Why have NASA gone back to the dangerous untethered EVA?

Question

campbelp2. said that he had not heard of them stopping and going back to untethered EVAs. I read somewhere last night that they used untethered EVAs but stopped using them because the suit started to compress, so they stopped it. However they have recently gone back and reduced the size of the backpack.

what I mean by untethered is where the astronauts don't have to use a wire to hold them to the spacecraft.

Answer 1

NASA never stopped doing untethered EVAs. They just stopped using the Manned Maneuvering Unit (MMU).
Any EVA is dangerous, but there are always an enormous amount of precautions taken. The MMU was abandoned back before the Challenger disaster since it was bulky and hard to operate.
Since then, American Astronauts have been using the self-propelled backpack: Simplified Aid for EVA Rescue (SAFER). It is much smaller and easier to operate, and is used during all untethered EVAs.
During a tethered EVA an umbilical supplying oxygen and water is attached to the astronaut's suit but during and untethered walk the astronaut needs to carry all of their resources with them.
untethered walks aren't performed often, because there is not regularly a need for them, but there are certain activities, like in STS-114 when Steve Robinson removed the gap fillers from between two heat shield tiles, that the umbilical could not be used, necessitating the need for a SAFER unit to be used.

Answer 2

Gone back? Did they stop doing that completely at some point? If so, I didn't hear about it. Did they then reverse the decision and go back to doing it? I never heard that either.