Safely covering the ruined remains of the Chornobyl nuclear power plant has been the mission since April 26, 1986, when the fourth reactor exploded, creating a deadly fallout that is still being calculated today in lives and environmental damage.

Today, more than 30 years later, the latest stage of the mission will be to position the New Safe Confinement — a massive, arched, steel structure — over the crumbling concrete sarcophagus. This will hopefully entomb the doomed reactor — and its lingering radiation – for at least a century.