WASHINGTON — The Defense Advanced Research Projects Agency announced May 24 that it has picked Boeing to develop an experimental reusable first stage with the promise of lowering launch costs for medium-sized payloads.
Boeing will develop its “Phantom Express” vehicle for phases 2 and 3 of DARPA’s Experimental Spaceplane 1 (XS-1) program, which has the goal of performing 10 flights in 10 days to demonstrate responsive and low-cost launch. Phase 2 will cover development of the vehicle and ground tests though 2019, with a series of 12 to 15 test flights planned for phase 3 in 2020.
DARPA spokesman Rick Weiss said the value of the award to Boeing is $146 million. The award is structured as a public-private partnership, with Boeing also contributing to the overall cost of the program, but Boeing declined to disclose its contribution.
“As it’s a competitive market, we do not plan to disclose our investment,” Boeing Phantom Works spokeswoman Cheryl Sampson said. “We are making a significant commitment to help solve an enduring challenge to reduce the cost of space access.”
The Phantom Express vehicle will take off vertically, with an upper stage carrying a satellite payload mounted on top of the fuselage. After releasing the upper stage, the suborbital vehicle would glide back to a runway landing.
“Phantom Express is designed to disrupt and transform the satellite launch process as we know it today, creating a new, on-demand space launch capability that can be achieved more affordably and with less risk,” said Darryl Davis, president of Boeing Phantom Works, in a company statement.
Phantom Express is powered by an Aerojet Rocketdyne engine designated the AR-22, based on the Space Shuttle Main Engine (SSME). In a statement, Aerojet Rocketdyne said it is providing two such engines “with legacy shuttle flight experience” using parts from both the company’s and NASA inventories of earlier versions of the SSME. The engines will be assembled and tested at NASA’s Stennis Space Center in Mississippi.
That engine represents an apparent switch in Boeing’s XS-1 concept. In phase 1 of the program, Boeing was partnered with Blue Origin, with the expectation Blue Origin would provide an engine for the spaceplane. “We selected the Aerojet Rocketdyne engine as it offers a flight proven, reusable engine to meet the DARPA mission requirements,” Sampson said.
DARPA announced the XS-1 program in 2013 as an effort to develop a reusable first stage that, coupled with an expendable upper stage, could lower the cost of launching payloads weighing up to 2,200 kilograms by an order of magnitude from the roughly $50 million the government pays for Minotaur 4 launches.
“The XS-1 would be neither a traditional airplane nor a conventional launch vehicle but rather a combination of the two, with the goal of lowering launch costs by a factor of ten and replacing today’s frustratingly long wait time with launch on demand,” said Jess Sponable, DARPA XS-1 program manager, in an agency statement.
Sponable, in past discussions of the XS-1, noted the use of “spaceplane” in the program’s name was meant to describe the goal of aircraft-like operations, not the design of the vehicle itself.
In 2014, DARPA announced three phase 1 awards for initial studies of the XS-1 concepts. In addition to Boeing, DARPA provided awards to Masten Space Systems, working with XCOR Aerospace; and Northrop Grumman, working with Virgin Galactic.
DARPA issued a call for proposals in April 2016 for phases 2 and 3 of the program. Boeing, Masten and Northrop Grumman all submitted proposals for phase 2, but DARPA also allowed other companies to compete. DARPA did not disclose the number of proposals it received.
A key aspect of the program retained from its earlier days is a requirement to carry out 10 flights in 10 days. In phase 2, the vehicle will fire its engine in ground tests 10 times in as many days, with the 10 flights in 10 days, at speeds up to Mach 5, in phase 3.
Later test flights of the Phantom Express will go up to Mach 10, another original goal of the program. At least one test flight will carry an upper stage that would place a demonstration payload into orbit.
DARPA and Boeing recently worked together on another program that attempted to provide less expensive and more responsive space access. DARPA selected Boeing in March 2014 to develop a launch vehicle for its Airborne Launch Assist Space Access (ALASA) program. The ALASA rocket, launched from an F-15 aircraft, was intended to place satellites weighing up to 45 kilograms into orbit for $1 million a launch, and do so on 24 hours’ notice.
ALASA suffered problems, though, linked to its use of an unconventional “mixed monopropellant” called NA7, a mixture of nitrous oxide and acetylene. Ground tests found that NA7 was less stable than expected and, in November 2015, DARPA changed the goals of ALASA to continue testing NA7, scrapping development of the launch vehicle.
DARPA, in its announcement of the XS-1 award, said that autonomous flight termination systems and related autonomous flight technologies developed as part of the ALASA program will be applied to Boeing’s Phantom Express vehicle.
