New Experimental aircraft

Artist's concept of DARPA's Experimental Spaceplane (XS-1), a proposed unmanned, hypersonic vehicle that the agency hopes will lower satellite launch costs substantially. Officials are targeting Mach 10 for the suborbital vehicle.

SAN DIEGO — The United States military is kick-starting a suborbital hypersonic vehicle program that also aims to launch payloads into orbit on the cheap.

The new program, run by the Defense Advanced Research Projects Agency, is called Experimental Spaceplane, or XS-1. It follows in the footsteps of previous DARPA hypersonic projects, such as the HTV-2 aircraft that reached 20 times the speed of sound in an August 2011 test flight.

Officials want the reusable, unmanned XS-1 to take advantage of capabilities to be showcased under another DARPA initiative, the Airborne Launch Assist Space Access (ALASA) program, which aims to launch small spacecraft (up to 100 pounds, or 45 kilograms) in the 2015-2016 time period for just $1 million per liftoff, including range costs. [The Top 10 Space Weapons]

The XS-1 endeavor would allow routine access to space for a larger payload class — 1, 000 pounds to 4, 000 pounds or so (454 to 1, 814 kg) — at about $5 million per launch, officials said.

'Radical and disruptive changes'

Former NASA astronaut Pamela Melroy is now deputy director of the Tactical Technology Office at the Defense Advanced Research Projects Agency (DARPA), scoping out low-cost access to space.

"We’re looking for radical and disruptive changes, " said former NASA astronaut Pamela Melroy, now deputy director of the Tactical Technology Office at DARPA. "We are about demonstrations. It’s not enough to just experiment. You have to actually prove it."

Melroy spoke here Thursday (Sept. 12) at the American Institute of Aeronautics and Astronautics' (AIAA) Space 2013 conference, during a panel session on aligning technology roadmaps

After her NASA career, Melroy helped to investigate the 2003 space shuttle Columbia disaster and also served as the acting deputy associate administrator and director of field operations in the Federal Aviation Administration’s Office of Commercial Space Transportation, a body that is starting to develop regulatory approaches for private manned spaceflight.