Manned Mining Mission - Dirty Dozen, Part 2

[joertexas]

Well, I ran some preliminary figures for a manned mining mission to one of the Dirty Dozen. With a four-person crew, it's going to take about 125,000kg of equipment and 600,000kg of fuel to get the mission done. That's 25 Falcon 9 Heavy flights, and we'd need a Dragon flight tossed in to assemble everything in orbit, and deliver the crew to the mining ship.

In round numbers, we're looking at about $3.5 billion for the whole mission, including the probes and the development costs. The lift flights alone will be $2.4 billion. That's a bunch of money, but the returns can be huge for whomever will risk it.

JR

[Rhyshaelkan]

Manned missions suck. :P

[joertexas]

Manned missions suck. :P

Ya, especially when I screw up the numbers <sigh>. I shouldn't be allowed near a computer when I'm tired...

The real numbers are: 117,000kg gross lift, which will fit in 4 Falcon 9 Heavy launches. The mission is still expensive at $1.2-1.6 billion, but better than the first estimate.

JR

[AeroSpike]

Are you sure about the propellant weights? I'm currently looking at a something like 7 km/s of delta-v to catch apophis in 2020. Assuming a very very small manned spacecraft of 9000 kg I'll need 99700 kgs of propellant if I use a 312s Isp rocket engine, and that's from orbit! Even if we use a magically efficient engine on the order of the SSMEs with 450s of isp, its still around 40-50000 kg of propellant for my little 9000 kg ship.

A simple hohmann transfer would be much more efficient but unfortunately my mass would be massive if I had to carry around the food for people to eat for the year long mission. :)

Of course you could just as easily be right and me wrong, we should swap spreadsheets, assumptions and information.

[joertexas]

Are you sure about the propellant weights? I'm currently looking at a something like 7 km/s of delta-v to catch apophis in 2020. Assuming a very very small manned spacecraft of 9000 kg I'll need 99700 kgs of propellant if I use a 312s Isp rocket engine, and that's from orbit! Even if we use a magically efficient engine on the order of the SSMEs with 450s of isp, its still around 40-50000 kg of propellant for my little 9000 kg ship.

A simple hohmann transfer would be much more efficient but unfortunately my mass would be massive if I had to carry around the food for people to eat for the year long mission. :)

Of course you could just as easily be right and me wrong, we should swap spreadsheets, assumptions and information.

The fuel requirements go up a lot for anything over 5 km/s. This will help you check your figures:

http://www.projectrho.com/rocket/dvNomogram01.pdf

This is a terrific website, even though it's written with SF authors in mind.

I'll be happy to send you my spreadsheet, but be warned, I'm no programmer...

JR

[joertexas]

I finally found a plotting program that I could manage: Jaqar's Swingby Calculator. Using that program, I've come to the conclusion that a manned asteroid mining mission isn't really feasible with chemical propulsion.

The average NEO mission will take about 500 days to complete, and the miner will need to generate about 10.5 to 11 km/s to reach the asteroid and return home. The craft ends up being essentially a booster in space, with about 95% of the mass being fuel, even with the mission starting from LEO.

The two options are to either fuel the craft from lunar derived sources, or use another method of propulsion. I'd still like to fly the asteroid probe mission, but the manned mission will have to wait for better support before it can be flown.

JR

[Rhyshaelkan]

We could always take a different tack on your Manned Mining Mission. Go out there without return fuel ;) Sounds dangerous and irresponsible for a manned mission. However if you could find a dormant comet. Pump out a slurry of water-ice. Crack it and fuel up your tanks for return. Plus having the "mining-module" able to crack and store water from LEO. It just might make some decent cash.

Selling 1kg of 1:6 ratio of LH/LOx for $3000. Depending on how much you return with...

Run multiple missions. One for sale, one for PERMANENT's use to return metallic ores from a PGM asteroid.

[joertexas]

We could always take a different tack on your Manned Mining Mission. Go out there without return fuel ;) Sounds dangerous and irresponsible for a manned mission. However if you could find a dormant comet. Pump out a slurry of water-ice. Crack it and fuel up your tanks for return. Plus having the "mining-module" able to crack and store water from LEO. It just might make some decent cash.

Selling 1kg of 1:6 ratio of LH/LOx for $3000. Depending on how much you return with...

Run multiple missions. One for sale, one for PERMANENT's use to return metallic ores from a PGM asteroid.

We could do that, but it really doesn't solve the original problem. For most asteroids, the lion's share of the delta vee has to be generated on the outbound leg. Coming home usually takes about 2km/sec or so.

JR