Feasibility of Capturing Hydrogen from the Solar wind

Question

Solar wind density is very low even at Venus it is only 10 or so H+ ions per cm$^3$ but it is moving at a brisk clip of 400 km/s for the slow wind and 750 or so for the fast wind. So (feel free to check my math here) if one collected all the H+ ions passing thru a 1 cm$^2$ square in a second you would collect 400 000 000 H+ a second. With a 388 km$^2$ set of collectors you would get a mole a second or about a liter a minute.

Build one of the dealy-bobs in venereal orbit. Use the mole a sec of hot H+ is reacted with the copious $CO_2$ available in the neighborhood in some kinda high energy Sabatier reaction

$CO_2 + 4 H_2 → CH_4 + 2 H_2O + energy$

producing about 9ml of water and 11.2 liters of methane a second. That's 778 liters of water a day enough for 259 people (who like to pee off the side of balloons far more with a conservation and recycling effort.) Of course, the collectors could be scaled up.

So here are the issues. 1) What does the collection tech look like? I assume it creates negatively charged fields to funnel the H+ ions into the atmosphere.

2) What amount of energy is needed to run it? Would Photovoltaic be enough at that range? Assuming highly efficient panels. Could the high energies of the particles themselves be used as an energy source?

Answer 1

I would imagine that you would have several different systems in place for this to work'

In space, you would have superconducting rings to act as funnels or traps for the hydrogen ions. This is a variation of the Magsail idea (using a superconducting ring to interact with the solar wind to generate thrust), the issue here is you need to negate the thrust, or at least moderated so the rings stay on station.

Once the hydrogen is funnelled through the ring(s), it will need to be slowed down, cooled and compressed. Hot ions of hydrogen will be difficult to work with, so you will need a cryogenic cooling plant in the system to bring the hydrogen into liquid form so it can be easily transported to Venus. (Blowing the hydrogen ions into the Venerian atmosphere will not initiate reactions, and the heat of Venus' atmosphere will ensure the hydrogen rapidly escapes back into space).

Tankers of liquid hydrogen can then be shipped to Venus (perhaps using the superconducting rings as magsails again) and dropped from orbit. Since the tanks can enter at an arbitrary speed and into an atmosphere with pressure of up to 90 bar, the reentry can be rather gentle and the hydrogen collected at the reformulating plant. Based on your question the plant is floating in the atmosphere and the reaction will take place in "mid air"

The Methane is not going to be very useful without oxygen to react with, so it can either be stored or used as a reactant to make various forms of carbon building materials like diamond, graphene or carbon nanotubes, and the hydrogen recycled into the reactor. If you do have either oxygen or a nuclear thermal rocket, the methane can also be used as rocket fuel or reaction mass as well.

As for the question of "how much energy", the answer is "it depends". Solar energy is very abundant (2643 w/M^2 in the orbit of Venus), so the amount of energy you will need depends on how large you want to scale the system, the conversion efficiency of the machinery and (vey importantly) how efficient the heat rejection system is. You will have a lot of waste heat, but the environment in the atmosphere of Venus will be very difficult for heat exchangers to reject waste heat into (the atmosphere near the surface is hot enough to melt lead). There are a lot of different assumptions you will need to determine to calculate you energy budget, but being able to operate on a large scale in space and go to Venus suggests that getting that amount of energy will be fairly easy.

Answer 2

The 'dealy-bob' needs to be an expandable sphere (like the toys yogis use to teach proper breathing) with a skin of foil with a rotating molten iron doughnut shaped core in the middle. The rotation of the iron will create a magnetic field just like on earth and capture the solar wind plasma through the poles just like auroras and direct it from opposing directions to the center of the core where it will collide, releasing energy to the metal and turning into gas. The whole sphere shall also rotate, so the gas migrates to the equator, cooling and liquefying in a ring shape in the process. The dimensions should be calculated such as the iron core radiates out as much energy out in space in a unit of time as energy is released to it from the cooling solar plasma. Once the liquid hydrogen reaches a certain volume the sphere is collapsed and trust into the atmosphere and at a level of 1 ATM expanded again as a balloon and a Sabatier reaction will be started until the flotation force of the sphere filled with the H gas at the ambient temperature is equal to the weight of the water and methanol produced(converting methane into liquid methanol on the side). The methanol can then be converted to plastics for construction of living spaces or more spheres and air-conditioners and the water used in biosphere preparation.

Answer 3

"2) What amount of energy is needed to run it?"

You can gain energy by doing it, because the hydrogen is ionized. What you need is a kind of reverse Dyson–Harrop satellite.

https://en.wikipedia.org/wiki/Dyson%E2%80%93Harrop_satellite