Europe’s research ministers are meeting in Lucerne, Switzerland, to decide whether or not to push ahead with plans to land a robot rover on mars in 2021.
The UK-assembled vehicle would search for life on the red planet by sampling soil drilled from under the surface.
But the project is late, and now needs another $430m to be sure of meeting its launch deadline.
Ministers from the member states of the European Space Agency will discuss the rover’s fate over two days.
ESA’s Director-General, Jan Woerner, has taken a hard line in the run-up to the Lucerne gathering.
He has told member states that the only way to proceed with the rover is to give it full and proper financial support or none at all.
The so-called Exomars rover has suffered chronic organisational problems throughout its development history, and has come close to being abandoned on a few occasions. In May, it was announced that its launch date would slip by a further two years because a number of industrial and scientific teams could not be sure of delivering their hardware on time.