Charlie Bolden, a former astronaut, took over the reins at Nasa today, inheriting a challenge perhaps greater than that faced by any of his predecessors in the US space agency’s 50-year history.

With the future direction of the American manned space programme at a crossroads, and its ageing space shuttle fleet set for retirement next year, Mr Bolden’s biggest task will be finding a way to get astronauts back to the Moon as cheaply and safely as possible.

The obstacles are numerous, not least tightened purse strings from the White House - Nasa’s budget for 2010 already includes a $566 million cut to funds originally allocated to its new human spaceflight programme, Constellation - and questions from Congress, the public and even within Nasa itself as to why and how astronauts go back to the Moon instead of heading for Mars.

President Obama has appointed a committee to review Constellation as technical problems mount. The panel is scheduled to deliver an interim report today amid speculation that it is preparing to ask Nasa engineers to tweak plans for the new Ares 1 rocket, set for its first test flight in this autumn, or even scrap the design altogether in favour of a cheaper alternative, sending them back to the drawing board.

Additionally, the new Nasa chief must find a way to inspire a new generation of scientists, engineers, technicians and astronauts after the shuttle era, during which American space policy was largely accepted to have lost its way.

In 1980, said Mr Bolden, 52, he could visit schools and ask children: “How many of you want to be an astronaut?”.

“Every hand went up,” he said. “When I go to a school today and ask that question, I may see three hands, and all of them want to go into business.”

But adversity is something that Mr Bolden, who flew four space shuttle missions as an astronaut, relishes.

“Today, we have to choose,” he said. “Either we can invest in building on our hard-earned world technological leadership or we can abandon this commitment, ceding it to other nations who are working diligently to push the frontiers of space.”

Just eight shuttle missions remain before retirement of the fleet in 2010. Today, the shuttle Endeavour will deliver seven astronauts to the International Space Station, joining the six-strong crew already there, creating the biggest ever human gathering in space.

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