All right, first thing I have to get off my chest is that I don't understand exactly what the Chinese are supposed to get out of destroying the entire Earth with their doomsday machine. To quote Dr. Strangelove, "The purpose of a doomsday device is to tell the world you have a doomsday device!! WHY DID YOU KEEP IT A SECRET ?!?!?!" It's not like the Chinese actually present a list of demands, or anything, before they blow up the world...it takes a super secret "Mission Impossible" spy mission to discover that the machine exists.Chairman Mao was never about blowing Red China up...it was always his intent to simply steam roll over the West with numbers and the power of Marxism, and allow China (and Communism) to achieve its glorious (and inevitable, in Commie eyes) destiny. <br /><br />2nd, if you're going to go to all the trouble of getting your key spy people into the DM facility, couldn't you maybe have them try to sabotage the thing once they discover it? Instead they just take some pictures and run home, heedless of the fact that the entire facility seems to have only 3 staff people in it, and the spies killed the 2nd and 3rd ones.<br /><br />I realize I am asking for waaaay too much for a simple, cheaply made SF clunker. But plot holes like this are woven into the very fabric of bad SF movies that will consign the genre to mediocrity for as long as people remember bad movies like this. <br /><br />The movie does have a few decent moments, mostly thanks to the cast. (That's why three stars instead of one). Bobby Van does pretty good low-key comedy relief and (later on) modest heroics. The oldest crew member (Wilcoxson) is dignified and likable in his role as the senior scientist/statesmen type. Mala Powers is in here, as is Ruta Lee, and sometimes they can almost manage a reading of a line that redeems the material. The scene where the launch site is put under martial law and the launch sequence is sped up is pretty good - there's a nice sense of strain, worry and foreboding. <br /><br />But as for the rest of it - sheesh. The movie can't decide which of two very different models is the actual space ship. The astronauts endure the strain and trauma of take off in what are very obviously easy chair recliners.The battle of the sexes that is the real reason for for movie plays out like the most ham handed soap opera you ever saw on daytime TV. The "end of the world" special effects include stock footage that implies that the astronauts POV suddenly switched to ground level on the planet- sights (and POV) that they couldn't possibly have seen. The plot brings up half baked science that wouldn't pass muster in the 7th grade, including a roll down curtain that supposedly blocks out bad radiation in the capsule, selective gravity, the idea that 3 couples are supposed to restart the human race on a planet that we knew even in 1970 was not habitable. And the last 10-15 minutes (apparently filmed years after the main portion of the movie, with an entirely different cast of actors) is the worst patch job I have ever seen - and I'm including the codas from "Time Of the Apes" and "The Devil Has Seven Faces" in that list.<br /><br />"Doomsday Machine" is painfully bad. Fortunately, it's so bad that watching it becomes an exercise in self-amusement, (except for the last 10 minutes, which are excruciatingly dull). Watch at your own risk.