The Space Review

 
ISRU testbed
While there have been some NASA experiments with ISRU, such as this test in Hawaii in 2008, there may be a greater role for the private sector to play in developing and demonstrating these technologies. (credit: NASA)

The need for private ISRU development


Bookmark and Share

With the success of SpaceX’s recent launches and Planetary Resources’s announcement, we are not far from breaking out into the inner solar system. Private companies have been developing the rockets and related technologies needed to travel into space, but relatively little work has been done on in-situ resource utilization (ISRU). This is not to denigrate what has already been researched, but ISRU technology largely exists on paper with few actual prototypes.

There is an opportunity for firms to demonstrate the viability of various ISRU processes and thus accelerate the expansion into the inner solar system by convincing mission planners to incorporate ISRU.

Depending on the nature of the mission, ISRU will enable or expand many activities off Earth. For instance, current closed-cycle life support systems can recycle 90% of the water and oxygen that astronauts need to survive, which is good enough for LEO but not for bases on the Moon. The picture is somewhat different on Mars, where oxygen and water can be procured from the local environment with much less energy than on the Moon. This is because lunar regolith consists of oxygen tightly bound to metals and silicon, while oxygen exists in looser carbon and hydrogen bonds on Mars.

Achieving closure greater than 90% for future life support systems will increase the mission’s power requirements, because of pumpdown efficiencies in airlocks. ISRU offers a way to make up the 10% of water and air that will be lost from the habitat on Mars without increasing the power requirements significantly. Additionally, ISRU can be a source of rocket propellant, plastics, and metals that would otherwise have to be imported from Earth. In that sense, it is no different from early Earth explorers living off the land.

Strangely enough, the latest NASA Design Reference Missions (DRMs) for Mars made little to no reference to ISRU. Given the reasons above, it would seem obvious to incorporate ISRU into human mission plans. There is an opportunity for commercial firms to demonstrate the viability of various ISRU processes and thus accelerate the expansion into the inner solar system by convincing mission planners to incorporate ISRU.

It has been said that asteroid mining will create the first trillionaire. Planetary Resources is actively looking for partners for their ventures. Water mining is the first thing they plan to attempt once a suitable asteroid has been identified. Any entity that can demonstrate successful extraction of pure water from asteroidal simulant in vacuum and microgravity, with nothing but solar power, will be able to benefit from Planetary Resources’s foray to the Earth-crossing asteroids. The same goes for metal ores as well.

The Planetary Society is also getting in on the action. From my communications with Bill Nye at the 2012 NewSpace Conference, they are looking at ISRU hardware to fly on their next space mission, most likely something that outputs pure oxygen from local resources, a proposed project they have not publicly discussed to date.

Given the potential payoffs, the commercial space industry should give at least as much thought to ISRU as it has for rocket engines and avionics.

Some ISRU technologies may not be able to benefit from partnerships with space mining companies right away. In order to turn a profit in the short term, it may be necessary to look for niche applications on Earth that will provide the funding needed to prepare these technologies for use off-planet. There is already commercial interest in the Sabatier reaction (carbon dioxide and hydrogen reacting to create methane and water) for various applications that require the elimination of carbon dioxide emissions. For this reason, there may be commercial potential for processes that output higher hydrocarbons, such as the reverse water-gas shift and Fischer-Tropsch reactions. From my reading of the technical literature, there has not been much development work on new Fischer-Tropsch catalysts. This technology will be useful on Mars to generate hydrocarbon feedstocks for the production of plastics. It has been neglected on Earth because of the relative ease of getting crude oil out of the ground, but this will change as oil reserves dry up.

In addition, carbon capture technology is only getting easier. Last summer, I met with Dr. Francis Huang at the Southwest Research Institute. He has invented a ceramic membrane that selectively separates carbon dioxide from industrial effluent gas at high temperatures, such as what would be found in a smokestack. The ability to separate carbon dioxide at low cost, combined with recent advances in decentralized hydrogen production, may make the abovementioned processes economically viable.

What I have discussed above is just scratching the surface on the possibilities of ISRU technology and its spinoffs on Earth. Some of them are as simple as miniaturizing existing Earth processes, while others require exotic methods that may pay off in future resource-extraction methods. Given the potential payoffs, the commercial space industry should give at least as much thought to ISRU as it has for rocket engines and avionics.


Home

Subscribe

Enter your email address below to be notified when new articles are published: