Lyric discussion by Gendo62 

Cover art for Hollow lyrics by Alice in Chains

I think the song and the clip are really matching about the theme : Hollow merely deals with slipping into mental breakdown and alienation when you're remaining alone for too long, just like the astronaut who can't stand his loneliness and the estrangement with his loved ones. In an almost psychotic way, your vitality is burning out and in the end all what's left is emptiness.