Mounted to the handle on Space Shuttle hatches for unlatching the hatch locking mechanism.
NASA photo shows STS-44 mission specialist Story Musgrave holding the side hatch knob as he looks through the hatch window of Atlantis.
NASA photo shows Space Shuttle Discovery’s airlock hatch as astronauts Scott Horowitz (left), commander of STS-105, and Frank Culbertson, Expedition Three mission commander prepare to open the hatch to enter the International Space Station. The hatch knob can be seen at the center of the image, with an enlarged view below.
