LE BOURGET, France — The European Space Agency (ESA) on June 17 signed the final industrial contract needed to complete ESA’s work on a 2016 mission to Mars with a telecommunications orbiter and entry, descent and landing module, and to continue development of a companion 2018 mission.

The contract, valued at about 230 million euros ($300 million), was signed with Thales Alenia Space Italy five years after the company originally won the competition to be prime contractor for the two-launch mission, called ExoMars.

The mission has survived multiple near-death moments as several ESA governments, notably France, questioned its value and whether the industrial team could meet the 2016 deadline. Further turbulence followed NASA’s decision not to provide two Atlas 5 rockets as initially foreseen.

The 20-nation ESA has now partnered with Russia’s Roscosmos space agency, which is providing two Proton rockets for ExoMars and is also leading development of a separate landing module to accompany a 350-kilogram European rover on the 2018 mission.

ESA still needs to find some 150 million euros, and perhaps more, to finish its share of the 2018 mission. But that task now seems much easier with Russia firmly on board, and with the signing of the full contract for the 2016 mission.

ESA Director-General Jean-Jacques Dordain said he would sign with Roscosmos later this week a detailed list of who provides what for ExoMars, whose most notable feature is the rover’s drill permitting it to plunge two meters below the Mars surface to look for signs of past or present martian life.

Dordain went out of his way at the contract-signing ceremony to praise the Thales Alenia Space Italy industrial team, whose work to guarantee it made the 2016 launch date was the subject of open skepticism in Europe.

Jean-Loic Galle, chief executive of Thales Alenia Space, returned the compliment to ESA, noting that Dordain has made ExoMars a personal cause. “ESA showed more than tenacity, it was a persistent commitment,” Galle said.

Vincenzo Giorgio, Thales Alenia Space Italy vice president for science, signed the contract with ESA. Giorgio said 146 million euros of the total sum of 230 million euros will be spent on the 2016 mission — telecommunications orbiter plus lander — and the remaining amount will go toward continued work on the European rover.

The solar-powered rover, equipped with Russian-supplied nuclear heaters to keep the instruments warm during the martian nights, is designed to operate for six months. It will then be put in a standby mode to wait out the martian dust storms before being activated again.

Peter B. de Selding was the Paris Bureau Chief for SpaceNews.