NASA astronauts Sunita Williams and Barry Wilmore are set to return to earth on Tuesday, March 18, after nearly 9 months. Both astronauts departed the International Space Station (ISS) early this morning in a SpaceX capsule.

Williams and Wilmore arrived at the ISS in 2024 as part of Expedition 72, which officially began on September 23. However, their return to Earth was significantly delayed due to technical issues with their Boeing Starliner.

An astronaut's journey back to Earth from space is a meticulously planned and executed process, to ensure their safe return after the mission. Here's a step-by-step breakdown of how astronauts return to Earth from the ISS:

1. Preparation for Return

Before leaving space, astronauts don their pressure suits to ensure protection during re-entry. The spacecraft’s hatch is securely closed, and a thorough leak check is performed to confirm an airtight seal. This step is crucial in maintaining the safety of the astronauts and the integrity of the spacecraft.

2. Separation from the ISS

Once everything is set, the spacecraft detaches from the ISS port. Small Draco thrusters fire to gently push the spacecraft away from the station. At this stage, the trunk of the Dragon capsule, which is used for additional cargo storage, is jettisoned to reduce weight and streamline the vehicle for re-entry.

3. Deorbit Burn

To initiate the descent, the spacecraft performs a deorbit burn. This involves firing its Draco thrusters in the opposite direction of its orbit, reducing its velocity significantly. As a result, the spacecraft begins its descent toward Earth, transitioning from orbital flight to atmospheric entry.

4. Entry into the Atmosphere

As the spacecraft re-enters the Earth's atmosphere, it travels at an astonishing speed of approximately 27,000 km/h. The intense friction with the air molecules generates extreme heat, raising the temperature around the capsule to about 1,650 degrees Celsius. During this phase, communication with the ground is temporarily lost for about 3-5 minutes due to ionization around the spacecraft.

5. Parachute Deployment and Landing

As the spacecraft slows down upon descent, two drogue parachutes deploy at around 18,000 feet to stabilize it. Once it reaches approximately 6,000 feet, four large main parachutes deploy, further reducing the descent speed to a safe 24 km/h. This controlled descent ensures a gentle landing in the ocean.

6. Splashdown and Recovery

The final step of the return process is splashdown—when the spacecraft lands in the sea. A recovery ship, already positioned at the landing site, quickly moves in to retrieve the capsule. Recovery teams approach the spacecraft, secure it, and lift it onto the ship. Once aboard, astronauts are safely evacuated, undergo medical checks, and are prepared for their journey back home.