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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

#51

Post by TangoTrotFox »

mturmon wrote: post #47
TangoTrotFox wrote: post #46

Earlier quoted context omitted.

I'm not sure what your link is supposed to show?

Well, you wondered, "I don't really care what their goal would be, as long as it would be a goal that they could work towards..." and that link shows the basic four orienting science questions (right panel in blue text) - how did life begin, how did the solar system evolve, how did the planets originate, etc. Those are the top-level questions that the National Academies panel doing the Decadal Survey arrived at and t…

And as an aside, one of the most important experiments for next Mars mission will be MOXIE. It's a proof of concept in generating oxygen from atmospheric CO2. It won't be ground breaking or exploring unknown territory, but it will advance society by proving yet another critical step in the process of getting people on Mars. And I think these things, if people understood the implications, are how we start advancing civilization and simultaneously also getting more people interested in science and technology because if people actually understood how close we are to things like actually colonizing other planets, it's incredibly exciting - and I could think of nothing more fulfilling than playing a role in this critical evolution of our species.

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

#52

Post by wil421 »

valuearb wrote: post #43
wil421 wrote: post #16

Earlier quoted context omitted.

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…

Why did the US give up all their airplane manufacturing capabilities to private companies?

You are confused on what I am saying. They shouldn’t just rely on booking flights with some private company.

They will never build in house and never have. Just like the military some large contractor will build the plane or spaceship according to their specs.

Boeing doesn’t create a figther jet and then sell it to someone. If space goes private it would be like this.

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

#53

Post by forapurpose »

InclinedPlane wrote: post #31
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 is practically no advantage to living on Venus other than that you get gravity. The only local resources available are the atmosphere, and you need to create a floating habitat that is also an interplanetary spacecraft port. Frankly, that's actually pretty far outside our realm of technology at present. Mars has many more advantages in comparison. For one you can build on the surface of the planet. There are ma…

> There is practically no advantage to living on Venus other than that you get gravity.

Ambient pressure is a huge advantage: Liquid water doesn't boil away,

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

#54

Post by mturmon »

TangoTrotFox wrote: post #49
mturmon wrote: post #47

Earlier quoted context omitted.

Well, you wondered, "I don't really care what their goal would be, as long as it would be a goal that they could work towards..." and that link shows the basic four orienting science questions (right panel in blue text) - how did life begin, how did the solar system evolve, how did the planets originate, etc. Those are the top-level questions that the National Academies panel doing the Decadal Survey arrived at and t…

Do you know what the Uranus probe's goals are? They're laid out here [1]. It's to measure wind speed and atmospheric densities/temperatures. And that is typical. This is what I was getting at when I said that these probes do not achieve near what many people seem to think they can. We have a limited budget and I think this budget should be directed towards things that can advance us in the most meaningful ways possib…

The instrument you link (I actually do know one of the co-authors on the paper you reference) isn't a full-up mission focused on the wind speed issue. It's one instrument that would be part of a larger flagship mission (i.e., many instruments on one spacecraft). When you put all the instruments together on a spacecraft, maybe you learn more about the history of Uranus. Isn't "send an orbiter to Uranus" a goal?

You mention the ambiguity of the animating goals. Part of this is just linguistic: of course you want to push down these top-level goals to more granular, 0/1 goals ("was there an ancient lake at this site on Mars?" Answer: yes). That's what the NAS report does. Now that we know how abundant water was on ancient Mars, we'd like to return samples to see if there was life. That's the next couple of missions.

You raise a worthwhile point, I think, about immediately-graspable 0/1 goals, like "man on moon". I see your point - but I'm really only here to talk about the unmanned program because my limited expertise covers part of that area.

You like SpaceX. So do I - two good friends left my lab to work there. But their achievement ("revolutionized space") is not unique. The little Mars pathfinder had about that much history. There are plenty of other examples over the same time period, like exoplanet discovery (as you noted), cosmology, and a host of Earth science stuff.

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

#55

Post by InclinedPlane »

forapurpose wrote: post #53
InclinedPlane wrote: post #31

Earlier quoted context omitted.

There is practically no advantage to living on Venus other than that you get gravity. The only local resources available are the atmosphere, and you need to create a floating habitat that is also an interplanetary spacecraft port. Frankly, that's actually pretty far outside our realm of technology at present. Mars has many more advantages in comparison. For one you can build on the surface of the planet. There are ma…

> There is practically no advantage to living on Venus other than that you get gravity. Ambient pressure is a huge advantage: Liquid water doesn't boil away,

That just means you can build your pressure vessels much lighter. But you can't not have your habitat built out of pressure vessels, people can't breathe pure CO2.

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

#56

Post by dzink »

JumpCrisscross wrote: post #42
dzink wrote: post #35

Earlier quoted context omitted.

It sounds bad only in English and partly because of the foreign spelling. In Bulgarian it the name spells and reads “Uran”.

> In Bulgarian it the name spells and reads “Uran” Uranus was discovered by British-Hanoverian William Herschel [1] and named after the Greek god of the sky, Οὐρανός [2], which anglifies to Ouranos. [1] https://en.wikipedia.org/wiki/William_Herschel [2] https://en.wikipedia.org/wiki/Uranus_(mythology)

The comical pronunciation is only comical when Our-/Ur- as a prefix resembles a relevant word in your language. The second part of the joke comes from the greek spelling/pronunciation which is also not used by all countries/languages referring to the same planet.

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

#57

Post by TangoTrotFox »

mturmon wrote: post #54
TangoTrotFox wrote: post #49

Earlier quoted context omitted.

Do you know what the Uranus probe's goals are? They're laid out here [1]. It's to measure wind speed and atmospheric densities/temperatures. And that is typical. This is what I was getting at when I said that these probes do not achieve near what many people seem to think they can. We have a limited budget and I think this budget should be directed towards things that can advance us in the most meaningful ways possib…

The instrument you link (I actually do know one of the co-authors on the paper you reference) isn't a full-up mission focused on the wind speed issue. It's one instrument that would be part of a larger flagship mission (i.e., many instruments on one spacecraft). When you put all the instruments together on a spacecraft, maybe you learn more about the history of Uranus. Isn't "send an orbiter to Uranus" a goal? You me…

You definitely make some good points. I think my issue here is not so much just the goal orientation, but rather goals that will directly advance other interests simultaneously. Again getting back to the point that funding since funding is limited, it seems like it would make the most sense to think of the big picture with that funding rather than thinking in the short term of what would be neat to do with their current funding?

So to make this more clear, one reason I think what SpaceX has already achieved and especially what they plan to achieve is so revolutionary is because of how it would impact other programs. Like you mention one of NASA's big goals is a sample return mission. And this is going to be highly complex and highly expensive. The OSIRIS-REx mission mission is a billion dollar, 7 year mission to get 0.1-2kg of debris from an asteroid that comes within 0.0002AU of Earth with a 6 year period. That's really not reasonable. These missions would be trivialized with technologies such as the BFR. Such technology would also enable vastly greater scope and scale of these sort of missions. A Uranus orbiter will provide some science that might have some value, but it's not really advancing anything. The chance of revolutionary discovery is practically 0, and it will be unlikely to have a meaningful effect on future missions or projects.

Basically it feels quite odd that we're using technology that is comparable in both price and capability to what we were using the 70s. It's quite peculiar, and I think this has been the major hold up in us achieving much more in space. Imagine for a minute that it's 1969. We've just seen live footage of men walking and driving rovers on the moon. And I tell you that in 50 years NASA's vision for a flagship mission will be sending a probe to Uranus. And no man would ever leave low earth orbit again after 1972. Wouldn't you say something has gone very wrong? And this wrongness continues to persist, and I think it is because of this 'Well I have $x. What should I spend it all on?' as opposed to aiming for directed evolution and progress.

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

#58

Post by azernik »

TheOtherHobbes wrote: post #29
cstross wrote: post #19

Earlier quoted context omitted.

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…

On the other hand, Mars requires you to live in a radiation-shielded pressure vessel.

I think the real killer is that it's hard to build and maintain infrastructure when floating on balloons - much easier to run a spaceport on Mars, or to get to all the useful surface resource deposits. On Venus you'd have to build literal castles in the air, using only only what you can pull out of the atmosphere or ship in from orbit.

Not to mention Mars is at the bottom of a much shallower gravity well.

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