Primary Life Support System

The primary life support system (PLSS) is a device worn by astronauts or cosmonauts to allow for extra-vehicular activity (EVA) with maximum freedom, independent of a spacecraft's life support system. The PLSS is a backpack-like device that recycles exhaled gases, removes carbon dioxide, and circulates water to regulate temperature. It also contains a radio transceiver and antenna for communications and a backup system in case of failure. The PLSS was used in the Apollo lunar landing missions, where it was tested in space for the first time on Apollo 9, and is currently used by Space Shuttle and International Space Station crews. The system has undergone modifications over the years, with the Apollo PLSS being replaced by a more advanced system on the Space Shuttle and International Space Station.learn more on wikipedia