EELV or never?
by Wayne Eleazer
|As a far as long-lived boosters go, they are the rule in the launch business.|
The SS-6 was, in many respects, a straight-line development of the World War 2 German V-2 ballistic missile. Today’s Soyuz booster engines still use hydrogen peroxide to drive the turbopumps, just like the V-2, and employ multiple thrust chambers, each of which is very close to the size used in the V-2. Even the thrust chamber injectors for the old Soviet and older German vehicles are close to being identical in design. The Soyuz is not just a bunch of V-2’s strapped together, but it doesn’t miss that concept by too much.
Okay, so the Soyuz is ancient; in fact, in space age terms, it is literally prehistoric. What about the other most popular boosters of the 21st century? Well, the next one after the Soyuz is the Proton, with about 40 launches. No spring chicken itself, the Proton dates from less than a decade after the SS-6, the mid-1960s, and similarly, originally was designed as an ICBM.
After the Proton, in terms of numbers of launches this century we have the Delta 2, with over 30 launches. The Delta 2 is a straight-line evolutionary development of the SM-75 Thor IRBM, which was a hurry-up American response to… the SS-6 Sapwood.
So, boosters hang on for a long time. In comparison to these venerable vehicles the new Delta 4 and Atlas 5 merely have a combined total of 15 launches. Of course, they just got started, which is something of a tragedy. They are not merely the newest launch vehicles the US government has developed; they are the first.
The vast majority of the launch vehicles we used in the 20th century were not designed as such but were adaptations of ballistic missiles. The Saturn series and the Shuttle were not really designed as launch vehicles but as manned spacecraft launchers, and they proved to be of little use for anything but that. Most “new developments” were based on taking a ballistic missile and modifying it a bit at a time. There are relatively few exceptions. The Scout was designed as a space booster, based on existing rocket motors. The relatively new Ariane series, dating from the 1980s, and the Japanese M series and H-2/H-2A boosters dating from the 1990s, were designed as space boosters from the outset, but they’re also very much in the minority compared to boosters such as Soyuz, Atlas, Thor, Delta, Titan, and Proton, either in this century or the last one. The same is true of the relatively new Russian Zenit series.
The EELV birds, Delta 4 and Atlas 5, are the first US boosters truly designed as general-purpose launch vehicles. Prior to the loss of the Shuttle Challenger in 1986, the official US policy was that no more expendable boosters would be developed. Following the loss of the Challenger, US policy allowed the development of new ELVs only if they could meet a combined set of USAF and NASA requirements.
In other words, the loss of the Challenger did not change the official policy on the development of new space boosters, at least in practical terms. Officially, we would develop new boosters—but in reality, no way.
There were many problems associated with developing a new booster to meet consolidated Air Force and NASA requirements, but one of the most challenging was literally what it took to even get started. The classic Air Force requirements definition process is what is known as threat-driven. DoD systems are developed in response to an identified threat from some potentially hostile foreign power, following a well-defined process for validating the threat and analyzing the method of responding to it. This process works pretty well with combat aircraft, in which it is possible to actually envision American fighters and bombers aircraft taking on hypothetical enemy airplanes. For launch vehicles the threat-driven process does not work at all. Space boosters don’t have to engage in combat with hostile weapons systems. Furthermore, expendable launch vehicles don’t even wear out and need to be replaced such as cargo aircraft do. Typically, the only need for a new booster is to meet requirements for larger, heavier payloads, and that usually can be handled by upgrades to existing hardware.
The Air Force and NASA came up with two programs to develop a new launch system in the late 1980s and early 1990s, the Advanced Launch System (ALS) and the National Launch System (NLS). Both of the programs featured measured, careful development of the basic systems and technologies required for a family of space boosters. And both were cancelled when the Air Force responded to Congressional cuts in aircraft programs by offering up alternative cuts in the form of new space booster development. The threat-driven approach triumphed, even in the post-Cold War era.
|The Atlas 5 and Delta 4 are not merely the newest launch vehicles the US government has developed; they are the first.|
NASA also used a threat-driven approach for defining new launch vehicle requirements. In this case, though, the threat was a reduction in the size of the NASA empire in general and the loss of the dream of human spaceflight in particular. NASA insisted in tacking on the development of a new orbital transfer vehicle to the new booster, resulting in the inevitable man-rating concerns. The net result of the combined Air Force/NASA inputs was an unwieldy set of requirements that neither agency could embrace wholeheartedly, combined with a lengthy and rather pricey development process, all of which Congress viewed with considerable suspicion. ALS and NLS floundered along for a while on small budgets each year, reduced to technology development programs in the wake of the inevitable budget cuts, limited to trying to figure out such details as how to reduce the parts count in a rocket engine injector.
The situation was so grim that at one point the US Senate even suggested that DoD consider buying launches on foreign launch systems: at least Arianespace and the Japanese actually were building and launching newly-developed flight hardware.
Suggestions for bolder development initiatives were brought forth each year, and all led to naught. Seeking outside inputs did not help. When asked if the best approach would be to develop new expendables or a new reusable system, the official reply came back from industry, “Yes! No!” (Well, at least they narrowed down the options.) Then came the Moorman Study.
In late 1993 a special study group was organized under Gen. Thomas Moorman aimed at addressing the question of future launch vehicle development. A former head of Air Force space acquisition efforts in the Pentagon, former vice-commander of Air Force Space Command, and former Air Force Vice Chief of Staff, Gen. Moorman was as savvy as they come. His study group did three things that were all but unheard of. They ignored the threat-driven approach. They tossed aside the usual “independent study group” approach so beloved in Washington DC circles, staffed the study with people from organizations that had real launch expertise, and actually asked the opinion of the real experts in the Air Force, NASA and industry. They worked to devise a workable approach rather that make the usual bold, broad, but ultimately useless recommendations.
The basic recommendation was to separate Air Force and NASA space launch requirements and proceed from there. The Air Force would develop a new expendable booster family on its own while NASA developed the next generation reusable launch vehicle.
The group’s more specific recommendation dealt with the new ELV. For the new expendable booster family, an “evolutionary” approach would be used. NLS and ALS had focused on the building blocks of technologies that would be useful for new boosters, beginning with the long pole in the tent, the engine. The evolutionary approach said to pretty much forget all that and evolve systems from where we were at technologically rather than where we would be years later.