The Air Force's Operationally Responsive Spacelift (ORS) effort is trying to close this gap by pushing for a launcher that is ready to go in "hours or days" instead of "weeks or months." It is also pushing for a large reduction in cost.

The current study phase of ORS has high-level Pentagon support from Air Force Undersecretary and National Reconnaissance Office Director Peter B. Teets, who would like to see the launch costs for a 400-lb. satellite be under $ 5 million (AW&ST Feb. 17, p. 33). Money is appearing in the Defense Dept. budgets a few years out for ORS, and $ 24 million is in the Fiscal 2004 budget for a related effort.

Air Force Space Command (AFSPC) started an "analysis of alternatives" (AOA) study on Mar. 1, and it is to end one year later in March 2004. The idea is to compare launcher concepts with customer needs, and create a development plan for ORS. Customers include the Army and Navy, for which the Air Force operates as executive agent, and the needs have been distilled into five representative satellites to span size, weight and orbit requirements. Officials have not been specific about a range of actual payload weights and orbits.

Col. Pamela L. Stewart, the AOA study director at AFSPC, said the output of the AOA is to be an acquisition road map with a related technology development road map, and plans for risk management and risk-reduction demonstrations. If ORS looks promising, Teets would like to get funding in the Fiscal 2006 budget, Stewart said. This requires preliminary AOA results by November-December, before the study is completed.

The timetable is aiming at a 2014 initial operational capability for ORS. An attempt to get funding in the Fiscal 2005 budget was not approved "but we got to the top of the unfunded list," Stewart said. The proposed 2007 budget already has ORS in it. The AOA itself is funded at $ 8 million.

The formal results are to be given to Teets in May 2004. At that point, he will decide if ORS proceeds into an acquisition program, becomes a technology development program or goes away.

The AOA is being performed within AFSPC, with help from The Aerospace Corp. and NASA. A prior 120-day AFSPC study that ended in early 2002 tried to make a common plan with NASA for a reusable launch vehicle and a military space plane, but once it ended, officials realized that they needed to consider expendable as well as reusable launchers. The effort expanded into the AOA, which is for unmanned vehicles that can be ground- or air-launched. Single-stage-to-orbit is considered impractical for the near term. The desired components in 2014 are:

-- A first stage. For air-launched designs, the aircraft is the first stage.

-- A second stage.

-- A modular insertion stage, which is a low-cost upper stage to take the payload from low-Earth orbit to mid- or geosynchronous altitude.

There also are plans for an orbital transfer vehicle that could be used to refuel or replace hardware on satellites, but it is not required by 2014 and won't be built if it's not cost-effective.

The study has not identified key technologies yet, Stewart said. It is taking a practical approach, focusing on what can be done soonest. But two areas will definitely get attention -- propulsion and thermal protection. "I think that liquid propellants are the future," she said, but the desire is to get away from hazardous liquids such as hydrazine. Liquid oxygen (LOX) and kerosene are likely propellants. Development of thermal protection is desired for the Common Aero Vehicle and if a reusable ORS is chosen.

Timing of ORS technology development is roughly aligned with NASA's Next Generation Launcher Technology program and Stewart expects teaming between the two efforts -- to a point. NGLT is aimed at a manned scheduled launcher, and ORS is to be an unmanned responsive launcher. "The efforts have to divide at some point," she said.

A related program already underway is being run by Brig. Gen. Simon P. Worden, director of transformation at the Air Force Space and Missile Systems Center in Los Angeles. Its purpose is to demonstrate that a small tactical satellite and launcher can perform a real mission at low cost by flying them in Fiscal 2007. The quick demonstration could include a subscale Common Aero Vehicle. It has been funded at $ 24 million in Fiscal 2004. "It has minimal effect on Operationally Responsive Spacelift but it will affect the Common Aero Vehicle," Stewart said.

Two companies are among those aiming at both ORS and Worden's effort. They are Microcosm and Space Exploration Technologies Corp., also known as SpaceX. Both companies are in El Segundo, Calif., conveniently near the Space and Missile Systems Center. Microcosm has been in business for two decades and its work on a low-cost launcher has resulted in two successful short-range flights so far. SpaceX sprang into being in June 2002, the brainchild of Elon Musk, a dot.com millionaire who thinks a cheaper and more reliable launcher is possible with current technology, and that there is a market for it.

The companies are taking a similar technical approach with a few important differences. They both have uncooled thrust chambers burning kerosene and LOX, an approach that has not yet been operationally used. But Microcosm uses pressure-fed engines on all stages while SpaceX has a turbopump on the first stage and a pressure-fed second stage. The Microcosm rocket is completely expendable while SpaceX plans to reuse the parachute-dropped first stage.

Microcosm envisions a family of launchers using its "Scorpius" technology. At the low end is Sprite, a three-stage rocket designed to take 700 lb. to a 100-naut.-mi. 28.5-deg. low-Earth orbit at a cost of $ 1.8 million by its 10th flight. SpaceX is designing its two-stage Falcon to take 1,000 lb. to the same orbit for $ 6 million. The existing launcher for light payloads is Orbital Sciences' air-launched Pegasus, which takes about 1,000 lb. to low-Earth orbit for $ 22-26 million.

Both companies use a carbon fiber thrust chamber protected from the heat by a silica phenolic ablative liner, with features such as an Astroquartz throat on the SpaceX version. This is one of the keys to low cost, because an uncooled composite chamber is much cheaper than a metal unit with complex cooling passages. Engineers try to minimize chamber erosion by running a cool film of fuel-rich mixture along the walls, and want to have less than 0.001-in. of erosion per sec. Microcosm has made 35 5,000-lbf. thrust chambers at an average cost of $ 4,000, and fired about 32 of them for periods up to 200 sec., compared with a maximum expected flight firing of 183 sec. They show about 1/8-in. erosion of the 1-in.-thick walls, said Robert E. Conger, Microcosm vice president. The company is now developing a 20,000-lbf. engine.

Microcosm's first stage tanks run at 550 psi. to provide 385 psi. chamber pressure. To keep weight down, they are made of carbon fiber that is filament-wound in-house. "We replace the turbopump with extra winds on the tank," said Microcosm President James R. Wertz. This makes them only 40% the weight of an equivalent aluminum tank and one-tenth the cost, he said. The main trick is to build a carbon fiber LOX tank that won't explode when shock causes the LOX and carbon to react. To solve this problem, the company has developed a composite liner material and construction process good for multiple chill and pressure cycles, Wertz said.

The company flew an SR-S rocket on Jan. 27, 1999, powered by a single 5,000-lbf. motor, and an SR-XM-1 rocket on Mar. 9, 2001, powered by a pair of these motors. It plans to fly a suborbital SR-XM-2 in early 2004 with a 20,000-lbf. motor.

SpaceX believes the turbopump is worth its expense for the tank weight it saves, Musk said. The Falcon uses aluminum tanks and he is skeptical whether a composite tank can work with LOX.

SpaceX hopes to make an orbital launch by the end of the year, pending government approval. Significant hardware, including the first stage tanks and turbopump, have already arrived from subcontractors at the company's shop here. Injector development is underway, firing into a solid copper testbed thrust chamber for a few seconds at a time. And the company already has launch orders from a Defense Dept. customer and a foreign government, Musk said.
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