NASAby CATHERINE THORBECKE, ABC News(NEW YORK) — Two months after a history-making launch, the first NASA-SpaceX astronauts finally have a return flight scheduled.Doug Hurley and Bob Behnken, who left Earth on May 30, are slated to undock from the International Space Station at 7:34 p.m. ET on Saturday and splash down off the coast of Florida at 2:42 p.m. ET on Sunday. Their journey will be broadcast live by NASA.Their return would mark the first time a commercially built American spacecraft returned from space. It’s also NASA’s first crewed water landing since 1975.Stakes are high as once the Crew Dragon spacecraft undocks from the ISS, the astronauts will only have 48 hours of oxygen in their capsule.Weather remains a top concern as Tropical Storm Isaias moves through the area, but the astronauts expressed confidence about the splashdown during a news conference from the ISS on Friday.“I still don’t feel nervous about it — we’re focused on the things we need to do to be as safe as possible,” Behnken said. “We won’t leave the Space Station without good landing opportunities in front of us. We don’t control the weather, we know we can stay up here longer, there’s more chow.” Teams from @NASA & @SpaceX continue to monitor weather, but we’re still on track for departure this weekend. Looking forward to climbing back into Endeavour for our trip home. #LandAmerica https://t.co/7IcG3WC4D6 pic.twitter.com/L93VCaIan2— Bob Behnken (@AstroBehnken) July 31, 2020Hurley said every spaceflight is a “once-in-a-lifetime experience” for astronauts, but “this one probably is a great topper, at least for me, personally.”“The water-landing portion of it is pretty challenging from a physiological standpoint,” he noted, especially after being in a microgravity environment for months. He said they have exercised “very hard” to help prepare.In addition, Hurley said if they get physically ill during their return they will have the “appropriate hardware.”“Just like an airliner, there are bags if you need them, and we’ll have those ready,” he added. “If that needs to happen, it certainly wouldn’t be the first time it’s happened in a space vehicle.”Splashdown expectationsThere are seven possible splashdown sites near coastal cities — Pensacola, Tampa, Tallahassee, Panama City, Cape Canaveral, Daytona, and Jacksonville — and NASA said it will make a final selection based on several factors, primarily weather. As of Friday, near Panama City was considered the primary site, with Tampa the backup.Once the spacecraft enters Earth’s atmosphere, it will deploy two sets of parachutes at about 18,000 feet in altitude and then four more at about 6,000 feet in altitude, according to NASA.After the splashdown, SpaceX will send two boats to first check the capsule and make sure the area around it is free of hypergolic propellant vapors. The second boat will recover the parachutes.The first boat then will hoist the capsule with Hurley and Behnken in it and move it to a stable location for the hatch to be opened as medical professionals look on. After a medical check, Behnken and Hurley will board a NASA plane to Houston.Behnken said Friday he is most excited to see his family and his 6-year-old son upon returning to Earth, saying, “He’s changed a lot in the couple of months that we’ve been up here.”Behnken added that he already has some tips for his wife, fellow astronaut Megan McArthur, who will be on a NASA-SpaceX mission scheduled to launch next spring.“A lot of them will be about how life on Space Station goes,” he said. “I’ll definitely have some advice about living inside of Dragon and where best to pack all your personal items so you can get to them conveniently.”Copyright © 2020, ABC Audio. All rights reserved.