Later this afternoon, Behnken and Hurley are expected to board their Crew Dragon spacecraft, named Dragon Endeavor, which has been docked at the space station since the astronauts arrived in May. If the weather forecast seems acceptable, the capsule will leave the space station around 7:30 p.m. ET and begin its 7-hour march to a dive off the coast of Florida. If the Crew Dragon is cleared to depart tonight, it is expected to reach its landing at 2:42 p.m. ET on Sunday.
The bigger question is whether the time will hold up.
NASA and SpaceX are closely monitoring Hurricane Isaias, which is expected to approach Florida’s east coast this weekend.
That’s why NASA is hoping Crew Dragon can land in the Gulf of Mexico off the west coast of Florida where forecasters expect calmer waters.
A NASA spokesperson said on Friday that officials are currently considering landing the capsule near Panama City – one of four potential gulf screening sites that have been shortlisted by NASA and SpaceX.
Officials will continue to keep tabs on the forecast leading up to the departure of Dragon Endeavor tonight. If all goes well, Hurley and Behnken will be attached to Crew Dragon. Immediately after undocking at 7:32 p.m. ET, the Crew Dragon’s engines will fire twice in a row to move the capsule away from the space station.
Next, Dragon Endeavor will slowly descend from the ISS, which orbits about 402 kilometers (250 miles) above Earth, using brief engine burns to lower its altitude overnight. Crew Dragon’s maneuvers will all be performed by on-board computers, and Behnken and Hurley will have plenty of food and water on the vehicle. They will also have the chance to sleep before the splash.
On Sunday afternoon, the Crew Dragon will be in orbit just above the thick halo of atmosphere surrounding Earth. The vehicle will re-ignite its engine as it weaves its way through the atmosphere, traveling at 17,500 miles per hour. The rapid compression of the air and the friction between the air and the spacecraft will heat the exterior of the spacecraft to about 3,500 degrees Fahrenheit – a dangerous part of the journey. But a thick heat shield will keep Behnken and Hurley safe inside.
The capsule will then deploy a series of parachutes to slow its descent. By the time it hits the water, it should be traveling less than 20 miles per hour, according to a NASA spokesperson.
“I don’t think we’re nervous,” Hurley said from the space station in an interview with CNN Business’s Rachel Crane last month. “We are confident the vehicle will perform exactly as it is designed to do. That being said, this is a completely different input profile than what we’re used to or used to in the Space Shuttle. ”
CNN will release live updates on the latter part of Hurley and Behnken’s journey on Sunday. NASA is also hosting a continuous webcast of their return starting at 5:15 p.m. ET on Saturday.