Europa Clipper Development, Build And Prelaunch Activities Options

[volcanopele]

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.......

[StargazeInWonder]

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.

[StargazeInWonder]

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/Operat...isto_flyby_test

[Explorer1]

A potentially serious issue with some of the rad hardened transistors

Blog post from NASA here; it appears there will be a report later this month.

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....

[mcaplinger]

the spacecraft we already have at Jupiter seems to be degrading much more slowly than was predicted...

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.

[rlorenz]

A potentially serious issue with some of the rad hardened transistors

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.

[nprev]

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.

[StargazeInWonder]

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.

[bobik]

Some background about the Europa Clipper radiation program.

[mcaplinger]

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/hig...-hard-mosfets/#

[vjkane]

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.

[Brian Swift]

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

[Holder of the Tw...]

Designed right, tested right, and then learn that a supplier failed to meet specs ...

Shades of Psyche.

[StargazeInWonder]

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-opt...es-on-schedule/

[StargazeInWonder]

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.