These factors will determine if the expected plan will enjoy the same glory as John F. Kennedy's 1961 pledge to place an American on the Moon by 1970 -- or whether history will dismiss it as a political flourish in an election year.

Sources in the US National Aeronautics and Space Administration (NASA) say the Bush scheme entails scrapping the ageing shuttle fleet by the end of this decade, pulling back from the International Space Station (ISS) a few years later and ploughing resources into lunar and then interplanetary manned missions.

Trips to the Moon, where Man last set foot more than 31 years ago, would resume around 2015, providing the experience and expertise for a later mission to Mars, according to these sources.

The phaseout of the discredited shuttles and cash-burning ISS will cause many scientists to heave sighs of relief.

Many rubbish these projects as rotations around Earth's back yard that do almost nothing to advance knowledge when compared to the low-cost unmanned missions such as the Mars rover Spirit.

Sending humans to Mars will test technical, psychological and financial resources to the limit.

"Going to the Moon is one thing, you can take them there in one or two days, but going to Mars is quite a different story," Hans Rickman, general secretary of the Paris-based International Astronomical Union (IAU), said.

Apollo 17 made a there-and-back mission to the Moon from December 7-19 1972.

But a voyage to the Red Planet, depending on the relative orbital positions of Earth and Mars, would take at least six months there and six months back with today's slow chemical rockets.

Factor in time spent on the planet's surface -- a hostile environment with an arid, rocky landscape, blood-freezing temperatures and a suffocating atmosphere of carbon dioxide -- and the trek would probably take some two years in all, imposing monstrous strains on the crew.

A spaceship to Mars would have to be roomy, shielded from cosmic radiation and collision with space rocks, and supplied with tonnes of food, water, oxygen and fuel.

There would have to be enough for the outward and return trips and the time spent on Mars itself, if no substitute can be found, grown or manufactured on the planet.

"Electric nuclear propulsion will be the key to going to Mars," said Richard Heidmann, a rocket motor engineer who is head of the French branch of the Mars Society, referring to the revolutionary concept of a fast-thrust ion engine.

All these amount to a bill with many zeroes on the bottom line.

The last time an American president made a Kennedyesque stab at setting foot on the Red Planet was in 1989.

And the dreamer was Bush's own father, who also saw a lunar stepping stone to Mars. The vision was put on hold after experts put the tab at between 400 and 500 billion dollars.

But the bill may not have to be that high, say others.

According to a 1997 NASA estimate, a Martian trip would cost between 30 and 40 billion dollars, about half of which would have to be spent on rocket boosters to get material into low orbit around Earth, and then to send the assembled ship zooming towards the Red Planet.

Dick Taylor, secretary of the British Interplanetary Society, said the cost of the heavy lifting of payloads could be slashed by using the Moon's low gravity.

Robots could build a lunar factory, extracting minerals and helium from moon rocks to manufacture propulsion systems, accommodation modules and fuel for long-term missions.

All rights reserved. � 2004 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.

Related Links
Whitehouse
Human Spaceflight at NASA
Apollo at The Smithsonian
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only