RIP Bruce McCandless. Your picture of you testing the MMU was amazing! But I was wondering, what was the backup plan if the MMU failed while he was so far away from the shuttle? Probably try to move the shuttle closer to him??? Is that even possible?
I guess I thought it would be hard to move the shuttle to catch up with someone floating away. But now that I think about it, I guess that isn't much harder than docking with the ISS. Silly me.
Quote from: SkipMorrow on 12/23/2017 12:15 pmI guess I thought it would be hard to move the shuttle to catch up with someone floating away. But now that I think about it, I guess that isn't much harder than docking with the ISS. Silly me.That's exactly why the MMU was retired after Challenger. Whatever the MMU could do, the orbiter could it at least 10x better. The MMU was developed when the actual controlability/maneuverability of the orbiter was still unknown. As the program went on they found that orbiter was far more maneuverable than initially thought and the MMU was deemed unnecessary. I think it even was on STS-41B that an Manipulator Foot Restraint (MFR) came loose and drifted away. They just moved the orbiter over to it and Bob Stewart just grabbed it when it was close enough and re-stowed in the payload bay. No need for the MMU.
Quote from: DaveS on 12/23/2017 12:22 pmQuote from: SkipMorrow on 12/23/2017 12:15 pmI guess I thought it would be hard to move the shuttle to catch up with someone floating away. But now that I think about it, I guess that isn't much harder than docking with the ISS. Silly me.That's exactly why the MMU was retired after Challenger. Whatever the MMU could do, the orbiter could it at least 10x better. The MMU was developed when the actual controlability/maneuverability of the orbiter was still unknown. As the program went on they found that orbiter was far more maneuverable than initially thought and the MMU was deemed unnecessary. I think it even was on STS-41B that an Manipulator Foot Restraint (MFR) came loose and drifted away. They just moved the orbiter over to it and Bob Stewart just grabbed it when it was close enough and re-stowed in the payload bay. No need for the MMU.No need for SAFER then? There was risk management concerns after STS-51L, MMU was deemed too dangerous, in addition to your points. The risk averse culture was born.
Slightly OT. But think it is not worth starting another thread.Will someone in the near future field something similar to the MMU? Specifically a maneuver unit operating with a spacesuit.
The primary mode for an MMU backup was to carry two (only two flight versions were ever built) so that the second could be used, by the second EVA crewmember, to go off and retrieve an untethered and stranded astronaut. If all the energy available for delta-V was focused through a single translation axis (almost impossible to contrive!) the MMU/astronaut would be 1.5 km away within one minute.