Capsules returning astronauts to Earth have been landing on the ground or splashing down on water for decades.
Russians and the Chinese have relied on land touchdowns, while Americans have mostly used the sea.
UAE astronaut Sultan Al Neyadi and his three colleagues will be departing the International Space Station aboard a SpaceX Dragon capsule on Sunday, which will splash down off the coast of Florida on Monday, at 8.07am, UAE time.
Hazza Al Mansouri, the first Emirati astronaut in space, landed on flat ground in the steppes of Kazakhstan aboard Russia’s Soyuz spacecraft in 2019.
'Felt like a head-on collision'
Both methods have proven reliable, with numerous missions touching down safely on either land or water.
Earth's atmosphere helps slow down a spacecraft, with parachutes used to further decelerate
The Dragon capsule uses Draco parachutes after re-entering to decrease its speed even more, then releases larger parachutes for an ocean landing.
Russia's Soyuz also uses parachutes but also activates a braking system before touchdown to reduce impact.
Italian astronaut Paolo Nespoli flew to the ISS in 2011 and landed back in Kazakhstan.
"The soft-landing is not really soft," he said in an interview with the European Space Agency in 2013.
"You prepare for it by putting your arms against your body, not talking and being as inside your seat as you can.
"You're waiting for this soft-landing to happen, which for me felt like a head-on collision.
"When it happened, everything shook and then silence. Then I looked at my crew members and said 'welcome back to Earth'."
'Water felt a bit softer than land'
American astronauts have been landing in the sea since the days of the Mercury, Gemini and Apollo capsules.
Like a plane, the Space Shuttle used to land on a runway.
Now, Nasa is using Elon Musk's SpaceX rockets and capsules to take astronauts to and from Earth, and eventually will be using Boeing Starliner capsules once they are ready for commercial operations.
Sea landings are slightly more comfortable because water provides an extra cushion to the capsule, reducing the need for additional braking.
US astronaut Shannon Walker said in 2021: "Landing in the water was interesting because none of us really knew what to expect but I would say from my standpoint it felt a little bit softer than landing on land.
"You spend less time under a parachute on the Dragon than you do under the Soyuz."
