The U.S. Governmental Accountability Office (GAO) announced on Monday that it is rejecting Sierra Nevada's protest regarding the $6.8-billion space taxi contracts that NASA awarded to Boeing and SpaceX.

On October last year, Sierra Nevada went to court to block the two companies from starting the space taxi project. The space taxi contract amounts to $6.8 billion as part of NASA's plan to cut its dependence from Russia by 2017. Boeing was awarded $4.2 billion to build its CST-100 while SpaceX received $2.6 billion for its Dragon V2 capsule. Both spaceships have capsules with parachute assisted landings. Sierra Nevada's Dream Chaser, on the other hand, is a mini-shuttle that needs a runway for landing.

Sierra Nevada started its protest in September, arguing that their bid will allow the space agency to save $900 million.

William Gerstenmaier, head of NASA's manned programs, explained the reason they chose the other bidders even if Sierra Nevada's proposal was cheaper. They found the vehicle design too technical and that it may need critical design decisions that might delay the project launch.

Still, the Southern California-based company decided to step up the legal battle and brought its protest to the U.S. Court of Federal Claims in Washington.

After careful evaluation of the alleged contract irregularities, the GAO ruled in favor of NASA's decision, according to the Washington Post.

"NASA recognized Boeing's higher price but also considered Boeing's proposal to be the strongest of all three proposals in terms of technical approach, management approach and past performance, and to offer the crew transportation system with most utility and highest value to the government," said Ralph White, NASA's managing associate general counsel, in a statement.

Sierra Nevada expressed its disappointment of the ruling, but did not say what its next step will be, Reuters reported.

"The outcome was not what SNC expected," Sierra Nevada said in a statement.