To put this in perspective, this experiment for space solar power is at the same level as Bell Lab's first ground solar panel around 1954. It took decades to reach large-scale use.

Micrometeorites and small debris have hit the ISS. But the critical parts are protected by standoff Whipple shields. For large debris, which can be tracked from the ground, the Station dodges if it would come too close.

At the speed things move in space, all materials turn to plasma on impact. It disperses over a wide area, and doesn't penetrate your pressure hull or other critical part.

The solar arrays are very large, and have been hit several times. But they are also very thin. So an impact just punches a small hole, and you lose one or two solar cells out of thousands.

For small holes they have patches and tape.

The abandon ship procedure it climb into the Soyuz and Dragon capsules and leave. Unfortunately the Soyuz is the thing that got hit.

Tiny particles make tiny craters. The blue rectangles are individual solar cells from Hubble's original panels, which got replaced by newer ones on a servicing mission. Bigger objects make correspondingly bigger craters. Big enough to cause serious damage depends what you are hitting.

What do you call the rising blobs in a Lava Lamp?

True. There are 21,888 cryptos. Most of them are "shitcoins" (i.e. they ain't worth shit). The top 5 account for 75% of the total value, and two of those are tied to the US dollar. Five is enough. The reason for more than one is swapping among different coins is part of how people hide what they are doing.

Coinbase is still around, even listed on the NASDAQ (COIN).

They won't, because their natural function is replacing wads of cash in the underground economy. So long as people want to hide what they are doing, there is an actual use for dodges like crypto coins. So they will have some value, just like people pay Western Union to move more legitimate funds.

Criminal negligence to start with, or whatever is the equivalent in the accounting world.

If traffic to a Skyhook is "unbalanced" (more mass going in one direction than the other) the orbit will change. You can make it up over time with electric propulsion. Since electric propulsion is at least ten time more efficient than rocket fuel, you still come out ahead.

In Earth orbit you can potentially react against the magnetic field by running a current through the ionosphere. That uses almost no fuels, just a little gas to make plasma contact.

This is why I mention the Skyhook elsewhere in these comments. It tapers from the center outwards rather than top to bottom. Also the stress ramps from center to tip linearly. So compared to a stationary vertical cable the total stress is 1/4 as much.

For example, a 587 km radius (twice that in total length) skyhook moving 2400 m/s at the tip at 1 g acceleration sees 294 g-km of total stress. A safe stress I showed above is 160 g-km, so the cable needs to taper by 6.27x in area from center to tip. This is fairly reasonable.

To avoid atmospheric drag, you place the tip when vertical at 200 km, and thus the center at 787 km. Orbit velocity is 7464 m/s at that height. The tip moves 2400 m/s counter to orbit at the low point, or 5064 m/s. The equator moves 465 m/s, so the tip moves 4599 m/s relative to the ground. That's the speed a rocket needs to match velocity. That can easily be done with a single stage.

In principle climbing the elevator takes the same energy as putting a payload in orbit with a rocket (33 MJ/kg). But the payload is only 2% of a rocket's weight. You eliminate the structure and fuel of the rocket stages below the payload.

Incredible simulation

Demand for transportation already existed before railroads. It was handled by horses and wagons on land, and sailing ships on the water.

What I am hoping is the SpaceX Starship will induce demand by lowering cost to orbit. Once the demand exists, people will look for ways to satisfy it even cheaper.

There is a figure of merit for materials, which is the breaking strength divided by the weight per meter. This gives the maximum length/height at which it fails under its own weight.

Best available carbon fiber is 385 km scale height. But nobody engineers a structure at the failing point. With a reasonable 2.4 factor of safety, you get a 160 km vertical cable as the maximum dangle.

Towers need epoxy to stabilize the fibers in compression, so the maximum erection height is less than that.

I'm an actual space systems engineer. Any illustration you see of a single cable going up from Earth is wrong. Earth orbit is filled with artificial debris, and the rest of space has natural meteoroids. You see those as meteors at night as they hit the atmosphere and burn up.

So any large space structure will get hit by stuff. In fact, both the Space Shuttle and Space Station have taken hits, fortunately not a big one.

But a 60,000 km space elevator will have a lot of exposed area to take hits. At orbit speeds, everything turns to plasma and makes a crater. A big enough crater cuts the cable.

The only way to design something like this that lasts is to have many cable strands, and space out the strands so they can't all be cut at the same time. You can build it in segments with load sharing. Then impact damage (which WILL happen) means replacing one broken segment of one strand, which is a maintenance task.

Right. Atomically perfect carbon fiber would be extremely strong, but no manufactured product is like that. Even if it were perfect in the factory, handling and exposure to the space environment would damage it.

The classic space elevator - tied to the ground and stretching beyond synchronous orbit - became obsolete in 1986 when Hans Moravec invented a better one, the orbital skyhook.

This is a rotating cable in orbit that picks you up at the low point and throws you higher at the high point. It can be 50 times shorter, and built from today's carbon fiber. Transit time is much shorter, around 15 minutes.

The cable knocks off about half the energy to reach orbit. The rest is supplied by a single-stage rocket similar to the Falcon 9 first stage that flies and lands today.

The economic problem, rather than technical one, is there isn't enough traffic to space to justify a 1250 km cable in orbit. Nobody would build a bridge or airport to use once a week, which is about how often we launch rockets. A skyhook is similar - expensive to build, but cheap to use once you have it. So you need lots of traffic to justify building it.

What good is an article you can't read?

The Vogtle Units 3 & 4 reactors in Georgia, the only ones still under construction, started construction on 22 June 2009. They are both planned to start operating next year. #3 has been fueled, but still doing tests before ramping up to full power.

What do you think the Sun runs on?

3200 tons, from Madagascar, seems to be the only African source. Don't know who owns the mines or where they send it.

Note that the "Rare Earths" are different than technical metals like cobalt.

Except his tunneling business, which started in the ground.

Countering air loss, both Earth and Mars have a flux of meteor/asteroid material coming in. Mars likely gets relatively more because its orbit skims the inner edge of the Asteroid Belt. Some of the incoming objects contain volatiles.

So a full accounting of mass flow needs to consider both loss and gain processes.

Lost in Space.

Mars has a lower escape velocity, and without a magnetic field the solar wind can more easily strip molecules from the atmosphere.

The original space colony work by Gerard O'Neill and others assumed a "Mass Driver" (coilgun) which launched 4 kg lumps of lunar soil at 4 times a second, which amounts to 500,000 tons per year.

The gun would be 300 meters long and each payload takes 1/3 of a second to get up to speed. That means slightly more than one payload is in the gun at a time, and a near steady-state power supply.

Assuming perfect efficiency of the gun, it then requires 32 MW of constant electric power. With more realistic efficiency and running other stuff for mining or packaging the payloads, you are looking at 40 MW of power.

For comparison, this is in the range of a naval nuclear reactor, except you don't have the ocean to dump waste heat to. Current NASA work is towards 10-30 kW electric reactors for the Lunar suface. So factor of 1000 too small.

But such an electric catapult still needs 24 MW of peak power for launching single payloads at a lower rate. That's because all the acceleration happens over 1/3 of a second. So you need some kind of storage if your power source is smaller, and then release it in a burst.

You think those are stars zipping by on the Enterprise main viewing screen? No. If they were, they would be different brightness and colors.

What they are is comets and other interstellar debris that the main deflector shield has to watch out for and avoid. They are ~10,000 times closer together than stars, so they go zipping by at warp speeds.