Space capsule
Encyclopedia
A space capsule is an often manned spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....

 which has a simple shape for the main section, without any wings or other features to create lift during atmospheric reentry
Atmospheric reentry
Atmospheric entry is the movement of human-made or natural objects as they enter the atmosphere of a celestial body from outer space—in the case of Earth from an altitude above the Kármán Line,...

.
Capsules have been used in most of the manned space programs to date, including the world's first Vostok
Vostok spacecraft
The Vostok was a type of spacecraft built by the Soviet Union. The first human spaceflight in history was accomplished on this spacecraft on April 12, 1961, by Soviet cosmonaut Yuri Gagarin....

 and Mercury
Project Mercury
In January 1960 NASA awarded Western Electric Company a contract for the Mercury tracking network. The value of the contract was over $33 million. Also in January, McDonnell delivered the first production-type Mercury spacecraft, less than a year after award of the formal contract. On February 12,...

 manned spacecrafts, as well as in later Soviet Voskhod
Voskhod spacecraft
The Voskhod was a spacecraft built by the Soviet Union's space program for human spaceflight as part of the Voskhod programme. It was a development of and a follow-on to the Vostok spacecraft...

, Soyuz
Soyuz spacecraft
Soyuz , Union) is a series of spacecraft initially designed for the Soviet space programme by the Korolyov Design Bureau in the 1960s, and still in service today...

, Zond/L1
Soyuz 7K-L1
The Soyuz 7K-L1 spacecraft was designed to launch men from the Earth to circle the Moon without going into lunar orbit in the context of the Soviet manned moon-flyby program in Moon race. It was based on the Soyuz 7K-OK with several components stripped out to reduce the vehicle weight...

, L3
Soyuz 7K-L3
The Soyuz 7K-LOK, or simply LOK was a Soviet spacecraft designed to launch men from Earth to circle the moon and developed in parallel to the 7K-L1. The LOK would carry two cosmonauts into orbit around the Moon, acting as "mother" spacecraft for the LK Lander, which would land one member of the...

, TKS
TKS spacecraft
TKS spacecraft was a Soviet spacecraft design in the late 1960s intended to supply the military Almaz space station. The spacecraft was designed for manned or autonomous cargo resupply use...

, US Gemini, Apollo
Apollo spacecraft
The Apollo spacecraft was composed of five combined parts designed to accomplish the American Apollo program's goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth...

, Chinese Shenzhou
Shenzhou spacecraft
Shenzhou is a spacecraft developed and operated by the People's Republic of China to support its manned spaceflight program. The name is variously translated as "Divine Craft," "Divine Vessel of God," "Magic Boat" or similar and is also homophonous with an ancient name for China...

 and currently developing US, Russia, India manned spacecrafts. A capsule is the specified form for the Crew Exploration Vehicle
Crew Exploration Vehicle
The Crew Exploration Vehicle was the conceptual component of the U.S. NASA Vision for Space Exploration that later became known as the Orion spacecraft...

.

A manned space capsule must have everything necessary for everyday life, including air, water and food. The space capsule must also protect astronauts from the cold and radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...

 of space. A capsule must be well insulated and have a system that controls the inside temperature and environment. It also must have a way that the astronaut
Astronaut
An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft....

s won't be knocked around during launch or reentry. Additionally, since the inside will be weightless
Weightlessness
Weightlessness is the condition that exists for an object or person when they experience little or no acceleration except the acceleration that defines their inertial trajectory, or the trajectory of pure free-fall...

, there must be a way for the astronauts to stay in their seats and beds during the flight. For this each seat, bed, table, and chair has a complicated system of straps and buckles. One of the most important things that a space capsule must have is a way to communicate with people back on Earth, or mission control.

Besides of manned purposes, space capsules as Recovery satellites uses for recovery of reconnaissance, biological, space-production and other payloads from orbit to Earth. Few countries only (USA, USSR, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, Europe/ESA
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

) achieved this serious technology.

Structure

Space capsules have typically been smaller than 5 meters in diameter, although there is no engineering limit to larger sizes. As the capsule is both volumetrically efficient and structurally strong, it is typically possible to construct small capsules of performance comparable in all but lift-to-drag ratio to a lifting body
Lifting body
A lifting body is a fixed-wing aircraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage with little or no conventional wing...

 or delta wing
Delta wing
The delta wing is a wing planform in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta .-Delta-shaped stabilizers:...

 form for less cost. This has been especially pronounced in the case of the Soyuz manned spacecraft
Soyuz spacecraft
Soyuz , Union) is a series of spacecraft initially designed for the Soviet space programme by the Korolyov Design Bureau in the 1960s, and still in service today...

. Most space capsules have used an ablative heat shield for reentry and been non-reusable. The Crew Exploration Vehicle
Crew Exploration Vehicle
The Crew Exploration Vehicle was the conceptual component of the U.S. NASA Vision for Space Exploration that later became known as the Orion spacecraft...

 appear likely, as of December 2005, to be a ten-times reusable capsule with a replaceable ablative shield. There is no limit, save for lack of engineering experience, on using high-temperature ceramic tiles or ultra-high temperature ceramic
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...

 sheets on space capsules.

Materials for the space capsule are designed in different ways, like the Apollo
Project Apollo
The Apollo program was the spaceflight effort carried out by the United States' National Aeronautics and Space Administration , that landed the first humans on Earth's Moon. Conceived during the Presidency of Dwight D. Eisenhower, Apollo began in earnest after President John F...

’s honey-combed structure of aluminum. Aluminum is very light, and the structure gives the space capsule extra strength. The early space craft had a coating of glass embedded with synthetic resin and put in very high temperatures. Carbon fiber
Carbon fiber
Carbon fiber, alternatively graphite fiber, carbon graphite or CF, is a material consisting of fibers about 5–10 μm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in crystals that are more or less aligned parallel to the long axis of the fiber...

, reinforced plastics and ceramic are new materials that are constantly being made better for use in space exploration.

Reentry

Space capsules are well-suited to high-temperature and dynamic loading reentries. Whereas delta-wing gliders such as the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

 can reenter from Low Earth Orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

 and lifting bodies are capable of entry from as far away as the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

, it is rare to find designs for reentry vehicles from Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

 that are not capsules. The current RKK Energia design for the Kliper
Kliper
Kliper is a partly reusable manned spacecraft, proposed by RSC Energia.Designed primarily to replace the Soyuz spacecraft, Kliper has been proposed in two versions: as a pure lifting body design and as spaceplane with small wings...

, being capable of flights to Mars, is an exception.

Engineers building a space capsule must take forces such as gravity and drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

 into consideration. The space capsule must be strong enough to slow down quickly, must endure extremely high or low temperatures, and must survive the landing. When the space capsule comes close to a planet’s or moon’s surface, it has to slow down at a very exact rate. If it slows down too quickly, everything in the capsule will be crushed. If it doesn’t slow down quickly enough, it will crash into the surface and be destroyed. There are additional requirements for atmospheric reentry. If the angle of attack is too shallow, the capsule may skip off the surface of the atmosphere. If the angle of attack is too steep, the deceleration forces may be too high or the heat of reentry may exceed the tolerances of the heat shield.

Capsules are formed in a rounded shape called a blunt body instead of a pointed one, as this forms a shock wave that doesn't touch the capsule, and the heat is deflected away rather than melting the vehicle.

The Apollo capsules were guided through the atmosphere — the center of mass
Center of mass
In physics, the center of mass or barycenter of a system is the average location of all of its mass. In the case of a rigid body, the position of the center of mass is fixed in relation to the body...

 of the capsule was offset from the center line. This angled the capsule's passage through the air, providing a sideways lift. Rotational thrusters were used to change the lift vector, allowing the capsule to be steered under either automatic or manual control.

At lower altitudes and speeds parachutes are used to slow the capsule down by making more drag.

The space capsules also have to be able to withstand the impact when they reach the Earth’s surface. All US manned capsules (Mercury, Gemini, Apollo) would land on water; the Soviet/Russian Soyuz and Chinese Shenzhou (and planned US, Russian, Indian) manned capsules uses small rockets to touch down on land. In the lighter gravity of Mars, airbags were sufficient to land some of the robotic missions safely.

Gravity, drag, and lift

Two of the biggest external forces that a space capsule experiences are gravity and drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

.

Drag is the space capsule’s resistance to it being pushed though air. Air is a mixture of different molecules, including nitrogen, oxygen and carbon dioxide. Anything falling through air hits these molecules and therefore slows down. The amount of drag on a capsule depends on many things, including the density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...

 of the air, and the shape, mass, diameter and roughness of the capsule. The speed of a space craft highly depends on the combined effect of the two forces — gravity, which can speed up a rocket, and drag, which will slow down the rocket. Space capsules entering Earth’s atmosphere will be considerably slowed because our atmosphere is so thick.

When the space capsule comes through the atmosphere the capsule compresses the air in front of it which heats up to very high temperatures (contrary to popular belief friction is not significant).

A good example for this is a shooting star
METEOR
METEOR is a metric for the evaluation of machine translation output. The metric is based on the harmonic mean of unigram precision and recall, with recall weighted higher than precision...

. A shooting star, which is usually tiny, creates so much heat coming through the atmosphere that the air around the meteorite glows white hot. So much more so, when a huge object like a space capsule comes through, even more heat is created.

As the space capsule slows down, the compression of the air molecules hitting the capsules surface creates a lot of heat. The surface of a capsule can get to 1480 °C (2700 F) as it descends through the Earth’s atmosphere. All this heat has to be directed away. Space capsules are typically coated with a material that melts and then vaporizes ("ablation"). It may seem counterproductive, but the vaporization takes heat away from the capsule. This keeps the reentry heat from getting inside the capsule. Capsules see a more intense heating regime than spaceplanes and ceramics such as used on the Space Shuttle are usually less suitable, and all capsules have used ablation.

In practice, capsules do create a significant and useful amount of lift. This lift is used to control the trajectory of the capsule. This controls allows for reduced g-forces for the crew, as well as reducing the peak heat transfer into the capsule. The longer the vehicle spends at high altitude, the thinner the air is and the less heat is conducted. For example the Apollo capsule had a lift to drag ratio of about 0.35. In the absence of any lift the Apollo capsule would be subjected to about 20g deceleration (8g for low-earth-orbiting spacecraft), but with lift the trajectory can be kept to around 4g.

History

Early space capsules were based on the designs of the late Maxime Faget
Maxime Faget
Maxime "Max" A. Faget was the designer of the Mercury capsule, and contributed to the later Gemini and Apollo spacecraft as well as the Space Shuttle.- Life :...

 and many Soviet engineers working under Sergei Korolev.

Before humans went into space, test orbital and suborbital flights of space capsules were made with monkey
Monkey
A monkey is a primate, either an Old World monkey or a New World monkey. There are about 260 known living species of monkey. Many are arboreal, although there are species that live primarily on the ground, such as baboons. Monkeys are generally considered to be intelligent. Unlike apes, monkeys...

s, dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...

s and mice
Mouse
A mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles...

. These were to see what effects a flight in space would have on a living organism. In 1957, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

 sent into orbit the first animal (dog) in Sputnik 2
Sputnik 2
Sputnik 2 , or Prosteyshiy Sputnik 2 ), was the second spacecraft launched into Earth orbit, on November 3, 1957, and the first to carry a living animal, a dog named Laika. Sputnik 2 was a 4-meter high cone-shaped capsule with a base diameter of 2 meters...

 but without recovery of space capsule to Earth. This was followed by other animal missions of developed as manned Vostok
Vostok spacecraft
The Vostok was a type of spacecraft built by the Soviet Union. The first human spaceflight in history was accomplished on this spacecraft on April 12, 1961, by Soviet cosmonaut Yuri Gagarin....

 spacecraft (first successful was Sputnik 5
Sputnik 5
Korabl-Sputnik 2 , also known as Sputnik 5 in the West, was a Soviet artificial satellite, and the third test flight of the Vostok spacecraft. It was the first spaceflight to send animals into orbit and return them safely back to Earth...

 in 1960), until Russian Cosmonaut Yuri Gagarin
Yuri Gagarin
Yuri Alekseyevich Gagarin was a Soviet pilot and cosmonaut. He was the first human to journey into outer space, when his Vostok spacecraft completed an orbit of the Earth on April 12, 1961....

 made a first manned orbital flight of Earth in 108 minutes on April 12, 1961. The first American to orbit Earth was in February, 1962 astronaut John Glenn
John Glenn
John Herschel Glenn, Jr. is a former United States Marine Corps pilot, astronaut, and United States senator who was the first American to orbit the Earth and the third American in space. Glenn was a Marine Corps fighter pilot before joining NASA's Mercury program as a member of NASA's original...

 in the Mercury
Mercury program
Mercury Program might refer to:*the first successful American manned spaceflight program, Project Mercury*an American post-rock band, The Mercury Program...

 capsule that previously was tested as unmanned and made manned suborbital missions (first of Alan Shepard
Alan Shepard
Alan Bartlett Shepard, Jr. was an American naval aviator, test pilot, flag officer, and NASA astronaut who in 1961 became the second person, and the first American, in space. This Mercury flight was designed to enter space, but not to achieve orbit...

 on May, 1961). Later, the Gemini
Project Gemini
Project Gemini was the second human spaceflight program of NASA, the civilian space agency of the United States government. Project Gemini was conducted between projects Mercury and Apollo, with ten manned flights occurring in 1965 and 1966....

 capsule took two (2) astronauts into space for longer periods of time. The Apollo capsule took three (3) astronauts to the moon, and the Lunar Module took two (2) of them to the surface. The Soviet Voskhod
Voskhod spacecraft
The Voskhod was a spacecraft built by the Soviet Union's space program for human spaceflight as part of the Voskhod programme. It was a development of and a follow-on to the Vostok spacecraft...

 space capsule has taken many cosmonauts into orbit.

Not all space capsule missions have been successful. Many people have lost their lives in space explorations. One of them, the Soyuz 11
Soyuz 11
Soyuz 11 was the first manned mission to arrive at the world's first space station, Salyut 1. The mission arrived at the space station on June 7, 1971 and departed on June 30, 1971. The mission ended in disaster when the crew capsule depressurized during preparations for re-entry, killing the...

 capsule, lost the air inside of it before reentry during the descend module separation, and although safely landed, all three cosmonauts were dead due to depressurization and asphyxiation. Another, Apollo 1
Apollo 1
Apollo 1 was scheduled to be the first manned mission of the Apollo manned lunar landing program, with a target launch date of February 21, 1967. A cabin fire during a launch pad test on January 27 at Launch Pad 34 at Cape Canaveral killed all three crew members: Command Pilot Virgil "Gus"...

 was destroyed by cabin fire during launch simulation and all three astronauts died due to smoke inhalation and burns.

First unmanned space capsule (recovery satellite) was US Corona
Corona (satellite)
The Corona program was a series of American strategic reconnaissance satellites produced and operated by the Central Intelligence Agency Directorate of Science & Technology with substantial assistance from the U.S. Air Force...

 reconnaisanse satellite at 1959.

Soviet/Russian

  • Vostok
    Vostok spacecraft
    The Vostok was a type of spacecraft built by the Soviet Union. The first human spaceflight in history was accomplished on this spacecraft on April 12, 1961, by Soviet cosmonaut Yuri Gagarin....

  • Voskhod
    Voskhod spacecraft
    The Voskhod was a spacecraft built by the Soviet Union's space program for human spaceflight as part of the Voskhod programme. It was a development of and a follow-on to the Vostok spacecraft...

  • Soyuz
    Soyuz spacecraft
    Soyuz , Union) is a series of spacecraft initially designed for the Soviet space programme by the Korolyov Design Bureau in the 1960s, and still in service today...

  • Prospective Piloted Transport System
    Prospective Piloted Transport System
    PPTS , unofficially called Rus, is a project being undertaken by the Russian Federal Space Agency to develop a new-generation manned spacecraft...


American

  • Mercury
  • Gemini
  • Apollo
    Apollo spacecraft
    The Apollo spacecraft was composed of five combined parts designed to accomplish the American Apollo program's goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth...

  • Orion
  • CST-100
  • SpaceX Dragon

Unmanned capsules

  • Corona
    Corona (satellite)
    The Corona program was a series of American strategic reconnaissance satellites produced and operated by the Central Intelligence Agency Directorate of Science & Technology with substantial assistance from the U.S. Air Force...

  • FSW
    Fanhui Shi Weixing
    Fanhui Shi Weixing is a series of Chinese recoverable reconnaissance satellites. The satellites were used for both military and civilian observation needs, with a total of 26 flights. The first flight was FSW-0 on 1969-06-01 and the last SJ-8 on 2006-09-09....

  • Foton
    Foton
    Foton is the project name of two series of Russian science satellite and reentry vehicle programs. Although unmanned, the design was adapted from the manned Vostok spacecraft capsule. The primary focus of the Foton project is materials science research, but some missions have also carried...

  • Raduga
    VBK-Raduga
    The VBK-Raduga capsule is a reentry capsule that was used for returning materials to Earth's surface from the space station Mir. They were brought to Mir in the Progress-M cargo craft's dry cargo compartment...

  • Progress
  • Yantar
    Yantar (satellite)
    Yantar is a series of Russian reconnaissance satellites, which supplemented and eventually replaced the Zenit spacecraft. Kosmos 2175, a Yantar-4K2 or Kobal't spacecraft, was the first satellite to be launched by the Russian Federation following the dissolution of the Soviet Union. Yantar-Terilen...

  • OREX
    OREX
    OREX was a NASDA reentry demonstrator prototype which was launched in 1994 on the H-II launcher. It was a precursor for the Japanese space Shuttle Hope....

    , Hyflex
    Hyflex
    Hyflex was a NASDA reentry demonstrator prototype which was launched in 1996 on the only flight of the J-I launcher...

  • SRE
    Space Capsule Recovery Experiment
    The Space Capsule Recovery Experiment is an Indian experimental spacecraft which was launched at 03:53 GMT on January 10, 2007 from Sriharikota by the Indian Space Research Organization . The launch was conducted using the PSLV C7 rocket, along with three other satellites...

  • Atmospheric Reentry Demonstrator
    Atmospheric Reentry Demonstrator
    The Advanced Reentry Demonstrator was a suborbital reentry test flown on the third Ariane 5 flight. The ARD was launched on October 21, 1998, and was released shortly after separation of the launcher's cryogenic main stage 12 minutes after lift-off from the Guiana Space Centre, Europe's spaceport...


Spacecrafts was designed as manned but flown unpiloted only

  • Zond/L1
    Soyuz 7K-L1
    The Soyuz 7K-L1 spacecraft was designed to launch men from the Earth to circle the Moon without going into lunar orbit in the context of the Soviet manned moon-flyby program in Moon race. It was based on the Soyuz 7K-OK with several components stripped out to reduce the vehicle weight...

  • L3
    Soyuz 7K-L3
    The Soyuz 7K-LOK, or simply LOK was a Soviet spacecraft designed to launch men from Earth to circle the moon and developed in parallel to the 7K-L1. The LOK would carry two cosmonauts into orbit around the Moon, acting as "mother" spacecraft for the LK Lander, which would land one member of the...

  • TKS
    TKS spacecraft
    TKS spacecraft was a Soviet spacecraft design in the late 1960s intended to supply the military Almaz space station. The spacecraft was designed for manned or autonomous cargo resupply use...


See also

  • Reentry module
  • Orbital module
    Orbital module
    The orbital module is a portion of spacecraft used only in orbit. These have developed from the Soviet Soyuz spacecraft.-Soyuz orbit module:The orbit module is a spherical part of Soviet-Russian Soyuz space ship series...

  • Service module
    Service module
    A service module is a spacecraft compartment containing a variety of support systems used for spacecraft operations. Usually located in the uninhabited area of the spacecraft, the service module is jettisoned upon the completion of the mission, and usually burns up during atmospheric reentry...

  • Command module
  • Space exploration
    Space exploration
    Space exploration is the use of space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft....

  • U.S. space exploration history on U.S. stamps
    U.S. space exploration history on U.S. stamps
    With the advent of unmanned and manned space flight a whole new era of American history had presented itself. Keeping with the tradition of honoring the country's history on the face of U.S. postage stamps, the U.S. Post Office began honoring the various events with its commemorative postage stamp...

  • Space suit
    Space suit
    A space suit is a garment worn to keep an astronaut alive in the harsh environment of outer space. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, and are necessary for extra-vehicular activity , work done outside spacecraft...

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