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Comment by nickserv | Hacker News Reader

I wonder why there isn't a balloon mission being studied.

The upper atmosphere has temperature and pressure similar to Earth at sea level.

Maybe the wind is a big problem? Or insertion from orbit?

"Soviet Union explored the Venus atmosphere with unmanned balloons in 1985 during the Vega mission". Wiki article: https://en.wikipedia.org/wiki/Vega_program#The_Venus_mission

I think upper atmosphere study would be great. There are some colony designs that suggest an oxygen filled colony would float at earth pressure. And with the sulfuric acid and co2 you have everything you need to make water air and fuel. Not to mention protection from asteroids and deadly rays. It would be a challenge but all of the planets and other bodies present their own challenges.

At the same ambient pressure, an O2 would float, but just barely. It wouldn't float like a hydrogen/helium balloon does on earth. If the pressure is the same on either side of the balloon, lift comes from different atomic weights of the gasses. Helium weights much less than air. But the O2 inside the Venus habitat doesn't weigh all that much less than the CO2 outside. As a practical matter, you would probably need lift balloons filled with something other than breathable air/O2. [1]

Then think about what you want to do in this habitat. A solar/nuke-powered refinery for producing rocket fuel? It would need lift bags the size of cities. Not the Goodyear blimp. Think bags filled with cubic kilometers of lifting gas.

[1] This is why balloons wouldn't work on Jupiter/Saturn etc. No balloon can float in a sea of hydrogen. We would need a 'balloon' filled with vacuum, or at least hydrogen under vacuum pressure in comparison to the hydrogen outside. Soft-sided bags wouldn't work.

Well not everything would need to float at earth pressure. The production of any fuels or materials that required heavier equipment could be done at lower atmosphere. You could engineer bacteria to break down sulfuric acid for the hydrogen based fuels, obviously the CO2 to O2 part would be easy, or bacteria to produce certain materials. Also I wasn't talking about methane fuel which would need nuclear I was thinking more basic hydrogen rockets which chemical reactions could be simple and effective enough to produce. Additionally solar is already getting thinner and lighter so I don't think that would be much of a problem. And remember on Venus it's not just CO2 it's very dense and high pressure as well. So earth atmospheric pressure air could lift quite a bit and you don't need to be at exactly sea level pressure all the time. Only real problem I see other than the constant threat of death that all colonies will face is launching to and from any floating colonies.

As for the large blimp colonies, I see nothing wrong with that. Sure they'll be big but not any more difficult than building reinforced lava tube colonies on the moon or going to Mars with building sized 3d printers or excavators that can be used to make long term shelters. Like I said all of the planets are going to have tough problems, short of an earth like planet you aren't going to find an ideal easy scenario. Personaly giant airships housing 50 or so people doesn't seem too bad. Like I said though it's the landing and taking off that seems a bit trickier.

> No balloon can float in a sea of hydrogen.

You could use a hot hydrogen balloon.

https://en.m.wikipedia.org/wiki/A_Meeting_with_Medusa

I wonder if you could synthesise a carbon based material directly from CO2 in the atmosphere and use that to build the gas/vacuum holders.

I know this isn't what you mean by "studied," but here's a NASA produced video mockup of manned blimps over Venus: https://youtu.be/0az7DEwG68A

50 km from the surface, there are hurricane force winds, with temp and pressure similar to earth, but carbon dioxide atmosphere infused with sulfuric acid. Would be a bumpy ride. I wonder if there are tornadoes within that.

From the link:

> This year, the Venera-D team released a report that covered a number of potential additions, including a balloon that could explore the cloudy atmosphere.

Because then conspiracy theorists will understand a weather ballon can be an alien spacecraft too.

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