What-if 0139: "Jupiter Descending"

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squall_line
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What-if 0139: "Jupiter Descending"

Postby squall_line » Fri Aug 07, 2015 7:07 pm UTC

Jupiter Descending

Image

I hope those struts are made by someone other than the contractor who made the struts on the SpaceX CRS-7 capsule.

rmsgrey
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Re: What-if 0139: Jupiter Descending

Postby rmsgrey » Mon Aug 10, 2015 12:45 am UTC

How many submarines come with windows? The Cold War-era military sub depicted definitely doesn't, making the answer "lots of flashing red warning lights"

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Re: What-if 0139: Jupiter Descending

Postby ijuin » Mon Aug 10, 2015 4:52 am UTC

Everything comes with Windows 8.1 these days.

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Re: What-if 0139: Jupiter Descending

Postby Echo244 » Mon Aug 10, 2015 8:57 am UTC

And a nagging process telling you to upgrade to Windows 10...
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Re: What-if 0139: Jupiter Descending

Postby mathmannix » Mon Aug 10, 2015 2:19 pm UTC

So... who's Ada?
I hear velociraptor tastes like chicken.

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Re: What-if 0139: Jupiter Descending

Postby RGB-es » Mon Aug 10, 2015 9:49 pm UTC

Where is medusa?

Spoiler:
And OT: Years after I read for the first time that great Clarke story, I discovered that the idea of a floating environment was introduced on the early 20 century by a sci-fy tale called "The Horror of the Heights" by... Conan Doyle! (you can find it on Gutenberg project)

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Re: What-if 0139: Jupiter Descending

Postby keithl » Tue Aug 11, 2015 2:27 am UTC

Jupiter's "surface" gravity is 2.4 gees, the hydrogen atmosphere is cold, and very dense at the levels that form visible ammonia or hydrogen clouds. That means the density increases rapidly, and so does the index of refraction. On Venus, the result is that light rays curve downwards, hence the apparent horizon curves upwards - it looks like you are inside a bowl, because light from a distance curves down at you.

I don't know whether hydrogen density gradients have the same optical effect, but if the blue scattering is similar, I would expect that. That means the horizon would not vanish in the distance to the side, but seemingly upwards. I think.

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Re: What-if 0139: Jupiter Descending

Postby cellocgw » Wed Aug 12, 2015 11:46 am UTC

mathmannix wrote:So... who's Ada?


Gotta be his daughter, named in honor of a famous woman in history ( I.e. Cleopatra)
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Re: What-if 0139: Jupiter Descending

Postby testrider » Mon Aug 17, 2015 3:54 pm UTC

For me the link to stormandsky does not work.

I can't post the url as it gets flagged as apam, but it is in caption [1]

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Re: What-if 0139: Jupiter Descending

Postby mishka » Tue Aug 18, 2015 6:19 am UTC

I must say that there's a problem with this What if. Why not use a glider? Use a ram air turbine for power. It seems very strange to focus on heatshields when those aren't completely required. For instance, the space shuttle uses a heatshield and also glides for reentry.

Autopilot for Jupiter's storms would be difficult... but not completely impossible.

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Re: What-if 0139: Jupiter Descending

Postby ijuin » Thu Aug 20, 2015 4:34 am UTC

If you have sufficiently strong material for an envelope, then a balloon might be worthwhile for lingering in the Jovian atmosphere. It would have to be bigger than the equivalent on Earth though since the Jovian atmosphere is mostly hydrogen and helium, and you'd probably be filling the balloon with mostly-pure hydrogen.

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Re: What-if 0139: Jupiter Descending

Postby Neil_Boekend » Thu Aug 20, 2015 8:34 am UTC

Place a RTG, fission reactor or fusion reactor inside it and use the waste heat to heat the hydrogen for additional lift.
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Re: What-if 0139: Jupiter Descending

Postby ijuin » Fri Aug 21, 2015 6:41 am UTC

Fission power is probably a good idea anyway given that you're probably too deep in the atmosphere for solar to be viable and there's no way you are carrying enough chemical fuel to last very long.

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Re: What-if 0139: Jupiter Descending

Postby serutan » Tue Aug 25, 2015 4:01 am UTC

RGB-es wrote:Where is medusa?

Spoiler:
And OT: Years after I read for the first time that great Clarke story, I discovered that the idea of a floating environment was introduced on the early 20 century by a sci-fy tale called "The Horror of the Heights" by... Conan Doyle! (you can find it on Gutenberg project)


Since it's a sub instead of Kon-Tiki, it probably went through that layer too fast for them to see anything through the
periscope.
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cyanyoshi
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Re: What-if 0139: Jupiter Descending

Postby cyanyoshi » Tue Aug 25, 2015 6:04 pm UTC

testrider wrote:For me the link to stormandsky does not work.

I can't post the url as it gets flagged as apam, but it is in caption [1]

The link doesn't work for me either. It is even broken on the Storm And Sky website. Luckily, there are plenty of neat pictures there that actually do show up!

There is also a problem with the link for the phrase "these carefully processed mosaics". I assume he was trying to link to this blog post
Spoiler:
Emily Lakdawalla wrote:Jupiter's swirling storms from Voyager 1

Posted by Emily Lakdawalla

2010/08/26 22:28 UTC

Topics: pretty pictures, amateur image processing, Voyager 1 and 2, Jupiter

Amateur image mage Björn Jónsson has recently turned his attention back to Voyager 1's close-up images of Jupiter. Before I get diverted into detail, I'll just post his latest work and let you feast your eyes on the fantastic details of turbulently swirling clouds.
High-resolution mosaic of Jupiter

NASA / JPL / Björn Jónsson
High-resolution mosaic of Jupiter
A 12-frame mosaic covering Jupiter's iconic Red Spot as seen from Voyager 1. Mosaics like this one were not produced at the time of the flyby because the computing power was not up to the task of warping and blending the component images.

Voyager 1 took lots and lots of images that were intended to be assembled into mosaics covering large swaths of the planet at high resolution, but few mosaics have entered the public domain because it is really really hard to make Voyager Jupiter mosaics that look very good. It took a considerable amount of time for the Voyagers to take photos, read them out from the camera, and record them or relay them to Earth, so that for the set of 24 frames required for the mosaic below, it took almost 40 minutes to acquire the data from start to finish. Jupiter rotates once in ten hours, so 24 degrees of longitude passed beneath Voyager during that time. That rotation introduces distortions into the apparent shapes and orientations of the clouds and bands that are hard to align.

It's possible to correct for that motion, but it's not easy. When Björn posted this to unmannedspaceflight.com he explained how he did it, beginning with 24 raw images, 12 each through orange and violet filters (he had to synthesize a green channel from these two). "The raw images were calibrated, reprojected to [a] simple cylindrical projection, mosaicked and then rendered using a typical viewing geometry (there is no such thing as a "correct viewing geometry" because the images were obtained over a 37 minute period with Jupiter rotating)."

What does he mean by "reprojected?" You should be familiar with the problems of representing spherical surfaces in 2D maps. There are many different kinds of map projections that use different geometry to transform spherical worlds to two-dimensional representations. Many geopolitical maps of Earth use the Mercator projection, which represents the shapes of the continents reasonably well but exaggerates the sizes of things at high latitudes; a different projection, appropriately named Polar projection, is often used to show the two poles. Space scientists often employ simple cylindrical projection, where latitude and longitude are converted directly to X and Y coordinates, which really really stretches things out at the poles, but which is really easy to read into software that can convert it to other projections. So what Björn is saying here is that he took the 2D images (which are their own type of projection, Jupiter's 3D appearance to projected on the plane of Voyager 1's camera detector), converted them to simple cylindrical, puzzle-pieced them all together, and then reprojected again to the viewing geometry that Voyager 1 would have had somewhere in the middle of this imaging sequence.

Björn went on: "I then fixed the color balance. The final step was to sharpen the resulting image a bit, mainly to compensate for all of the resampling that the previous processing steps required. This image shows lots of features: The Great Red Spot and one of the three white ovals present during the Voyager flybys, smaller spots, scalloped belt/zone boundaries, gravity waves, a bright equatorial plume and the dusky south polar region. I don't think I'm bragging by saying that this is probably the best Voyager 1 Jupiter mosaic that I know of, mainly because of its size (12 images)."

If you aren't bragging, Björn, you have every right to! He pointed out later on that Voyager images of Jupiter provide higher resolution views than Galileo images did, although Galileo improved on Voyager in the fact that it covered a wider expanse of the electromagnetic spectrum, through red and into near-infrared wavelengths.
with this image: http://planetary.s3.amazonaws.com/asset ... p_8bit.jpg

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Re: What-if 0139: Jupiter Descending

Postby Kith000 » Fri Aug 28, 2015 5:41 am UTC

Sorry if a bit off topic, but does anyone know whether or not the What-If's are still updated on a regular schedule. I could have sworn it used to be every Tuesday, but I don't think that's the case anymore is it?

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Re: What-if 0139: Jupiter Descending

Postby cyanyoshi » Sat Aug 29, 2015 8:44 pm UTC

The What-Ifs aren't uploaded at a set schedule anymore. They come out as they come out.

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Re: What-if 0139: Jupiter Descending

Postby cantab314 » Mon Aug 31, 2015 5:48 pm UTC

ijuin wrote:If you have sufficiently strong material for an envelope, then a balloon might be worthwhile for lingering in the Jovian atmosphere. It would have to be bigger than the equivalent on Earth though since the Jovian atmosphere is mostly hydrogen and helium, and you'd probably be filling the balloon with mostly-pure hydrogen.
For lighter-than-air flight on Jupiter or Saturn I think the better lifting gas would be hot (Jovian/Saturnian) air, which is guaranteed to offer lift even in a pure hydrogen atmosphere. I believe you'd still need a bigger balloon than on Earth because the weight of gas displaced would be less.

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Re: What-if 0139: Jupiter Descending

Postby ijuin » Wed Sep 02, 2015 6:46 am UTC

Yes, but keeping the air in the envelope sufficiently hot to maintain lift is probably going to require an onboard nuclear power source--chemical fuel would run out in a few days at most, and there is not enough sunlight beneath the cloud tops of Jupiter or Saturn for solar power to be adequate to the task.

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Re: What-if 0139: Jupiter Descending

Postby HES » Wed Sep 02, 2015 4:37 pm UTC

Are solar-powered hot air balloons possible anywhere? I'd've thought that if there were sufficient sunlight, the surrounding air would also be hotter and the goalposts would shift.
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cyanyoshi
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Re: What-if 0139: Jupiter Descending

Postby cyanyoshi » Wed Sep 02, 2015 5:23 pm UTC

HES wrote:Are solar-powered hot air balloons possible anywhere? I'd've thought that if there were sufficient sunlight, the surrounding air would also be hotter and the goalposts would shift.

Yes they are possible. I'm no expert, but I speculate that a lot of their lift comes from riding the convection current of the surrounding warm air.

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Re: What-if 0139: Jupiter Descending

Postby cantab314 » Wed Sep 02, 2015 5:30 pm UTC

HES wrote:Are solar-powered hot air balloons possible anywhere? I'd've thought that if there were sufficient sunlight, the surrounding air would also be hotter and the goalposts would shift.
Unheated greenhouses can be warmer inside than outside. The same should work for balloons.

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Re: What-if 0139: Jupiter Descending

Postby SDK » Wed Sep 02, 2015 6:27 pm UTC

ijuin wrote:Yes, but keeping the air in the envelope sufficiently hot to maintain lift is probably going to require an onboard nuclear power source--chemical fuel would run out in a few days at most...

I think you'd be okay considering what you're travelling through. Whatever layer of clouds you're in, apart from helium, you should be able to run an engine just burning the ammonia or hydrogen or whatever. Hmm... Unless you ran out of oxidizer, I guess...
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Re: What-if 0139: Jupiter Descending

Postby ijuin » Thu Sep 03, 2015 4:00 am UTC

Ok, then you'll run out of oxygen (or whatever) to combine with the hydrogen/ammonia/methane/whatever you're taking from the air. Either way, chemical-based power is only going to last for a few days of flight before you start needing more chemical stuff than your balloon can carry.

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Re: What-if 0139: Jupiter Descending

Postby FOARP » Wed Sep 09, 2015 11:55 am UTC

It's been more than a month since the last What If - is Randall nuking this feature? I mean, since this is a comic we read for free I guess we have no right to make demands or anything, but its a pity he has to go out like this.

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Re: What-if 0139: Jupiter Descending

Postby keithl » Thu Sep 10, 2015 5:48 am UTC

FOARP wrote:It's been more than a month since the last What If - is Randall nuking this feature?
I hope he is simply swamped with last-minute work on Thing Explainer. Or taking a break before the five city book tour. Or preparing to escape in his submarine to Jupiter, to get away from annoying people like us.

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Re: What-if 0139: Jupiter Descending

Postby Kith000 » Fri Sep 11, 2015 8:42 pm UTC

What-If's used to be the highlight of my Tuesday mornings. I really hope he's just swamped.

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Re: What-if 0139: Jupiter Descending

Postby Neil_Boekend » Sat Sep 12, 2015 11:04 am UTC

I have a feeling that he will do them as long as he likes to do them. Since this seems to be a hobby of his I assume he's just swamped. Don't complain, enjoy what you get, for this is typically a type of thing that starts to suck when rushed.
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Re: What-if 0139: Jupiter Descending

Postby mulrich » Tue Sep 15, 2015 1:10 pm UTC

Neil_Boekend wrote:I have a feeling that he will do them as long as he likes to do them. Since this seems to be a hobby of his I assume he's just swamped. Don't complain, enjoy what you get, for this is typically a type of thing that starts to suck when rushed.


I'm perfectly happy waiting but a little information about his plans for the project would be appreciated. I thought after the last long break he said he would be getting back to a regular schedule so that's what I was expecting (I could be wrong). I would never ask for a more frequent schedule (this is a free website, not even ads, so I'm in no position to ask) but it would be nice to have a general idea of how often I should check for updates.

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Re: What-if 0139: Jupiter Descending

Postby ijuin » Wed Sep 16, 2015 4:37 am UTC

Yes, a "hey, I'm still working on this stuff" announcement now and then would be nice.

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Re: What-if 0139: Jupiter Descending

Postby Echo244 » Wed Sep 16, 2015 12:58 pm UTC

Even if it does say "still working on this stuff for the next What-If book, pre-order for next Christmas"...
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