Resupplying the International Space Station

Image courtesy of NASA

As it grows, the International Space Station will demand a lot of supplies. So even before we are shipping lunar oxygen to commercial rockets, hotels, and cruise ships in orbit, we can resupply the space station with lunar material.

Even with the water loop as closed as NASA can get it, the International Space Station will need a tremendous amount of resupply water. To get into this business, we must be able to:

1. extract oxgyen from the moon,
2. put it into tanks made from lunar material, and
3. sling it off the moon into Earth orbit, and
4. do all that for less cost than the International Space Space can resupply itself from the ground.

Less wear and tear on the Shuttle fleet

This scenario saves the Shuttle fleet for carrying things we cannot reasonably supply for the moon any time soon, such as experiment racks, scientific equipment, and crewmembers. NASA only has four Space Shuttles, each certified for 100 flights. They might be able to overhaul the Shuttles to keep them flying longer, but in any case the fleet is a precious national resource that will be kept very busy servicing the space station. We can expect that any program that reasonably alleviates the load on the fleet will be welcomed by the US government.

The prox ops conundrum

There is a drawback, however. The process of certifying a spacecraft to operate in the vicinity of the International Space Station is so complex that it almost complete precludes commercial resupply, or any commercial use of the space station that involves flying a vehicle near the station. The cost of certifying a spacecraft would exceed the cost of developing and flying it.

A commercial orbital maneuvering vehicle solves the problem

On the other hand, if we develop an Orbital Maneuvering Vehicle that is certified for approach and docking with the space staton, we can eliminate this problem. Commercial suppliers could drop off their cargo in a parking orbit within the range of the OMV and have it take care of proximity operations and docking.

Several years ago, NASA studied an Orbital Maneuvering Vehicle that would be able to pick up payloads from the Space Shuttle and deploy them as high as geosynchronous orbit. They went as far as the preliminary design phase in this study, so development of an OMV is entirely within the realm of possibility.

Perhaps such a vehicle could be commercially developed and then leased to NASA on a shared-use basis. The US government could alleviate some of the business risk by leasing it full time, but allowing the commercial OMV operator to buy back some of the vehicle's time so that the OMV can be used for other missions.

Alternatively, NASA could guarantee that it would purchase a certain amount of the vehicle's use per year for a given number of years -- enough to justify development of the vehicle. Beyond that, the commercial operators would be free to sell the vehicle's services wherever they can.

This program would be great news for the Artemis Project. A commercial OMV would be the first step toward development of the Lunar Transfer Vehicle. It also would be valuable for resupplying the LTV as well as the Artemis Project's staging base in low earth orbit.

Propellants for the space station?

Unfortunately, we probably will not be in a position to resupply the space station's propellant needs as it is currently designed. The current plan is to ship up a whole new propulsion module when the reboost rockets run out of gas. However, the ability to evolve is inherent in the design of the International Space Station so even this may change.