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Re:Space Solar Power Demonstrator ends first in-space mission by JumpCrisscross on Tuesday January 16, 2024 @06:32PM (#39020715)
> What’s the bullish story for why solar panels in space with microwave beaming is better than solar panels on earth?

Space-based solar power (SBSP) has three advantages over terrestrial solar: flexibility, footprint and theoretical efficiency.

The classic case for flexibility is disaster zones; it's easier to set up receiving meshes than build new power plants. The problem is humanitarian crises don't pay. The real sell is military and mining. Beaming power to remote operations simplifies logistics.

Footprint is minor, but worth mentioning: the receivers for space-based solar are smaller and could be laid over e.g. farmland.

Last, but not least, the atmosphere absorbs a lot of solar energy. In this model, the space-based rig is a lens, converting the well-absorbed frequencies that generate power into microwaves to which dry air is more transparent. If you can get a focussed beam, a SBSP rig could also be placed far enough out that it's less subject to Earth's day-night cycles. These factors boost its theoretical efficiency.

I haven't run the numbers for several years. But they only become compelling if you have ISRU and in situ manufacturing of panels. I don't think SBSP is a beachhead market for asteroid mining. But it's feasible if we have it.

Re:Space Solar Power Demonstrator ends first in-space mission by flandish on Tuesday January 16, 2024 @07:51PM (#39021550)
> The problem is humanitarian crises don't pay.

That’s only a problem if profit/exploitation is more important than humanity.

IMHO, space based technology needs to be public owned (not corporate) and not allowed to profit, with its goals and designs fit to benefit humanity before profit.

Re:Space Solar Power Demonstrator ends first in-space mission by aperrien on Tuesday January 16, 2024 @11:10PM (#39023178)
One other important note is that is possible to put solar arrays in orbit that are always facing the sun, so they can deliver power 24 hours a day.
Re:Space Solar Power Demonstrator ends first in-space mission by jacquesm on Tuesday January 16, 2024 @11:33PM (#39023355)
You'd need them to be in geosynchronous orbits unless you plan on powering the planet instead of the United States. And orbits that always face the sun are polar orbits, so you'd need a polar geosynchronous orbit. This would likely mean that the distance from the ground stations is way too large for meaningful power transfer. It would also require the whole installation to be somewhat movable. to correct its orbit as it slips over time because the installation is so large that different parts of it will be in slightly different orbits!
Re:Space Solar Power Demonstrator ends first in-space mission by dabluecaboose on Wednesday January 17, 2024 @12:26AM (#39023625)
Quick quibbles:

1. Geostationary orbits are in 24/7 sunlight except for a short period each day near the equinoxes

2. Geostationary polar orbits do not exist. Geostationary orbits are, by definition, 0° inclined. A polar geosynchronous orbit, like you mentioned, would not offer much besides being over the same point on the Earth at the same instant every day.

Re:Space Solar Power Demonstrator ends first in-space mission by jacquesm on Wednesday January 17, 2024 @12:37AM (#39023685)
> A polar geosynchronous orbit, like you mentioned, would not offer much besides being over the same point on the Earth at the same instant every day.

It would offer a lot: the ability to send down an absolutely massive amount of power without having the corridor shift around so that it can be reliably routed around by air traffic. Having the equivalent of a microwave scythe moving across a large area would be kind of counterproductive.

Re:Space Solar Power Demonstrator ends first in-space mission by dabluecaboose on Wednesday January 17, 2024 @12:42AM (#39023721)
Which is why a geostationary orbit would be much more feasible. Constant solar exposure with a minimal ground-track footprint that can be reliably pointed at the same ground station 24/7.

In fact, if we're already beaming power (assuming this works reliably enough) it might make sense to have a set of birds "surfing the terminator" in a polar orbits that can then transmit to geostationary birds which in turn transmit to ground stations.

Re:Space Solar Power Demonstrator ends first in-space mission by jacquesm on Wednesday January 17, 2024 @02:04AM (#39024242)
It makes for good science fiction. But the footprint of the spot on the receiving end would be such that most of the energy would be lost. Even at an opening angle of only 10 degrees (which would be pretty good) from LEO you'd be looking at a 50 km spot size.
Re:Space Solar Power Demonstrator ends first in-space mission by Projectiboga on Wednesday January 17, 2024 @12:32AM (#39023662)
A satellite could be illuminated over 99% of the time and be in Earth's shadow a maximum of only 72 minutes per night at the spring and fall equinoxes at local midnight.[44] Orbiting satellites can be exposed to a consistently high degree of solar radiation, generally for 24 hours per day, whereas earth surface solar panels currently collect power for an average of 29% of the day.[45]

That is the big potential with solar satellites, 24 hour a day power.

https://en.m.wikipedia.org/wiki/Space-based_solar_power#:~:t....