Russian scientists want to launch a nuclear-powered spacecraft - and could have the prototype ready by 2012.
But while the ambitious plan would give Russia's space programme an atomic lift, not everyone is convinced it will get off the ground.
And environmental activists fear it is too dangerous to consider firing atomic materials into space owing to the risk of problems on re-entry.
Federal Space Agency chief Andrei Perminov got the backing of President Dmitry Medvedev for the plan, the Associated Press reported.
But Houston-based rocket engineer James Oberg was sceptical about the plan, saying Perminov was looking for a backer "with more dollars than sense".