Expanding into Space

Call me a romantic, but so far the future has been pretty lame. Science fiction has given me grand visions of space (if you are interested, I mainly read stuff by Neal Stephenson, Larry Niven, and Vernor Vinge). However, I’m worried that major space industries won’t be feasible until well after my time. Let me give you some examples…
(If you are interested in more stuff on realistic space travel advice for science fiction writers, check out Atomic Rockets)

Asteroid Mining

Some asteroids contain tons (literally) of rare minerals. When sources on Earth become so depleted that it will be more economic to look to the stars than to churn through dirt, asteroid mining will be the way. The current problem is getting the equipment out there, which could take lots of delta-V and therefore lots of money. Self-replicating robots is one of the cooler ideas. Launch a small module equipped with a mining rig, material processor, additive manufacturing unit, and ion drive. Once the probe gets to the asteroid, it starts making an assembling more of itself. It could build engines that run off of regolith. Depending on how soon you want the minerals, the asteroid could be boosted straight to Earth, or use the ITN. One restriction is that there are a limited number of asteroids close to Earth that hold desirable materials. However, if we established either a moon base or a Mars colony, we could eventually manufacture and launch mining rigs from there. Alternatively, we could have the asteroid and mining drones stay put and instead launch periodic flights back to Earth carrying the minerals. The problem with this is that there are potentially billions of tons of materials in each asteroid. It would make more sense to harvest close to Earth. Either manned missions or a human colony in the asteroid belt is another possibility. Miners could prospect asteroid on the spot for more accurate evaluations. However, manned missions currently make no economical sense. Until we start mining asteroid and have the materials in space to begin with, long-range manned spaceships are hardly practical. Getting out there and back would also take a very long time.

Space Elevators

I think a ribbon-style space elevator would just be the coolest thing. Due to tensile strength issues, a material like carbon nanotubes would be necessary, and right now we can only produce a few feet of them at a time. The general idea is that space elevators on Earth won’t be possible for another 100 years at least. On the Moon, however, we could build a space elevator right now using a material like Kevlar. A lunar space elevator wouldn’t be as useful though.

Another possibility is a space fountain. The name is slightly misleading; a space fountain is actually a giant tower that is held up using a transfer of energy. A stream of pellets (hence the fountain part) is shot up the tower. The pellets are braked (transferring momentum) and then turned around using a large magnet. When the pellets are redirected, they impart upwards force on the top of the tower. Due to high energy usage, the tower would probably need a dedicated nuclear reactor; a power failure, even momentary, would cause the entire tower to come crumbling down. Such a structure would take an enormous amount of money to build. I haven’t worked out the math, so I’m not sure whether the savings in rocket fuel would make it economical even in the range of 20 years. On the plus side, it could be built right now.

Manufacturing

One way to save money on spaceship launches is to build the payloads in space in the first place. DARPA is already taking the first steps towards this with its Phoenix program. The aim of the program is to build new communications satellites using the antennas from old abandoned satellites. A central satellite would grapple with an old satellite and remove the antenna. It would then attach the heavy and expensive part to a new “satlet”, which is a barebones satellite frame that piggybacks on a commercial satellite launch. Additive manufacturing is also an attractive method of building in space. More commonly known as 3D printing, additive processes can use a variety of raw materials and can produce tough but complicated parts. A factory satellite could construct space station frames which are then finished using more complicated pieces hauled from the ground.

Moon and Mars Bases

This subject has received a lot of attention. I’m all for putting a base on the moon to mine regolith, and a base on Mars to terraform it. Instead of going into the specifics, I’ll just reference you to the Mars trilogy, which I think gives a great overview of what terraforming Mars might be like. There is a great study going on right now which examines how a flight to Mars might affect the astronauts.


I’ll pick up this thread later. Time to go watch football like the consumer I am.

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