One of three privately owned space taxis being developed in partnership with NASA to ferry crews to the International Space Station took to the skies over Mojave, Calif., this weekend, but the successful debut test flight was marred by a landing gear problem.

A full-scale mockup of Sierra Nevada’s seven-person Dream Chaser space plane was hauled to an altitude of 12,500 feet by a heavy-lift Sikorsky skycrane helicopter and released for a one-minute glide back to the runway.

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The primary goal of the test flight was to validate the aerodynamic design of the winged Dream Chaser, the first so-called “lifting body” human spaceflight vehicle to fly since NASA’s prototype space shuttle Enterprise 40 years ago.

In addition, the test was intended to show that the vehicle could autonomously fly and land itself.

“We accomplished all those, so from our perspective it was a successful test,” Sierra Nevada Corp. vice president Mark Sirangelo told Discovery News.

Not so successful was what happened after the space plane touched down on a runway at Edwards Air Force Base in California. One of Dream Chaser’s three landing gears failed to drop down, leaving the vehicle struggling for balance as it shot down the landing strip.

Ultimately, the mockup, which is about the size of a regional airplane, skidded off the runway and ended up in the sand, Sirangelo said.

No one was injured, nor was there any damage to the runway.

Damage to the Dream Chaser is still being assessed, he added.

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The vehicle had been scheduled for a second autonomous flight, but Sirangelo said Saturday’s test was so successful, the company may be able to skip the second unmanned glide and proceed directly to a piloted test flight slated for next year.

In that case, Dream Chaser would be returned to Sierra Nevada’s manufacturing facility in Colorado for repairs and to be outfitted for the piloted flight, Sirangelo said.

The landing gear, which was deployed 10 seconds to 15 seconds before touchdown, is not the same equipment planned for Sierra Nevada’s orbital ship, he added.

“The vehicle ended upright on its gear. It skidded off the runway, so it did wind up ending as it would have landed on its gear off the runway. It went through some maneuvers where it did shake and turn and move over,” but it doesn’t appear to have cartwheeled, Sirangelo told reporters during a conference call on Tuesday.

“We’re still studying the footage. There was a lot of dust out there,” he added.

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Sierra Nevada, SpaceX and Boeing are working under separate NASA partnership agreements to develop passenger spaceships by 2017.

Sierra Nevada on Tuesday released video of Dream Chaser’s glide, but not the botched landing.

“We’re going through an accident (investigation) right now. We think this is a private test and a private program. We’re trying to be open about it, but we’ll see what we’ll do. I haven’t made that determination (to release the rest of the video) yet,” he said.

Watch the successful drop test here:

Image: Coming in for a touchdown — sans left landing gear. Credit: Sierra Nevada Corp video/Screenshot Irene Klotz, Discovery News.