Achieving Mastery of Space Operations by Transforming Space Logistics

Logistics Spectrum, Jan-Mar 2005 by Snead, James Michael

To meet the U.S. Space Transportation Policy's requirement for assured space access, at least two types of near-term systems would be deployed. With three operational systems of each type, six operational systems would be brought into service. Assuming that one system of each type in is depot for maintenance, the four systems in flight status would have a mission capacity of about 50 missions per year at IOC and perhaps as many as 200 missions per year at FOC. With an average delivered cargo of 12 tons and 80 percent of the missions used to transport cargo, this modest fleet could transport about 1,900 tons and 400 passengers to orbit each year once FOC is achieved.

It is expected that these projections of mission capabilities will be greeted with some measure of skepticism, in part because similar claims were made during the early years of the Space Shuttle program. However, noting that by the time these new reusable spacelift systems could be initially flying around 2012 and reach FOC in about 2017, their design will have benefited from over 40 years of technology and system design advancements since the start of the Space Shuttle program in 1972. It is time to update expectations of what is possible to achieve. After all, this is nearly twice the length of time as took place between the breaking of the sound barrier in 1947 and the first lunar landing in 1969.

The other near-term option is to augment the near-term reusable spacelift capability with an unmanned Super Heavy Spacelift capability. This would be a Saturn V-class system capable of placing approximately 160,000-180,000 pounds into an east orbit from KSC. For perspective, this is the equivalent to the weight of about three empty Shuttle external tanks.

Why the need for such a Super Heavy Spacelifter? Because this provides the capability to launch large and heavy components of space systems into orbit for later assembly in LEO, as described in more detail below. The need to be able to transport oversize components during the construction of terrestrial logistics infrastructure is quite common. The additional transportation cost is offset by the assembly and operational advantages achieved.

The third best solution for meeting this Super Heavy Spacelift need has been under study for almost 30 years. It is a Shuttlederived system as shown in Figure 3. Because this Super Heavy Spacelifter would be developed concurrently with the reusable space access systems, this solution would provide acceptable performance and flight rates - perhaps three to five flights per year - while minimizing program development cost and risk compared with a "clean-sheet" approach. This solution also provides for generating continued value from and providing for a measured upgrading of an important element of the existing space industrial base. It neatly transforms the existing manned Shuttle system into a critical element of an emerging integrated space logistics infrastructure.

These two near-term solutions, which through the emphasis on the use of TRL 6 technologies could be available near the time Space Shuttle operations are ended, provide a significant improvement in space access for passengers and cargo. Not only will this change substantially decrease current space access costs, it will also provide additional capacity to exploit the lower costs, as typically happens as new logistics infrastructure is brought into operation. More importantly, these changes provide the transportation improvements needed to take the next steps in transforming in-space mobility and logistics support.