Take Material to Space or Make It There?
Most human missions in space have been brief, lasting only days or weeks, and they have taken all the materials they need. Using the alternate method, the International Space Station recycles water and oxygen, and it is often assumed that future Moon and Mars missions should also recycle their life support materials. The “take or make” decision is primarily based on cost, and making or recycling material on longer space missions can sometimes be less expensive than taking it. Longer missions favor recycling over resupply when the initial cost to provide recycling equipment is less than the cost to provide resupply. Recycling was clearly cheaper than taking material to the space station in the space shuttle era when launch costs were very high. Launch costs have decreased and the take or make decision point has changed. The recent reduction in launch cost by a factor of about twenty-five to fifty makes taking material cost less than making or recycling it for much longer missions. The cost breakeven point when making rather than taking material is less expensive is now much farther out in time than before. Material recycling or in situ production no longer saves cost except for very large or very long missions.