Europe has formally invited Russia to participate in financially troubled unmanned space missions to Mars set for 2016 and 2018, officials said.

An agreement with the Russian Roscosmos space agency may be the only way to keep the projects, at risk of being canceled for lack of money, going forward, the BBC reported Friday.

The 2016 mission would put a satellite in orbit to study the martian atmosphere while the 2018 effort would land a robot rover on the planet's surface.

Both mission have been planned in cooperation with NASA, which is also dealing with budget cuts.

If Russia agrees to provide its Proton rocket to launch the 2016 satellite, it should make both planned missions financially feasible, officials said.

In return, Russia would likely ask to provide instrumentation and technology for the missions and for its researchers to be included in the science teams.

"Everything is open for discussion," Alvaro Gimenez, European Space Agency director of science, said.