A Mars sample return mission will be too big for any one agency

They have published a document that contains their common space goals, agreed after months of discussion.

The document outlines the rationale for society to explore space and the current interest in returning to the Moon and exploring Mars.

The document is non-binding, instead proposing a framework for the future co-ordination of space programmes.

The US space agency (Nasa) says the document, called The Global Exploration Strategy: The Framework for Co-ordination, will help different countries exchange information on their space plans.

In addition, it will help identify gaps, duplication and potential areas for collaboration.

'Global endeavour'

Nasa said the framework document was "an important step in an evolving process towards a comprehensive global approach to space exploration".

The agency added that the contents were consistent with "ongoing bilateral and multilateral discussions" on co-operating with other agencies.

SPACE AGREEMENT Space agencies involved in the agreement are: Asi (Italy) BNSC (UK) CNES (France) CNSA (China) CSA (Canada) CSIRO (Australia) DLR (Germany) Esa (European Space Agency) ISRO (India) JAXA (Japan) KARI (South Korea) Nasa (USA) NSAU (Ukraine) Roscosmos (Russia)

The UK's science and innovation minister Malcolm Wicks said: "The Framework for Co-ordination sets out a common vision for a new era of international collaboration.

"I welcome the fact that the UK can use this to inform our national plans while joining together in a truly global endeavour."

The US, Russian, Chinese and European space agencies have all outlined programmes of exploration of the Moon and Mars.

The European Space Agency's (Esa) exploration roadmap calls for a mission to return samples of rock and soil from Mars.

But experts say this the costs and technological demands of this project would be too much for any one agency to shoulder.

And both Esa and Nasa say they are keen to replicate the success of the Cassini-Huygens mission to Saturn.

But the first crucial mission in Esa's roadmap is facing a tough test, as ministers decide whether to approve a costly upgrade to the ExoMars rover project.

Observers fear Esa delegates could baulk at the expense - estimated at tens of millions of euros - of launching the rover with an orbiter to relay data back to Earth.

China has already said it will launch a joint mission with Russia to Mars, calling this a "milestone" in space co-operation between the two countries. But Russia last month said the US had rejected its offer to join forces on exploring the Moon.

Nasa wants to send astronauts back to the lunar surface by 2020, with a view to building a permanent lunar base.