What Movie Is This? Sci-Fi / Horror / Late 80's or Early 90's?

...might you be thinking of the 1985 sci-fi horror shocker, and a definate 'Alien' knock-off, entitled "Creature"??? The plot, which you describe, sounds very much similar, especially when you mentioned the hapless crew being on a moon (...in this film, the moon is called Titan, which was actually part of the name of the film's original title, "Titan Fiend")...