July 18 – Extreme Vehicle Day

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On this day in 1990, the airlock hatch on the Soviet space station Mir was damaged during a spacewalk and could not be closed. Their supply of oxygen running out, cosmonauts Anatoly Solovyov and Aleksandr Balandin had to use the middle compartment of the space station module as an airlock. A week later, they managed to finally close the hatch and repressurize the middle compartment.

The Mir

Do you know what an airlock does? It is an airtight room with two doors—one to the interior of the spaceship, which has air, and one to the airless vacuum outside of the spaceship. Astronauts go into the airlock while it has air, put on their pressurized suits with oxygen tanks, and then use the controls that pump the air out of the room. Once the airlock is a vacuum (airless), the outer door is opened to space.