How do you back away from the International Space Station, the most expensive object ever built by humans?

Slowly and carefully.

Once the four astronauts of Crew-9 are safely sealed inside the SpaceX Crew Dragon capsule, seated and wearing protective flight suits, the departure begins.

With the spacecraft’s computer in charge, the Dragon will release the hooks that have firmly held it to the International Space Station since September. Over the next hour and 40 minutes, the spacecraft will perform a series of thruster firings to nudge itself away from the space station.

When it reaches a safe distance, the capsule will rely on its computer to execute the next series of thruster firings, lowering the capsule’s altitude and lining it up with the landing site off Florida’s gulf coast. This process will take the better part of half a day.

At about 5:06 p.m. on Tuesday, the cylindrical bottom half of the spacecraft — what SpaceX calls the trunk — will be jettisoned. Then, a big firing of the thruster, known as the deorbit burn, will cause the capsule to fall toward the Earth’s atmosphere.

The nose cone will shut before the spacecraft enters the atmosphere with the heat shield at the bottom protecting the astronauts inside. At 5:53 p.m., small parachutes known as drogues will deploy, followed by the main parachutes a minute later, slowing the spacecraft to a gentle impact with the waters off Florida.

A SpaceX recovery ship will then pluck the capsule out of the water.