The military is building a space plane. Now it looks to have an engine up to the task

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A new generation of GPS satellites is set to launch into orbit later this year. As with other national security missions, a roughly 200-foot-tall rocket will blast the massive satellite to space, fulfilling a contract worth more than $80 million.

But as nations develop technology to disable or shoot down satellites, the U.S. military has started to look at ways to rapidly and cheaply launch smaller craft into space. One option: a reusable space plane that could launch small satellites 10 times in 10 days, spearheaded by a Pentagon research agency and aerospace giant Boeing Co.

The vehicle’s first test flight is set for 2021, which hints at the Defense Department’s growing interest in reusable rocket technology, particularly its potential to drive down launch costs and speed up turnaround time.


In recent weeks, the space plane’s rocket engine, known as the AR-22, completed 10 test fires in 240 hours without need for refurbishments or major repairs, said Jeff Haynes, program manager at Aerojet Rocketdyne. The test firing took place at NASA Stennis Space Center in Mississippi from June 26 to July 6.

The engine test is “really good progress,” said Claire Leon, director of Loyola Marymount University’s graduate program in systems engineering and former director of the launch enterprise directorate at the U.S. Air Force’s Space and Missile Systems Center.

“SpaceX has had its success,” she said. “I think this engine test also demonstrates that other companies are doing the technology development and having success that will enable reusability.”

The first reusable space launch system was NASA’s Space Shuttle, though more recently, several commercial space firms, including Microsoft co-founder Paul Allen’s Stratolaunch and British billionaire Richard Branson’s Virgin Orbit, have developed systems that would reuse aircraft to launch satellites from the belly of a plane. Inc. Chief Executive Jeff Bezos’ Blue Origin space firm also has reused its New Shepard rocket and space-capsule system numerous times.

Elon Musk’s SpaceX brought the concept of reusability back into the public eye with its 13 flights of used first-stage boosters since 2017, though Defense Advanced Research Projects Agency and Boeing officials say their experimental space plane is aimed at a much lighter weight class of satellites. SpaceX’s workhorse Falcon 9 rocket is capable of carrying payloads of about 50,000 pounds to low-Earth orbit.


Scott Wierzbanowski, experimental space plane program manager at DARPA, described it as a “launch on demand” kind of service, in which smaller satellites could be taken to a specific orbit when they need to, rather than piggybacking onto scheduled launches that revolve around the needs of the larger, primary payload.

“The military right now is really reassessing their needs,” said Bill Ostrove, aerospace and defense analyst at Forecast International. “DARPA is trying to see what is possible.”

The Air Force has also developed the X-37B experimental space plane, which looks like a smaller version of the space shuttle orbiter. Details of its missions are scarce, but the uncrewed robotic space plane’s last mission involved 718 days in orbit before returning to Earth.

Southern California has played a role in the DARPA space plane’s development, with some design work, engineering and program management taking place in the region, largely at Boeing’s Huntington Beach facility, but also in Seal Beach and El Segundo. Engineering staff for the rocket engine, manufactured by Aerojet Rocketdyne, are based in Canoga Park.

The 100-foot-long vehicle with a 62-foot wingspan is being designed for rapid reusability similar to that of commercial aircraft, program officials said. The space plane, however, will launch vertically like a typical rocket, deploy an expendable second-stage booster that will push the satellite to its intended orbit and then return to Earth and land horizontally like a plane on a runway.

To do this, Boeing has leaned on its commercial aircraft division. The composite materials used for the space plane’s fuel tanks, wing skins and other areas were based on investments made during development of the company’s 787 jetliner, which has an outer structure largely made of composites.


The space plane’s design approach was also derived from commercial aircraft to make the vehicle easier to maintain and operate, said Steve Johnston, director of launch at Boeing Phantom Works.

The vehicle’s engine has been designed and tested to hold up in space and includes parts that powered NASA’s Space Shuttle.

The space plane is expected to launch satellites to low-Earth orbit weighing up to 3,000 pounds. That means the spacecraft would be well below the weight of the typical school bus-sized spy satellites that are launched to a higher, geostationary orbit.

But they would be heavier than satellites weighing hundreds of pounds that are envisioned as the core of commercial constellations — of hundreds or even thousands of spacecraft — to provide broadband or Earth-imaging capabilities.

DARPA recently launched a separate challenge focused on commercial small-satellite launch companies, providing cash prizes for teams that can launch tiny payloads with minimal notice. Wierzbanowski of DARPA said he could envision the two programs working together and said their focuses were “complementary.” The concept of having more rapid launch capabilities has taken on more importance as other nations develop anti-satellite capabilities, as China did in 2007 when it shot down one of its own satellites with a ground-based ballistic missile.

Total government funding for the space plane program is estimated at $146 million. Boeing declined to disclose its investment, saying only that it was a “significant commitment.” The ultimate goal is to reach a per-launch cost of $5 million, Wierzbanowski said.


That could make the space plane, once operational, significantly cheaper than the existing rockets already aimed at the medium-sized satellite market, including India’s PSLV, Europe’s Arianespace Vega and Northrop Grumman Corp.’s Minotaur IV. The launch price for a Minotaur or Vega rocket can range from $35 million to $40 million, said Phil Smith, senior space analyst at Bryce Space and Technology.

Boeing plans to commercialize the space plane, which it calls the Phantom Express, offering it to government and commercial customers.

But the unique design concept is no guarantee of success, Smith said.

“The engine test was spot on in terms of the expectations for that engine to support the mission,” he said. “But it does remain to be seen.”

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