NASA astronauts are returning to Earth aboard the SpaceX Crew Dragon spacecraft.

NASA astronauts Robert Bainken and Douglas Hurley leave the International Space Station on SpaceX’s Crew Dragon spacecraft after completing their orbital laboratory mission on August 1 to mark the end of their historic mission to the International Space Station. They began their journey back to Earth at 5:15 p.m. EST and landed off the west coast of Florida.

NASA astronauts are returning to Earth aboard the SpaceX Crew Dragon spacecraft.

Returning to Earth from orbit is not easy, and the two astronauts have a long journey before returning to Earth. After Bainken and Hurley leave the space station, they will spend 18 hours in orbit, slowly pulling away from the International Space Station before diving into the Earth’s atmosphere. The dive can be challenging, as crew Dragon will experience extreme temperatures of up to 3,500 degrees Fahrenheit and slow down from 17,500 miles per hour.

It is expected that around 5:45 p.m. EST, the Crew Dragon spacecraft will close the hatches and they will stay inside until 7:34 p.m. Eastern time, when the hooks of the crew Dragon spacecraft retract and release the capsule into space. Immediately after, the thrusters aboard the Crew Dragon spacecraft will burn twice quickly to further separate from the International Space Station.

Within hours of the lifting, the spacecraft will have another engine burn, putting the craft on its way to the planned landing site. Now, NASA and SpaceX are aiming for a sputtering landing off the coast of Pensacola, Florida, in the Gulf of Mexico. The site is one of seven possible locations around Florida. NASA and SpaceX would prefer crew Dragon to land on the east side of Florida, near the Kennedy Space Center in Cape Canaveral, Florida. However, Tropical Storm Isaias is expected to pass over eastern Florida this weekend, forcing two astronauts to move west. If it doesn’t work, Crew Dragon will head to a backup location outside Panama. If one of the sites succeeds, it will be the first time the spacecraft has landed in the Gulf of Mexico.

NASA astronauts are returning to Earth aboard the SpaceX Crew Dragon spacecraft.

The two astronauts will try to get a nap before they make a scheduled descent through the atmosphere on Sunday afternoon. At around 1:44 p.m. EST on Sunday, SpaceX will drop a large payload of the spacecraft: the capsule’s trunk before landing. This is a cylindrical hardware connected to the back of the capsule that provides support during launch and provides extra space to carry cargo. It also holds all the solar panels and generates electricity for the spacecraft during flight. But by the time it landed, SpaceX didn’t need the trunk, so it separated, fell into the Earth’s atmosphere and burned out.

The final descent will begin at 1:49 p.m. EST on Sunday. The Crew Dragon will once again burn the thruster, take the capsule out of orbit and drive it to Earth. This starts a series of quick events. When the Crew Dragon descends in the atmosphere, it will begin to heat up, and the outer thermal shield of the capsule will protect the spacecraft and its crew. The heating plasma that accumulates around the capsule interferes with communication signals, followed by what is known as the difficult six-minute silence of communication.

The atmosphere helps cushion the fall of Crew Dragon, which greatly slows it down. But the spacecraft needs a little extra help to safely descend. At an altitude of about 18,000 feet, the capsule will be moved from the spacecraft at 350 miles per hour. The small parachutes slow down the capsule to about 119 miles per hour before the main parachute unfolds. When the Crew Dragon drops to an altitude of 6,000 feet, four large red and white parachutes will unfold, constantly braking the aircraft, causing it to slowly splash into the sea at around 2:41 p.m. EST.

Once the capsule is in the water, two SpaceX operational vessels carrying dozens of people will join the Crew Dragon. They will lift the capsule out of the sea, retrieve their parachutes, and then take Bainken and Hurley to safety, where the astronauts will be airlifted to a helipad on shore, where they will be taken by helicopter to a plane and returned to Houston.

NASA’s YouTube channel has been streaming the entire process at 5:15 p.m. EST, and viewers can follow the channel to see every aspect of the two astronauts’ homecoming.