Who remembers the little song that the children sang on a trip “The boss’s car has a hole in the rubber and we’ll fix it with chewing-gum”? 400 kilometers above our heads, on board the International Space Station (ISS), something like this happened for the second time. Except that instead of chewing gum, tea leaves made from a sachet that the astronauts are equipped with were used to make an invigorating drink between one experiment and another.
Since September 2019 on the ISS, in particular in the Russian Zvezda module, there is a problem: a leak of air from very small cracks that have formed after more than twenty years of stay in orbit. Nothing that could endanger the life of those on board: the cracks are equivalent to a hole with a diameter of 0.2 millimeters and the pressure loss is equal to 0.4 millimeters of mercury per day, far from the threshold of 0.5 millimeters per minute. To compensate for the loss, the ISS is regularly replenished with air, nitrogen and oxygen, with on-board reserves and with supplies arriving from Earth.
An unconventional method
But how to find the position of these tiny cracks in order to seal them and block the annoying air leak in space? From mission control they worked hard and told the astronauts to drop thin strips of paper into the access section of the Zvezda module. On the ISS the gravity is about 90% that of the Earth’s surface, but by traveling through the orbit at high speed, the Space Station is in a condition of “free fall” with the result that it is in a situation of microgravity and everything that is not fixed, objects and astronauts, floats in the air. Floating in the air, the paper is attracted to where the pressure is lower, that is, towards the slots. In this way, three possible points of air leakage were identified. The access section was closed after releasing the tea leaves in microgravity. These gradually approached a precise point on the wall where there was a crack.
Seven on board
The astronauts have plugged the hole with special adhesive tape, but it is a solution that will not be enough in the long run. In fact, in the next mission, the most resistant material will be brought on board so that the seal is more durable. There are currently seven people on board: the Russians Sergey Ryzhikov and Sergey Kud-Sverchkov, the Americans Kathleen Rubins, Michael Hopkins, Victor Glover and Shannon Walker, and the Japanese Soichi Noguch.
March 17, 2021 (change March 17, 2021 | 16:50)