54 PM
Nice talk by Bob Pappalardo on Europa Clipper was presented on May 12, and can be watched on YouTube:
https://www.youtube.com/watch?v=8ZMZuiiaAmQ&t=4s
Posted by: volcanopele Jul 23 2021, 08:45 PM
Europa Clipper now has a launch vehicle: a SpaceX Falcon Heavy. Launch is now set for October 2024.
https://www.nasa.gov/press-release/nasa-awards-launch-services-contract-for-the-europa-clipper-mission
Posted by: stevesliva Jul 26 2021, 04:29 AM
Should go back to launching in pairs for this price.
Posted by: djellison Jul 26 2021, 05:07 AM
The rocket isn't the expensive part. For this mission it's less than 5% of the budget.
Posted by: Explorer1 Jul 27 2021, 12:19 AM
$178 million is pocket change compared with SLS anyway. Massive savings by any measures (I could say more about SLS, but the p-word would be involved)....
Having a launch vehicle finalized is a big milestone; will be an impressive sight!
Posted by: StargazeInWonder Feb 13 2022, 11:07 PM
This description of the Europa Clipper radar instrument, REASON, has a date of 2015, but seems to remain valid:
https://www.lpi.usra.edu/opag/meetings/aug2015/presentations/day-1/8_f_REASON.pdf
There is good reason to believe that the icy shell will have a fair degree of global consistency for depth and structure, with local exceptions. The radar campaign of Europa Clipper will not map Europa's surface comprehensively, but rather provide a partial grid of widely-separated tracks, with good vertical resolution along those tracks. This should provide excellent coverage of the global parameters for the shell's structure, surface texture, and – if existing conceptions of the shell's
depth and REASON's performance hold – thickness. If exceptions to the global trends (eg, pockets of liquid water closer to the surface) are not very rare, then the grid of ground tracks will intersect them, sampling them occasionally. I guess if there's an extended mission, there would be high priority on additional ground tracks to target areas of suspected interest that were missed or grazed during the main mission. The coverage map in the linked paper shows that at least in many locations the coverage will be pretty dense. Amusingly, the ground tracks look quite similar in distribution to the linea features around longitude 225W and elsewhere, so hopefully we don't end up just missing something of interest if the ground tracks remain parallel to geological features for thousands of km, just missing them along the entire length.
Posted by: scalbers Sep 22 2023, 09:47 PM
Live video stream of Europa Clipper assembly:
https://europa.nasa.gov/spacecraft/assembly/
https://www.youtube.com/watch?v=yk0X3Sh2gIE
Posted by: Steve G Apr 17 2024, 12:22 AM
Europa Clipper will be arriving in Jupiter orbit in April 2030. It will take about a year to get it into the science orbit. I can't locate any schematics of the initial orbits, and potential flybys of Ganymede, Calisto, or distant observations of Io. Can anyone assist?
Posted by: mcaplinger Apr 17 2024, 12:36 AM
https://ntrs.nasa.gov/citations/20160008162 is an old paper that describes an earlier tour design. I couldn't find anything more recent that wasn't paywalled.
At one point the claim was made that there would be no science observations made of the other satellites to save costs, but I doubt that will hold once they're flying.
Posted by: volcanopele Apr 17 2024, 03:38 AM
I will note that the current tour SPICE kernel is on the NAIF kernel site. If you know how to use something like spiceypy, one could create a python script that gives you all the flybys.......
Posted by: StargazeInWonder Apr 17 2024, 02:04 PM
Here is a map that aggregates all of the ground tracks, which displayed an impressively dense grid-like coverage of the entire surface, though with some concentrations reflecting the realities of orbital geometry.
https://www.hou.usra.edu/meetings/lpsc2023/pdf/1518.pdf
It notes, at a high level, that the early orbits will focus on the anti-Jupiter hemisphere and then the later orbits will focus on the sub-Jupiter hemisphere.
Other commentary is here.
https://www.nasaspaceflight.com/2024/04/ec-jpl-interview/
https://europa.nasa.gov/mission/timeline/
Because the main mission coverage is a bit uneven spatially, there's the prospect that features that seem intriguing given coverage from the main mission could be the targets of specific focus during any possible extended mission. This will introduce luck and chance as factors – will there be uniquely interesting features that just happen to be located near/far from the closest ground tracks, and how will the spacecraft hold up as radiation damage takes its toll? I think the subtext is that potential targets for any future landers will be of prime interest, and only time will tell if there are uniquely promising locations for a lander (as on Mars) or if there are, effectively, many areas that are more or less equally intriguing. We already know that there are isolated areas with more recent exposure to subsurface activity than is typical, but we don't have sufficient coverage from Galileo to characterize what might be the best locations.
The overlap with JUICE is important context, should both missions function perfectly. This would make EC's coverage of Ganymede and JUICE's coverage of Europa seemingly less important, but the instrument suites are not exactly identical, so perhaps those differences will be highlighted by circumstances where each observes the "other" moon. And it highlights the importance of the observations of Callisto, which is not the primary target of either mission, but will be visited a total of 21 times by these two orbiters, which would seem to offer the potential for excellent and definitive coverage (Galileo flew by Callisto only 3 times in the primary missions and 8 times in all). In fact, both EC and JUICE will each fly by Callisto more times than Galileo ever did.
Posted by: StargazeInWonder Apr 19 2024, 04:48 PM
To the point, I think, of Steve's question, I took a look at the Galileo-era maps of the four Galileans and how coverage has varied, which is to say the least considerable. For each, portions have been mapped at scales of 1km/pixel or much better, while other large portions have been imaged at no better than 5km/pixel.
The successful completion of EC and JUICE will utterly supersede current imagery for Europa and Ganymede, and the contributions of each mission to "the other" moon in that pair will be essentially redundant, in terms of mapping. (I'm curious if the two different radar instruments will produce interestingly complimentary data in cases where the ground tracks cross.)
Neither will approach Io closely, but will potentially come as close to Io as Europa is to Io. That won't advance our global maps of Io except in the sense that Io's time-varying vulcanism makes even remote observations potentially interesting.
Callisto is the wildcard. As long as the flybys aren't completely undermined by redundant geometry, nightside closest approaches and/or policies against performing observations, those 21 combined flybys – nearly half as many as EC will make of Europa – should amount to the definitive exploration of Callisto. ESA is quite focused on their end of this; note that the mission name itself is not specific to Ganymede and Callisto is indeed a primary target of the mission, even if it's not as primary as Ganymede. Some interesting and fun discussion here:
https://www.esa.int/Enabling_Support/Operations/Juice_aces_Callisto_flyby_test
Posted by: Explorer1 Jul 12 2024, 04:52 PM
https://www.science.org/content/article/vulnerable-transistors-threaten-upend-europa-clipper-mission
https://blogs.nasa.gov/europaclipper/2024/07/11/nasa-continues-assessing-electrical-switches-on-europa-clipper/
The main consolation is that the best people in the world are working on this, and the spacecraft we already have at Jupiter seems to be degrading much more slowly than was predicted. I will be eager to see what sort of fix, if any, is needed, or modifying the flight plan....
Posted by: mcaplinger Jul 12 2024, 06:47 PM
I wouldn't draw a lot of conclusions from the Juno experience, since the radiation environment Clipper sees is modeled to be a lot worse.
Posted by: rlorenz Jul 15 2024, 02:51 AM
Well, I hope they can sort this out. It is a little galling that a radiation issue should come up for Europa. In the 2008 Outer Solar System flagship competition the argument was made (in effect) that the radiation challenge at Jupiter/Europa was understood and manageable, while the balloon technology for Titan (hot air balloons first flew in 1783...) was considered immature. Caveat Emptor.
Posted by: nprev Jul 15 2024, 05:18 AM
Admin mode: Just a gentle reminder for all to please ensure that discussion of this evolving situation complies with Forum rule 2.6 (provided below for review.) Obviously we aren't privy to all the details, and this is an extremely stressful and difficult time for the team. We don't need to add to that stress. Thanks!
2.6 When mentioning scientists, engineers, or other mission personnel, please write as though they are reading the Forum. In fact, many of them are. In particular, avoid criticizing missions on the basis of hindsight and/or incomplete information.
Posted by: StargazeInWonder Jul 15 2024, 05:39 AM
Unless there are classified missions to Jupiter, the components in question failed for a satellite that was presumably in Earth orbit. That would seem to be rather concerning for the case of a Europa craft, but that keyword "classified" makes it pretty futile to try to figure anything out before the insiders report back. As described above, the root cause isn't really so much about the intrinsic hazard at Europa as it is about anomalies in the process. The timing is really concerning; the components they describe seem like they are really easy to make radiation-proof, in general, but if they have to replace anything now, that is now a tight deadline before the launch.
In general, trajectories to Jupiter come back around pretty often, but if they have to postpone, the Mars gravity assist might make what would be a small slip into a larger one.
Posted by: bobik Jul 15 2024, 07:45 AM
Some background about the https://nepp.nasa.gov/docs/etw/2021/14-JUN-21_Mon/1130_McClure-Keynote-Europa-CL21-2225.pdf.
Posted by: mcaplinger Jul 15 2024, 02:15 PM
Having worked on several unsuccessful Europa proposals over the past quarter-century, one of the few parts it seemed we didn't have to worry about were MOSFETs, so this is pretty dismaying.
I think the problems were detected in ground testing. There is a system for parts problems to be reported to the wider community ( https://gidep.org/home ) but I can't share any information from there or from other sources.
You can learn more about the parts in question at https://www.infineon.com/cms/en/product/high-reliability/space/power/rad-hard-mosfets/#
Posted by: vjkane Jul 15 2024, 03:49 PM
This must be every teams worst nightmare. Designed right, tested right, and then learn that a supplier failed to meet specs on a component in a way the project couldn't have tested for it.
Posted by: Brian Swift Jul 20 2024, 03:14 AM
Coincidently, I recently read about how MOSFETs on SMAP became more sensitive to radiation failure after an over-voltage condition. https://llis.nasa.gov/lesson/27701
Posted by: Holder of the Two Leashes Jul 21 2024, 03:06 AM
Shades of Psyche.
Posted by: StargazeInWonder Jul 21 2024, 01:33 PM
The headline and one quote inside offer optimism, but there isn't much basis in specifics offered.
As it happens, there's also some Mars Sample Return commentary.
https://spacenews.com/nasa-science-head-optimistic-europa-clipper-launches-on-schedule/
Posted by: StargazeInWonder Aug 21 2024, 04:22 PM
For the news to raise that concern about the MOSFETs, followed by weeks without an update seems like a disconnect, at least as far as communications go. One tweet briefly says that two inside sources expect the launch to go ahead, but there isn't anything public that addresses the issue. I guess that either the investigation is continuing silently and in parallel with launch preparations or it has concluded silently. In about 7 weeks, we'll either have a mission on the way or some implicit statement that the MOSFET issue has been addressed one way or another.
Posted by: mcaplinger Aug 22 2024, 06:08 PM
It is a little surprising that there hasn't been an update.
Speaking only from my experience, many parts are sensitive not only to the total radiation dose but also the dose rate (see, for example, "Dose-Rate Sensitivity of 65-nm MOSFETs Exposed to Ultrahigh Doses" https://ieeexplore.ieee.org/document/8340851 )
Since vendors can only test at a limited number of dose rates, and it's very difficult to predict what the actual dose rates experienced in flight will be, this may be difficult to nail down as well as one might like. A part could be fine at one dose rate and fail much sooner at another.
Posted by: StargazeInWonder Aug 23 2024, 05:00 PM
I see also that that source tested uncharged electromagnetic radiation while the Jupiter environment has charged particles, including of masses that you'd rarely see on Earth. And one of the hazards of the jovian environment is that sustained dosage of charged particles can cause charge buildup, and destructive discharge arcs. As for how that plays out in the complex structures of one particular spacecraft that's never been flown before, in a part of the jovian environment that has never had a spacecraft spend long durations of time in before… I have no idea how one has hope of testing or validating that. Build to tolerance way above the estimated worst case, I guess.
Posted by: mcaplinger Aug 23 2024, 05:23 PM
Most electronics respond quite similarly to gamma ray exposure and charged-particle exposure, but gamma ray testing is much easier to do since you can use a Co60 source that just sits there and pumps out gamma rays. There are exceptions, typically optoelectronics, but most parts can be meaningfully tested with gamma.
Spacecraft charging is fairly easy to deal with, see "Mitigating In-Space Charging Effects-A Guideline" https://standards.nasa.gov/standard/nasa/nasa-hdbk-4002
Admittedly the jovian environment is an extreme case but Juno hasn't had any charging issues I'm aware of.
Posted by: john_s Aug 28 2024, 08:00 PM
Good news on Clipper! https://blogs.nasa.gov/europaclipper/2024/08/28/nasas-europa-clipper-mission-moving-toward-october-launch-date/
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
Posted by: mcaplinger Aug 28 2024, 09:50 PM
I guess that's good news, but generally I don't use words like "suggests" or "baseline" for an unambiguously favorable result. It would be unfortunate if there's no chance of an extended mission because of this (of course, I don't know what the prospects for an extended mission were to begin with.)
Maybe this is just expectation management, I can sympathize.
Posted by: StargazeInWonder Aug 29 2024, 01:39 AM
Huge if true!
An interesting thing about the structure of the mission is that all of the anti-jovian flybys of the main mission occur first, followed by all of the sub-jovian flybys of the main mission. I guess that would make an early end of mission (say, only 40% or even 80% of the flybys occur) more painful than if, say, the anti- and sub- flybys were sort of interspersed, because flybys with a given ground track will provide pretty good resolution for areas beyond the ground track. An early end of mission with this profile will mean that the anti-jovian hemisphere would still be well or completely covered, with serious gaps for the sub-jovian hemisphere. But that's the pessimistic scenario.
There's a significant difference in resolution between the global mapping and targeted high resolution imaging (and radar ground tracks) so it seems like an extended mission would want to target locations identified in the main mission as having particular interest – possible plume vent locations or future landing locations. It's anybody's guess where those would turn out to be and the orbital mechanics suggest that some of them could end up being in locations that are hard to target immediately after the last orbit of the main mission. Another value of the extended mission would be temporal, offering more opportunities to study intermittent plume activity if those are indeed intermittent. There's also an unknown capacity for supporting remote observations as the JWST will likely be operating then; new, massive terrestrial telescopes will likely begin operating by then. Lots of unknowns there, including the radiation damage itself, even aside from the MOSFETs.
Anyway, good news conditionally for now.
Posted by: StargazeInWonder Aug 29 2024, 02:57 AM
A tweet from the mission's account adds:
The next major milestone for our mission in NASA's standard process is Key Decision Point E on Sept. 9, when the agency will decide whether we're ready to proceed to launch. A media briefing targeted for that same week will provide more information.
Posted by: Explorer1 Aug 29 2024, 02:59 AM
Good news for now, certainly.
https://www.jpl.nasa.gov/news/nasas-europa-clipper-gets-set-of-super-size-solar-arrays.
Posted by: stevesliva Aug 29 2024, 02:13 PM
I read hope for graceful degradation rather than catastrophic (unambiguously terrible) failure modes. Really knowing if the failure modes are recoverable is a large part of digesting the info, right?
Posted by: StargazeInWonder Aug 31 2024, 12:10 AM
Here's documentation of some past testing:
https://nepp.nasa.gov/files/24915/NSREC2013_Lauenstein_W38.pdf
Here's some documentation of Jupiter's radiation environment. Europa's orbit is at 9.6 Jupiter radii. That was extensively probed by Galileo (which, of course, approached Europa many times).
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016JA023059
What's not public facing, AFAIK, is how well shielded these transistors are, and how the electronics of Europa Clipper depend upon nominal function. Any given component inside the craft will be protected to greater extents by the craft itself in some directions than others. I guess that these components, having been above suspicion of failure when the craft was designed, are not located to maximize the greatest amount of shielding by intention, but may accidentally benefit from more or less shielding in the details of their location and what the orientation of the craft is during flybys. (Eg, note that the trailing hemisphere of Europa receives more radiation than the leading hemisphere.) The directionality of the instruments' bore sights during closest approach is non-negotiable, but perhaps the rotation of the craft around that axis is a variable that can be manipulated productively. Above my pay grade, but hopefully the team's ambiguously-stated confidence reflects the required optimism!
Posted by: john_s Sep 9 2024, 08:15 PM
Europa Clipper is go for launch, with the nominal mission! https://www.nasa.gov/live/
Edit: https://www.youtube.com/watch?v=7FWdvN_hsTo, which hopefully will persist after the event. More technical details about the response to the MOSFET issue than previously released.
John
Posted by: StargazeInWonder Sep 9 2024, 10:21 PM
I have listened to only part of the audio of the press event, but copy-pasted the automatically-extracted transcript into a local file, and it's semi-readable. The intriguing conclusion is that while radiation will degrade the MOSFET transistors during each passage through the most intense radiation of the mission, the transistors will "heal" during the longer intervals between such events, and that this cycle of degradation and healing will allow successful completion of the mission.
The transcript mangles the key word "annealing" as "kneeling" and other transmutations of the word, but that appears to be the key idea. They plan to keep the mission as originally planned. Questions regarding an extended mission drew optimistic answers: "We have no reason to expect anything other than a great four years and an extended Mission beyond that."
Posted by: mcaplinger Sep 9 2024, 10:22 PM
Here's a quick edit of the specifics about the MOSFETs from the automatically-generated captions from the today's press conference. Any errors not part of the autogeneration are mine.
transistors, which was back at the beginning of May at JPL, we moved
quickly as a project and as a lab and agency with our partners as well
to quickly analyze the risks and conduct tests. [We] generated
tremendous amount of data. We know a lot about the the Jupiter
radiation environment from previous NASA missions including the
current Juno Mission which is at Jupiter right now.
We completed extensive testing to validate the transistors on the
spacecraft. We ran tests 24 hours a day over the last four months at
multiple locations at the Jet Propulsion Laboratory, at the Applied
Physics Laboratory and at the NASA Goddard Space Flight Center. We
simulated flight like conditions to illuminate any issues that the
transistors might have over our four-year science Mission across the
variety of applications we have on the spacecraft.
We put these representative transistors into these environments,
radiated entire circuits and to see how the system behaves and not
just the transistors themselves. We looked at transistor temperatures
while the spacecraft was outside of Jupiter's most intense radiation
environment to determine how much recovery we might be able to get
from these transistors while we're not in that intense radiation
environment. After each flyby we've replicated that transistor
self-healing, or annealing as it's called, that occurs by heating them
to room temperature while they they essentially rest far from that
intense radiation environment as we go around each orbit of Jupiter
before [coming back to] Europa again.
The underlying issue was that there was a gap in how industry
qualifies the kind of hardware like MOSFETS for high radiation
environments. The parts in question, the semiconductor in the
transistors are cut from silicon wafers and those silicon wafers met
the radiation hardness requirements that we needed, but then those
semiconductor Wafers degraded while in storage. We concluded after
all of this testing um that during our orbits around Jupiter while
Europa Clipper does dip into the radiation environment, once it comes
out it comes out long enough for those transistors the opportunity to
heal and partially recover between flybys. we're going to continue to
closely monitor the both the radiation environment we have a radiation
monitor on board as well as the performance of the transistors from
the ground once we are in flight and once we arrive at the Jupiter
system to accomplish this. we've received help from many corners
including the vendor. the vendor's been immensely proactive and
helpful throughout all of our work.
To reiterate what's already been said we can and I have very high
confidence, and the data bears it out, complete the original mission
which is 49 flybys of Europa and amounts to 80 orbits of Jupiter...
As Jordan said, they have margin and we have no reason to to expect
anything other than a great four years and an extended mission beyond
that.
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