NASA has unveiled a plan to fund a fleet of "space taxis" that would replace its decades-old shuttle program, which the space agency retired in July. But rather than design and build these space taxis itself, NASA is bringing in private contractors to do the work. The agency is calling this an "Integrated Design Contract," which calls for private firms to provide "rockets, spaceships, launch services, ground and mission control operations, and spacecraft recovery after landing," says Tariq Malik at Here, a guide to this announcement:

Why does NASA need space taxis?
To get astronauts to and from the International Space Station. Currently, only the Russian Soyuz spacecraft is able to ferry people to the ISS. But "a Russian cargo ship failed last month to reach orbit after a launch accident, exposing the vulnerability of having only one way for crew to fly to the space station," says Irene Klotz at MSNBC.

Who is expected to win these NASA contracts?
That question should be answered in a few months, though four companies are frequently cited as prime candidates: Boeing, California-based SpaceX, Sierra Nevada Corp. of Colorado, and Blue Origin, an aerospace company set up by Amazon's Jeff Bezos in Kent, Wash.

How much will these taxis cost?
The fare for these taxis is expected to total $1.61 billion, to be doled out between 2012 and 2014, though "actual funding could be significantly lower than the total proposed in the Obama administration's 2012 budget," says James Dean at Florida Today. By outsourcing the taxi plan to these private companies, "NASA can focus its energy and resources on deep space exploration," says NASA official Charles Bolden.

Sources: Florida Today,,,