Marcus Wandt left the ISS on Wednesday afternoon after 17 days on the space station. Due to the weather, the departure in the Dragon capsule has been postponed several times.
The plan is to enter the atmosphere on Friday afternoon. Time is not set in stone. The astronauts can spend a relatively long time in the capsule waiting for the right opportunity if needed.
Extreme heat
The Swedish Space Agency’s head of research Johan Köhler says that re-entry into the atmosphere is the most risky moment. On February 1, 2003, the space shuttle Columbia tore apart in the atmosphere, killing all seven on board.
The Dragon capsule turns on its engines for 17 minutes to decelerate, then turns nose up to direct the heat shields down.
A hole in the heat shields can be fatal. It gets so hot around the capsule, upwards of 1,600 degrees, that the air turns into plasma.
– Then you cannot send radio to and from the capsule. There are a few minutes when you can’t actually find out how things are going. You have to wait for the capsule to slow down, says Köhler.
Important angle
According to the European Space Agency ESA, the angle is extremely important. If it is too steep, the forces can tear the capsule. If it is too flat, the capsule travels much further than intended and hits the wrong place, or the journey takes too long, so that the thermal insulation burns up and the temperature in the capsule becomes too high. If the orbit is too flat, the capsule can end up in temporary orbit again, enter the atmosphere about an hour later, and land in a different place than intended.
Experts are closely monitoring the weather off the coast of Florida. Mainly, you want to avoid lightning strikes in the capsule on the way down, as well as too high waves at sea.
Can sink
– If the sea is too rough, it can lead to problems picking up the capsule. If it’s really bad, it can drop, says Köhler.
A tangled parachute could also be devastating. They are described as some of the safest in the world by the manufacturer Space X, but the launch was delayed due to deviations in the parachutes.
– You don’t need to read anything into that. Rather, you should take it as income, that you take the sure before the uncertain. You don’t take chances, says Köhler.
After the capsule has been picked up by boat, investigations await in the United States, before the astronauts travel to ESA’s facility in Cologne for further tests.