AMERICA'S plans for manned missions to the Moon are set for a shake-up that could make or break the country's lead in the space race – and bring new risks.
Dr Michael Griffin, who was appointed to lead Nasa by President George Bush four years ago, is expected to step down this Friday after the incoming Barack Obama failed to renew his tenure.
The removal of the 59-year-old rocket engineer – credited
with restoring credibility and purpose to Nasa after the Columbia disaster of 2003, in which seven astronauts died – paves the way for potential changes to Constellation, the programme by which humans will again step on to the Moon and venture beyond to Mars using new spaceships.
But extending the life of the shuttle to close the gap between its planned retirement next year and the launch of its replacement in 2015, an option Mr Obama has proposed, would cost an extra $3 billion (£2 billion) a year and vastly raise the chances of another deadly accident, Dr Griffin has warned.
Flying the shuttle twice a year from 2011 to 2015 would pose "about a one-in-eight chance of losing another crew on one of those ten flights", he told a meeting of the Space Transportation Association. "It can be done. Whether it should be done is another question," he said.
Keeping the shuttle flying beyond its intended retirement date would also risk diverting manpower, money, equipment and facilities such as launchpads and assembly plants away from Constellation, causing further slippage.
One of the major issues being examined by Mr Obama's transition team, with whom Dr Griffin is said to have clashed in recent weeks, is whether Ares 1 – the $2.7 billion rocket model currently under development as a means of launching humans into space after the shuttle – should be scrapped.
Critics say it is flawed and too expensive, and Nasa should fall back on alternative designs or existing military models that could also speed up the programme. But Dr Griffin and other proponents say Ares is America's best chance of a new era of space exploration and that changing tack now would threaten the timetable.
Nasa owns three shuttles – Atlantis, Discovery and Endeavour, the oldest of which is now 28 years old.
They are due to fly another eight missions to ferry crew, equipment and construction parts to the International Space Station (ISS) 220 miles above Earth – plus one to repair the Hubble space telescope another 160 miles further out – before being withdrawn from service at the end of 2010.
After that, under the current plan, Nasa would have to pay the Russian space agency to ferry American astronauts back and forth until Ares – and Orion, the new crew-carrying spaceship that will launch on top of it – are ready to head to the ISS. Such a move would be a major humiliation to the US.
"Our space programme is something the US has taken a leadership position in for almost 50 years and to say we are not going to try to maintain that leadership in some significant way would be a negative sign," said Professor John Logsdon, a space policy expert at the Smithsonian Institution's National Air and Space Museum.
Under present plans, the aim is to get American astronauts back on the lunar surface by 2020, 51 years after Neil Armstrong made his first giant leap for mankind.
Prof Logsdon said: "The Moon by 2020 is already a difficult goal.
If we switch goals it means we are changing our plans for the Moon, or delaying the first return to the Moon."
Frontrunners for Dr Griffin's job include Charles Bolden, a former space shuttle commander, and Charlie Kennel, a former head of Nasa's Earth science division and chairman of the National Academy of Science's Space Studies Board.
Prof Logsdon added: "It's time to retire the shuttle and put the resources into the next programme rather than continue to fly it out of pride."
BACKGROUND
EACH shuttle was originally designed by NASA for a projected lifespan of 100 launches or 10 years' operational life – the oldest is now nearly 28, which is a testament to the durability of the vessel. Six air-worthy shuttles have been built; the first orbiter, Enterprise, was not built for space flight and was used only for testing purposes. Five space-worthy orbiters were built: Columbia, Challenger, Discovery, Atlantis and Endeavour.
Challenger disintegrated 73 seconds after launch in 1986, and Endeavour was built as a replacement. Columbia broke apart during re-entry in 2003. It is estimated that the space shuttle programme has cost about $170 billion (£112 billion) up to 2008. This works out to an average cost per flight of about $1.5 billion (£989.5 million).
