Apollo 15 makes contact with the Pacific Ocean.Locations ofAtlantic Ocean splashdowns of American spacecraft prior to the 21st centuryLocations ofPacific Ocean splashdowns of American spacecraft
As the name suggests, the vehicleparachutes into anocean or other large body of water. Due to its low density and viscosity, water cushions the spacecraft enough that there is no need for abraking rocket to slow the final descent as is the case with Russian and Chinese crewed space capsules orairbags as is the case with theStarliner.[1]
The American practice came in part because American launch sites are on the coastline and launch primarily over water.[2] Russian launch sites such asBaikonur Cosmodrome are far inland, and most early launch aborts would descend on land.
The splashdown method of landing was used forMercury,Gemini andApollo (includingSkylab, which used Apollo capsules).Soyuz 23 unintentionally landed on a freezing lake with slushy patches of ice during a snowstorm.[3][4]
On early Mercury flights, a helicopter attached a cable to the capsule, lifted it from the water and delivered it to a nearby ship. This was changed after the sinking ofLiberty Bell 7. All later Mercury, Gemini and Apollo capsules had a flotation collar (similar to a rubber life raft) attached to the spacecraft to increase their buoyancy. The spacecraft would then be brought alongside a ship and lifted onto deck by crane.
After the flotation collar is attached, a hatch on the spacecraft is usually opened. At that time, some astronauts decide to be hoisted aboard a helicopter for a ride to the recovery ship and some decided to stay with the spacecraft and be lifted aboard ship via crane. All Gemini and Apollo flights (Apollos 7 to 17) used the former, while Mercury missions from Mercury 6 to Mercury 9, as well as all Skylab missions and Apollo-Soyuz used the latter, especially the Skylab flights as to preserve all medical data. During the Gemini and Apollo programs, NASA usedMV Retriever for the astronauts to practice water egress.
Apollo 11 was America's first Moon landing mission and marked the first time that humans walked on the surface of another planetary body. The possibility of the astronauts bringingpathogens from the Moon back to Earth was remote, but not ruled out. To contain any possible contaminants at the scene of the splashdown, the astronauts donned special Biological Isolation Garments and the outside of the suits were scrubbed prior to the astronauts being hoisted aboardUSS Hornet and escorted safely inside aMobile Quarantine Facility.[5]
The splashdown of the SpaceX CRS-25 resupply mission
Both theSpaceX Dragon 1 andDragon 2 capsules were designed to use the splashdown method of landing.[a] The original cargo Dragon splashed down in the Pacific Ocean off the coast ofBaja California. At the request of NASA, both the crew and cargo variations of the Dragon 2 capsule splash down off the coast ofFlorida, either in theAtlantic Ocean or theGulf of Mexico.[7][8]
The early design concept forOrion (then known as theCrew Exploration Vehicle) featured recovery on land using a combination of parachutes and airbags, although it was also designed to make a contingency splashdown if needed. Due to weight considerations, the airbag design concept was dropped for Orion, and it conducts landings via splashdown in the Pacific Ocean off the coast of California.[9]
Perhaps the most dangerous aspect is the possibility of the spacecraft flooding and sinking. For example, when the hatch ofGus Grissom'sLiberty Bell 7 capsule blew prematurely, the capsule sank and Grissom almost drowned. Since the spacecraft's flooding will occur from a location in its hull where it ruptures first, it is important to determine the location on the hull that experiences the highest loading.[10] This location along the impacting side is determined by the surrounding `air cushion' layer, which deforms the water surface before the moment of impact, and results in a non-trivial geometry of the liquid surface during first touch-down.[11][12][13]Soyuz 23 was dragged under a frozen lake by its parachutes. The crew became incapacitated bycarbon dioxide and were rescued after a nine-hour recovery operation.[14]
If the capsule comes down far from any recovery forces, the crew may be stranded at sea for an extended period of time. As an example, Scott Carpenter inAurora 7 overshot the assigned landing zone by 400 kilometers (250 mi). These recovery operation mishaps can be mitigated by placing several vessels on standby in different locations, but this can be an expensive option.
Exposure to salt water can have adverse effects on vehicles intended for reuse, such asDragon.[15]
Space Shuttle SRB being recovered byFreedom Star after splashing down onSTS-133
Some reusable launch vehicles recover components via splashdown. This was first seen with theSpace ShuttleSRBs, withSTS-1 launching in 1981. Out of 135 launches,NASA recovered all but two sets of SRBs.[16]
SpaceX has conducted propulsive splashdowns of theFalcon 9 first stage,Super Heavy booster, andStarship spacecraft. These vehicles are designed to land on land ormodified barges and do not always survive intact after tipping over in the water; SpaceX has mainly conducted propulsive splashdowns fordevelopment flights. After the launch ofCRS-16, the booster experienced a control issue and splashed down in the ocean instead of making an intended landing atLanding Zone 1.[17]
Rocket Lab intended to catch the first stage of theirElectron rocket with a helicopter as it descended under parachute, but abandoned this idea in favor of parachute splashdown. In 2020, Rocket Lab made their first booster recovery.[18]
^Dragon 2 was originally intended to propulsively land using itsSuperDraco engines, but this was abandoned except for contingency in case of parachute failure.[6]
Ezell, Linda Neumann (1988),NASA Historical Data Book(PDF), vol. II Programs and Projects 1958 - 1968 (NASA SP-4012),archived(PDF) from the original on October 9, 2022
Ezell, Linda Neumann (1988),NASA Historical Data Book(PDF), vol. III - Programs and Projects 1969 - 1978 (SP-4012),archived(PDF) from the original on October 9, 2022
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The dictionary definition ofsplashdown at Wiktionary