National geographic channel,what was the title/vol of the doentary about future life in other planet?

i watch it b4,the story was about going to the nearest sun and find a planet same with earth then they will try living on that planet.it was a doentary futuristic plan of NASA i think..i forgot the title or volume of that episode.i try surfing on national geographic but my connection is very slow,,downloading pix n page takes long time..thanks,,i will show it on my friends in school they wont believe it