NASA plans to more than triple its investment in commercial space taxis, with new awards to three of the four firms already hired to design passenger ships to put astronauts — and tourists — into Earth orbit.

Sticking with its tried and true, NASA signed agreements worth more than $1 billion for  Boeing, SpaceX and Sierra Nevada Corp to continue work on commercial space taxis that could fly astronauts to the International Space Station.

The new awards, announced Friday, will enable the trio to continue work through May 2014.

Boeing and SpaceX, which are both working on capsules, will split the lion’s share of the funds, receiving $460 million and $440 million, respectively.

Sierra Nevada, which is developing the winged Dream Chaser vehicle, will receive $212.5 million.

Shut out of the competition was ATK, which offered a rocket based on the space shuttle’s solid boosters and a crew capsule originally developed as an alternative to NASA’s planned deep-space Orion capsule. founder Jeff Bezos’s startup, Blue Origin, which won $25.7 million during two predecessor programs, did not bid for the integrated design contracts awarded Friday.

Three other firms — Space Operations, American Aerospace and Space Design — submitted proposals but were eliminated for not meeting requirements, NASA’s associate administrator for space operations Bill Gerstenmaier said during a conference call with reporters.

The new awards will more than triple NASA’s investments in commercial crew programs, which so far total about $365 million.

In its proposal, SpaceX said that if funding and technical milestones were met, it could conduct a crewed test flight in 2015. Boeing’s target is the end of 2016.

 Image: Artist's rendering of SpaceX passenger Dragon capsule in orbit. Credit: SpaceX