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The density at that altitude is 1 bar like earth so you have a very large amount of mass above you just like the earth’s surface atmosphere mass. How many meteorites make it all the way through earth full pressure stop. Micro meteorites are not making it to the earth’s surface. Even a hand sized full meteorite that makes it to earth’s surface is only going to punch a hand sized holes in your envelope given the sheer volume of the sphere it would take months to effect the buoyancy plenty of time to send a robot up the outside and plug the small hole. Or up the inside and plug both sides.

Crazy thing is lifting mass doesn’t scale linearly a 2km sphere can support 6 million tonnes of mass. Double the radius and you get more than six times the lift while the exoskeleton doesn’t weight six times as much. Nitrogen mass is going to be a limiting factor since its only 3.5% of.Venus atmosphere you will need some serious cryo distillation capacities to fill such a sphere. Water is limiting its only 20 ppm in the atmosphere pretty much going to be importing every drop but the asteroid belt has plenty and its much lower delta V from even that far vs the moon or worse earth’s deep.gravity well. Even Mars surface is less delta V than Earth’s surface to Venus just barely depends on where the planet’s are in orbit alignment but still less. Imagine that it takes less energy to mine water from Mars and deliver it to Venus than launch it from Earth.

Still Venus has two of three critical gasses, and you can make O2 from CO2. There is detectable PH3 in the atmosphere so phosphorus must be present either as apatite in flood basalts or some other igneous rocks.

The six critical life elements are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Venus has carbon,nitrogen,oxygen , sulfur in the atmosphere in huge amounts. Lacking is hydrogen and P hydrogen will need to be brought in as water and closely conserved in a closed cycle system. Phosphorus could be robotic retrieval from the surface via rock mining with the kind of lifting capacity you could lower a 50km carbon fiber or nanotube cable with a dredge like apparatus to pull up surface rocks if they are basalts they would have apatite and P in them.

Venus starts to look more like a nice place at 50km once you realise you have not only meteorite protection but also cosmic rays that thick atmosphere is good shielding even without a internal magnetic field. Venus has a induced magnetosphere that also offers protection. Water is the real limiting factor at 20ppm you are not mining it from the atmo.