I watched this movie on VHS around 93′ to 95′. Characters are on a desolate planet and are scientists possibly. A man whom looms like Shel Silverstein is in a tunnel and gets his hands chopped off by a weapon that he throws. He falls to the bottom of the hole/tunnel and the scene cuts to a naked woman. This woman walks around and eventually has her head bitten off (still nude) by a giant spider. That’s all I recall. It was the first R-rated movie I ever saw and it terrified me for years.