Reusable Launch Vehicles Edge Closer To Reality

Space tourism market beckons to many design teams, but ‘reusability’ poses significant challenges

Printed headline: RLV Hurdles Aplenty

The concept of using a booster repeatedly makes sense, especially if it drastically lowers the cost of placing a payload in orbit. Although a true RLV has not yet been fielded, those looking to stake a claim on the potentially lucrative space tourism market plan to take a step in that direction. Scaled Composites will begin SpaceShipTwo drop and powered-flight tests this year.Credit: CHAD SLATTERY Today, the U.S. space shuttle—which is only partially reusable—is the closest thing to an RLV. Development of a fully reusable launch vehicle, whether by government or private industry, is no easy task. Although many RLV designs look straightforward, the hurdles are significant. To be reusable, a launch vehicle must be more robust than an expendable booster to sustain launch, reentry and landing loads many times during its operation. RLVs also must allow easy access to components for maintenance and replacement, and incorporate monitoring and recovery systems to bring them safely back to Earth. Another major challenge is the launch market itself. Developing a large orbital RLV does not make sense in the current business environment owing to low demand. And in recent years the market has proved fast-changing and unpredictable. While expendable launchers can be adapted to changing demands with stretched stages and larger payload fairings, an RLV’s basic design would essentially remain fixed and potentially uncompetitive. Design-office floors are littered with RLV concepts that never made it off the drawing board, and those that made it to the prototype stage were usually canceled because of escalating costs. RLVs are no less expensive to develop than expendables, and the cost benefits of reusability would not be fully realized until after many successful flights. For these reasons, the development costs of reusable boosters have proven prohibitive. Those still in the game are focused on the space tourism services market, estimated by some to be worth a potential $500 million. Virgin Galactic is just one of a number of companies determined to take a slice of that pie. Reusable suborbital spacecraft that could become potential competitors include the Lynx by XCOR Aerospace and the New Shepard vertical-takeoff-and-landing (VTOL) rocket by Blue Origin. For now, Virgin Galactic, headed by Richard Branson, is a step ahead of the rest; it is working with a tested design—something that cannot be said for its competitors. Also, Virgin is having no trouble funding development of its spacecraft. The company plans to direct initial profits back into the program to make improvements and reduce costs. Virgin should be carrying customers to suborbital space around 2011, when it expects to be able to make about 50 flights with the SpaceShipTwo. XCOR Aerospace’s two-seat vehicle called Lynx is roughly the size of a small aircraft and is being designed to carry people or payloads to an apogee of 61 km. (38 mi.). After powered flight and a coast to microgravity, the vehicle would reenter the atmosphere and glide to a horizontal landing. XCOR expects the vehicle will be able to fly several times a day, and to take flight around the same time as SpaceShipTwo in 2011. Amazon.com founder Jeff Bezos set up Blue Origin in a bid to capture a share of the space tourism market. Since the company’s founding, news on the New Shepard vehicle has been hard to come by. Three test flights have taken place so far, and more are planned. According to a recent time table, Blue Origin will fly the vehicle unmanned in 2011 with the goal of a manned flight in 2012. New Shepard is a wingless, conical spacecraft with a rounded base, similar in design to the DC-X, an unmanned prototype built in the early 1990s to demonstrate the concept of a VTOL RLV. The market for developing and fielding RLVs at this moment is clearly tied to space tourism, and there is little will to develop a suborbital RLV for any other application. The good news for these three companies is that several surveys have shown that interest in space tourism has grown considerably during the past 10 years.