Apollo 15 makes contact with the Pacific Ocean.Locations of Atlantic Ocean splashdowns of American spacecraft prior to the 21st centuryLocations of Pacific Ocean splashdowns of American spacecraft
As the name suggests, the capsule parachutes into an ocean or other large body of water. The properties of water cushion the spacecraft enough that there is no need for a braking rocket to slow the final descent as is the case with Russian and Chinese crewed space capsules (while Shenzhou designed a raft and balanced capsule in case of splashdown), which return to Earth over land. The American practice came in part because American launch sites are on the coastline and launch primarily over water.[1] Russian launch sites are far inland and most early launch aborts were likely to descend on land.[citation needed]
The splashdown method of landing was used for Mercury, Gemini and Apollo (including Skylab, which used Apollo capsules). Soyuz 23 unintentionally landed on a freezing lake with slushy patches of ice during a snowstorm.[2][3]
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 of Liberty 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 used MVRetriever 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 bringing "Moon germs" back to Earth was remote, but not impossible. 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 aboard USSHornet and escorted safely inside a Mobile Quarantine Facility.[4]
The splashdown of the SpaceX CRS-25 resupply mission
Both the SpaceX Dragon 1 and Dragon 2 capsules were designed to use the splashdown method of landing. The original cargo Dragon splashed down in the Pacific Ocean off the coast of Baja California. At the request of NASA, both the crew and cargo variations of the Dragon 2 capsule splashes down off the coast of Florida, either in the Atlantic Ocean or the Gulf of Mexico.[5][6]
The early design concept for the Orion Spacecraft (then known as the Crew Exploration Vehicle) featured recovery on land using a combination of parachutes and airbags, although it was also designed to make a contingency splashdown (only for an in-flight abort) if needed. Due to weight considerations, the airbag design concept was dropped. The present design concept features landings via splashdown in the Pacific Ocean off the coast of California.[7]
Disadvantages
The most dangerous aspect is the possibility of the spacecraft flooding and sinking. For example, when the hatch of Gus Grissom's Liberty 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.[8] 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.[9][10][11]
If the capsule comes down far from any recovery forces, the crew are exposed to greater danger. As an example, Scott Carpenter in Aurora 7 overshot the assigned landing zone by 400 kilometers (250mi). These recovery operation mishaps can be mitigated by placing several vessels on standby in several different locations, but this is quite an expensive option.
↑ Jain, U.; etal. (2021). "Air entrapment and its effect on pressure impulses in the slamming of a flat disc on water". Journal of Fluid Mechanics. 938 (4): A31. arXiv:2012.10137. doi:10.1017/jfm.2021.846.
↑ Jain, U.; etal. (2021). "Air-cushioning effect and Kelvin-Helmholtz instability before the slamming of a disk on water". Physical Review Fluids. 6 (4): L042001. arXiv:2106.09551. doi:10.1103/PhysRevFluids.6.L042001.
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
Apollo 7 was the first crewed flight in NASA's Apollo program, and saw the resumption of human spaceflight by the agency after the fire that had killed the three Apollo 1 astronauts during a launch rehearsal test on January 27, 1967. The Apollo7 crew was commanded by Walter M. Schirra, with command module pilot Donn F. Eisele and lunar module pilot R. Walter Cunningham.
Apollo 9 was the third human spaceflight in NASA's Apollo program. Flown in low Earth orbit, it was the second crewed Apollo mission that the United States launched via a Saturn V rocket, and was the first flight of the full Apollo spacecraft: the command and service module (CSM) with the Lunar Module (LM). The mission was flown to qualify the LM for lunar orbit operations in preparation for the first Moon landing by demonstrating its descent and ascent propulsion systems, showing that its crew could fly it independently, then rendezvous and dock with the CSM again, as would be required for the first crewed lunar landing. Other objectives of the flight included firing the LM descent engine to propel the spacecraft stack as a backup mode, and use of the portable life support system backpack outside the LM cabin.
The Space Race was a 20th-century competition between two Cold War rivals, the United States and the Soviet Union, to achieve superior spaceflight capability. It had its origins in the ballistic missile-based nuclear arms race between the two nations following World War II and had its peak with the more particular Moon Race to land on the Moon between the US moonshot and Soviet moonshot programs. The technological advantage demonstrated by spaceflight achievement was seen as necessary for national security and became part of the symbolism and ideology of the time. The Space Race brought pioneering launches of artificial satellites, robotic space probes to the Moon, Venus, and Mars, and human spaceflight in low Earth orbit and ultimately to the Moon.
Zond 8, also known as L-1 No.14, was the last in the series of circumlunar spacecraft, a member of the Soviet Zond program, designed to rehearse a piloted circumlunar flight, an uncrewed version of Soyuz 7K-L1 crewed circumlunar flight spacecraft. The project was initiated in 1965 to compete with the Americans in the race to the Moon but lost its importance once three astronauts orbited the Moon on the Apollo 8 mission in December 1968.
Human spaceflight programs have been conducted, started, or planned by multiple countries and companies. Until the 21st century, human spaceflight programs were sponsored exclusively by governments, through either the military or civilian space agencies. With the launch of the privately funded SpaceShipOne in 2004, a new category of human spaceflight programs – commercial human spaceflight – arrived. By the end of 2022, three countries and one private company (SpaceX) had successfully launched humans to Earth orbit, and two private companies had launched humans on a suborbital trajectory.
Gemini 3 was the first crewed mission in NASA's Project Gemini and was the first time two American astronauts flew together into space. On March 23, 1965, astronauts Gus Grissom and John Young flew three low Earth orbits in their spacecraft, which they nicknamed Molly Brown. It was the first U.S. mission in which the crew fired thrusters to change the size and shape of their orbit, a key test of spacecraft maneuverability vital for planned flights to the Moon. It was also the final crewed flight controlled from Cape Kennedy Air Force Station in Florida, before mission control functions were moved to a new control center at the newly opened Manned Spacecraft Center in Houston, Texas.
Apollo–Soyuz was the first crewed international space mission, carried out jointly by the United States and the Soviet Union in July 1975. Millions of people around the world watched on television as an American Apollo spacecraft docked with a Soviet Soyuz capsule. The project, and its handshake in space, was a symbol of détente between the two superpowers during the Cold War.
Skylab 4 was the third crewed Skylab mission and placed the third and final crew aboard the first American space station.
The Apollo command and service module (CSM) was one of two principal components of the United States Apollo spacecraft, used for the Apollo program, which landed astronauts on the Moon between 1969 and 1972. The CSM functioned as a mother ship, which carried a crew of three astronauts and the second Apollo spacecraft, the Apollo Lunar Module, to lunar orbit, and brought the astronauts back to Earth. It consisted of two parts: the conical command module, a cabin that housed the crew and carried equipment needed for atmospheric reentry and splashdown; and the cylindrical service module which provided propulsion, electrical power and storage for various consumables required during a mission. An umbilical connection transferred power and consumables between the two modules. Just before reentry of the command module on the return home, the umbilical connection was severed and the service module was cast off and allowed to burn up in the atmosphere.
Project Gemini was the second United States human spaceflight program to fly. Conducted after the first, Project Mercury, and while the Apollo program was still in development, Gemini was conceived in 1961 and concluded in 1966. The Gemini spacecraft carried a two-astronaut crew. Ten Gemini crews and 16 individual astronauts flew low Earth orbit (LEO) missions during 1965 and 1966.
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A launch escape system (LES) or launch abort system (LAS) is a crew-safety system connected to a space capsule. It is used in the event of a critical emergency to quickly separate the capsule from its launch vehicle in case of an emergency requiring the abort of the launch, such as an impending explosion. The LES is typically controlled by a combination of automatic rocket failure detection, and a manual activation for the crew commander's use. The LES may be used while the launch vehicle is still on the launch pad, or during its ascent. Such systems are usually of three types:
Spacecraft call signs are radio call signs used for communication in crewed spaceflight. These are not formalized or regulated to the same degree as other equivalent forms of transportation, like aircraft. The three nations currently launching crewed space missions use different methods to identify the ground and space radio stations; the United States uses either the names given to the space vehicles or else the project name and mission number. Russia traditionally assigns code names as call signs to individual cosmonauts, more in the manner of aviator call signs, rather than to the spacecraft.
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