Boeing [BA] and Space Exploration Technologies Corp. (SpaceX) on Tuesday won a pair of contracts from NASA totaling $6.8 billion for Commercial Crew (CCP), the civil space agency's highly-anticipated effort to taxi astronauts to and from the International Space Station (ISS) by 2017. Boeing was awarded $4.2 billion and SpaceX $2.6 billion, a NASA official said Tuesday during a briefing. Sierra Nevada Corp. (SNC) and Jeff Bezos-backed Blue Origin lost out on Commercial Crew, which is provide an alternative to relying…