I have this futuristic setting in which humanity constructs habitable surfaces around the gas giants and ice giants of the Solar System. A similar idea was proposed by Paul Birch which uses dynamic support and has the surfaces outside the planets' atmospheres; however, this version of humanity wants to try something different. They want to have the surfaces inside the atmospheres of the giant planets, supported by atmospheric pressure. This idea was also proposed by Birch, but in the context of colonising Venus.
- They start by dropping self-replicating factories into the giant planets. These factories deploy balloons of heated hydrogen (one of the only things that can be buoyant in atmospheres that are mostly hydrogen) and stop descending at a certain altitude.
- The factories replicate themselves, using materials from the surrounding atmosphere and energy from either wind or fusion power, at a rate of once per year.
- The factories also produce hot hydrogen balloons, again at a rate of once per year, that float up to a higher altitude. The factories and the balloons they make work on the same principle as bubblehabs from Orion's Arm. The balloons are 1 km in diameter and also have smart matter surfaces that can vary their reflectivity to light at multiple wavelengths.
- The balloons increase in number until they cover the entire surface area of the giant planets. They also vary their reflectivity to control the amount of sunlight absorbed and the amount of infrared radiation emitted by the planets (inspired by Orion's Arm's weather machines). In doing so, they calm the strong winds that are typical of giant planets.
- Once the atmospheres are calm enough, the balloons start clinging together until they form a continuous solid surface.
- Now colonisation of the solid surface begins. The surface would be held up by the pressure of all the gas underneath, allowing it to support more weight than the balloons could when they were floating individually. At first, people would live in sealed habitats since the upper atmosphere is still mainly hydrogen with no oxygen.
- Over a long period of time, the hydrogen is pumped down into the lower atmosphere while oxygen (produced by electrolysis of water from the lower atmosphere) and other gases are added to the upper atmosphere. The end result is a breathable atmosphere of oyxgen and helium (and traces of nitrogen, carbon dioxide, water vapour etc.).
My question is: how long would each of these steps take, assuming realistic or mostly realistic technology (so no teleportation or perpetual motion machines)? From what I can tell, the most time-consuming step would probably be the calming of the atmosphere: this might take centuries or even millennia.