The United States has taken a major step towards once again launching astronauts into orbit from U.S. soil.

The U.S. space agency NASA named two private companies — Boeing and Space Exploration Technologies Corporation — to build and launch spacecrafts to and from the International Space Station.

NASA has relied on Russia to transport crews since it retired its space station fleet in 2011.

It hopes to resume launches from the U.S. in 2017.

NASA chief Charlie Bolden said Tuesday that the Obama administration has made it clear that what he calls the "greatest nation on Earth" should not have to depend on others to fly astronauts into space.

Bolden also says turning over low-orbit space missions to private companies would allow NASA to focus on the next major project — a manned mission to Mars.