Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

daniel-suarez.com

Post reply on HN
Print view View original

71–80 of 92 posts

Re: Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

#71

Post by noir_lord »

evgen wrote: post #62
noir_lord wrote: post #61

Earlier quoted context omitted.

> Most people forget that it costs almost as much delta-V to get down as it does to get up in the first place Doesn't that depend on how you get it down. Metal foam dropped from orbit into an ocean would float, you could have a retrieval vessel go pick it up.

Metal anything dropped from orbit at the speeds we are talking about would either burn up in the atmosphere or else hit the ocean surface and become lots of small chunks of something that is now sinking to the ocean floor. You need to shed a huge amount of delta-V just to get to the point where the landing site is described using any term other than 'impact crater.' Most of the mechanisms for dumping this energy tend…

If the foam ball you drop is large enough losses from ablation wouldn't be a big deal.

You can certainly get the speed down enough so that the words impact crater wouldn't be in the report, also you smack them into oceans not land (though smacking them into the desert would be an option I guess if you could shed enough speed).

For a 10 meter sphere of nickel foam with a density of 2000kg/m3 (so about 60% 'air' by volume) it's ~2000 miles per hour[1].

http://hyperphysics.phy-astr.gsu.edu/hbase/airfri2.html#c5

Fast but not insurmountable.

That sphere would be ~8000 tonnes of pure nickel minus ablative losses (which would reduce the impact speed).

Of course you'd want the density to be below 1000KG/m3 or it'd sink.

So a 10m sphere at 850kg/m3 would have a terminal velocity of ~1300 miles per hour - or about mach 2 and you'd be picking up about 3500 tonnes of pure nickel bobbing about.

I'd quite like to see that actually (from a good distance away).

Re: Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

#72

Post by evgen »

LargoLasskhyfv wrote: post #70
evgen wrote: post #62

Earlier quoted context omitted.

Metal anything dropped from orbit at the speeds we are talking about would either burn up in the atmosphere or else hit the ocean surface and become lots of small chunks of something that is now sinking to the ocean floor. You need to shed a huge amount of delta-V just to get to the point where the landing site is described using any term other than 'impact crater.' Most of the mechanisms for dumping this energy tend…

When you have the ability to make it into foam in space, why not use that to make lifting bodies out of it, and let them glide down, instead of crashing like a stone? Stop thinking in terms of projectiles. Just because the Space Shuttle came down like brick in a controlled crash doesn't mean there are no other ways to do this. Without the need for ablation, btw!

You can't 'glide down' from orbit. You need to dump your delta-V somewhere. Stop thinking of orbit as though this chunk of metal is suspended from some big balloon out there. _Everything_ in space is moving, 0.0% if it is moving at the right speed and direction to enter the atmosphere and soft land without a lot of external assistance.

Re: Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

#73

Post by evgen »

noir_lord wrote: post #71
evgen wrote: post #62

Earlier quoted context omitted.

Metal anything dropped from orbit at the speeds we are talking about would either burn up in the atmosphere or else hit the ocean surface and become lots of small chunks of something that is now sinking to the ocean floor. You need to shed a huge amount of delta-V just to get to the point where the landing site is described using any term other than 'impact crater.' Most of the mechanisms for dumping this energy tend…

If the foam ball you drop is large enough losses from ablation wouldn't be a big deal. You can certainly get the speed down enough so that the words impact crater wouldn't be in the report, also you smack them into oceans not land (though smacking them into the desert would be an option I guess if you could shed enough speed). For a 10 meter sphere of nickel foam with a density of 2000kg/m3 (so about 60% 'air' by vol…

3.4 million kg, traveling at 600 m/sec, and you think you would end up with a big ball of floating nickle? Okay....

Not a physicist, but my thinking would lead me to say that when this ball hits the water (after having already been heated a bit by ablation on the way down) it is going to compress into a pancake. Assuming the energy released at impact does not break the ball into lots of smaller pieces, the energy of the impact is going to vaporize a lot of water and melt a lot of nickle. I think what you are going to end up with after the large impact event is a compressed blob of nickle that is now rapidly sinking to the floor of the ocean.

We already know what happens to big chunks of metal from outer space that impact the surface of the earth, it tends not to be pretty. Oh yeah, and try to convince any country on the planet to let you drop your giant ball of awe-inspiring kinetic energy on a path that happens to cross over them. Not. Going. To. Happen.

Re: Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

#74

Post by LargoLasskhyfv »

evgen wrote: post #72
LargoLasskhyfv wrote: post #70

Earlier quoted context omitted.

When you have the ability to make it into foam in space, why not use that to make lifting bodies out of it, and let them glide down, instead of crashing like a stone? Stop thinking in terms of projectiles. Just because the Space Shuttle came down like brick in a controlled crash doesn't mean there are no other ways to do this. Without the need for ablation, btw!

You can't 'glide down' from orbit. You need to dump your delta-V somewhere. Stop thinking of orbit as though this chunk of metal is suspended from some big balloon out there. _Everything_ in space is moving, 0.0% if it is moving at the right speed and direction to enter the atmosphere and soft land without a lot of external assistance.

I know that. I've written elsewhere how I imagine that. With modular thrusters which initiate the deorbiting, detaching when it is en route. Could be autonomous, could be 'tugboats' with human crew, I don't care. Doesn't really matter, as long as the lifting body of refined raw materials has the right weight to surface ratio, and therefore rarely even peaks above 400°C for a short time.

Re: Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

#75

Post by noir_lord »

LargoLasskhyfv wrote: post #70
evgen wrote: post #62

Earlier quoted context omitted.

Metal anything dropped from orbit at the speeds we are talking about would either burn up in the atmosphere or else hit the ocean surface and become lots of small chunks of something that is now sinking to the ocean floor. You need to shed a huge amount of delta-V just to get to the point where the landing site is described using any term other than 'impact crater.' Most of the mechanisms for dumping this energy tend…

When you have the ability to make it into foam in space, why not use that to make lifting bodies out of it, and let them glide down, instead of crashing like a stone? Stop thinking in terms of projectiles. Just because the Space Shuttle came down like brick in a controlled crash doesn't mean there are no other ways to do this. Without the need for ablation, btw!

The lifting body idea is interesting, shape it so that it's got a flat side that self orientates (basically like an uncontrolled shuttle) and 'glide' (if you can call mach 1 gliding) it in, neat. You'd want to be very sure it was going to come down where you expected or you might affect rental prices.

Re: Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

#76

Post by LargoLasskhyfv »

noir_lord wrote: post #75
LargoLasskhyfv wrote: post #70

Earlier quoted context omitted.

When you have the ability to make it into foam in space, why not use that to make lifting bodies out of it, and let them glide down, instead of crashing like a stone? Stop thinking in terms of projectiles. Just because the Space Shuttle came down like brick in a controlled crash doesn't mean there are no other ways to do this. Without the need for ablation, btw!

The lifting body idea is interesting, shape it so that it's got a flat side that self orientates (basically like an uncontrolled shuttle) and 'glide' (if you can call mach 1 gliding) it in, neat. You'd want to be very sure it was going to come down where you expected or you might affect rental prices.

I think one could aim for a https://en.wikipedia.org/wiki/Landing_footprint in the seas near the coastline without much trouble.

Re: Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

#77

Post by Symmetry »

LargoLasskhyfv wrote: post #68
Symmetry wrote: post #52

Earlier quoted context omitted.

So, the current price to bring something from space to Earth is for a capsule that keeps the material in a comfortable Earth-like atmosphere with minimal heating and g forces on the way down the way humans like it. If you instead have an object that doesn't need to breath and doesn't mind pulling 1000s of gs then things are much simpler, just take a reasonably sized sphere of your platinum ore, wrap it in some cheape…

Why not shaping it into some sort of lifting body, made out of honey comb like structures, and have that land into the ocean near the coast, to be towed to the next factory complex on land and disassamble the refined raw materials there? Combine with maybe inner compartments for standardized space containers for whatever else? This could be completely passive and autonomous, where the attached engine modules for deor…

I was just talking about the minimal viable product. Yeah, metal foam is something you can make in space but not on Earth and it might be valuable to send metal down for that reason. Using a glider will increase uncertainty about where the results end up, though, compared to a simpler measure of decent. I think accepting some ablation as the price of accuracy is probably the way to go.

Re: Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

#78

Post by vkou »

lopmotr wrote: post #35
vkou wrote: post #20

Earlier quoted context omitted.

The process chain necessary to turn rock into a single useful metal is colossal, and has been since antiquity. The effort required to set such a chain up, in space, for not one, but for dozens of metals (modern manufacturing requires many of them), as well as other chemicals (many of whom are inputs into other processes) would be astronomical. And then you would actually need to do something useful with that metal. I…

As I understand it, there iron and nickel asteroids that aren't chemically combined with other substances like ore is on Earth. So perhaps the only processing required would be melting and reforming it.

A kilogram of iron currently costs ~40 cents. That's because iron makes up 6% of the earth's crust.

A kilogram of nickel costs ~13$. And nickel makes up a mere 0.0009% of the earth's crust.

It's completely pointless to mine them, with the hope of returning them to Earth. It's also completely pointless to mine them, with the hope of using them in space, for many, many reasons.

1. A spacecraft factory employs thousands of people, and requires hundreds of millions of cubic feet of space.

2. The supply chains that feed a spacecraft factory employ hundreds of thousands of people, and require billions of cubic feet of space.

3. They also require a long tail end of chemical inputs that are not iron and nickel.

The difference between 'We have a space factory that is fed by an asteroid miner and builds more spacecraft/space factories' and 'We have a proof of concept where we spent a billion dollars to mine and refine 20 grams of iron, which we fed to a 3d-metal printer (Never mind all the other consumable inputs into it), to print a little figurine of a rocket' is rather large... And only the latter is achievable in my lifetime.

Re: Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

#79

Post by LargoLasskhyfv »

Symmetry wrote: post #77
LargoLasskhyfv wrote: post #68

Earlier quoted context omitted.

Why not shaping it into some sort of lifting body, made out of honey comb like structures, and have that land into the ocean near the coast, to be towed to the next factory complex on land and disassamble the refined raw materials there? Combine with maybe inner compartments for standardized space containers for whatever else? This could be completely passive and autonomous, where the attached engine modules for deor…

I was just talking about the minimal viable product. Yeah, metal foam is something you can make in space but not on Earth and it might be valuable to send metal down for that reason. Using a glider will increase uncertainty about where the results end up, though, compared to a simpler measure of decent. I think accepting some ablation as the price of accuracy is probably the way to go.

Honestly I don't think this would be a really big problem.

But to be absolutely sure nothing bad can ever happen(TM):

Why not have purpose built catching planes match up with them, once they are low and slow enough? I imagine something Airbus A380 sized, or large Antonovs, C5 Galaxy, releasing a clamp or hook on a cable or boom, connecting to that glider in the air. And tow it to its designated splash down area.

Like in https://en.wikipedia.org/wiki/Mid-air_retrieval

There! Solved that for you :)

Re: Delta-V: Designing the Asteroid Mining Ship 'Konstantin'

#80

Post by WalterBright »

Super_Jambo wrote: post #56
WalterBright wrote: post #41

Earlier quoted context omitted.

When the Spanish extracted all the silver and gold they could from South America, it caused a dramatic reduction in the value of silver and gold in Europe. I.e. dropping a huge chunk of rare Earths onto Earth will make them not-so-rare and prices will collapse.

Only if you don't have a monopoly...

You have to sell it to make money.

It's like if Jeff Bezos dumped a big chunk of his Amazon stock on the market. The price would collapse.

Post reply on HN