
NASA Study Proposes Airships, Cloud Cities for Venus Exploration - sohkamyung
http://spectrum.ieee.org/aerospace/space-flight/nasa-study-proposes-airships-cloud-cities-for-venus-exploration
======
ant6n
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.

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

~~~
pharke
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.

~~~
fsloth
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](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 :)

~~~
pharke
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 (density1 _vol1 +
density2_ vol2) / (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](http://en.wikipedia.org/wiki/Hybrid_airship#Dynastats)

~~~
jccooper
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.

~~~
fsloth
" 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.

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

------
3pt14159
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!

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

~~~
nitrogen
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).

~~~
kamaal
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.

~~~
nitrogen
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.

~~~
philwelch
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.

~~~
mc808
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.

~~~
chriswarbo
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.

------
diltonm
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.

~~~
delecti
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.

------
wtracy
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.

~~~
lukeschlather
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.

~~~
dalke
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...](http://en.wikipedia.org/wiki/Orion_%28spacecraft%29#Exploration_of_a_near_Earth_asteroid)
), 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.

~~~
lukeschlather
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.

~~~
dalke
"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.

~~~
lukeschlather
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.

~~~
dalke
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.

------
jvickers
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.

~~~
outworlder
> 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.

~~~
masklinn
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.

------
chriskanan
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.

~~~
ForHackernews
Actually, one suggestion has been colonizing Venus in floating cities:
[http://www.universetoday.com/15570/colonizing-venus-with-
flo...](http://www.universetoday.com/15570/colonizing-venus-with-floating-
cities/)

~~~
danielweber
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.

~~~
moron4hire
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.

------
rwhitman
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...](http://www.science20.com/robert_inventor/will_we_build_colonies_that_float_over_venus_like_buckminster_fullers_cloud_nine-127573)

~~~
pharke
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.

------
dr_zoidberg
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...](http://web.archive.org/web/20110807004311/http://gltrs.grc.nasa.gov/reports/2003/TM-2003-212310.pdf)

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

------
gd1
I don't think there was any discussion in the link about how they would get
back into orbit? Did I miss it?

~~~
jccooper
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.

------
afterburner
Nah, just send one of those amazingly retro Russian landers again:
[http://rammb.cira.colostate.edu/dev/hillger/Venera-9_lander_...](http://rammb.cira.colostate.edu/dev/hillger/Venera-9_lander_image.jpg)

------
nickhalfasleep
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.

~~~
seanflyon
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.

------
whoisthemachine
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.

~~~
yongjik
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?

~~~
skorgu
"...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...](http://selenianboondocks.com/2013/11/venus-isru-what-do-we-have-to-
work-with/)

~~~
teamonkey
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.

------
grondilu
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.

~~~
krampian
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.

------
peter303
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.

~~~
bunderbunder
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...](http://www.washingtonpost.com/sf/national/2014/12/15/nasas-349-million-
monument-to-its-drift/)

------
q2
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.

~~~
NeverEnough
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.

~~~
q2
It takes _billions_ of years for sun to die.

[http://www.huffingtonpost.com/david-j-eicher/14-things-
you-d...](http://www.huffingtonpost.com/david-j-eicher/14-things-you-didnt-
know-_b_5692426.html)

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.

~~~
NeverEnough
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](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?

