Paris - The second part of a joint European-Russian mission to probe Mars for traces of life has been delayed two years, with a new launch date set for July 2020, officials say.
In the first phase, the European Space Agency (ESA) and its Russian counterpart, Roscosmos, hoisted two probes bound for the Red Planet in mid-March.
The Tracer Gas Orbiter (TGO) will examine Mars' atmosphere and a lander - dubbed Schiaparelli, after a 19th-century astronomer - will settle on the planet's surface in a trial run.
The planned second stage of the mission will dispatch a European rover capable of drilling up to 2m into the Martian surface in search of organic matter.
Space agency officials had warned that the follow-on ExoMars mission, originally scheduled for launch in 2018, might be delayed due to technical problems and cost overruns.
Schiaparelli will test heat shields and parachutes in preparation for a subsequent rover landing, a feat the ESA said "remains a significant challenge".
The 2020 payload will also be lifted into space by a Russian rocket.