MOSCOW — Russia should build a new nuclear-powered spaceship for prospective manned missions to Mars and other planets, the nation's space chief said Thursday.

Anatoly Perminov first proposed building the ship at a government meeting Wednesday but didn't explain its purpose. President Dmitry Medvedev backed the project and urged the government to find the money.

Perminov said the preliminary design could be ready by 2012, and then it would take nine more years and cost 17 billion rubles (about $600 million, or euro400 million) to build the ship.

"The project is aimed at implementing large-scale space exploration programs, including a manned mission to Mars, interplanetary travel, the creation and operation of planetary outposts," Perminov's Web statement said.

NASA's plan to retire its shuttle fleet next year will force the United States and other nations to rely on the Russian spacecraft to ferry their astronauts to and from the International Space Station until NASA's new manned ship becomes available.

Igor Lisov, a Moscow-based expert on Russian space program, said the prospective ship would use a nuclear reactor to run an electric rocket engine.

"It will be quite efficient for flight to Mars," he told The Associated Press on Thursday. Lisov said Soviet work on a nuclear-powered electric rocket engine dates back to the 1960s when Soviet engineers began developing plans for a manned flight to Mars. He said Russia's experience in building nuclear-powered satellites would also help develop the new spaceship.

"It will require a significantly more powerful nuclear reactor, but the task is quite realistic," Lisov said.