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Missions could see NASA spacecraft heading to Uranus and Neptune

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Re: Missions could see NASA spacecraft heading to Uranus and Neptune

#21

Post by azernik »

vlovich123 wrote: post #17
forapurpose wrote: post #15

I wait and hope for someone with more planetary knowledge than I have to explain the lack of interest in Venus as a habitable planet and thus the center of NASA's attention ahead of Neptune, Uranus, and of course, Mars. Based on what I've read, which includes a paper from a NASA (or was it JPL?) engineer, Venus' surface is not very hospitabl, but at a certain altitude it looks like an oasis in the Solar System: Venus…

I'm not an expert, but the wikipedia page alone doesn't paint that bright a picture. > Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid. We know very little about it. Also, I'm sure you'll need to coat any probes/spacecraft to protect against the sulfuric acid. > The water has probably photodissociated, and the free hydrogen has been swept into interplanetary space by the solar wind b…

Solar wind is a negligible factor in the trajectories of large-payload rockets - it's more of a radiation hazard that any interplanetary crewed mission has to deal with.

Re: Missions could see NASA spacecraft heading to Uranus and Neptune

#22

Post by dizzystar »

forapurpose wrote: post #15

I wait and hope for someone with more planetary knowledge than I have to explain the lack of interest in Venus as a habitable planet and thus the center of NASA's attention ahead of Neptune, Uranus, and of course, Mars. Based on what I've read, which includes a paper from a NASA (or was it JPL?) engineer, Venus' surface is not very hospitabl, but at a certain altitude it looks like an oasis in the Solar System: Venus…

I hope this is connected, but how much oxygen would it take to sustain these craft? A cursory look seems to suggest that the ISS generates oxygen from water electrolysis, which generates about 20lbs of oxygen a day.

The big difference is you can fire off a rocket and get water to the ISS in comparatively shorter time and less fuel, which makes it feel much more challenging to get in the sky of Venus.

I obviously have no idea what I'm talking about here, but I'm thinking the continued challenges of floating -vs- hard ground will be very high. Plus we don't really have any direct experience with that, right?

Re: Missions could see NASA spacecraft heading to Uranus and Neptune

#23

Post by elsonrodriguez »

forapurpose wrote: post #15

I wait and hope for someone with more planetary knowledge than I have to explain the lack of interest in Venus as a habitable planet and thus the center of NASA's attention ahead of Neptune, Uranus, and of course, Mars. Based on what I've read, which includes a paper from a NASA (or was it JPL?) engineer, Venus' surface is not very hospitabl, but at a certain altitude it looks like an oasis in the Solar System: Venus…

I can't speak to Neptune or Uranus, since they are so far out that even Jupiter and Saturn begin to feel more compelling due to Europa and Enceladus.

But in the debate about Mars vs Venus, for me two things stand out:

- We can kick off a Mars terraforming project with our current level of technology. I've heard it said that within a few hundred years we can get it so that all you need outside is thermal protection and an oxygen mask. Reversing the situation on Venus will basically take Star Trek level tech.

- You can leave your habitat on Mars, get some rocks, and pile those rocks up to make more habitat. On Venus, you will have to basically "drill" down to the surface to recover any materials, and I don't think you can easily build dirigibles out of rocks and atmosphere as easily as you can build a hut.

Re: Missions could see NASA spacecraft heading to Uranus and Neptune

#24

Post by elsonrodriguez »

wil421 wrote: post #16
searine wrote: post #14

Earlier quoted context omitted.

Constellation/SLS was important when there wasn't a commercial launch market because the programs maintained technical and manufacturing know-how. Now that there are several competitive and reliable commercial launch providers who maintain that know-how, we need to stop subsidizing bloated defense contractors and instead spend that money on buying launches and making satellites.

Why would the US give up all of their launch capabilities to private companies? From a strategic point of view it’s not a good approach. I’m sure someone in Washington is making a similar case. I agree there should be a balence but NASA shouldn’t have to solely rely on the likes of Space X. Bloated defense contractors are a symptom of the problem, look at the scope creep of the F35. Is it the government contractors o…

I don't know that NASA has ever built a heavy launch system in-house without contractor help.

What's missing is a few more start-ups like SpaceX to totally crowd out the likes of Boeing from the contractor feeding trough.

Re: Missions could see NASA spacecraft heading to Uranus and Neptune

#25

Post by Symmetry »

forapurpose wrote: post #15

I wait and hope for someone with more planetary knowledge than I have to explain the lack of interest in Venus as a habitable planet and thus the center of NASA's attention ahead of Neptune, Uranus, and of course, Mars. Based on what I've read, which includes a paper from a NASA (or was it JPL?) engineer, Venus' surface is not very hospitabl, but at a certain altitude it looks like an oasis in the Solar System: Venus…

There are advantages to each and solid ground can be pretty useful. But Selenian Boondocks did an excellent series on how use Venus's resources a while back which I really have to share.

http://selenianboondocks.com/category/venus/page/2/

Re: Missions could see NASA spacecraft heading to Uranus and Neptune

#26

Post by Symmetry »

dizzystar wrote: post #22
forapurpose wrote: post #15

I wait and hope for someone with more planetary knowledge than I have to explain the lack of interest in Venus as a habitable planet and thus the center of NASA's attention ahead of Neptune, Uranus, and of course, Mars. Based on what I've read, which includes a paper from a NASA (or was it JPL?) engineer, Venus' surface is not very hospitabl, but at a certain altitude it looks like an oasis in the Solar System: Venus…

I hope this is connected, but how much oxygen would it take to sustain these craft? A cursory look seems to suggest that the ISS generates oxygen from water electrolysis, which generates about 20lbs of oxygen a day. The big difference is you can fire off a rocket and get water to the ISS in comparatively shorter time and less fuel, which makes it feel much more challenging to get in the sky of Venus. I obviously have…

Water is on the order of 50 parts per million in that part of Venus's atmosphere which is pretty dry compared to Earth but still straightforward to extract from the air. In Venus's atmosphere you basically have all the Hydrogen, Nitrogen, Carbon, Oxygen, Sulfur, and Argon you need and pretty good access to Helium, Neon, Chlorine, and Florine. It's everything else that's the problem, like Silicon or metals.

Re: Missions could see NASA spacecraft heading to Uranus and Neptune

#27

Post by galaga99 »

Coincidentally this week Fermat's Library highlighted a paper about the Voyager mission, the only spacecraft (Voyager 2) to visit Uranus and Neptune.

Super interesting paper. Turns out Voyager was the first spacecraft that could be reprogrammed "mid flight". In fact, if it wasn't for that we would have not gotten back images of Uranus or Neptune!

https://fermatslibrary.com/s/voyager-mission-telecommunicati...

Re: Missions could see NASA spacecraft heading to Uranus and Neptune

#29

Post by TheOtherHobbes »

cstross wrote: post #19
vlovich123 wrote: post #17

Earlier quoted context omitted.

I'm not an expert, but the wikipedia page alone doesn't paint that bright a picture. > Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid. We know very little about it. Also, I'm sure you'll need to coat any probes/spacecraft to protect against the sulfuric acid. > The water has probably photodissociated, and the free hydrogen has been swept into interplanetary space by the solar wind b…

However, an interesting aspect of floating habitats in the Venusian stratosphere is that a terrestrial breathable gas mix (80% N2 / 18% O2 / 2% trace others) is a lifting gas that's about as effective as Helium here on Earth. (Venus's atmosphere is > 90% carbon dioxide, which has a significantly higher molecular weight than air.) And it's protected from solar UV and radiation to a considerable extent by the layers of…

You'd be floating in a haze of CO2 and sulphuric acid garnished with hydrogen sulphide, battered by raging convective winds which would make it very hard indeed to stay at a fixed altitude - which means the outer temperature would fluctuate by 10C to 50C or so without massively powerful altitude control.

You can't just drift there as if you're in a hot air balloon eating sandwiches and enjoying the view.

Venus might not be completely impossible, but it's still one of the less hospitable destinations in the solar system.

Also, smelly because of the H2S.

Re: Missions could see NASA spacecraft heading to Uranus and Neptune

#30

Post by mturmon »

TangoTrotFox wrote: post #13

I really do wish NASA had a focus. The 60s showed the power of NASA given a clear goal and direction, but now a days they feel like they're operating a mile wide and an inch deep. Probes are great, but I think many overestimate the amount of information they can genuinely provide. Even on Mars where we have had multiple rovers on the surface, there are still ongoing debates about things such as whether the streaks on…

Not a down voter, but: This isn't accurate. Planetary science (as in the OP) tends to be more diverse and exploratory than Earth or Astrophysics, but it still has a strategy. It's not just stamp collecting. See: https://science.nasa.gov/solar-system/focus-areas
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