It was meant to be a groundbreaking mission to search for life on Mars that would launch in 2018 — now, it won’t happen for another two years.

Russia and Europe are now looking at 2020 for the launch of the life-scouting rover mission ExoMars, as that will be when Earth and Mars are next best aligned for an interplanetary flight, according to a European Space Agency statement.

The statement noted that while Russian and European experts tried their best to make the 2018 launch date, a panel investigating their options decided that it would be best to reschedule for July 2020. Program managers will be going back to their project teams and industry contractors to work on new schedules.

The new launch date will put the mission in parallel with NASA’s Mars 2020 mission, which is a follow-up to the Curiosity rover. That mission aims to assess the habitability of Mars which could provide the basis for a manned mission in the coming decades.

“The successful implementation of both ExoMars missions will allow Russia and Europe to jointly validate cutting-edge technologies for Mars entry, descent, and landing, for the control of surface assets, to develop new engineering concepts and service systems that can be used by other Solar System exploration missions, and to carry out novel science at Mars,” the statement reads.