Aerospace firm Northrop Grumman released artwork this week of its XS-1 space plane, which it is designed under a $3.9 million contract from the U.S. Defense Advanced Research Projects Agency (DARPA).

Northrop Grumman is one of three companies competing for the right to build the unmanned space plane. XS-1 is short for "Experimental Spaceplane," according to SPACE.com.

The other two companies competing with Northrop Grumman are Boeing and Masten Space Systems. Both companies also won yearlong "Phase 1" initial design contracts last month.

DARPA wants the XS-1 to make spaceflight more affordable and much more routine than it has been in the past. They want the vehicle to be able to fly 10 times in a 10-day span and launch around 3,000-to-5,000-lb. payloads to orbit for less than $5 million per flight, according to officials.

There is a good chance XS-1 will feature a reusable first stage and one or more expendable upper stages, according to SPACE.com. The first stage will fly to suborbital space at hypersonic speeds, then return to Earth to be used again. Upper stages will then deploy payloads to orbit.

Northrop Grumman is working with other companies on its design, like Scaled Composites, which will run manufacture-and-assembly work, and Virgin Galactic, which will lead XS-1 operation.

"Our team is uniquely qualified to meet DARPA's XS-1 operational system goals, having built and transitioned many developmental systems to operational use, including our current work on the world's only commercial spaceline, Virgin Galactic's SpaceShipTwo," Doug Young, vice president for missile defense and advanced missions at Northrop Grumman Aerospace Systems, said in a statement last week.

"We plan to bundle proven technologies into our concept that we developed during related projects for DARPA, NASA and the U.S. Air Force Research Laboratory, giving the government maximum return on those investments," he added.

Masten is working with XCOR Aerospace, and Boeing is teaming with Jeff Bezos' secretive firm Blue Origin on their designs.

DARPA will likely hold a Phase 2 competition next year to figure out which company makes it to the flight-test stage of XS-1 development. The agency only has enough money for one XS-1 contractor, according to SPACE.com.

The first orbital mission of XS-1 is expected to take place sometime in 2018.

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