Both the shuttle and the International Space Station have normal air mixtures that mimic our atmosphere. This pre-breathing of pure oxygen eliminates the nitrogen from the astronaut's blood and tissues, thereby minimizing the risk of the bends. The astronaut breathes out carbon dioxide. In the confined space of the suit, carbon dioxide concentrations would build up to deadly levels. Therefore, excess carbon dioxide must be removed from the spacesuit's atmosphere.
Spacesuits use lithium hydroxide canisters to remove carbon dioxide.
These canisters are located either in the spacesuit's life support backpack or in the spacecraft, in which case they are accessed through an umbilical cord. To protect the astronauts from collisions with micrometeroids, spacesuits have multiple layers of durable fabrics such as Dacron or Kevlar. These layers also prevent the suit from tearing on exposed surfaces of the spacecraft or a planet or moon. Radiation Spacesuits offer only limited protection from radiation. Some protection is offered by the reflective coatings of Mylar that are built into the suits, but a spacesuit would not offer much protection from a solar flare .