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I heard of the idea of having a manned station floating in the atmosphere of Venus, where the pressure is roughly equal to earth sea level.

The idea is exciting, but what I don't understand is how the crew is supposed to come back to Venus orbit, let alone back to earth.

Let us suppose the Venus to Earth vehicle is parked in orbit around Venus (no need to take down then up again all this fuel). The crew only has to get to orbit in a small capsule and rendez vous with it.

Venus is massive like Earth, and the floating station would be nowhere near orbital velocity. So basically, to put a manned capsule akin to the Soyuz back in orbit, they would need the same thing we need to leave Earth: a full blown Soyuz rocket.

How is it planned to descend such a rocket ready to launch at the level of the floating station, and launch it without the facilities of a launch pad, not even the possibility to touch ground (the rocket would melt...)

or is it just a "detail" that have been hand waved so far ?

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  • $\begingroup$ Makes me wonder how feasible a launch off a floating platform would be; wouldn't the force of the rocket sort of put the whole station at risk of sinking too deep into the atmosphere? $\endgroup$ – Magic Octopus Urn May 16 at 17:33
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    $\begingroup$ @MagicOctopusUrn You wouldn't want the exhaust of your rocket playing over your platform if you wanted to use the platform again. More because of heat than "force". For a first mission you abandon the platform and let it burn. Later you might lower the rocket on a cable before ignition (or even just drop it) or push it out to one side on a boom of some kind. $\endgroup$ – Steve Linton May 16 at 17:44
  • $\begingroup$ A boom or a cable holding a 67 tonnes rocket from a glorified zeppelin. Looks like the stuff dreams are made of. $\endgroup$ – armand May 16 at 23:33
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The HAVOC study has a concept design for a mission that lets a crew of 2 spend 30 days in an airship in the upper atmosphere of Venus. Their Venus Ascent Vehicle is a pencilled in as a 67 tonne RP1/LOX fueled two stage rocket which transports a small (2 ton) capsule up to Low Venus orbit where the crew transfer to the main vehicle to return to Earth.

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A good first question! You're absolutely right, any crew on a Venus cloud station would need a big rocket to get back to orbit, so they'd have 2 realistic choices:

  1. Land a fully fuelled rocket on the station (or it could be part of the station when it's inserted into the atmosphere). This would likely be a solid fuelled rocket as the propellants would be stable, liquid fuels would be more problematic. Landing a fuelled rocket once the station is in the atmosphere would almost certainly mean using another powerful rocket
  2. Land an empty rocket and fuel it by processing the atmosphere. Venus' atmosphere is mostly CO2, if you bring hydrogen you can make liquid oxygen and methane, which has been mooted as a possible solution on mars. There's details in this question about making rocket fuel. Nuclear thermal propulsion is also a possibility, this could use liquid CO2 or liquid Nitrogen extracted from the atmosphere. I'm not sure the specific impulse would be enough though using those fuels, and the exhaust is radioactive. This isn't sci-fi, nuclear thermal rockets were developed, there were plans to use them in the Apollo program but none ever flew. On Venus we'd arguably be less concerned about the radiation, but it could still be a hazard for a manned crew, presuming any would be left after launch

There are other, more exotic choices like tethers, but they are very far from being reality so I'm not going to go into any detail.

As for what options have been explored I'm sure it's been considered as part of the studies, I haven't seen anything about what options they think could work. Most likely they are still working that out.

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