Orbital Man
The MMUs were used twice more in 1984, during the April STS 41-C mission and the November STS 51-A mission. After that, they were never used again, with NASA citing safety reasons. Moreover, NASA found other, safer ways, for astronauts to perform work outside the Shuttle.
Related article: The Coolest—and Most Frightening—Spacewalks in History
That said, NASA did perform an untethered spacewalk in September 1994 to test a backpack known as Simplified Aid for EVA Rescue (SAFER), which is strictly meant for emergencies should astronauts become untethered during EVAs.
