Achieving Mastery of Space Operations by Transforming Space Logistics

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

Sir Watson Watt was not arguing that near-term imperatives prevented the use of technologies that had not yet been operationally deployed. Rather, he argued that, at the time of system development, a measure of the maturity of the technology needs to be considered. Today, this is accomplished through the use of Technology Readiness Levels (TRL), where the current maturity is assessed on a scale of 1-9 with "9" being a technology or subsystem currently in successful operation. Within the aerospace industry it is generally accepted that when the enabling technologies reach a TRL of 6 - system/subsystem model or prototype demonstration in a relevant environment (ground or space) the technologies are sufficiently mature to support a decision to initiate a formal development program. Hence, near-term system solutions are those employing TRL 6-9 critical technologies whose development can be initiated without unacceptable cost or delay.

Transforming Space Access

There is no avoiding the fact that to transform space logistics and achieve an initial mastery of space operations space access must first be transformed. This is an area that has been the subject of considerable debate, but without clear resolution. The primary issue is a broad public perception of what may be called a "space access barrier." Reinforced by the loss of two Space Shuttles and the failure of the X-30 and X-33 programs to realize their single-stage goals, the popular perception is that substantial further technology advancement is required to achieve "aircraft-like" routine and safe space access. However, popular perceptions are not always on target. Looked at from the context of what practical near-term options are available today, two sets of solutions become evident.

First would be the development of fully-reusable, vertically-launched, rocket-powered two-stage-to-orbit (TSTO) space transportation systems. These would replace the Space Shuttle and Expendable Launch Vehicles for transporting passengers and most medium-class payloads to LEO. Recall that the original Space Shuttle design proposals from the late 1960s were fully reusable, rocket-powered two-stage systems - only later changed to the current partiallyexpendable system design to meet development funding constraints. With nearly 35 years of further technology advancement, there is no reason today to believe that industry could not now successfully develop such systems. Recent government and industry conceptual design studies support this contention. These studies indicate that these unmanned reusable systems would transport 25,000-35,000 pounds to LEO when launched east from Kennedy Space Center (KSC). With the carriage of a small winged spaceplane in place of an external cargo module, the system could also transport about 10 passengers to LEO. (see Figure 2.)

Consistent with the current TRL 6-9 technologies used in these systems, they would be suitable for what is referred to as "routine" spacelift. Each of these flight systeMs would be capable of being turned around for re-launch about every four weeks at the initial operational capability (IOC) and perhaps as frequently as every week when full operational capability (FOC) is achieved. Such systems are thus distinguished from a "responsive" spacelift capability, discussed in the updated U.S. Space Transportation Policy, that aims for turning a system around in only one day or less. Recent studies indicate that responsive spacelift systems, as well as system designs employing advanced airbreathing propulsion, require further technology investment prior to the start of development and, hence, are not considered to be near-term options.