NASA Study Proposes Airships, Cloud Cities for Venus Exploration | Hacker News Reader

NASA Study Proposes Airships, Cloud Cities for Venus Exploration

spectrum.ieee.org

127 pointssohkamyung97 comments

Within the CO2 atmosphere of Venus, air is a lifting gas. One could make large balloons out of air which double up as habitats for humans. Make it large and thin enough, and a dome-city would be a balloon on Venus.

I love the idea but could you lay out the numbers (I'm a bit busy...)?

This won't help with specifics, but there have been past discussions (HN?) about tethered floating cities on Earth that rely on heated air within the space to keep them afloat. I think one of those discussions had vague figures, from memory.

Mostly from sources regarding hot air balloon flight and I don't in any way claim to be qualified in this area but:

Normal Air Mixture, Dry at sea level (1013.25 hPa) and 20 degrees Celsius: 1.205 kg/m3

Normal Air Mixture, Dry at sea level (1013.25 hPa) and 100 degrees Celsius: 0.946 kg/m3

Difference: 0.259 kg/m3

C02 at sea level (1013.25 hPa) and 20 degrees Celsius: 1.829 kg/m3

Difference from Normal Air at 20 deg C: 0.637 kg/m3

C02 at seal level (1013.25 hPa) and 75 degrees Celsius: 1.541 kg/m3

Difference from Normal Air at 20 deg C: 0.336 kg/m3

As you can see, by these rough numbers a normal air mixture as present on Earth should theoretically be able to act as a lifting gas at least equivalent to hot air given the conditions in the layer of the Venusian atmosphere that the article is considering. Feel free to correct if you see any obvious errors, I just used the ideal gas law and some figures for gas constants I found on engineeringtoolbox.com and I'm definitely not a physicist by any means.

Cool... thanks for looking those up!

Back of the envelope:

Vehicle mass: Let's just arbitrarily add three Apollo capsules (http://en.wikipedia.org/wiki/Apollo_Lunar_Module), that should contain enough gear and personnel for.. something:

45000 kg

At the 50 km height in venusian atmosphere in 75 degrees celsius this would need a volume of normal air mixture of 45000 kg / (0.336 kg/m3) = 133928 m3

for neutral buoyancy.

Which, in a ball shape, would mean a ball of radius of:

((133928 m3) * 3 / (4 * 3.14))^-3 = 31,7m

So a sphere with a diameter of 60 meters filled with normal air mixture would roughly compare with a vehicle encompassing enough gear to fill three Apollo capsules.

Which is really an arbitrary measure but means that the idea about bubble vehicles filled with fresh air bouncing in the Venusian atmosphere is actually feasible at least in the science fiction if not necessarily engineering sense of the word :)

I wonder if these numbers could be improved by considering an oxygen-helium atmosphere rather than an oxygen-nitrogen atmosphere. I'm not sure how feasible this would be in a large enclosed space, my initial concern would be the development of pockets of high helium and low oxygen concentration but perhaps a simple ventilation system could keep the air mixed at an acceptable ratio. I believe oxygen-helium was considered for the Apollo missions but not used.

According to some quick calculations a mixture of 22% oxygen and 78% helium would have a gas density of 0.423 kg/m3 at 20 deg C. I used (density1vol1 + density2vol2) / (vol1 + vol2) with density1 = 1.331 and density2 = 0.1664 and a total volume of 1000m3.

The fact that Venus' gravitation is only 90% of Earth's and further (though slightly) modified due to the height of 50 km above the surface would mean that the gravitational attraction would be somewhere around 8.722 m/s2 which is about 88.9% Earth standard.

A Venusian (Venerian?) habitat also has the benefit of less disastrous consequences of developing a small leak in the wall of the habitat since the pressure differential would not be so great though an all out failure of atmospheric containment would unfortunately not be at all survivable even if protective equipment were being worn at the time. The only chance would be immediate activation of the ascent vehicle. Although I would be curious to know if the entire habitat could be constructed in such a way as to remain a rigid shape once it had been deployed, possibly in the form of a Hybrid Airship or Dynastat[1] This could allow a longer grace period on evacuation should it be necessary and might have added benefits to maneuverability during the mission. Take off and landing concerns could be ignored since there would be none other than the initial mid-descent inflation and fuel capacity would only be limited by the available sunlight.

[1] http://en.wikipedia.org/wiki/Hybrid_airship#Dynastats

Airships are fairly robust. It took the British a couple years in WWI before they managed to get enough firepower on a Zeppelin to kill it. Which is to say: they handily survive light machine gun fire. Which would give me a little bit of comfort were I strolling about inside one on Venus.

" they handily survive light machine gun fire"

While I consider war abhorrent, after this comment I cannot help myself but think about WW1 style aerial combat in Venus amidst spherical balloon habitats.

I like it. That'd be a great visual for some pulp-retro-scifi story.

I've been advocating a Venus over Mars strategy for quite some time now. It is weird seeing your opinions hit the mainstream. On the one hand you are happy that other people have finally come around to your line of thinking, but on the other hand you worry that others will repeat the conclusion with little idea of the reasoning that went behind it.

I was also ahead of the curve on the simulation argument. When Elon Musk started talking about it I realized it was finally becoming mainstream. I'm hoping he gets on board with a Venus first space exploration too!

What is the "simulation argument"? I read the article but don't remember that.

It's a fallacious extrapolation of Moore's law into the idea that our universe must be a computer simulation (of course there's more to it than my flippant summary suggests, but I still find the arguments unconvincing even if the idea itself is interesting).

The rate at which computers have gotten powerful is simply mind boggling. Even as early as 20 years ago, something like an iPhone would sound like wishful thinking to someone who would think rationally. Heck WWW, internet, mobile phones and this whole thing looks right out of a science fiction book for some one in early part of 1900's

Its hard to imagine how much more computers can go. But I believe people in the future will look at our way of thinking about computing limits(Moore's law) in the same we look at vaccum tubes. Or the way we look at people who thought heavier than air flying objects are impossible by laws of physics.

We just don't know how many 'transistor events' or 'wright brother' events there are going to be in the future which will work around the laws of science orthogonally.

There is a limit to the amount of computation that can be done by a given amount of matter that only new physics could change. Given that limit, at best you would need every particle in our universe just to simulate an identical one. It's more likely that the best possible simulation would have significantly reduced fidelity and/or size with respect to its host universe, thus the inevitability component of the simulation argument falls apart.

What would convince me we are a simulation is evidence (e.g. proof that quantum randomness is caused by floating point rounding errors, or that entanglement is caused by lazy expression evaluation), hard empirical measurements. Not arguments from pure logic and extrapolation.

That said, I agree that we have done some amazing things with computers; I just doubt (in the extreme) the simulation argument is valid.

As far as I can tell, you don't even disagree with the simulation argument. The simulation argument is that one of three propositions is true:

1. It is impossible to create a simulated world that people can live in.

2. People consistently do not choose to create such simulations.

3. We are almost certainly living in such a simulation right now.

You haven't said anything to undermine the basic logic of the argument at all; instead, you're arguing that statement 1 is true. But the simulation argument is that one out of statements 1-3 is true. Hence you agree with the simulation argument. You just don't think you do because you identify the whole argument with statement 3.

Based on what you just said, the simulation "argument" is no argument at all. The three propositions cover all possible cases. How can you argue against that? What would be the counter-argument?

The counterargument would be simple: a counterexample where all three propositions are false at the same time.

The Simulation Argument is really a tool, and a challenge. It sets things up such that, if we manage to disprove 1 and 2 empirically, we get stuck with a shocking realization about the basic facts of our existence. It gives us an unusual way of indirectly testing whether or not we are living in a simulation. That's a lot out of something that "isn't an argument at all".

> The Simulation Argument is really a tool, and a challenge.

No it isn't. It is Pascal's Wager updated for the 21st century. The only way it can be "proved" is if we are living in a really bad, poorly maintained, fundamentally broken, cheaply outsourced simulation.

The argument seems to be missing a proposition:

4. It is possible to create and live in a simulated world, but not with the level of fidelity/flexibility necessary for the infinite regress that would make #3 convincing.

You can fold that into #1 if you want, or fold 1 and 2 together, but they're largely equivalent formulations.

I don't think it fits cleanly into 1 or 2. Maybe people choose not to live in deeply nested simulations because of the degradation, but that still misses the possibility that simulated people do want to keep the process going but it becomes increasingly difficult.

That's possible, but besides the point. The point is not to set up clear, unambiguous, "perfect" choices, but to wade into the long lasting philosophical question of whether our reality has a physical existence - one of the oldest questions of philosophy - and recast it in terms of technology.

The point is that unless there's some fatal logical flaw in the set of choices, some combination of the choices needs to be true, and whichever choice or combination is the correct one, it has profound implications on us.

The simulation could be lazy, only simulating what it needs to for the observers contained within. Keep in mind that if you are inside a simulation, your sense of time is artificial. When something requiring more fidelity is run, the entire simulation could slow down, or stop momentarily while lazy contexts are evaluated, and you wouldn't know it.

The problem isn't runtime, it's the memory. The earth is the most efficient storage of all the information about the positions/trajectories of all particles that make up earth.

That's missing the point, I think. In the simulation the Earth doesn't exist. Instead, some high-level model is used to generate the observations we make at the macro scale. Only when we perform sensitive experiments which require a finer resolution is that detail generated in such a way as to remain consistent with observations made so far.

Of course as someone who writes simulations I can tell you that it is not so easy in our computational models. Indeed it would seem very difficult, though not fundamentally impossible for a high level model to correct macro behavior in all cases. But we cannot know the constraints of the universe which contains our simulation, which may be very different from ours.

Just to nit-pick, the simulation argument doesn't rely on simulations-in-simulations, let alone an "infinite regress".

If we consider the proposed form of simulation to be feasible/reasonable/etc. then the existence of one simulation would give us 50/50 odds of being inside it. With two simulations running, we're more likely to be simulated than not.

The simulation argument claims that, if such simulations are possible at all, then there will be very many of them. In which case, the improbability of being in a particular simulation is more than compensated by the number of simulations.

What if the simulation of the fidelity required surpasses the energy and time available in any sensible host universe? If the slowdown in a simulation universe is say 10, then it doesn't need many nested universes before life would never get the time to form in the client universe before the host dies (though of course you could set up the universe from 10 seconds ago, which seems like a cheat).

The argument is wrong, or at least, incomplete. Another possibility is:

It's possible to create a simulated world, but it would be much smaller than the world we live in, hence our world is probably not simulated.

On the other hand, jail inmates and astronauts in the International Space Station will (eventually) reasonably be able to consider option (3).

Except that there exist a #4: "We are unusual".

It's a big jump to conclude that we are usual in every way, one that normaly leads to flawed conclusions.

Then, apart from some serious anthropomorphization in 1 and 2, the simulation argument as you have described it is a tautology. I also never agreed with 1; I don't think simulation is impossible, just infinitely recursive simulation.

You don't need to simulate every particle in the universe to have a convincing simulation, from the perspective of a small number of observers (or just one).

How many particles are you currently observing, in sufficient detail, to be sure they are being individually modeled, rather than the subject of macro-approximations? The answer is likely 'zero', or at least a number much closer to zero than the number of particles in the rumored universe.

Also, if you are in a simulation, you can't reason about the size and computational capabilities of the physics of the simulating system. All the limits you've ever perceived may be arbitrary choices of the simulation, countless orders-of-magnitude more limited than the "host" universe.

"Flatland" comes to mind with respect to the latter part of what you wrote.

> All the limits you've ever perceived may be arbitrary choices of the simulation

Such as the speed of light? That's the simulation tick rate.

More like step. There is no such thing as time. The simulation could be paused for (real) years, then continued and there would be no way for entities in the simulation to notice that. This is also why we technically don't need super fast computers for such a simulation; it would be slow to us, not to those inside. Although it's not practical to have a very slow simulation of course.

"There is a limit to the amount of computation that can be done by a given amount of matter that only new physics could change. Given that limit, at best you would need every particle in our universe just to simulate an identical one. It's more likely that the best possible simulation would have significantly reduced fidelity and/or size with respect to its host universe, thus the inevitability component of the simulation argument falls apart."

Or, potentially, one would only need to simulate the minds of any observesers in the simulation, not every particle in the simulated universe.

Or, potentially, one would only need to simulate the minds of any observesers in the simulation, not every particle in the simulated universe.

...for every possible interaction those minds could have with the simulated universe. The only lossless way to simulate a mind's interaction with a universe is to simulate the universe. Further, one must define "observer", as well as simulate accurately what happens to non-"observer" objects, animals, microbes, etc. while "observers" aren't looking.

Or the way we look at people who thought heavier than air flying objects are impossible by laws of physics.

Did any people actually think this? That would be weird, considering how we are surrounded by heavier-than-air flying animals.

Everybody rational knew that it cannot be done.

"cannot be done" means "too difficult to be feasible" more often than it means "impossible by laws of physics"

A philosophical bauble: http://www.simulation-argument.com/simulation.html

The idea is that if computers continue to become more and more powerful, then we'll run more and more simulations on them, including simulations of ourselves; and if we can simulate consciousness, as some suggest, the the statistical likelihood is that we are living in a simulation, because it the least computationally expensive assumption. Conversely, if we're not living in a simulation then either we will never be able to simulate consciousness or there will be some other factor that makes it an unpopular activity.

What does all of this have to do with the simulation argument?

This is encouraging. I've wondered for several years why Mars when you've got places like Venus as potentially more interesting locations. Doing long term atmospheric existence there could teach us a lot about what we don't know about space travel and our ability to push ourselves. If I didn't have two bad discs and was 3 decades younger; I'd be asking where to sign up.

Edit: Reading further, "while the crewed version would be nearly 130 meters long, or twice the size of a Boeing 747.". NASA needs to get much bolder in their thinking. Two people isn't enough. You need at least the size of a submarine crew to make it work and that means an airship 5000 meters long.

Edit 2: "At this point, things get crazy.". Well, it wouldn't be worth it otherwise.

Obviously getting to the moon is step one. Getting to Venus and Mars are at least on a comparable level of difficulty, and Mars is much more like the moon than Venus is, so we're already used to getting around it.

I think it's more a case of going with the devil you know, even if Venus might be better overall for various reasons.

If EVA isn't even an option, what exactly is this manned mission supposed to accomplish that an entirely robotic one can't? It seems like a manned mission purely for the sake of being a manned mission.

Eva is an option in general, just not for that planned mission. The problem with Venus isnt the temperature and pressure, it's that the ground is too far down. At air ship altitude it's comfortable except for the acid.

My guess is the main advantage is feasibility - a manned airship-like laboratory in the upper atmosphere of Venus is something we could likely accomplish sooner than a manned mission to Mars, if we chose to make that a priority. Though the scientific benefit of such an effort would largely be secondary to other considerations. But that is fairly normal in the politics of human spaceflight.

It sounds like one of their main arguments is that it would be a less difficult and/or dangerous way to get some experience with medium to long-term human habitats on other planets, partially in preparation for a Mars trip. Also, while robots can do any specific experiment we devise before the trip, it's much harder to make one that can support improvisation or hacking together a follow-up experiment if an interesting result is found. The pace of iteration for experiments would probably be much higher with a human present.

I would argue that you could get that experience by establishing a colony on the bottom of the ocean. Conditions there are also deadly to human life without protection, and getting there and back is also not easy. Not as hard as getting to a different planet, but if we want to learn how to sustain human life in artificial habitats, then a colony 10km under water sounds like a way to start.

> It sounds like one of their main arguments is that it would be a less difficult and/or dangerous way to get some experience with medium to long-term human habitats on other planets, partially in preparation for a Mars trip.

I'm still not sure why we're interested in inhabiting Mars. Virtually no atmosphere and one-third of Earth's gravity means that humans will always have immense difficulty colonizing the planet. People who lived on Mars for any extended period of time, for example, would have huge difficulties in adjusting to Earth's gravity, if they could at all. People would always have to live in pressurized habitats.

Meanwhile Venus has a thick atmosphere and a much more Earthlike gravity. There's certainly huge problems with Venus (most obviously: it's very hot) but I can at least imagine with time and technological advances we could terraform the planet to be suitable for Earth life - all the raw material is there.

This is not to say, of course, that establishing some kind of manned scientific facility on Mars wouldn't be worthwhile. But long-term habitation? I just don't see it.

Yeah, I happen to agree about Mars, at least with our current state of technology. It may become feasible to establish something out there with some big advances in biotech though (engineering much more rugged species that would make the transition easier for us).

I have to admit that I'm excited by the prospect of exploring our solar system though, regardless of whether or not it makes economic sense. Having people up there in a semi-permanent arrangement seems like it would really put innovation in overdrive for the development of colony-building technology. There's something important about being there that just makes things move faster.

> what exactly is this manned mission supposed to accomplish that an entirely robotic one can't?

Honestly, to satisfy a bunch of people's personal science fetish using other people's money.

From the atmosphere, humans can control surface probes in near real-time, enabling them to carry out experiments that are nearly impossible when you have to wait minutes to see the results of every action.

You look at the way the Rosetta/Philae mission went, there were a few things that went wrong with Philae that might have been addressed by a human crew if Rosetta had one.

For example, Philae had to do a fully autonomous landing, but a crew on Rosetta could potentially have piloted the lander in real-time and made course corrections to avoid the crash. More concretely, a thruster designed to keep Philae from bouncing was damaged - a human crew could have repaired it before releasing the lander.

If Rosetta had an operations crew nearby - even just one person - the cost of the mission would have been, what, 100x greater? Surely enough more expensive to pay for multiple robotic probes.

Total mission cost for Rosetta = 1.4 billion Euros. It costs something like $50,000/kg for GEO, so I'll use that as the baseline. The Orion capsule weighs 21 tons and the Deep Space Habitat at least 50 tons. Add one person and the 5 kg of consumables per day, for a mission of 300 days, gives another 2 tons. That's $3 billion already, or 2.4 billion Euros. Now add the development costs, support staff, communications, etc. and you'll see that it's a lot cheaper to send a small fleet of redundant probes than to send a single human.

To double check, an Orion capture of an asteroid in an orbit close to Earth's is $2.6 billion (see http://en.wikipedia.org/wiki/Orion_%28spacecraft%29#Explorat... ), again, excluding development costs.

In any case, we have no way to put a human on the same orbit as a comet, much less return the human safely to Earth, so only a robot mission is possible.

I didn't mean to suggest Rosetta should have been manned. I was giving concrete examples of how humans can save missions.

Venus has a highly corrosive atmosphere, and surface probes die within a couple hours. I can't find figures on the cost of historical Venusian surface probes, but I think it's safe to say they're more expensive than Rosetta and tremendously harder to operate from a planet away. I also don't think it's a stretch to suggest that humans could make a 10 or even 100 time multiplier on their effectiveness.

"Saving a mission" is not as important as doing the science. If three robot missions are needed to get the equivalent science from one human-supported mission, then it's still better off to send three robots, because outside of near-Earth space it's going to be a lot cheaper to send 10 robot missions than a single human mission.

It's certainly slower to control a rover on Mars from the Earth, rather than in Mars orbit. On the other hand, 5kg of consumables/day * $50K / kg is a $250,000 per day of operations overhead, just to keep the person alive. If the mission is delayed a few days due to dust storms, that's $1 million doing nothing.

Operations from Earth is slower, but Curiosity has been on Mars for three years. With a 100x multiplier, you propose the same might be done in 11 days. With a maximum speed of 90 meters/hour and assuming 8 hours of operation, that's a maximum of 8 km, or less than 1/2 of its current mission. That's of course excluding the time it takes to make measurements, like the hours needed to drill a sample.

Your 100x multiplier is therefore physically impossible. (A rover that could make more effective use of human time would also be heavier, and Curiosity was about the biggest we could manage.)

And remember, robots don't need to come back. Humans do. The rocket equation really hurts when you need to apply it twice.

I feel like you're intentionally changing the subject. On Venus you do not have 3 years, you have 3 hours, tops.

The 100x multiplier is clear when you only have 3 hours to do your experiments and get your telemetry back.

My apologies. You are correct. I have difficulties in drawing any conclusions about Venus as I can't think of anything where 3 hours of human time would make a difference, so I used Mars (and to a lessor extent Rosetta) as the comparisons.

I researched various proposed Venus landings, like VISE, but still struggle to find something where a human in the near proximity would make that big of a difference.

That is, assuming landing can wait until Earth and Venus are at conjunction, and that 7° of angular separation is enough for a good single, then they are about 38 million kilometers apart, or 2.2 light minutes, so there's a 4.5 minute lag for ground control on Earth. Compare to Mars, which at best is 54.6 million km from Earth, or 3 light minutes, giving a 6 minute lag.

So I can only assume you're talking about driving a rover, which would require a lot of feedback. But a rover can't go far in a couple of hours, and if it's traveling the entire time then it's not drilling or taking spectrographs .. neither of which require much decision making.

Instead, the blue sky plans are for things like the Landsailing Rover, which use passive wind power to move around. And unlike Mars, it seems that Venus doesn't require much in the way of navigation, with little in the way of geography, so autonomous systems might be fine for most travel.

Really, I struggle your proposal, so I'm trying to give real-world comparisons so I'm not just blabbling negativity on the internet. But do you have any examples of where the science is worth the cost of putting a human on the scene, compared to spending the same amount of money on multiple robotic probes? Because if it means putting 1 rover on Venus for 3 hours or sending 20 probes for multi-year missions to orbit around all of the other planets, plus 3 rovers on the Moon, then I can't see how the human-near-Venus rover mission is worthwhile.

In order to go to Mars, and come back quickly and safely, it would make sense to send supplies of various sorts on a robotic mission (or a number of them). This way there would be plenty of fuel on Mars.

Another possibility would be having a launchpad in Earth orbit, so that many different modules would be assembled (a lot like the ISS), but in a configuration that's designed to travel to Mars. Launching it all at once from Earth does not seem like the safest or most efficient answer to getting a very large mission payload into space, given current technology. This way, there would be allowances for failed launches, while the human crew is brought into orbit using more tried and tested methods (with sufficient rescue mission planning), on a much smaller budget than the whole mission cost.

Some kind of Exploratory Space Station seems like the way to do it.

> Launching it all at once from Earth does not seem like the safest or most efficient answer to getting a very large mission payload into space, given current technology

Or any non-scifi technology that we know of. The rocket equation is harsh.

Even scifi generally does assembly in space. Short of the ability to teleport stuff outside the gravity well for free Δv remains much more manageable by sending lots of smaller payloads.

Wouldn't our ability to learn about more than the atmosphere of Venus be extremely impaired from an airship? If one of the goals is ultimately colonization, how would we harvest materials beyond those available in the atmosphere? Even robots would have great difficulty doing this task for us due to Venus' hellish conditions on the ground, assuming they could get the materials back up to the sky city or airship.

Actually, one suggestion has been colonizing Venus in floating cities: http://www.universetoday.com/15570/colonizing-venus-with-flo...

Colonization includes expansion.

For now assume that all the carbon, nitrogen, and oxygen you want is available in the atmosphere and solar power. You still need hydrogen to make plastics, and you are going to need silicon to build more solar panels, and you need metals you can forge. The surface of Venus is 50km below, which isn't as far away as the ISS, but it's still 50km straight down and then back up for anything.

It might be a nice vacation spot, or a penal colony.

For hydrogen, you have sulfuric acid.

There is work being done to replace silicon with graphene. It's of course a long shot, but would make this a lot more feasible if possible.

If you're interested in the topic of Venus colonization, I read this article a few weeks ago and loved it: http://www.science20.com/robert_inventor/will_we_build_colon...

Some interesting opinions here, but I can't agree with his speculation that you could build a floating habitat from wood and cotton cloth. He also seems to have gotten the concentrations of C02 and N mixed up as he believes the latter is abundant (on Venus) when it is actually ~3% If it were the reverse as he believes, normal air would not be a lifting gas.

To everyone asking "why" or "what for", please read [1] and [2]. The data behind may not be as abundant as other studies, but the conditions are met in Venus and extremophiles could already be living in the upper atmosphere. A mission like this one could potentially take exobiology from theoretical to empirical.

Alternatively, we could take extremophiles cultures from earth, take a sample of venusian atmosphere, and study their survival in such an environment -- of course, taking care not to contaminate the atmosphere.

[1] http://web.archive.org/web/20110807004311/http://gltrs.grc.n...

[2] http://en.wikipedia.org/wiki/Atmosphere_of_Venus#Possibility...

I don't think there was any discussion in the link about how they would get back into orbit? Did I miss it?

Yeah, that's a pretty sticky part. Venus has appx earth gravity and atmosphere at that point, so you'd need an Earth-class launcher to get off; something at least like an Atlas or Titan II. The launcher itself we could get there reasonably, but the propellant, well... that's an awful lot of mass to send to Venus. It gets much easier if you can do ISRU, which may be easier on Venus, but is still a novel development project.

EDIT: after further reading the article...

In the article it shows that most of the payload (60k kg out of the 70k kg payload) of the airship module is the ascent vehicle. Each of the two transit modules is launched by what looks like 4 Delta IVs and one SLS Block2--each. (Plus two crew capsule launches at each end of the mission for Earth departure and return.) So I guess they have some mass to work with. Heck of a launch schedule.

That 60k kg ascent rocket is just a bit bigger than the Pegasus XL, which can launch 443 kg. A Mercury capsule is 1200kg. Granted the ascent capsule doesn't need a heat shield, but that's not a lot of rocket for two people.

You did - there's a rocket ship attached to the bottom of the airship (accounting for 6/7ths of the mass of the airship IIRC).

Nah, just send one of those amazingly retro Russian landers again: http://rammb.cira.colostate.edu/dev/hillger/Venera-9_lander_...

I think venus holds more promise for massive teraforming. I can't find the link but calculations have been done about spinning a large occluding shield at the L1 Lagrange point to cool the surface over a few hundred years. Then with proper reflectivity adjustments, the surface could be made earth-normal. Heck, take all the extra CO2 and boost it to Mars to help them fill their greenhouses.

Interesting idea, but Mars isn't lacking in CO2. I'm not sure if shipping it there from Venus would be economically feasible for a long time.

I think Venus is short on hydrogen to make water. terraforming might require scooping large quantities of hydrogen from Jupiter and using it to burn off some the the CO2 producing water and carbon.

And actually, one of the things that's not mentioned is the other extremely advantageous feature of Venus: plenty of energy to extract, in already combustible or nearly combustible form, which would be nice to have if humanity is to become an interplanetary species. It also helps that the planet is almost certainly devoid of lifeforms.

According to Wikipedia, Venus's atmosphere is 96.5% CO2, 3.5% N2, and trace amounts of other stuff. Not sure what "combustible form" of energy you are talking about?

"...at 50km, the abundance [of H2SO4] works out to ~14mg/m^3 or about 7ppm. So, between sulfuric acid and water vapor, you have about half as much mass per cubic meter as water vapor in the air near the ALMA observatory in the Atacama desert in Chile. Bone dry by terrestrial standards, but sopping wet compared to say the Moon." [0]

That plus higher-than-earth solar radiation to electrolyze it into H2 and O2 and you've got yourself a floating, solar-powered rocket fuel mine.

[0] http://selenianboondocks.com/2013/11/venus-isru-what-do-we-h...

Water is more common elsewhere in the solar system. There might be water ice on the Moon, even Mercury. Comets are largely water ice, so are C-type asteroids. Many moons of the outer planets are supposed to have liquid or water ice in their cores. Titan and Europa possibly have more water than Earth.

Which is to say, there's probably easier and (eventually at least) cheaper planetary targets for H2 and O2 factories.

A fuel mine deep inside a gravity weel as big as our own. It's very usefull for going into space again, but not for a refueling station.

Yeah sorry my sleeping through Gen Chem all those years ago really showed in that comment. I did however do some research and CO2 seems useful for storing energy, so that is interesting in it's own right, especially given the amounts of sunlight and wind present on that planet. [1]

I also want to backtrack on the "the planet is almost certainly devoid of lifeforms" comment, as it seems there has been speculation that the clouds of Venus do host life. [2]

[1] http://arpa-e.energy.gov/?q=slick-sheet-project/electrochemi... [2] http://en.wikipedia.org/wiki/Atmosphere_of_Venus#Possibility...

It's definitely worth considering. At the very least, they could make a demonstration mission with a small, unmanned airship.

Also, question: 50km is pretty high, but is this too high for any chance of visibility to the ground? Such a mission would be much more interesting if it was possible to view at least a bit of the surface.

Direct line of sight probably would be off the table because of the thick cloud layer in the Venusian atmosphere. Radar imaging as has been previously been done by orbiting probes should certainly be possible. More interestingly, it seems to me the airships would be good launching pads for all kinds of unmanned drones which could go down from there to take a look and return to base later.

NASA has a huge number of exciting proposals, but can only fund a handful of them per decade. I thought the end of the Shuttle would free up money for robotic exploration. But science and manned exploration are separate budgets.

And they probably should be. Otherwise NASA's money for science would end up being sacrificed as a burnt offering to executive and congressional diddling, too. The spend on manned exploration expands to consume all available space.

Case in point: http://www.washingtonpost.com/sf/national/2014/12/15/nasas-3...

Humans are given earth and they polluted it, destroyed its environment in the name of development and now going after Mars or Venus...etc.

There may be some entities with good intentions in exploration but over a period of time, entities with evil intentions may join and story will be same like on earth, only timeline, tools, people, circumstances, places will be different.

life on earth isn't sustainable anyway. how can you not be aware of that?

the sun is dying. if humans don't 'develop' enough before then, it is unlikely that any of earth's legacy will be preserved.

It takes billions of years for sun to die.

http://www.huffingtonpost.com/david-j-eicher/14-things-you-d...

Moreover, if sun dies, how Mars/Venus will help us? They are in our solar system. Is n't it?

So we need not worry. Moreover if death is natural process, then some alternative star may born by that time. As of now, Science may not be that much advanced to capture new star.

But that won't give a reason to destroy/pollute earth and move on. Can you guarantee it won't happen to Mars or Venus?

It is just fear mongering, nothing else.

mars and venus are the first step. we aren't going to jump out of the solar system on our first try. we will be lucky if we don't have a lot of failures in that endeavor, even after the experience and materials we gain from the solar system.

>Moreover if death is natural process

humans are also a natural process.

>some alternative star may born by that time.

you mean a new star is going to come to our solar system before the sun dies? I think I must be misunderstanding. If not, that's asinine.

I don't really get how you can call it fearmongering. who is supposed to be afraid? most people only think as far ahead as two generations. the only people who are disturbed by your strange brand of environmentalism are people who think hundreds of years into the future, ie other environmentalists.

http://en.wikipedia.org/wiki/Timeline_of_the_far_future

your billions figure is also a gross overestimate. our timeline is not so generous.

and don't forget that life took (actually) billions of years to evolve. what are you trying to protect on mars and venus that is more important than that?

Humans weren't 'given' earth - we evolved from the survivors of the last mass extinction event, alongside and in competition with everything else here. We have no more right to survival than a termite, say, but we have the same right to shape our landscape to suit our needs. Expansion beyond earth is a logical and necessary manifestation of the survival strategy our species employs: applied intelligence.

Enlightened self interest requires that we treat other forms of life on earth better, but only because that same applied intelligence shows us how connected our own survival is to theirs. Equally, that same self interest should encourage us to study and preserve indigenous life on other planets, since it may provide knowledge which assists our own survival on those planets.

Reply on news.ycombinator.com