By Dr David Whitehouse BBC News Online science editor

Should we return to the Moon...

Retired Admiral Harold Gehman, who led the accident investigation team, said their report will not address the future of the space shuttle. But he also said it will be more than just an accident report.

Likewise, many space officials and politicians see it, along with the US Government's and Nasa's response, as setting the direction for the future of US manned spaceflight.

Nasa's immediate goal is to get the shuttle flying again, hopefully by next summer. The fate of the International Space Station (ISS) is tied to the shuttle.

But what is the future of the space shuttle?

Old technology

Critics say that because it first flew in 1981 it is fundamentally based on 1970s technology, and in the new millennium Nasa should have developed something more advanced.

Certainly the efforts made to develop a successor have been faltering with false starts, cancellations, and an obvious lack of commitment. Many hope that the Columbia accident will change that.

...or go on to Mars?

Before the accident Nasa had suggested that the shuttle fleet could remain active until 2020. Now that seems inconceivable.

Whatever happens to the shuttle it is unrealistic to expect no more fatal accidents. Getting into space will always be dangerous involving the liberation of barely-contained energies unforgiving of accidents.

But there are larger issues thrown up by the enforced reappraisal of manned spaceflight. Many believe that Nasa is in need of a new goal, and a new strategy to reach it.

Some are arguing for less emphasis on the ISS, saying that it is neither bold, nor exciting enough to inspire the public's interest in manned spaceflight.

Critics point out that since 1972, the date of the last moon landing, Nasa astronauts have literally been going around in circles. Since then no astronaut has ventured more than a few hundred miles from Earth.

So is it about time to go somewhere? Would the public more readily accept and understand the risks of manned spaceflight if we give explorers a destination?

There are only two places to go. Should it be a return to the Moon or the conquest of Mars?

Been there, done that

The Moon is close at hand and astronauts could resume voyages to it within years but some would say we have "been there, done that".

Sending humans to Mars is a far greater task than returning to the Moon.

At the moment Nasa is uncommitted to the manned exploration of the Red Planet.

It says that decisions about sending astronauts to Mars do not have to be made yet, and that the unmanned projects underway to explore Mars are just what are needed if they ever decide to send men to Mars.

For some that pragmatic approach is the problem. A goal, they argue, is only a goal if it involves stated commitment and true ambition - the missing factor in manned missions that endlessly circle the Earth.