By Jonathan Amos
Science reporter, BBC News, Kennedy Space Center
The boss of the European Space Agency has asked his officials to find a new name for the flagship ExoMars mission.
Jean Jacques Dordain said the rover concept had changed so radically since first envisioned and costed that it was really now a new venture.
Mr Dordain will ask ministers in November for a near doubling of the 650-million-euro budget for ExoMars they originally agreed in 2005.
The robot rover - whatever its name - should launch for Mars in 2013.
"I am asking [my officials] to find a different way to define ExoMars because if we say 'this is ExoMars', for most of the ministers it means 'over-cost'.
"And this is not over-cost because we are not speaking at all of the same mission; it is a completely different mission. This is to try to make ministers understand that this is not over-cost."
ExoMars will be Europe's big space exploration project in the next decade.
The plan is to put a hi-tech vehicle on the Red Planet's surface with a range of instrumentation capable of investigating the planet's life potential - past and present.
When the idea was first put to European space ministers three years ago, they embraced the project and actually gave it slightly more money than was being asked for at the time.
But as the detailed design work was carried out, it became clear the original concept would not meet the expectations of scientists; and a decision was taken within the European Space Agency (Esa) to beef up the mission.
EXOMARS MISSION CONCEPT
Set to leave Earth in 2013; primary aim is to search for life
Will launch on a heavy-lift Proton or Ariane 5 rocket
Vented landing bags allow for a larger payload
Rover will carry a 16.5kg 'Pasteur' instrument suite
30kg geophysics/environment static station also possible
This would study the weather and listen for 'Marsquakes'
Concept to cost Esa states more than first estimates
"Today what I call 'ExoMars 2008' is different from the 'ExoMars of 2005'," Mr Dordain said.
"This is why I'm looking for a different name. In 2005, it was mostly a technological mission with some scientific passengers. But the interest in Mars, and specifically exobiology, meant that I had a queue of scientists wanting to go onboard ExoMars.
"Now we have a scientific mission as much as a technological mission, meaning that the ExoMars 2008 is heavier, is more complex and is more costly."
The increased cost may present real problems for some countries, however.
In particular, the UK, which had signed up to be a lead partner on the mission, now faces having to find tens of millions of euros extra to maintain its position on the project.
Next week, the British government will unveil a new space strategy. It has made clear its desire to increase its Esa contributions, and to host a specialist Esa research centre, most probably one that investigates space robotics.
Detailed legal work on that centre is being conducted now and the facility itself could be approved at the Esa Council meeting at ministerial level in The Hague on 25-26 November.
Mr Dordain said he had been encouraged lately by the UK's attitude, which in the past he has described as "anomalous" because of the nation's relative reluctance to get involved in the agency compared with Germany, France and Italy.
"The UK is the second richest country in Europe and the sixth [largest] contributor in Esa," he told BBC News.
"And this is all the more an anomaly because there are a lot of capabilities in the UK; there is a fantastic scientific community, there are good industrial capabilities and it is a pity that the British government is not taking more benefit from these assets."
Mr Dordain was speaking here in Florida after the launch of the Columbus science laboratory to the International Space Station, one of the voluntary Esa programmes in which the UK currently refuses to get involved.