In the beginning of the mission, it's mentioned that 12 pioneers went out to try to find a new world for humanity. During the duration of the film, they only visit 3 of those 12 planets and respective astronauts. What happened to the other 9? Did they communicate back to NASA that their planet was inhospitable?
Since only one system with 3 worlds show promise, we can infer that the other 9 astronauts are dead. Either they didn't make it to their worlds or they landed on uninhabitable worlds.
Twelve possible worlds. Twelve Ranger launches carrying the bravest humans ever to live, led by the remarkable Dr Mann.
Each person’s landing pod had life support for two years - but they could use hibernation to stretch that, making observations on organics over a decade or more. Their mission was to assess their world, and if it showed promise, send a signal, bed down for the long nap, and wait to be rescued.
And if their world didn’t show promise?
Hence the bravery.
Because you don’t have resources to visit all twelve.
No. Data transmission back through the wormhole is rudimentary, simple binary ’pings’ on an annual basis to give some clue as to which worlds have potential. One system shows promise.
One? Kind of a long shot.
One system with three potential worlds ... no long shot.
Full script here