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amen zwa, esq.Fighting WordsThe <a href="https://mathstodon.xyz/tags/HP" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#HP</a>-15C (the original <a href="https://mathstodon.xyz/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> Series) is, far and away, the best <a href="https://mathstodon.xyz/tags/engineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#engineering</a> <a href="https://mathstodon.xyz/tags/RPN" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#RPN</a> calculator, on balance: capability, size, shape, quality, durability, aesthetics.OK, in a more civil tone, I realise my 15C is significantly less capable, in one way or another, than my 41CX, 32S, 28S, 48GX, 35s, Prime, ....But why this irrational adoration?Well, you'd know, if you're an engineer of a certain age who used calculators in your daily life.

AkaSci 🛰️Let's take a moment to marvel at the design of the Voyager spacecraft. Built using 1970s technology - computing hardware/software, instruments, RTGs, thrusters, comms, etc. - most of which are still operational after 47 years in the harsh environment of space, 23:14 and 19:30 light hours away resp., with no maintenance or repairs, just workarounds around few failures, quietly exploring where no spacecraft has explored before. 👏 <a href="https://science.nasa.gov/mission/voyager/where-are-voyager-1-and-voyager-2-now/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://science.nasa.gov/mission/voyager/where-are-voyager-1-and-voyager-2-now/</a> <a href="https://fosstodon.org/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> 3/n

KellyTour Saint-Jacques, Paris, France á Les Halles <a href="https://pixelfed.social/discover/tags/paris?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#paris</a> <a href="https://pixelfed.social/discover/tags/parisien?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#parisien</a> <a href="https://pixelfed.social/discover/tags/parisienne?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#parisienne</a> <a href="https://pixelfed.social/discover/tags/france?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#france</a> <a href="https://pixelfed.social/discover/tags/français?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#français</a> <a href="https://pixelfed.social/discover/tags/française?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#française</a> <a href="https://pixelfed.social/discover/tags/french?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#french</a> <a href="https://pixelfed.social/discover/tags/travel?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#travel</a> <a href="https://pixelfed.social/discover/tags/voyager?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#voyager</a> <a href="https://pixelfed.social/discover/tags/photography?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#photography</a> <a href="https://pixelfed.social/discover/tags/europe?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#europe</a> <a href="https://pixelfed.social/discover/tags/leshalles?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#leshalles</a> <a href="https://pixelfed.social/discover/tags/tour?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#tour</a> <a href="https://pixelfed.social/discover/tags/toursaintjacques?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#toursaintjacques</a> <a href="https://pixelfed.social/discover/tags/architecture?src=hash" class="u-url hashtag" rel="nofollow noopener noreferrer" target="_blank">#architecture</a>

SpockoStolen from <a href="https://mastodon.online/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> & sold off, The Doctor winds up enslaved at an alien hospital, where social status strictly defines the quality of provided <a href="https://mastodon.online/tags/healthcare" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#healthcare</a>Sometimes <a href="https://mastodon.online/tags/StarTrek" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#StarTrek</a> stories are "bonk bonk on the head" with a message, but this teleplay by James Kahn, an American medical specialist, was very well done.The "Allocator" is a computer program that determines who gets care & for how long. Allocator: You have 6 minutes to treat Patient B3Sound familiar?<a href="https://m.imdb.com/title/tt0708870/quotes/?item=qt5401135&ref_=ext_shr_lnk" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://m.imdb.com/title/tt0708870/quotes/?item=qt5401135&ref_=ext_shr_lnk</a> S7E5

RealGravitas -Citizen Saboteur<a href="https://astrodon.social/@ClaireLamman" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@ClaireLamman</a> IMG! That’s fantastic! My holidays are better for this <a href="https://sfba.social/tags/gingerbread" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#gingerbread</a> <a href="https://sfba.social/tags/voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#voyager</a> Is the plaque on there?

Kathy ReidAfter nearly 50 years in space, the thermoelectric radioisotope generators used in the <a href="https://aus.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> probes are running out of energy as their plutonium-238 <a href="https://aus.social/tags/nuclear" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#nuclear</a> power source decays. <a href="https://www.wired.com/story/the-end-is-near-for-nasas-voyager-probes/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.wired.com/story/the-end-is-near-for-nasas-voyager-probes/</a>

Phil StookeCassini surmised, correctly, that Iapetus had a dark side and a bright side, and could be seen easily only when the bright side was facing the observer. As the visibility was always good on the same side of the planet he concluded Iapetus was in synchronous rotation like our Moon. Here is one of the Voyager 1 images of the area I want to examine. Not much to see... that dark ring is presumably a crater but we don't see it very clearly. But we will see more... <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/iapetus" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#iapetus</a>

Phil StookeI am now turning to Iapetus, a moon of Saturn which was not well seen by Voyager. Let's start with a map from the USGS based on the Voyager images of Iapetus. The most prominent thing is the vast black area now called Cassini Regio. J. D. Cassini discovered the moon in 1671 but he could only see it when on one side of Saturn. Later with a better telescope he could see it faintly on the other side of the planet. What's going on? <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/Iapetus" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Iapetus</a>

RichardThinking about my <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> model I am <a href="https://mastodon.social/tags/3dprinting" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#3dprinting</a> , it might be funny enough to me to make a <a href="https://mastodon.social/tags/Klingon" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Klingon</a> bird of prey for the other end of the room.yes, in the film it was <a href="https://mastodon.social/tags/pioneer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#pioneer</a> not Voyager. that the Klingons destroyed .But I can't quite make a V'ger ;) can I ‽

Phil StookeThis observation of Mimaldi shows that there can be unexpected finds in Voyager images. That's not so important when we have Cassini images, but what about places where we don't have great images and not much chance of getting better ones for a long time? We've seen a few moons of Uranus here, but what about Neptune's Triton, especially the side not seen closely. Or the other sides of Pluto and Charon? Tomorrow, something much more dramatic than Mimaldi. <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/Rhea" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Rhea</a>

Phil StookeLet's have a look for Tirawa. Here is an image - actually a composite of a few frames of a multispectral sequence - showing the right part of Rhea. It's near a full phase, so not much topographic shading. The black arrows show the full outline of the Tirawa basin. But what about the white arrows? They outline another basin called Mimaldi (see yesterday's map with names). It wasn't noticed at the time of Voyager and I wasn't confident enough to argue for it. <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/Rhea" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Rhea</a>

Phil StookeHere is the set of Voyager images of Saturn's moon Rhea. The blank square separates Voyager 1 images (top) from Voyager 2 images, just 6 of the latter. The closer images show lots of craters - wall to wall craters. That one crescent image of Rhea shows an arc of shadow which is something bigger, an impact basin which was named Tirawa. It's not easy to find in the other images but it is there. Is it alone? <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/Rhea" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Rhea</a>

Phil StookeEvander is located in the unmapped southern section of Dione in that USGS map. The map could have been extended towards both poles using low resolution images. This isn't the only large impact basin which escaped notice in Voyager images. I already mentioned Tethys in that respect. Tomorrow we will see another example... but I'm saving the best until last. <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/Dione" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Dione</a>

Phil StookeThose images of Dione are hiding something. Here is one of the distant images enlarged to show an oblique view of a 300 km diameter circular impact basin. It's now called Evander. Here is a Cassini map with names:<a href="https://asc-planetarynames-data.s3.us-west-2.amazonaws.com/dione_comp.pdf" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://asc-planetarynames-data.s3.us-west-2.amazonaws.com/dione_comp.pdf</a>And here is my 2002 LPSC abstract on its discovery:<a href="https://www.lpi.usra.edu/meetings/lpsc2002/pdf/1553.pdf" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.lpi.usra.edu/meetings/lpsc2002/pdf/1553.pdf</a>I presented this but never wrote it up, being bogged down in much bigger projects at the time (and ever since).<a href="https://mastodon.social/tags/maps" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#maps</a> <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/Dione" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Dione</a>

Phil StookeThis is the full set of useful images of Dione (by useful I mean useful for geology, not distant navigation images or very narrow crescents). The top set of 13 images are Voyager 1, the last 5 are Voyager 2. It's a beautiful world with craters, fractures and bright streaks. One image does not have a typical dark background - it was imaged against Saturn itself. <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/Dione" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Dione</a>

Phil StookeMoving on to Dione - I didn't make a map but here is a US Geological Survey airbrushed map made using Voyager images. I loath this map projection but 40 years ago it was very fashionable because it made it easy to compress digital files, back when it mattered how big a file was. The distortions along the diagonal sides are horrible. But it shows image coverage. The poles are missing. That bit of the equator not shown is not really missing, as we will see. <a href="https://mastodon.social/tags/maps" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#maps</a> <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/Dione" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Dione</a>

Phil StookeHere is the northern hemisphere of Mimas in that full Voyager mosaic.These maps are never going to look great compared with Cassini imaging. My intention here is to show how some details not noticed at the time were indeed present in Voyager images. We will see some more of these in the coming days. <a href="https://mastodon.social/tags/maps" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#maps</a> <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/Mimas" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Mimas</a>

Phil StookeAt last, here is the composite map using Voyager 1 and 2 images of little Mimas. Most of the surface is covered. You might like to compare it with this Cassini map:<a href="https://www.jpl.nasa.gov/images/pia17214-mimas-global-map-june-2017/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.jpl.nasa.gov/images/pia17214-mimas-global-map-june-2017/</a>I pointed out that my map and the USGS map don't agree in crater positions in places. Neither of them match this very well. Pointing uncertainties, an incorrect shape model of Mimas in early mapping (not really a sphere) and other errors affect both of them. <a href="https://mastodon.social/tags/Saturn" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Saturn</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/Mimas" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Mimas</a>

Richard<a href="https://mastodon.social/tags/3dprinting" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#3dprinting</a> a <a href="https://mastodon.social/tags/voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#voyager</a> probe, (<a href="https://mastodon.social/tags/NASA" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#NASA</a> not <a href="https://mastodon.social/tags/Trek" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Trek</a> ) I've had to slice the dish into 4 to allow for the extra size.this is the first thing I've printed of this size with zero infill. this could be interesting or an interesting disaster

Ben Royce 🇺🇦"The reports of my death are greatly exaggerated"There's engineeringThen there's *engineering*I am in awe of this probe, its makers, and its support team"The National Aeronautics and Space Agency (NASA) has confirmed that its engineers have successfully restored contact with Voyager 1. The dwindling power supply in the spacecraft caused a blackout for several weeks, but it's operating normally now, the agency said."<a href="https://www.ndtv.com/world-news/nasas-voyager-1-after-weeks-long-blackout-nasas-voyager-1-continues-to-operate-normally-7168714" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.ndtv.com/world-news/nasas-voyager-1-after-weeks-long-blackout-nasas-voyager-1-continues-to-operate-normally-7168714</a><a href="https://mastodon.social/tags/Voyager1" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager1</a> <a href="https://mastodon.social/tags/Voyager" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Voyager</a> <a href="https://mastodon.social/tags/NASA" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#NASA</a>

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