NASA needs a design for $1 billion space-tug for International Space Station

Taking the aging International Space Station (ISS) out of orbit will require a potentially $1 billion space-tug – and NASA just recently kicked off its search for design proposals of such a spacecraft.

The space-tug that NASA has started fielding proposals for will be “focused on the final deorbit activity” of the entire process that will ultimately see it come out of orbit somewhere over an ocean far away from people, NASA said earlier this month in a blog post. The spacecraft, which can be a novel design or a modification of an existing one, has been officially referred to as the U.S. Deorbit