Kdjykuj

In a story I am writing there is a being with Superman level strength, flight, the ability to produce lasers, and survive in space. He has decided to solve the mineral crisis by finding and grabbing an asteroid and taking it back to earth so that it can be used to build lots of cool things and green tech.

They have the backing of an eccentric billionaire, and moderate political will in support of them, and modern earth technology.

How would they best, with brutal physical strength, flight, and lasers get that mineral wealth from space to earth?

Some constraints- they can, essentially forever, produce 200 megawatts of power for use in flight or lasers.

Their flight doesn't require notable reaction mass.

They are durable enough to survive space and high accelerations essentially forever, and air isn't a concern.

They don't have magical forcefields to make asteroids stay together or behave.

Ideally, humanity will be functional as a civilization by the end, with no world ending impacts. Props to any answer which involves less loss of human life, or none.

To summarize- how could a being with 200MW of power eternal best harvest asteroids?

Edit. As JBH noted, science based questions don't have to have fully plausible scientific questions, the answers have to be plausible. That said, you can replace the superman with a 200MW fusion spaceship if you prefer with lasers and flight.

The best way to solve the mineral crisis isn't to get the asteroid to Earth but to get the equipment from Earth into space to allow the harvest and processing.

The cost of getting materials into space is around $25K a kilo. If Superman provided an cheap taxi service to get people and materials into space, people could go get their own asteroids.

There's good news and bad news. First... the bad news

The lasers are almost useless

Have you ever picked up dirt clods with your hand? Have you ever picked up a lot of them? It's a slow process. It wouldn't matter how super-strong or super-fast he is, anything's more efficient than picking up dirt clods — and that's what lasers would make of the asteroids, dirt clods.

The only reason to use them is to quickly knock away huge chunks of less-valuable rock to get at the more-valuable rock.

However, if there's so little valuable material in asteroids that you're regularly knocking off huge chunks of less-valuable rock, then using the super strength to get stuff out of the ground of good old Earth would be more efficient. Remember, it takes time to get to asteroids.

But, there's good news!

Your superperson can haul a net. A big, honking net^{Obligatory XKCD} made out of steel cable. A net that would allow him to haul a whomping big bag 'o asteroid home with him. This is good, because 200MW will haul almost any amount of asteroids home. The problem isn't getting them back to Earth orbit.

It's getting them down from Earth orbit.

Maybe the lasers have value after all...

How much energy do we have to work with? Let's do some quick math. Let's assume superdude's a buff and beautiful 235 pounds (106.6 Kg). He's gotta go 7 miles a second (11.3 Km/s). OK, F=mA, we need 1.2e⁶ Newtons of force. Basically, newtons = watts, so 1.6MW are needed to get up and he'll need the same to get down unless he's planning to land in the ocean or make a hole someplace.

That gives us 198.4MW to work with. That means he can land 13.2 metric tons of material. The price of gold will plummet.

And that's really good news! Well... not the price plummeting part...

What this means is that superdude can put the bag 'o asteroids into orbit, then shuttle 13.2 metric tons of it down at a time. All he needs is (literally) a world-class net or bag.

My father would be proud! I got my money back and nobody got [hurt]. (Source)

Okay, so according to this article, the rotation needed to break apart the average asteroid is equivalent to one revolution every 2.2 hours. Doing some quick math, I found that the maximum acceleration an asteroid could withstand under these parameters without breaking up is 8.157 * [asteroid radius in meters] meters per hour squared, or 0.000000629 * [asteroid radius in meters] meters per second squared.

To put that in perspective, if the superpowered being wanted to move the largest known asteroid, Ceres, with a radius of 476 km, the maximum acceleration that it could receive is 0.299 meters per second squared. Considering Ceres is about 2.77 AU away from Earth (4.1439 * 10^8 km), it would take 1664880 seconds to move it to Earth (about 19.25 days). However, at the end of this, it would be moving 497799 meters per second (0.001 of the speed of light).

If instead the super hero went out and got the smallest known asteroid, 2012 DA14, with a radius of 10 meters, in 2013, when it passed within 27000 km of Earth, the maximum acceleration would be 0.00000629 meters per second squared, it would take 2930030 seconds to get here (about 34 days), and it would be moving only 18.430 meters per second when it got here.

So, in conclusion, if your superhero wanted to transport an asteroid, they would either be able to safely get not enough material here, or get a sizable quantity of material at a far too dangerous speed.

Working with simplified physics, 720GJ per second, after 10s and disregarding gravity, assuming 90kg... 7200GJ=45kg*v^2 => v = sqroot(7,200GJ/45kg) or 4Mm/s or slightly over 0.001c

That means they can move fast.

Realistically, physics gets wonky at high speeds. Maybe they could use an array of space mirrors to melt asteroid surfaces and change their orbits. Maybe they could fly out to the asteroids and change the orbits there. Really, it depends on far too many factors: how much food they need, how far the target is, how much mass the target has, the velocity vector of the target, the technology available to the civilization, and so forth.

I recommend not explaining whatever madness you are angling towards here and leaving it up to the reader-- or just having them sit on some electricity-generating bicycles. It'd be a lot simpler...