Unfortunately, none of these assumptions are true. India is investing massively in new reactors, including the thorium-U233 breeder cycle, which eliminates the need for isotopic enrichment. Wind and ground-based solar are growing exponentially, and although intermittent they reduce fossil fuel use. Ground-based power storage and transport as hydrogen are probably much cheaper than SPS. Even fossil has gained many years with a combination of natural gas, CO2 sequestration, and politics.

Earlier SPS studies were based on huge TSTO fully reusable shuttles that reduced cost. These would still be a good idea. But ground-based energy technology is a moving target. The problems of energy storage are minor compared to the problem of the cost of spaceflight. Unfortunately, no unbiased study has yet shown that Space Solar Power is economically feasible.

We may be depot nuts but you are just plain nuts and don’t what you are talking about. There is no need to precool a tank. The tanks will always have some LH2 in them.

The hydrogen that has been sent into space is already in ortho/para equilibrium for its storage temperature. There is no need to convert it; it’s already converted. The concern occurs when hydrogen is being liquefied from gas at room temperature. The liquefaction process does not necessarily remove energy from the nuclear spin degrees of freedom, so care must be taken to ensure to ensure this happens (for example, by passing cooled materials over substances that catalyze the exchange of energy with these states).

In space, if the propellant depot has an active cooling system that re-liquefies warm hydrogen, that system will need to include just such a catalyst. Similarly, if hydrogen is produced from lunar volatiles, the cryo plant that liquefies it also need to do this.

Liquid hydrogen, sitting by itself in a tank, will not suddenly acquire significant nonequilibrium amounts of ortho hydrogen. This would require non-thermal energy input; where do you propose this energy comes from? Certainly not cosmic radiation; the energy density of that would be far too low to be a significant problem (think: the efficiency by which such energy input could produce o-H2 would be lousy, so if it were a concern it would be for boiling the LH2 away rather than subtly charging it with extra o-LH2.)

Cosmic radiation is irrelevant to the functioning of depots, they have to deal with radiation from the Sun and Earth, which is much higher in LEO.

You again demonstrate that you don’t know what you’re talking about. At a Lagrange point the thermal environment is better than in LEO.

Looks like the other way around to me. You depot nuts ignore the basic problems with storing hundreds of tons of Liquid Hydrogen in space. It takes time to convert ortho form to Para form; the more liquid the more the stuff changes when disturbed and the more conversion is required. In orbit the cosmic radiation is cut in half and comes in one direction mostly (that’s what a gravity well has to do with it) but is space it is doubled and comes in from all directions making it more difficult in terms of generating gaseous hydrogen- and converting the resulting ortho form back to Para form. Anytime hydrogen is transferred to another tank that tank must be pre-cooled first with liquid nitrogen and then with liquid hydrogen and then these coolants must be recovered and the ortho form generated in both the tank and the coolant must be converted.

You depot proponents do not want this discussed.

You don’t even know the first thing about propellant management. They don’t mix, ever hear of propellant settling thrusters. You just discredited yourself with the lack of basic spaceflight knowledge

Gravity level has nothing to do with radiation.

No cryogenic propellants have ever been transferred in space- they have no experience.

They do it every time a Centaur delivers a satellite to GEO. And even if it were true, it’s a stupid argument. It implies that nothing can ever be done for a first time.