Reusable Rocket Is Proposed as Possible Shuttle Replacement : Aerospace: Lockheed and Rocketdyne have teamed up to compete with other aerospace companies for $167 million in NASA grants to study the feasibility of a ‘single-stage-to-orbit’ rocket.

Lockheed Corp. and Rocketdyne have proposed a radical, reusable wedged-shaped spacecraft with rocket engines to lift it into orbit and return in one piece, and which could by next decade replace the current space shuttle and the country’s fleet of expendable rockets.

Lockheed, based in Calabasas, and Rocketdyne, the Canoga Park division of Rockwell International, have teamed up, and are among several aerospace companies competing for $167 million in grants from the National Aeronautics and Space Administration (NASA) over the next five years to explore the feasibility of a so-called “single-stage-to-orbit” rocket, or SSTO.

The reason behind all this is to save money. Lockheed could develop the new single-stage rocket vehicle at a cost of about $6 billion by the end of this century, said Bob Baumgartner, chief engineer of Lockheed’s AeroBallistic Rocket SSTO program in Palmdale. After that, the cost per launch would be about $20 million, he said. By contrast, the current space shuttle costs about $322 million per launch, NASA official Ivan Bekey said.

But some consider the single-stage-to-orbit rocket to be a pie-in-the-sky idea. “I suppose it can be made to work. The question is at what price,” Caltech aeronautics professor Wolfgang Knauss said. The potential pratfalls are numerous, Knauss said, adding that the idea of a single-stage rocket is still viewed as “a little far out.”

Materials that work well in the lab might surprise once they’re in space, Knauss said. Newer, lightweight materials proposed for SSTO rockets “have all this promise, but they haven’t really been explored for engineering purposes,” he said.

Whether Congress would support such a plan is far from clear. Also uncertain is whether the Pentagon and the White House will back the SSTO concept. Both are now completing separate studies on revamping U. S. rocket launch systems, and are expected to release their recommendations in coming weeks.

Still, the idea of a single-stage reusable rocket is being taken seriously by NASA. The agency’s own study estimates that it would cost NASA $18 billion for development, and $19 billion for production of a fleet of seven SSTO rockets to begin replacing current launching systems by around 2008.

NASA, though, is hoping the government will never have to pay for this new generation of launching vehicles. The agency wants an SSTO program to mark a new era of privatization of rocket systems in which American companies develop and own spacecraft, while NASA would simply be a customer among many.

The idea behind an SSTO is to reach orbit with a single-stage rocket, without jettisoning engines or fuel tanks. Such a vehicle would make repeated trips to space with a minimum of tinkering.

This is a radical departure from current methods. All of the country’s existing fleet of expendable rockets drop bits of themselves in stages, lightening the load as they climb.

The current space shuttle fleet is closer to being truly reusable. The shuttles drop two solid fuel boosters and a fuel tank in flight. Once they are fished from the ocean, the boosters can be used a few more times, but refurbishing the shuttle for repeat flights is a mammoth project that keeps thousands of government workers in constant employment.

The current multiple-stage rockets are wasteful and costly, Baumgartner said. But a single-stage rocket must also overcome considerable technical hurdles. It must be both light enough, and powerful enough, to reach orbit intact, he said.

Lockheed’s new concept is similar to several other proposals for SSTOs. McDonnell Douglas has proposed a craft that would return to earth by landing vertically and descending slowly onto a landing pad, with its nose pointed skyward.

Lockheed’s SSTO rocket would be more like the shuttle. It would shoot up vertically from the launching pad like current rockets, and descend by landing horizontally on a runway like an airplane.

Company officials say it’s no coincidence the design comes not from its missile division, but from Lockheed Advanced Development Co. in Palmdale, also known as the Skunk Works, the group which has produced various spy planes and fighter jets. “This is a radical change, a leapfrog,” Baumgartner said. “We see it as aircraft that goes into orbit rather than a rocket that lands.”

Rocketdyne has the contract to make engines for the current space shuttle, and wants to remain in the vanguard as NASA plans what could be the shuttle’s successor.

If they do get funding to build an SSTO, Lockheed and Rocketdyne’s engineers have plenty of technical hurdles to overcome because the very features that make a craft reusable tend to add weight: For instance, reusable rockets must be swaddled in heat-resistant material to avoid charring when they re-enter the atmosphere. And more powerful engines usually weigh more.

Lockheed, however, believes it can master these trade-offs. Its proposed design for an SSTO rocket craft is a wingless, 110-foot-long, 110-foot-wide, triangular-shaped wedge. Technology advances make such an SSTO rocket possible today, Baumgartner contends. The most important of these is improved materials, particularly light and durable graphite composites.

Graphite composites have been used for the bodies of military aircraft for years, Baumgartner said. They would be used to form the internal body and the hydrogen fuel tanks in Lockheed’s SSTO design. A new, super-light aluminum would be used to build the liquid oxygen fuel tanks while heat-resistant ceramics and other high-temperature metals would shield the rocket from the heat of re-entry, Baumgartner said.

These materials are not only light, they are more durable than the tiles now used to protect the space shuttle, and they would not require time-consuming inspection and waterproofing after each flight, he said. The craft would carry a payload of about 40,000 pounds, compared with the space shuttle’s 50,000 pounds, and run on liquid hydrogen and liquid oxygen fuel, Baumgartner said.

Seven engines manufactured by Rocketdyne are to be mounted in the rear of the craft. The engines are flatter than ordinary, bell-shaped rocket engines, and while they are heavy, they would in theory make up for it by conforming to the body’s weight-saving design.

Rocketdyne’s “linear aerospike” engine was studied initially for space shuttle use in the early 1970s, but was never tested because NASA instead decided to use more traditional bell-shaped rocket engines, said Don Fulton, program director of advanced launch system engines at Rocketdyne.

In traditional rockets, the engine nozzle is an enclosed series of tubes. In the linear aerospike it is just a curved plate of metal. The gases expand against the plate and are contained by the friction of the surrounding atmosphere.

Lockheed projects the cost of launching its proposed SSTO would be about $500 per pound of payload, as contrasted with about $7,000 per pound average for the current U. S. rocket fleet and for the cheapest available commercial launch systems.

But as Lockheed and Rocketdyne concede, the SSTO project hinges on a slew of unknowns. Much of the technology needed to make an SSTO has yet to be tested. For instance, it’s unknown whether graphite composite fuel tanks can be designed to survive repeated launches without leaking, Baumgartner said. And the effects of the atmosphere against the body of the craft is another unknown, as is the performance of the engine once mounted in the rocket.

NASA, however, favors development of an SSTO over other cost-saving alternatives, such as updating current rockets, in part because it believes an SSTO would restore American dominance of the world market for launching systems. Since the mid-1970s, the American share of the private rocket market has slipped from 100% to about 30% of launchings worldwide, while French, Chinese and Russian shares have steadily grown.

But critics question whether the commercial market for SSTOs would justify the cost of developing one. “The idea is that . . . if you lower the cost of access, it will make people want to do things in space. I think that remains to be seen,” said John Logsdon, director of the Space Policy Institute at George Washington University.