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mcaplinger
Posted on: Yesterday, 10:50 PM


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QUOTE (Webscientist @ Dec 16 2024, 02:31 PM) *
Maybe nasaspaceflight.com...

I would try reading it for a while before you actually make an account. IMHO it has gotten almost intolerable over the past couple of years, but YMMV.
  Forum: Important Announcements · Post Preview: #265136 · Replies: 69 · Views: 22059

mcaplinger
Posted on: Dec 4 2024, 05:40 PM


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QUOTE (vjkane @ Dec 4 2024, 10:18 AM) *
I don't know the orbit mechanics of whether a direct flight if launched now could beat Clipper to Jupiter (or whether Starship could propel a large enough craft with fuel to be interesting).

The OP can find many kindred spirits extolling the world-changing aspects of Starship over at https://forum.nasaspaceflight.com/

I'll make a couple of points, but bear in mind that I am old and jaded:

1) launch vehicle costs are typically only a small fraction of total mission costs. Despite its success, Falcon 9 has not substantially changed the science mission landscape so far. F9 is far from free, it's at best half the cost of alternatives and usually not that good for a NASA mission.

2) AFAIK the current Starship architecture can't get out of Earth orbit with a reasonable payload without refueling from multiple tankers, so it's not very suitable for traditional mission architectures. Enthusiasts have proposed various solutions for upper stages (generically called "Starkicker") but whether that ever materializes is anyone's guess.
  Forum: Jupiter · Post Preview: #265111 · Replies: 86 · Views: 82014

mcaplinger
Posted on: Dec 2 2024, 04:12 PM


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QUOTE (nprev @ Dec 1 2024, 10:29 PM) *
EC most definitely is essential to provide the best achievable decision data needed before designing & greenlighting any surface mission.

Useful, yes, but essential? A fair amount of effort was spent a few years ago to design a Europa lander that would fly shortly after Clipper and use some of its data, but not rely on it for basic design. See "Science Goals and Mission Architecture of the Europa Lander Mission Concept" https://iopscience.iop.org/article/10.3847/PSJ/ac4493 especially section 5.4, which explicitly states how far we have come since Viking.

Of course, the political backing and then the funding for this was lost, making it a moot point, and I wouldn't hold my breath for a Europa lander until after Clipper now.
  Forum: Jupiter · Post Preview: #265102 · Replies: 86 · Views: 82014

mcaplinger
Posted on: Dec 1 2024, 07:03 PM


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QUOTE (StargazeInWonder @ Dec 1 2024, 11:18 AM) *
A lingering curiosity for me was, how does Europa Clipper facilitate the next mission at Europa?

The cynic in me would suggest that such considerations are at best rationalizations to argue for money, and that Clipper was merely the best mission that could be done with the available funding. https://en.wikipedia.org/wiki/Streetlight_effect
  Forum: Jupiter · Post Preview: #265097 · Replies: 86 · Views: 82014

mcaplinger
Posted on: Nov 30 2024, 11:58 PM


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From my biased perspective, the forum's zenith was reached during the first two imaging orbits of Juno -- go back and read those threads and the excitement is palpable: http://www.unmannedspaceflight.com/index.php?showtopic=8236 and http://www.unmannedspaceflight.com/index.php?showtopic=8245

The Junocam team was somewhat prepared to process images when we got into Jupiter orbit in 2016, but the level of expertise and perseverance shown by the amateur community was, TBH, a total surprise to us. It's completely fair to say that the public interest in Junocam images was almost entirely due to amateur processing: the three covers of SCIENCE with Junocam images all involved amateurs (see https://www.science.org/content/blog-post/t...-imaging-career )

Shoutouts to Gerald, John, Roman, Bjorn, Eli, Brian, Kevin, Matt, and all the other tireless image processors whose efforts really made Junocam shine!
  Forum: UMSF Legacy · Post Preview: #265093 · Replies: 13 · Views: 2085

mcaplinger
Posted on: Nov 22 2024, 04:25 PM


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"Titan had been called the most colorful world in the Solar System -- not excluding Earth; if the sunlight had been more powerful, it would have been positively garish." -- Arthur C. Clarke, IMPERIAL EARTH, Chapter 10

Unfortunately I think Clarke's ideas have been rendered obsolete by Huygens, but I guess we'll see.
  Forum: Saturn · Post Preview: #265036 · Replies: 221 · Views: 326372

mcaplinger
Posted on: Nov 22 2024, 01:21 AM


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QUOTE (vjkane @ Jul 7 2024, 11:44 AM) *
Unfortunately, given the distance and lack of relay, it won't be the bounty of images from the Mars rovers.

Well, it depends. Certainly I would expect a lot more use of data compression than we typically need from Mars, where nearly every image is sent lossless. And of course Dragonfly will have some geometric limitations on what it can image from a given location, just because all of the cameras are fixed. I'm not sure what the data rates one can expect from the current design are, but https://dragonfly.jhuapl.edu/News-and-Resou...4_03-Lorenz.pdf suggests the data return would be something like 10 GB per year - that's roughly 10,000 5 Mpixel Dragoncam images compressed 5:1, not that shabby.

Alas, this forum won't be around in 10 years to see any of this.
  Forum: Saturn · Post Preview: #265031 · Replies: 221 · Views: 326372

mcaplinger
Posted on: Nov 21 2024, 11:28 PM


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QUOTE (john_s @ Nov 21 2024, 01:54 PM) *
Though I could do without the animated GIFs…

You haven't used the Mars2020 internal team Mattermost -- if discord bothers you, MM is much much worse smile.gif

See Calvin Kasulke, "Several People Are Typing" https://www.npr.org/2021/08/28/1031965187/-...k-at-the-office
  Forum: Important Announcements · Post Preview: #265028 · Replies: 69 · Views: 22059

mcaplinger
Posted on: Nov 21 2024, 04:52 PM


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QUOTE (fredk @ Nov 12 2024, 12:21 PM) *
It's a real shame we don't have the people to migrate to and maintain phpBB/simple machines/whatever.

Honestly, while it would be wonderful to migrate everything seamlessly to a new forum, preserving all existing content, that's very difficult. And given that a lot of the time people ask the same questions over and over anyway, how much are we really losing by not having that going forward? (Completely agreed that preserving the historical record is important, but don't conflate the two problems.)

The thing that set this place apart is the well-defined set of ground rules and the aggressive moderation to enforce them. Setting up a forum is easy, maintaining that standard of quality is much harder.
  Forum: Important Announcements · Post Preview: #265023 · Replies: 69 · Views: 22059

mcaplinger
Posted on: Nov 13 2024, 12:23 AM


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"The anomalous state of Uranus’s magnetosphere during the Voyager 2 flyby", Jasinski et al, https://www.nature.com/articles/s41550-024-02389-3
QUOTE
The Voyager 2 flyby of Uranus in 1986 revealed an unusually oblique and off-centred magnetic field. This single in situ measurement has been the basis of our interpretation of Uranus’s magnetosphere as the canonical extreme magnetosphere of the solar system; with inexplicably intense electron radiation belts and a severely plasma-depleted magnetosphere. However, the role of external forcing by the solar wind has rarely been considered in explaining these observations. Here we revisit the Voyager 2 dataset to show that Voyager 2 observed Uranus’s magnetosphere in an anomalous, compressed state that we estimate to be present less than 5% of the time.

  Forum: Uranus and Neptune · Post Preview: #264968 · Replies: 3 · Views: 1471

mcaplinger
Posted on: Nov 8 2024, 12:13 AM


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QUOTE (djellison @ Nov 7 2024, 11:56 AM) *
I'm also going to reach out to the server hosts to asks if they can snapshot the entire system and send it to me in some way come the shutdown at the end of Dec.

Thanks, Doug.

For what it's worth, if you want to archive everything that a particular member has written, you can search for that user using "find member's posts", take the resulting URL, and write a simple script to guery for the URL with an "st=N" at the end where N=i*25 (since the search only shows 25 items at a time) over as large a range as you need. For example:

CODE
echo a | awk '{for(i=0;i<250;i++) print "wget \"http://www.unmannedspaceflight.com/index.php?
act=Search&nav=au&CODE=show&searchid=a3ee0c223f8599e24109a060992cd99e
&search_in=posts&result_type=posts&hl=&st=" i*25 "\""}' | sh


That gets you every message in HTML form with a whole bunch of extra stuff, but it's better than nothing if you want to save someone's pearls of wisdom for posterity.
  Forum: Important Announcements · Post Preview: #264934 · Replies: 69 · Views: 22059

mcaplinger
Posted on: Nov 7 2024, 05:40 PM


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I've found a couple of forum scraping tools, https://nrsyed.github.io/proboards-scraper/html/index.html and https://github.com/mikwielgus/forum-dl , that seem to be able to read this board's format. But for various Python versioning reasons I haven't been able to get either of them to work on my system. What are the prospects of doing a forum backup looking like?
  Forum: Important Announcements · Post Preview: #264932 · Replies: 69 · Views: 22059

mcaplinger
Posted on: Oct 18 2024, 09:33 PM


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There's no shortage of available forum software and hosting services, it's the porting of the existing content that's an issue. Using another obsolete system doesn't seem like much of an improvement.

My impression is that there's no interest in setting up and moderating a new forum, regardless of platform, even if the existing content is not migrated.
  Forum: Important Announcements · Post Preview: #264808 · Replies: 69 · Views: 22059

mcaplinger
Posted on: Oct 8 2024, 11:36 PM


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QUOTE (Bjorn Jonsson @ Oct 8 2024, 04:15 PM) *
If I understand correctly, launching at the start (or end) of the launch window usually requires slightly more fuel for trajectory corrections (esp. long burns like deep space maneuvers).

Usually the optimum is in the middle of the launch period (more or less by definition), but I haven't seen any quantitative discussion of this specific case. See https://ntrs.nasa.gov/citations/20160008162 for an old analysis of the 2021/2022 launch periods -- that 2021 launch was from 15 Nov to 5 Dec and optimal was 24 Nov.

It's typically a small, probably negligible, difference.
  Forum: Jupiter · Post Preview: #264729 · Replies: 86 · Views: 82014

mcaplinger
Posted on: Oct 3 2024, 12:39 AM


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QUOTE (djellison @ Oct 1 2024, 08:07 PM) *
At the very least, a dump of all the attachments and the fairly modest sized SQL DB that drives the place are easy 'gets' which I would zip up and throw on archive.org - you're right that their waybackmachine snapshots are marginal at best.

I came here in 2005 after the egroups lists "ISSDG" started dying (presumably after Yahoo bought them). Just for fun I tried to see what I could find from that list on archive.org, but since it was private there's no content, only metadata, even if you look at CSV and tar files. So all of that content is presumably "lost in time, like tears in rain."

It'd be nice to do better than that, but these forums that have dynamic content are typically hard to archive.
  Forum: Important Announcements · Post Preview: #264678 · Replies: 69 · Views: 22059

mcaplinger
Posted on: Oct 2 2024, 05:41 PM


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QUOTE (stevesliva @ Oct 2 2024, 09:41 AM) *
I've wondered about NSF whether any of the planetary science threads are paywalled.

I don't know what happens in the paywalled "L2" area but I don't know of anything specific to planetary. From what's implied, people posting there, if they have real inside information, are breaking their project rules of the road at a minimum, if they're not guilty of actual ITAR/EAR violations. IMHO even some of the stuff posted in the public areas (by one NASA insider in particular) is skirting the rules.

So in that regard it's a good source of information, although the SNR is extremely low (mostly from fanboys of a company with X in its name). I've more or less given up posting there (pearls before swine, as they say.) YMMV.
  Forum: UMSF Legacy · Post Preview: #264667 · Replies: 41 · Views: 12933

mcaplinger
Posted on: Oct 2 2024, 01:17 AM


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QUOTE (djellison @ Sep 30 2024, 09:37 PM) *
We will attempt to archive the forum as best we can around the beginning of December and upload it to archive.org...

Let me know if there's anything I can help with in that regard. AFAIK archive.org can't/doesn't crawl into any forum topic so everything currently there is pretty useless (top-level topic links you can't navigate into.)
  Forum: Important Announcements · Post Preview: #264640 · Replies: 69 · Views: 22059

mcaplinger
Posted on: Sep 9 2024, 10:22 PM


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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.

QUOTE
As soon as we had learned that there might be an issue with our
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.
  Forum: Jupiter · Post Preview: #264520 · Replies: 86 · Views: 82014

mcaplinger
Posted on: Aug 28 2024, 09:50 PM


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QUOTE (john_s @ Aug 28 2024, 01:00 PM) *
Analysis of the results suggests the transistors can support the baseline mission

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.
  Forum: Jupiter · Post Preview: #264448 · Replies: 86 · Views: 82014

mcaplinger
Posted on: Aug 23 2024, 05:23 PM


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QUOTE (StargazeInWonder @ Aug 23 2024, 10:00 AM) *
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.

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.
  Forum: Jupiter · Post Preview: #264416 · Replies: 86 · Views: 82014

mcaplinger
Posted on: Aug 22 2024, 07:34 PM


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Images now all on missionjuno.
  Forum: Juno · Post Preview: #264408 · Replies: 6 · Views: 3997

mcaplinger
Posted on: Aug 22 2024, 06:08 PM


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QUOTE (StargazeInWonder @ Aug 21 2024, 09:22 AM) *
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.

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.
  Forum: Jupiter · Post Preview: #264407 · Replies: 86 · Views: 82014

mcaplinger
Posted on: Aug 1 2024, 12:54 AM


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Apparently this was released in a limited fashion, and then the distribution company went out of business, and the rights were bought by another company. And then there was a protracted legal battle which has just now been resolved according to a post I saw on Facebook.

Did anyone ever see it?

https://en.wikipedia.org/wiki/In_Saturn%27s_Rings is quite out of date.
  Forum: Chit Chat · Post Preview: #264303 · Replies: 5 · Views: 22366

mcaplinger
Posted on: Jul 20 2024, 12:47 AM


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QUOTE (StargazeInWonder @ Jul 19 2024, 01:57 PM) *
An editorial by David Southwood about MSR has appeared in Science. It doesn't try to go deep on technical or scientific details, but has thoughtful commentary on process and the path forward.

Seems way too ESA-centric to me, YMMV.
  Forum: Past and Future · Post Preview: #264227 · Replies: 579 · Views: 574531

mcaplinger
Posted on: Jul 20 2024, 12:44 AM


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Couldn't find anything not paywalled, but https://www.latimes.com/science/story/2024-...or-jpl-has-died

Pete was the chairman for the first MS98 design review we had. We didn't pass completely but didn't deserve to, and the instruments turned out better for it.
  Forum: Mars · Post Preview: #264226 · Replies: 3 · Views: 16606

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