Manhattan from space: Critics say Nasa should now stay public

The move would remove the shuttle operation from direct control by Nasa and make it a customer. But the proposal is not without controversy.

One senator has questioned the timing of such a move given the US war in Afghanistan, but the Bush administration is keen to press ahead with the money-saving scheme.

The space shuttle may be a technological marvel but it is a financial millstone. Each launch costs around $400m, which is why most of the flights to the International Space Station (ISS), for example, use cheaper Russian rockets.

Some Nasa officials believe that privatising the shuttle fleet could save them money. There is a precedent.

Strategic importance

Five years ago the agency contracted a private company to tend the shuttles when they are on the ground, to clean them and prepare them for flight. This arrangement has saved over $1bn so far.

However, taking the entire shuttle operation, the flagship of the American space programme, out of public hands would be a far more controversial step, not least because of its strategic importance.

Senator Bill Nelson, a former astronaut, said this was the worst time of all to consider such a move. He pointed to the shuttle's role in putting intelligence satellites into orbit.

But the Bush administration wants to reduce Nasa's budget, and has pressed the agency to explore privatisation, which could result in up to 1,000 staff, as well as the shuttles themselves and perhaps launch facilities too, being placed in private hands.

Nasa stresses that no decision has been reached, and any changes would not come into force before 2004 at the earliest.

An independent panel has criticised Nasa for overspending and has described its running of the International Space Station as "not credible".