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Taurus launch
The Taurus was an earlier version of an operationally responsive launch vehicle, but has flown only six times since its introduction in 1994. (credit: Orbital Sciences Corporation)

Operationally Responsive Spacelift: A solution seeking a problem?

The latest buzzword that has swept the launch industry has been “operationally responsive spacelift.” This mouthful of a phrase emerged earlier this year courtesy, not surprisingly, of the Defense Department. Peter Teets, the Air Force Undersecretary for Space and head of the National Reconnaissance Office, promoted the concept because he felt that current launch vehicles took too long to prepare for launch. Instead of waiting weeks to months to carry out a launch, Teets wanted a small launch vehicle that could launch in days, if not hours.

This summer DARPA followed up on Teets’ concept with the announcement of a new program, Force Application and Launch from CONUS [Continental US], or FALCON. The purpose of FALCON, according to DARPA, is to “develop and demonstrate technologies that will enable both near-term and far-term capability to execute time-critical, global reach missions.” This vision for FALCON includes the ability to launch hypersonic vehicles from the US that could deliver payloads—munitions—anywhere in the world on just a few hours notice, far faster than any existing delivery system short of ICBMs. One part of the FALCON program is the development of a Common Aero Vehicle (CAV), the hypersonic vehicle itself, while the other part is the development of a small launch vehicle (SLV) capable of launching on short notice to carry the CAV and other payloads. This SLV “must be at least an order of magnitude more responsive than existing satellite launch systems and must have a low launch cost,” according to DARPA.

To begin work on FALCON, DARPA issued a call for proposals for initial studies of the concept. One task of the proposal called for studies for the development of the CAV, while the other called for concepts for the SLV. Specifically, DARPA wanted “technical approaches for SLV design(s) suitable for launching either a global range CAV (Enhanced CAV) with an approximate 1,000 pound [455 kilogram] munitions payload or a small satellite to a specified low Earth orbit.” This phase of the project would include “conceptual booster designs, performance predictions, and CONOPS [concept of operations] and ROM [rough order of magnitude] costs for development and operation.”

The FALCON SLV “must be at least an order of magnitude more responsive than existing satellite launch systems and must have a low launch cost,” according to DARPA.

The response to the FALCON concept by industry has been, by all accounts, very positive. Proposals were due into DARPA last month and by some reports as many as two dozen companies submitted proposals for the SLV. (This has led some people to wonder if there really are two dozen companies in the US truly capable of the analyses required for this phase of the proposal, let alone able to build the vehicle itself.) DARPA plans to award up to five contracts for the SLV study with values ranging from $300,000 to $540,000 each: a relative pittance compared to the demand for those contracts. DARPA is expected to announce the awards in the relatively near future.

Different approaches

While the number of companies that have submitted FALCON SLV proposals has been widely discussed, few companies have stepped forward to confirm that they have, in fact, submitted proposals. However, during a session of the AIAA Space 2003 conference last month in Long Beach, California devoted to operationally responsive spacelift, several companies discussed at least how they would address the problem.

The company that has received the most attention in the small launch vehicle market in recent months has been Space Exploration Technologies, or SpaceX. Founded by Elon Musk, who made his millions in Internet ventures, notably PayPal, SpaceX has been actively developing a small launcher coincidentally named Falcon. SpaceX’s Falcon is a two-stage vehicle designed to place over 600 kilograms into LEO. The development of Falcon is entering its final stages, and the company plans to conduct its first launch as early as January 2004, when the Falcon carries an as-yet unidentified Defense Department satellite (thought to be TacSat-1, an experimental Navy spacecraft) from Vandenberg Air Force Base in California.

Falcon’s biggest selling point has been its price: $6 million per launch, a value that Musk believes could drop depending on his company’s ability to reuse the vehicle’s first stage. However, in Long Beach Musk emphasized that SpaceX was keeping reliability in mind while developing Falcon. He quoted an Aerospace Corporation study that found that 91 percent of launch vehicle failures were caused by engine, staging, and avionics problems. SpaceX is mitigating this risk by using only two stages with one engine in each stage, as well as dual redundant avionics.

Speaking to the concept of operationally responsive spacelift, Musk emphasized that the Falcon is relatively easy to transport to a launch site and requires minimal infrastructure, comparing it to the former Soviet Union’s SS-20 ballistic missile. The erector used to raise the Falcon into the vertical position for launch also acts a strongback to support the vehicle even in relatively high winds. Final preparations for launch could be performed quickly: Musk suggested that the limiting factor would only be how fast liquid oxygen could be pumped into the rocket.

SpaceX's biggest selling point for the Falcon has been its cost, but the company is also emphasizing its reliability and responsiveness.

Microcosm, located, like SpaceX, in the Los Angeles suburb of El Segundo, has arguably been working on operationally responsive spacelift far longer than the term has been in the lexicon. For several years the company has been working on its Scorpius family of launch vehicles, ranging in size from small sounding rockets to heavy-lift boosters, using a modular approach. The company had only flown two sounding rocket flights to date, but has three other rockets in development to test technologies for its Spite Mini-Lift small launcher.

Bob Conger, Microcosm vice president and Scorpius program manager, noted that the Scorpius family of vehicles is designed to launch essentially on demand. During one sounding rocket test, Conger noted, they were able to launch eight hours after arriving at an unimproved launch site at White Sands, a time that could be reduced to as little as four hours. “There is a growing demand for low cost and responsive access to space,” he said.

Frank Krens, vice president of Coleman Aerospace discussed an air-launched alternative to responsive spacelift. Coleman has developed a system that deploys a rocket out the back of a C-17 cargo aircraft for sounding rocket tests; the rocket parachutes down a short distance before firing its engines. The system, including both the launch vehicle and the control panels, use standard cargo pallets: this means that no modifications are needed to the aircraft, although it does need to be recertified, according to Krens. While this system is not capable of launching payloads into orbit, Krens said the company is looking at a scaled-up version that could carry small payloads, although that might necessitate a shift from the C-17 to the larger C-5 cargo plane.

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