Thursday, March 28, 2013

Space Mining Operation Imagined

Deep Space Industries and Planetary Resouces want to mine asteroids and perhaps comets.  For years many people imagined that asteroids and comets were good for extracting minerals.  How would such an operation work in space?  We will look at what these small space bodies are made of, the scouts, the miners, and processors that are needed to extract the goods.

To find out the content of comets and asteroids, NASA had some significant missions that provided answers.  Deep Impact spacecraft was successful in giving us analysis of the composition of comet Tempel 1 in 2005.  Stardust was a spacecraft that collected samples of comet Wild 2.  It finished its primary mission in 2006 and then had an add on mission to look at Temple 1 after Deep Impact's mission.   NEAR Shoemaker mission did some spectrography on an asteroid in 1997.  The findings of these missions are posted in the journal Science (membership required - a free one is available).  From what I read in Science articles, comets are full of water, carbon-dioxide, and hydrogen cyanide.  Asteroids seem to have elements to include iron, magnesium, silicon, and calcium, among others.  That's important because that is what is peaking the interest of companies to go and perform mining operations.

To really get a good understanding of what particular asteroids are made of, the companies will have to send out scouts.  Instead of a geologist, they will be remotely operated unmanned spacecraft.  Now, until recent history, unmanned exploration spacecraft either did flybys over specific routes, or went to orbit only one space body.  After their launch, which gave them the velocity they needed to get to their destination, they only had thrusters to steer themselves and no real main propulsion.  DAWN is the first unmanned spacecraft to have its own main propulsion via an ion drive.  Now its on its way to Ceres after orbiting and orbiting Vesta.  That's what you want in a scout.  It needs to orbit several asteroids by jumping from one to another.  Ion drives were first tested on NASA's Deep Space 1 mission with a mission manager that felt like Captain Kirk, Marc Rayman.  He also manages DAWN.

Marc is a pretty neat guy.  After the video interlude, let's get back to our topic.  As for finding the needed materials, and impactor and a spectrograph could be a quick way of determining the composition of asteroids or comets.  A scout could have several impactors.  This would be similar to the Deep Impact mission, but I imagine smaller and simpler impactors would be preferable.  Another way is to simply spectrograph the surfaces of the asteroids or comets.  I also would imagine marking the asteroids and comets by landing a small radio code transmitters.  This would be useful for the miners to come to them and find them.  Then on Earth, an automatic ground based system could track them without the need of an astronomer.

Deep Space 1
After marking the asteroids, miners come to extract the ore.  What would a robotic miner look like?  Now landing on an asteroid would seem tricky because of their irregular potato shape and the fact that they are spinning.  In 2005 Hayabusa landed on an asteroid and collected a sample.  A miner could do the same, but it must collect a lot of soil, do some preliminarily sifting (optional), and send the soil to a processing plant.  The container for the soil would have to be large and have its own service module (like a reusable space tug).  There should be several of these container ships going from the mining site to the processing plant.  They could be refueled at the processing plant and, if necessary, refuel the miner.

The processing plant should not be on Earth.  It should be in a place that is easily accessible from Earth and from deep space.  Earth-Moon, or Sun-Earth  L2 could be ideal places.  The processing plant would be a complex piece of machinery that perhaps would need humans to maintain it when it breaks.  Now such a plant would process the ore and have some material left over.  The waste material could be either sent to the moon or be collected next to the station, effectively making a ever growing pile of rubble that becomes an asteroid itself.

NEAR Schoemaker
After the ore is processed into some usable material, it could be sent to Earth, but why?  Well the simple answer is: that's where the factories are.  Yet, it seems rhetorical to get useful material in space to be only used on Earth where such material already exists.  That would be economically unsound.  An alternative is to take the material and make it usable for 3D printers to create whatever is needed for infrastructure in space and sell these items to other space companies for parts or new space structures.  These structures would use the elements from asteroids like iron, calcium, magnesium, and such.  The other types of product these processing plants could create would be consumables like water, oxygen, and hydrogen.  These consumables would be used by space stations, and even unmanned systems for fuel as well as the obvious.

Now, I've heard an alternate motivation for mining asteroids and that is for precious and rare minerals.  Whether such minerals exist in asteroids, I don't know nor have I read anything to that effect.  In such a case, bringing such material to Earth would be appropriate.  Such minerals could be sold in existing markets.

The use scouts, miners, and processing plants is the heart of my imagined space mining plan.  Now this little thought exercise is nice but is by no means the only way.  I just laid out a way that I thought would work.  It's fun to let you imagination run with a solution.  I even thought of an alternative which would make the miner and processor into one vehicle.  Yet, every plan will have different benefits and liabilities.  I'm sure you can come up with your own space mining operation plan.  It's a fun activity.