Talks to resolve the design of Europe's rover mission to Mars are converging on a "best solution for science", a senior space official has told the BBC.
The option in question would require an upgrade to the original vision.
But observers fear some European Space Agency (Esa) delegates could still baulk at the enormous costs of an enhanced mission.
More: http://news.bbc.co.uk/2/hi/science/nature/6693879.stm