WHY NOW? NASA astronauts Butch Wilmore and Sunita Williams returned to Earth on Tuesday (March 18) after a nine-month-long stay at the International Space Station (ISS). The SpaceX Dragon capsule sent to bring them back to Earth splashed down off the Florida coast, also carrying NASA astronaut Nick Hague and Russian cosmonaut Aleksandr Gorbunov. TO RECAP On June 5, 2024, Wilmore and Williams set off on an eight-day test flight of the Boeing Starliner to the ISS. The goal was to test the Boeing spacecraft’s capabilities and provide NASA with an alternative (apart from the Elon Musk-owned SpaceX) to carry astronauts into Space. However, the spacecraft almost immediately experienced problems with its thrusters and propulsion system. Safety concerns led to its return to Earth without a crew, and the two astronauts remained at the ISS for 286 days. A planned SpaceX mission for their return was also delayed. On February 11, 2025, NASA announced that Williams and Wilmore would return in a flight-tested Crew Dragon spacecraft on the Crew-10 mission with Hague and Gorbunov, instead of waiting for SpaceX to finish work on a new spacecraft for this purpose. SO WHAT IS A SPLASHDOWN? It is the method favoured by American spacecraft – such as NASA’s Mercury, Gemini, and Apollo – to re-enter Earth. In a splashdown, the Space vehicle parachutes into an ocean or a large water body upon re-entering Earth. The low density and viscosity of water cushions the spacecraft against the impact of re-entry. BUT WHY SPLASH DOWN? One is the high speed at which the spacecraft is travelling. Landing in water results in a gentler impact compared to a terrestrial landing. Secondly, due to the friction experienced upon re-entry, the spacecraft may experience up to 3,500° F of extreme heat. There is also the matter of convenience. Landing in a large water body removes the need to identify a suitable area and eliminates the risk of landing in a populated region. Many American launch sites are located along the coastline, with Space launches made close to water bodies as well. In comparison, Russian cosmonauts do not splash down but descend on land, since their launch sites, such as the Baikonur Cosmodrome, are located inland. SIMPLIFYING SPACECRAFT DESIGN Water landings also reduce the complexity of spacecraft design. The Russian Soyuz capsule, designed for terrestrial landings, deploys a heat shield to prevent the spacecraft from burning up on re-entry. Braking parachutes, which help decelerate aircraft speeds, and other systems are also required. On Tuesday, the Dragon enabled its heat shield to prevent the craft from burning up. It deployed two sets of parachutes, called drogue chutes or drag chutes, to slow it down further after re-entry. These were deployed at about 18,000 feet as the vehicle travelled at about 350 miles per hour (563 kmph), according to an ABC News report. To stick the landing, the Dragon deployed its four main parachutes at about 6,000 feet while slowing down to 15 miles per hour (about 24 kmph) before splashing down.
