Mann is an ice planet that orbits the black hole Gargantua.
It takes its name from the first astronaut to land there named Dr. Mann,
He gets there ten years prior to the launch of Endurance.
Mann realizes his planet was uninhabitable. He dropped probes at nearby locations with the hope of finding a rocky, habitable surface, below the frozen clouds they stood on.
After years of probing and exploration, he found no surface. He uses the power-source of one of the automated machines programmed with artificial intelligence created by NASA for extra energy for his hypersleep chamber.
When the Cooper arrives on the planet, he awaken Dr. Mann, who convinces him that his world is habitable.
Some informations: no surface was ever found, in fact, the planet is honeycombed with seemingly endless layers of frozen ice-cloud crevices and mountains.
The clouds must freeze and evaporate repeatedly, which could be caused by the eccentricity of Mann's orbit.
The planet's gravity is 80% of Earth's gravity. It is so cold that even the clouds are frozen, giving the disconcerting view of vertical mountains.
While the planet has water and an atmosphere, it is thick with ammonia, making it deadly to breathe.