Europe is to continue its plan to put a UK-assembled robotic rover on the surface of Mars in 2021.
Research ministers meeting in Lucerne, Switzerland, have agreed to provide the outstanding €400m needed to take the project through to completion.
The mission is late and has cost more than originally predicted, prompting fears that European Space Agency (ESA) member states might abandon it.
However, the ministers have reaffirmed their commitment to it.
They have also said that ESA participation in the International Space Station (ISS) should run until at least 2024, which will open new opportunities for European astronauts.
The Ministerial Council was convened to set the policies, programmes and funding for ESA over the next three to five years.
Officials at the agency had put a variety of activities before member state delegations valued at €11bn, covering all manner of activities ranging from rockets and Earth Observation to big data management and satellite navigation.
At the end of one and a half days of deliberations, the 22 governments agreed to fund €10.3bn.