I was watching this video of an Apollo ascent module taking off (captured by a lunar rover credit: NASA) and there is no evidence of a rocket motor not even a glint of light that would signal rocket exhaust. Now I wonder if there even was a motor on board or if there was just an explosive under there that pushed it to lunar orbital velocity.
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1$\begingroup$ Hypergolic bungee cord. $\endgroup$– HABOSep 21, 2022 at 18:08
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$\begingroup$ @HABO hm. on the module itself, I don't see an engine. maybe it's stowed somewhere? $\endgroup$– Deko Revinio -leaning away-Sep 21, 2022 at 18:12
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2$\begingroup$ In the model in the article HABO linked, it's visible at the bottom. In the video you linked, the engine fires at nine seconds into the video, and again at 24 seconds, after the "tipover" maneuver is announced. Lunar orbital velocity is about a kilometer per second, and at no point in the video has the module reached that speed yet. A single explosion could not have put the module into orbit around the moon. $\endgroup$– notovnySep 21, 2022 at 19:40
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8$\begingroup$ Please do some basic research before posting questions. Once again, this is fully covered at Wikipedia. en.wikipedia.org/wiki/Apollo_Lunar_Module#Ascent_stage Also see the tool-tip on downvoting questions, it begins "This question does not show any research effort..." $\endgroup$– Organic MarbleSep 21, 2022 at 19:44
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$\begingroup$ Will you please look at my answer of this space.stackexchange.com/questions/37762/… question? You will see the ascent engine there. To use an explosive under there would not push it to lunar orbital velocity, it would destroy the lunar module. $\endgroup$– UweSep 21, 2022 at 19:46
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1 Answer
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The ascent stage had a rocket engine, known as the Ascent Propulsion System.
The exhaust plumes of rocket engines firing in vacuum aren't very prominent -- the yellow exhaust that you see from some Earth-side rocket launches are due to hot carbon soot reacting with oxygen in the atmosphere.
The propellants used by the LM (Aerozine-50 and nitrogen tetroxide) contain relatively little carbon, and burn fairly clear even in atmosphere (as you can see in pictures of Titan II launches; that rocket uses the same propellants); in vacuum the plume is almost invisible.
The engine itself is recessed in the ascent stage, so you don't see the engine bell, and in fact a cover over the body of the engine takes up significant space within the LM's cabin.
A simple explosive wouldn't give enough momentum to the ascent stage to reach orbit.
answered Sep 22, 2022 at 5:02