User-contributed essays on diverse topics
Thursday, July 15, 2004
Jess Sponable was the USAF engineering officer responsible for the remarkable successful DC/X program that demonstrated feasibilities of re-usable rockets.
THE NEXT CENTURY OF FLIGHT
One vision of flight in the future is remarkably consistent. Almost everyone involved in space flight looks to a 21st century frontier opened by reusable launch vehicles (RLVs) that fly reliably and routinely to orbit with "aircraft-like" operational efficiencies. The vision is shared by NASA, the U.S. Defense Dept. and the commercial sectors. And it dates to the origins of the space program. Realizing this vision, however, has proven to be a huge challenge.
Six years ago, the DC-X single-stage-to-orbit (SSTO) technology demonstrator suggested a road map--flight test vehicles that prove the potential for low-cost operations versus the glittering allure of newer, ever more complex technology.
NASA Administrator Daniel S. Goldin took cues from the DC-X and the Clementine mission to the Moon and became the leading advocate of the "faster, cheaper, better" philosophy. He pushed to reinvent the space agency with a host of low-cost projects. NASA launched a spectrum of successful new satellites, and returned to the Moon and Mars for an astoundingly low cost.
Launchers have presented a different story. In the private sector, several companies were started to capitalize on the DC-X success with their own concepts for RLVs. But as we approach the next century of flight, all of these commercial companies are either badly underfinanced or nearly bankrupt.
Meanwhile, to begin reducing the cost of space access, NASA initiated a host of X-vehicles, including the DC-XA, X-33, X-34, X-43 and most recently X-37. The technologies being developed include radically different aerospike engines, complex multilobe cryogenic tanks, elaborate thermal protection, and light-weight SSTO composite structures.
The U.S. has been down this technological high road before. Not too many years ago, the National Aero-Space Plane (NASP) program spent more than $3 billion trying to develop an even more complex, rocket-based combined-cycle ramjet/scramjet propulsion system. I was one of the early team members in the NASP program, and later I was DC-X program manager. Those experiences led me to believe that if we are to fulfill this dream of cheap, reliable access to space, we must focus on the fundamental lessons from both programs. What America needs is not newer launch technology, but today's technology applied to RLVs designed to fly with aircraft-like operational efficiencies.
Low-cost, two-stage spaceships using commercially available Russian engines are potentially far cheaper to operate than the much more complex "new technology" vehicles. The Russian engines are as reliable as our own early turbojets, putting them two generations ahead of equivalent rocket engines built in the U.S. Because of the inherently lower development and operating costs involved, many small companies have baselined Russian engines in their vehicle designs.
The challenge is not building these RLVs; the challenge is getting them financed. Wall Street is rightly skeptical, given the history of broken promises about low-cost launchers. My experience in the private and government sectors is that financing on Wall Street, or acceptance at the Pentagon, cannot be won with viewgraphs. Rather, it will come only when demonstrators are flying routinely and reliably with lower costs and greater efficiency and durability.
Indeed, the DC-X and NASA's DC-XA were flown primarily to prove very-low-cost rockets could be incrementally flight-tested with the efficiency and operability of modern aircraft. Even the DC-X vertical-landing mode was selected for its better operability qualities. Among the modern rocket-powered X-vehicles, only the vertical lander is inherently able to fly through a slow and safe incremental test program analogous to that of aircraft. The DC-X had many achievements--the first in-flight abort and vertical landing, a mere two flight controllers and seven vehicle ground technicians, and a turnaround measured in hours, not weeks.
None of NASA's new X-vehicles will have an operability approaching that of the DC-X. I'm a supporter of all these X-vehicles. But I fear we've forgotten that operations is itself a technology and a prerequisite to proving the potential for low-cost flight. Attracting commercial financing will require a wide range of operating demonstrators proving the plausibility of dramatically lower costs to orbit.
Operability demonstrators need not fly to orbit, but they should prove the viability of durable, long-lifetime vehicles capable of flying to orbit. More importantly, they must fly routinely, reliably and at very low cost. "Faster, cheaper, better" reusable rockets demonstrating aircraft-like operability will be powerful levers for opening Wall Street coffers. Indeed, operations is the seminal "technology" for next-generation commercial RLVs.
The government has an important role to play in helping to introduce next-generation, low-cost space transportation, just as it helped develop every other new form of transport--from the steamship to transcontinental trains to highways and aircraft. If we can navigate the treacherous path to commercially viable reusable spaceships, then the U.S. will lead the world into a new era of global security and vast wealth on the space frontier. But we must start with the basics: proof of concept operability demonstrators.
Reprinted with permission. Aviation Week 5/24/99
Lt. Col. Jess Sponable (USAF, Ret.) is vice president for flight operations at Universal Space Lines in Newport Beach, Calif. Charles Lurio, an aerospace consultant in Boston, contributed to this piece.