Crewman Poole (left) naps as Bowman checks condition of three hibernating astronauts locked in their individual hibernaculums. hostile towards us, or will they think that we are so primitive that they will pass us by and look elsewhere for other beings more nearly equal to them? If we get a signal from outer space, what should we do about it? Should we answer it and invite visitors, or should we ignore it and continue to live in the Universe as if we are alone? Or have we already been visited? Has some extraterrestrial civilization left artefacts for us to find when we get to the moon or the planet Mars? If we find life in the Universe-perhaps beings more intelligent than ourselves-what will we come to think