The acronym for the protective suits Apollo 11 astronauts wore after splashdown was BIG, meaning Biological Isolation Garment.
The suits were part of NASA’s quarantine and recovery plan. Officials considered the chance of dangerous lunar organisms extremely remote, but Apollo 11 was the first mission to return humans and samples from another world, so NASA adopted strict precautions against possible biological contamination.
After Columbia splashed down, recovery swimmer Clancy Hatleberg passed the garments through the spacecraft hatch. Armstrong, Collins, and Aldrin put them on before leaving the capsule and entering a life raft. They were then decontaminated and transferred to the Mobile Quarantine Facility aboard USS Hornet.
BIG was not the same thing as the astronauts’ lunar spacesuit. The lunar suits supported work in vacuum, while the Biological Isolation Garments were lightweight post-splashdown barriers. The astronauts’ exhaled air was filtered, and the garments were worn until the crew entered isolation facilities.