Spaceflight
Encyclopedia
Spaceflight is the act of travelling into or through outer space
. Spaceflight can occur with spacecraft
which may, or may not, have humans on board. Examples of human spaceflight
include the Russia
n Soyuz program
, the U.S. Space shuttle program
, as well as the ongoing International Space Station
. Examples of unmanned spaceflight include space probe
s which leave Earth
's orbit
, as well as satellite
s in orbit
around Earth
, such as communication satellites. These operate either by telerobotic control or are fully autonomous
.
Spaceflight is used in space exploration
, and also in commercial activities like space tourism
and satellite telecommunications. Additional non-commercial uses of spaceflight include space observatories
, reconnaissance satellites and other earth observation satellite
s.
A spaceflight typically begins with a rocket
launch
, which provides the initial thrust to overcome the force of gravity and propels the spacecraft from the surface of the Earth. Once in space, the motion of a spacecraft—both when unpropelled and when under propulsion—is covered by the area of study called astrodynamics
. Some spacecraft remain in space indefinitely, some disintegrate during atmospheric reentry
, and others reach a planetary or lunar surface for landing or impact.
The realistic proposal of space travel goes back to Konstantin Tsiolkovsky
. His most famous work, "" (The Exploration of Cosmic Space by Means of Reaction Devices), was published in 1903, but this theoretical work was not widely influential outside of Russia.
Spaceflight became an engineering possibility with the work of Robert H. Goddard
's publication in 1919 of his paper 'A Method of Reaching Extreme Altitudes'; where his application of the de Laval nozzle
to liquid fuel rockets gave sufficient power that interplanetary travel became possible. He also proved in the laboratory that rockets would work in the vacuum of space; not all scientists of that day believed they would. This paper was highly influential on Hermann Oberth
and Wernher Von Braun
, later key players in spaceflight.
The first rocket to reach space, an altitude of 100 km, was the German
V-2 Rocket
, on a test flight in June, 1944. On the 4th of October, 1957, the Soviet Union
launched Sputnik 1
, which became the first artificial satellite
to orbit the Earth
. The first human spaceflight
was Vostok 1
on April 12, 1961, aboard which Soviet cosmonaut
Yuri Gagarin
made one orbit around the Earth. The lead architects behind the Soviet space program
's Vostok 1 mission were the rocket scientists Sergey Korolyov
and Kerim Kerimov
.
Rockets remain the only currently practical means of reaching space. Other non-rocket spacelaunch
technologies such as scramjet
s still fall far short of orbital speed.
A rocket launch
for a spaceflight usually starts from a spaceport
(cosmodrome), which may be equipped with launch complexes and launch pad
s for vertical rocket launches, and runways for takeoff and landing of carrier airplanes and winged spacecraft. Spaceports are situated well away from human habitation for noise and safety reasons. ICBM
s have various special launching facilities.
A launch is often restricted to certain launch window
s. These windows depend upon the position of celestial bodies and orbits relative to the launch site. The biggest influence is often the rotation of the Earth itself. Once launched, orbits are normally located within relatively constant flat planes at a fixed angle to the axis of the Earth, and the Earth rotates within this orbit.
A launch pad
is a fixed structure designed to dispatch airborne vehicles. It generally consists of a launch tower and flame trench. It is surrounded by equipment used to erect, fuel, and maintain launch vehicles.
The most commonly used definition of outer space
is everything beyond the Kármán line
, which is 100 kilometres (62.1 mi) above the Earth's surface. (The United States sometimes defines outer space as everything beyond 50 miles (80.5 km) in altitude.)
Rocket
s are the only currently practical means of reaching space. Conventional airplane engines cannot reach space due to the lack of oxygen. Rocket engines expel propellant
to provide forward thrust
that generates enough delta-v
(change in velocity) to reach orbit. Propulsion systems for different applications include:
For manned launch systems launch escape system
s are frequently fitted to allow astronauts to escape in the case of catastrophic failures.
and rotovators require new materials much stronger than any currently known. Electromagnetic launchers such as launch loop
s might be feasible with current technology. Other ideas include rocket assisted jet planes such as Reaction Engines Skylon or the trickier scramjet
s. Gun launch has been proposed for cargo.
n space vehicles successfully achieved very high altitudes without going into orbit. NASA
considered launching Apollo
missions directly into lunar trajectories but adopted the strategy of first entering a temporary parking orbit
and then performing a separate burn several orbits later onto a lunar trajectory. This costs additional propellant because the parking orbit perigee must be high enough to prevent reentry while direct injection can have an arbitrarily low perigee because it will never be reached.
However, the parking orbit approach greatly simplified Apollo mission planning in several important ways. It substantially widened the allowable launch window
s, increasing the chance of a successful launch despite minor technical problems during the countdown. The parking orbit was a stable "mission plateau" that gave the crew and controllers several hours to thoroughly check out the spacecraft after the stresses of launch before committing it to a long lunar flight; the crew could quickly return to earth, if necessary, or an alternate earth-orbital mission could be conducted. The parking orbit also enabled translunar trajectories that avoided the densest parts of the Van Allen radiation belts.
Apollo missions minimized the performance penalty of the parking orbit by keeping its altitude as low as possible. For example, Apollo 15
used an unusually low parking orbit (even for Apollo) of 92.5 by 91.5 nautical miles (171x169 km) where there was significant atmospheric drag. But it was partially overcome by continuous venting of hydrogen from the third stage of the Saturn V
, and was in any event tolerable for the short stay.
Robotic missions do not require an abort capability or radiation minimization, and because modern launchers routinely meet "instantaneous" launch windows, space probes to the moon and other planets generally use direct injection to maximize performance. Although some might coast briefly during the launch sequence, they do not complete one or more full parking orbits before the burn that injects them onto an earth escape trajectory.
Note that the escape velocity from a celestial body decreases with altitude above that body. However, it is more fuel-efficient for a craft to burn its fuel as close to the ground as possible; see Oberth effect
and reference. This is another
way to explain the performance penalty associated with establishing the safe perigee of a parking orbit.
Plans for future crewed interplanetary spaceflight missions often include final vehicle assembly in Earth orbit, such as NASA's Project Orion
and Russia's Kliper
/Parom
tandem.
Non-rocket orbital propulsion methods include solar sail
s, magnetic sail
s, plasma-bubble magnetic systems, and using gravitational slingshot
effects.
. The theory behind reentry is due to Harry Julian Allen
. Based on this theory, reentry vehicles present blunt shapes to the atmosphere for reentry. Blunt shapes mean that less than 1% of the kinetic energy ends up as heat that reaches the vehicle and the heat energy instead ends up in the atmosphere.
The Mercury, Gemini, and Apollo capsules all splashed down
in the sea. These capsules were designed to land at relatively slow speeds.
Russian capsules for Soyuz make use of braking rockets as were designed to touch down on land.
The Space Shuttle and Buran glide to a touchdown at high speed.
technique was used to recover the film canisters from the Corona
spy satellites.
on April 12, 1961, on which cosmonaut
Yuri Gagarin
of the USSR made one orbit around the Earth. In official Soviet documents, there is no mention of the fact that Gagarin parachuted the final seven miles. The international rules for aviation records stated that "The pilot remains in his craft from launch to landing". This rule, if applied, would have "disqualified" Gagarin's spaceflight. Currently the only spacecraft regularly used for human spaceflight are Russian Soyuz spacecraft
and the U.S. Space Shuttle
fleet. Each of those space programs have used other craft in the past. Recently, the Chinese Shenzhou spacecraft
has been used three times for human spaceflight, and SpaceShipOne twice.
the spacecraft reaches space and then returns to the atmosphere after following a (primarily) ballistic trajectory. This is usually because of insufficient specific orbital energy
, in which case a suborbital flight will last only a few minutes, but it is also possible for an object with enough energy for an orbit to have a trajectory that intersects the Earth's atmosphere, sometimes after many hours. Pioneer 1
was NASA's first space probe
intended to reach the Moon. A partial failure caused it to instead follow a suborbital trajectory to an altitude of 113854 kilometres (70,745.8 mi) before reentering the Earth's atmosphere 43 hours after launch.
The most generally recognized boundary of space is the Kármán line
(actually a sphere) 100 km above sea level. (NASA alternatively defines an astronaut as someone who has flown more than 50 miles (80.5 km) or 80 km above sea level.) It is not generally recognized by the public that the increase in potential energy required to pass the Kármán line is only about 3% of the orbital energy (potential plus kinetic energy) required by the lowest possible earth orbit (a circular orbit just above the Kármán line.) In other words, it is far easier to reach space than to stay there.
On May 17, 2004, Civilian Space eXploration Team
launched the GoFast Rocket on a suborbital flight, the first amateur spaceflight. On June 21, 2004, SpaceShipOne was used for the first privately-funded
human spaceflight
.
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A minimal orbital spaceflight
requires much higher velocities than a minimal sub-orbital flight, and so it is technologically much more challenging to achieve. To achieve orbital spaceflight, the tangential velocity around the Earth is as important as altitude. In order to perform a stable and lasting flight in space, the spacecraft must reach the minimal orbital speed
required for a closed orbit
.
Interplanetary travel is travel
between planets within a single planetary system
. In practice, the use of the term is confined to travel between the planets of the Solar System
.
on escape trajectories. The one farthest from the Sun is Voyager 1
, which is more than 100 AU
distant and is moving at 3.6 AU per year. In comparison Proxima Centauri
, the closest star other than the Sun, is 267,000 AU distant. It will take Voyager 1 over 74,000 years to reach this distance. Vehicle designs using other techniques, such as nuclear pulse propulsion
are likely to be able to reach the nearest star significantly faster.
Another possibility that could allow for human interstellar spaceflight is to make use of time dilation
, as this would make it possible for passengers in a fast-moving vehicle to travel further into the future while aging very little, in that their great speed slows down the rate of passage of on-board time. However, attaining such high speeds would still require the use of some new, advanced method of propulsion
.
.
Spacecraft are vehicles capable of controlling their trajectory through space.
The first 'true spacecraft' is sometimes said to be Apollo Lunar Module
, since this was the only manned vehicle to have been designed for, and operated only in space; and is notable for its non aerodynamic shape.
s for propulsion
, but other propulsion techniques such as ion drives are becoming more common, particularly for unmanned vehicles, and this can significantly reduce the vehicle's mass and increase its delta-v
.
's Space Shuttle
and the SpaceX
Falcon 1
use multi-stage
expendable launch systems to reach space.
The first reusable spacecraft, the X-15, was air-launched on a suborbital trajectory on July 19, 1963. The first partially reusable orbital spacecraft, the Space Shuttle, was launched by the USA on the 20th anniversary of Yuri Gagarin
's flight, on April 12, 1981. During the Shuttle era, six orbiters were built, all of which have flown in the atmosphere and five of which have flown in space. The Enterprise
was used only for approach and landing tests, launching from the back of a Boeing 747
and gliding to deadstick landings at Edwards AFB, California. The first Space Shuttle to fly into space was the Columbia
, followed by the Challenger
, Discovery
, Atlantis
, and Endeavour
. The Endeavour was built to replace the Challenger, which was lost
in January 1986. The Columbia broke up
during reentry in February 2003.
The first (and so far only) automatic partially reusable spacecraft was the Buran
(Snowstorm), launched by the USSR on November 15, 1988, although it made only one flight. This spaceplane
was designed for a crew and strongly resembled the U. S. Space Shuttle, although its drop-off boosters used liquid propellants and its main engines were located at the base of what would be the external tank in the American Shuttle. Lack of funding, complicated by the dissolution of the USSR, prevented any further flights of Buran.
Per the Vision for Space Exploration
, the Space Shuttle is due to be retired in 2011 due mainly to its old age and high cost of the program reaching over a billion dollars per flight. The Shuttle's human transport role is to be replaced by the partially reusable Crew Exploration Vehicle
(CEV) no later than 2014. The Shuttle's heavy cargo transport role is to be replaced by expendable rockets such as the Evolved Expendable Launch Vehicle (EELV) or a Shuttle Derived Launch Vehicle.
Scaled Composites
SpaceShipOne was a reusable suborbital spaceplane
that carried pilots Mike Melvill
and Brian Binnie
on consecutive flights in 2004 to win the Ansari X Prize
. The Spaceship Company
will build its successor SpaceShipTwo. A fleet of SpaceShipTwos operated by Virgin Galactic
planned to begin reusable private spaceflight
carrying paying passengers (space tourists
) in 2008, but this was delayed due to an accident in the propulsion development.
rocket exploded 13 seconds after launch on January 17, 1997, there were reports of store windows 10 miles (16.1 km) away being broken by the blast.
Space is a fairly predictable environment, but there are still risks of accidental depressurisation and the potential failure of equipment, some of which may be very newly developed.
In 2004 the International Association for the Advancement of Space Safety
was established in the Netherlands to further international cooperation and scientific advancement in space systems safety.
In a microgravity environment such as that provided by a spacecraft in orbit around the Earth, humans experience a sense of "weightlessness." Short-term exposure to microgravity causes space adaptation syndrome
, a self-limiting nausea caused by derangement of the vestibular system
. Long-term exposure causes multiple health issues. The most significant is bone loss, some of which is permanent, but microgravity also leads to significant deconditioning
of muscular and cardiovascular tissues.
Further away from the Earth, solar flare
s can give a fatal radiation dose in minutes, and the health threat from cosmic radiation
significantly increases the chances of cancer over a decade exposure or more.
, the life support system is a group of devices that allow a human being to survive in outer space. NASA
often uses the phrase Environmental Control and Life Support System or the acronym ECLSS when describing these systems for its human spaceflight
missions. The life support system may supply: air, water
and food
. It must also maintain the correct body temperature, an acceptable pressure on the body and deal with the body's waste products. Shielding against harmful external influences such as radiation and micro-meteorites may also be necessary. Components of the life support system are life-critical
, and are designed and constructed using safety engineering
techniques.
. It is distinct from the concept of weather
within a planetary atmosphere, and deals with phenomena involving ambient plasma
, magnetic fields, radiation
and other matter
in space (generally close to Earth but also in interplanetary, and occasionally interstellar medium
). "Space weather describes the conditions in space that affect Earth and its technological systems. Our space weather is a consequence of the behavior of the sun, the nature of Earth's magnetic field, and our location in the solar system."
Space weather exerts a profound influence in several areas related to space exploration and development. Changing geomagnetic conditions can induce changes in atmospheric density causing the rapid degradation of spacecraft altitude in Low Earth orbit
. Geomagnetic storms due to increased solar activity can potentially blind sensors aboard spacecraft, or interfere with on-board electronics. An understanding of space environmental conditions is also important in designing shielding and life support systems for manned spacecraft.
. Many solid rockets have chlorine in the form of perchlorate
or other chemicals, and this can cause temporary local holes in the ozone layer. Re-entering spacecraft generate nitrates which also can temporarily impact the ozone layer. Most rockets are made of metals that can have an environmental impact during their construction.
In addition to the atmospheric effects there are effects on the near-Earth space environment. There is the possibility that orbit could become inaccessible for generations due to exponentially increasing space debris
caused by spalling of satellites and vehicles (Kessler syndrome
). Many launched vehicles today are therefore designed to be re-entered after use.
that is purely commercial, although the launchers themselves are often at least partly funded by governments.
Uses for spaceflight include:
There is growing interest in spacecraft and flights paid for by commercial companies and even private individuals
. It is thought that some of the high cost of access to space is due to governmental inefficiencies; and certainly the costs of the governmental paperwork surrounding NASA
is legendary. If a commercial company were able to be more efficient, costs could come down significantly. Space launch vehicles such as Falcon I have been wholly developed with private finance, and the quoted costs for launch are lower.
Outer space
Outer space is the void that exists between celestial bodies, including the Earth. It is not completely empty, but consists of a hard vacuum containing a low density of particles: predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, and neutrinos....
. Spaceflight can occur with 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 may, or may not, have humans on board. Examples of human spaceflight
Human spaceflight
Human spaceflight is spaceflight with humans on the spacecraft. When a spacecraft is manned, it can be piloted directly, as opposed to machine or robotic space probes and remotely-controlled satellites....
include the 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...
n Soyuz program
Soyuz programme
The Soyuz programme is a human spaceflight programme that was initiated by the Soviet Union in the early 1960s, originally part of a Moon landing project intended to put a Soviet cosmonaut on the Moon...
, the U.S. Space shuttle program
Space Shuttle program
NASA's Space Shuttle program, officially called Space Transportation System , was the United States government's manned launch vehicle program from 1981 to 2011...
, as well as the ongoing International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...
. Examples of unmanned spaceflight include space probe
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
s which leave Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
's orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
, as well as satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
s in orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
around Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, such as communication satellites. These operate either by telerobotic control or are fully autonomous
Autonomous robot
Autonomous robots are robots that can perform desired tasks in unstructured environments without continuous human guidance. Many kinds of robots have some degree of autonomy. Different robots can be autonomous in different ways...
.
Spaceflight is used in 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....
, and also in commercial activities like space tourism
Space tourism
Space Tourism is space travel for recreational, leisure or business purposes. A number of startup companies have sprung up in recent years, hoping to create a space tourism industry...
and satellite telecommunications. Additional non-commercial uses of spaceflight include space observatories
Space observatory
A space observatory is any instrument in outer space which is used for observation of distant planets, galaxies, and other outer space objects...
, reconnaissance satellites and other earth observation satellite
Earth observation satellite
Earth observation satellites are satellites specifically designed to observe Earth from orbit, similar to reconnaissance satellites but intended for non-military uses such as environmental monitoring, meteorology, map making etc....
s.
A spaceflight typically begins with a rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
launch
Rocket launch
A rocket launch is the takeoff phase of the flight of a rocket. Launches for orbital spaceflights, or launches into interplanetary space, are usually from a fixed location on the ground, but may also be from a floating platform such as the San Marco platform, or the Sea Launch launch...
, which provides the initial thrust to overcome the force of gravity and propels the spacecraft from the surface of the Earth. Once in space, the motion of a spacecraft—both when unpropelled and when under propulsion—is covered by the area of study called astrodynamics
Astrodynamics
Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and Newton's law of universal gravitation. It...
. Some spacecraft remain in space indefinitely, some disintegrate 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,...
, and others reach a planetary or lunar surface for landing or impact.
History
Konstantin Tsiolkovsky
Konstantin Eduardovich Tsiolkovsky was an Imperial Russian and Soviet rocket scientist and pioneer of the astronautic theory. Along with his followers the German Hermann Oberth and the American Robert H. Goddard, he is considered to be one of the founding fathers of rocketry and astronautics...
. His most famous work, "" (The Exploration of Cosmic Space by Means of Reaction Devices), was published in 1903, but this theoretical work was not widely influential outside of Russia.
Spaceflight became an engineering possibility with the work of Robert H. Goddard
Robert H. Goddard
Robert Hutchings Goddard was an American professor, physicist and inventor who is credited with creating and building the world's first liquid-fueled rocket, which he successfully launched on March 16, 1926...
's publication in 1919 of his paper 'A Method of Reaching Extreme Altitudes'; where his application of the de Laval nozzle
De Laval nozzle
A de Laval nozzle is a tube that is pinched in the middle, making a carefully balanced, asymmetric hourglass-shape...
to liquid fuel rockets gave sufficient power that interplanetary travel became possible. He also proved in the laboratory that rockets would work in the vacuum of space; not all scientists of that day believed they would. This paper was highly influential on Hermann Oberth
Hermann Oberth
Hermann Julius Oberth was an Austro-Hungarian-born German physicist and engineer. He is considered one of the founding fathers of rocketry and astronautics.- Early life :...
and Wernher Von Braun
Wernher von Braun
Wernher Magnus Maximilian, Freiherr von Braun was a German rocket scientist, aerospace engineer, space architect, and one of the leading figures in the development of rocket technology in Nazi Germany during World War II and in the United States after that.A former member of the Nazi party,...
, later key players in spaceflight.
The first rocket to reach space, an altitude of 100 km, was the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
V-2 Rocket
V-2 rocket
The V-2 rocket , technical name Aggregat-4 , was a ballistic missile that was developed at the beginning of the Second World War in Germany, specifically targeted at London and later Antwerp. The liquid-propellant rocket was the world's first long-range combat-ballistic missile and first known...
, on a test flight in June, 1944. On the 4th of October, 1957, the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
launched Sputnik 1
Sputnik 1
Sputnik 1 ) was the first artificial satellite to be put into Earth's orbit. It was launched into an elliptical low Earth orbit by the Soviet Union on 4 October 1957. The unanticipated announcement of Sputnik 1s success precipitated the Sputnik crisis in the United States and ignited the Space...
, which became the first artificial satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
to orbit the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. The first human spaceflight
Human spaceflight
Human spaceflight is spaceflight with humans on the spacecraft. When a spacecraft is manned, it can be piloted directly, as opposed to machine or robotic space probes and remotely-controlled satellites....
was Vostok 1
Vostok 1
Vostok 1 was the first spaceflight in the Vostok program and the first human spaceflight in history. The Vostok 3KA spacecraft was launched on April 12, 1961. The flight took Yuri Gagarin, a cosmonaut from the Soviet Union, into space. The flight marked the first time that a human entered outer...
on April 12, 1961, aboard which Soviet cosmonaut
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....
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 one orbit around the Earth. The lead architects behind the Soviet space program
Soviet space program
The Soviet space program is the rocketry and space exploration programs conducted by the former Union of Soviet Socialist Republics from the 1930s until its dissolution in 1991...
's Vostok 1 mission were the rocket scientists Sergey Korolyov
Sergey Korolyov
Sergei Pavlovich Korolev ; died 14 January 1966 in Moscow, Russia) was the lead Soviet rocket engineer and spacecraft designer in the Space Race between the United States and the Soviet Union during the 1950s and 1960s...
and Kerim Kerimov
Kerim Kerimov
Lieutenant-General Kerim Aliyevich Kerimov was an Azerbaijani-Soviet/Russian aerospace engineer and a renowned rocket scientist, one of the founders of the Soviet space industry, and for many years a central figure in the Soviet space program. Despite his prominent role, his identity was kept a...
.
Rockets remain the only currently practical means of reaching space. Other non-rocket spacelaunch
Non-rocket spacelaunch
Non-rocket space launch is a launch into space where some or all needed speed and altitude is provided by non-rocket means, rather than simply using conventional chemical rockets from the ground. A number of alternatives to rockets have been proposed...
technologies such as scramjet
Scramjet
A scramjet is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow...
s still fall far short of orbital speed.
Launch
Rocket launch
A rocket launch is the takeoff phase of the flight of a rocket. Launches for orbital spaceflights, or launches into interplanetary space, are usually from a fixed location on the ground, but may also be from a floating platform such as the San Marco platform, or the Sea Launch launch...
for a spaceflight usually starts from a spaceport
Spaceport
A spaceport or cosmodrome is a site for launching spacecraft, by analogy with seaport for ships or airport for aircraft. The word spaceport, and even more so cosmodrome, has traditionally been used for sites capable of launching spacecraft into orbit around Earth or on interplanetary trajectories...
(cosmodrome), which may be equipped with launch complexes and launch pad
Launch pad
A launch pad is the area and facilities where rockets or spacecraft lift off. A spaceport can contain one or many launch pads. A typical launch pad consists of the service and umbilical structures. The service structure provides an access platform to inspect the launch vehicle prior to launch....
s for vertical rocket launches, and runways for takeoff and landing of carrier airplanes and winged spacecraft. Spaceports are situated well away from human habitation for noise and safety reasons. ICBM
Intercontinental ballistic missile
An intercontinental ballistic missile is a ballistic missile with a long range typically designed for nuclear weapons delivery...
s have various special launching facilities.
A launch is often restricted to certain launch window
Launch window
Launch window is a term used in spaceflight to describe a time period in which a particular launch vehicle must be launched. If the rocket does not launch within the "window", it has to wait for the next window....
s. These windows depend upon the position of celestial bodies and orbits relative to the launch site. The biggest influence is often the rotation of the Earth itself. Once launched, orbits are normally located within relatively constant flat planes at a fixed angle to the axis of the Earth, and the Earth rotates within this orbit.
A launch pad
Launch pad
A launch pad is the area and facilities where rockets or spacecraft lift off. A spaceport can contain one or many launch pads. A typical launch pad consists of the service and umbilical structures. The service structure provides an access platform to inspect the launch vehicle prior to launch....
is a fixed structure designed to dispatch airborne vehicles. It generally consists of a launch tower and flame trench. It is surrounded by equipment used to erect, fuel, and maintain launch vehicles.
Reaching space
Outer space
Outer space is the void that exists between celestial bodies, including the Earth. It is not completely empty, but consists of a hard vacuum containing a low density of particles: predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, and neutrinos....
is everything beyond the Kármán line
Karman line
The Kármán line lies at an altitude of above the Earth's sea level, and is commonly used to define the boundary between the Earth's atmosphere and outer space...
, which is 100 kilometres (62.1 mi) above the Earth's surface. (The United States sometimes defines outer space as everything beyond 50 miles (80.5 km) in altitude.)
Rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
s are the only currently practical means of reaching space. Conventional airplane engines cannot reach space due to the lack of oxygen. Rocket engines expel propellant
Rocket propellant
Rocket propellant is mass that is stored in some form of propellant tank, prior to being used as the propulsive mass that is ejected from a rocket engine in the form of a fluid jet to produce thrust. A fuel propellant is often burned with an oxidizer propellant to produce large volumes of very hot...
to provide forward thrust
Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....
that generates enough delta-v
Delta-v
In astrodynamics a Δv or delta-v is a scalar which takes units of speed. It is a measure of the amount of "effort" that is needed to change from one trajectory to another by making an orbital maneuver....
(change in velocity) to reach orbit. Propulsion systems for different applications include:
- Expendable launch systemExpendable launch systemAn expendable launch system is a launch system that uses an expendable launch vehicle to carry a payload into space. The vehicles used in expendable launch systems are designed to be used only once , and their components are not recovered for re-use after launch...
- Single stage to orbit
For manned launch systems launch escape system
Launch escape system
A Launch Escape System is a top-mounted rocket connected to the crew module of a crewed spacecraft and used to quickly separate the crew module from the rest of the rocket in case of emergency. Since the escape rockets are above the crew module, an LES typically uses separate nozzles which are...
s are frequently fitted to allow astronauts to escape in the case of catastrophic failures.
Other ways of reaching space
Many ways other than rockets to reach space have been proposed. Ideas such as the space elevatorSpace elevator
A space elevator, also known as a geostationary orbital tether or a beanstalk, is a proposed non-rocket spacelaunch structure...
and rotovators require new materials much stronger than any currently known. Electromagnetic launchers such as launch loop
Launch loop
A launch loop or Lofstrom loop is a proposed system for launching objects into space orbit using a moving cable-like system attached to the earth at two ends and suspended above the atmosphere in the middle...
s might be feasible with current technology. Other ideas include rocket assisted jet planes such as Reaction Engines Skylon or the trickier scramjet
Scramjet
A scramjet is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow...
s. Gun launch has been proposed for cargo.
Leaving orbit
Achieving a closed orbit is not essential to lunar and interplanetary voyages. Early RussiaRussia
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...
n space vehicles successfully achieved very high altitudes without going into orbit. NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
considered launching 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...
missions directly into lunar trajectories but adopted the strategy of first entering a temporary parking orbit
Parking orbit
A parking orbit is a temporary orbit used during the launch of a satellite or other space probe. A launch vehicle boosts into the parking orbit, then coasts for a while, then fires again to enter the final desired trajectory...
and then performing a separate burn several orbits later onto a lunar trajectory. This costs additional propellant because the parking orbit perigee must be high enough to prevent reentry while direct injection can have an arbitrarily low perigee because it will never be reached.
However, the parking orbit approach greatly simplified Apollo mission planning in several important ways. It substantially widened the allowable launch window
Launch window
Launch window is a term used in spaceflight to describe a time period in which a particular launch vehicle must be launched. If the rocket does not launch within the "window", it has to wait for the next window....
s, increasing the chance of a successful launch despite minor technical problems during the countdown. The parking orbit was a stable "mission plateau" that gave the crew and controllers several hours to thoroughly check out the spacecraft after the stresses of launch before committing it to a long lunar flight; the crew could quickly return to earth, if necessary, or an alternate earth-orbital mission could be conducted. The parking orbit also enabled translunar trajectories that avoided the densest parts of the Van Allen radiation belts.
Apollo missions minimized the performance penalty of the parking orbit by keeping its altitude as low as possible. For example, Apollo 15
Apollo 15
Apollo 15 was the ninth manned mission in the American Apollo space program, the fourth to land on the Moon and the eighth successful manned mission. It was the first of what were termed "J missions", long duration stays on the Moon with a greater focus on science than had been possible on previous...
used an unusually low parking orbit (even for Apollo) of 92.5 by 91.5 nautical miles (171x169 km) where there was significant atmospheric drag. But it was partially overcome by continuous venting of hydrogen from the third stage of the Saturn V
Saturn V
The Saturn V was an American human-rated expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. A multistage liquid-fueled launch vehicle, NASA launched 13 Saturn Vs from the Kennedy Space Center, Florida with no loss of crew or payload...
, and was in any event tolerable for the short stay.
Robotic missions do not require an abort capability or radiation minimization, and because modern launchers routinely meet "instantaneous" launch windows, space probes to the moon and other planets generally use direct injection to maximize performance. Although some might coast briefly during the launch sequence, they do not complete one or more full parking orbits before the burn that injects them onto an earth escape trajectory.
Note that the escape velocity from a celestial body decreases with altitude above that body. However, it is more fuel-efficient for a craft to burn its fuel as close to the ground as possible; see Oberth effect
Oberth effect
In astronautics, the Oberth effect is where the use of a rocket engine when travelling at high speed generates much more useful energy than one at low speed...
and reference. This is another
way to explain the performance penalty associated with establishing the safe perigee of a parking orbit.
Plans for future crewed interplanetary spaceflight missions often include final vehicle assembly in Earth orbit, such as NASA's Project Orion
Orion (spacecraft)
Orion is a spacecraft designed by Lockheed Martin for NASA, the space agency of the United States. Orion development began in 2005 as part of the Constellation program, where Orion would fulfill the function of a Crew Exploration Vehicle....
and Russia's 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...
/Parom
Parom
The Parom is a space tug that has been proposed by RKK Energia. The purpose of this vehicle is to replace most of the Progress' active components. Progress spacecraft have flown re-supply missions since 1978. Nikolai Bryukhanov, RKK Energia's deputy general designer, said in May 2005 that the...
tandem.
Astrodynamics
Astrodynamics is the study of spacecraft trajectories, particularly as they relate to gravitational and propulsion effects. Astrodynamics allows for a spacecraft to arrive at its destination at the correct time without excessive propellant use. An orbital maneuvering system may be needed to maintain or change orbits.Non-rocket orbital propulsion methods include solar sail
Solar sail
Solar sails are a form of spacecraft propulsion using the radiation pressure of light from a star or laser to push enormous ultra-thin mirrors to high speeds....
s, magnetic sail
Magnetic sail
A magnetic sail or magsail is a proposed method of spacecraft propulsion which would use a static magnetic field to deflect charged particles radiated by the Sun as a plasma wind, and thus impart momentum to accelerate the spacecraft...
s, plasma-bubble magnetic systems, and using gravitational slingshot
Gravitational slingshot
In orbital mechanics and aerospace engineering, a gravitational slingshot, gravity assist maneuver, or swing-by is the use of the relative movement and gravity of a planet or other celestial body to alter the path and speed of a spacecraft, typically in order to save propellant, time, and expense...
effects.
Reentry
Vehicles in orbit have large amounts of kinetic energy. This energy must be discarded if the vehicle is to land safely without vaporizing in the atmosphere. Typically this process requires special methods to protect against aerodynamic heatingAerodynamic heating
Aerodynamic heating is the heating of a solid body produced by the passage of fluid over a body such as a meteor, missile, or airplane. It is a form of forced convection in that the flow field is created by forces beyond those associated with the thermal processes...
. The theory behind reentry is due to Harry Julian Allen
Harry Julian Allen
Harry Julian Allen , also known as Harvey Allen, was an aeronautical engineer and a Director of the NASA Ames Research Center, most noted for his "Blunt Body Theory" of re-entry aerodynamics which permitted successful recovery of orbiting spacecraft. His technique is still used to this...
. Based on this theory, reentry vehicles present blunt shapes to the atmosphere for reentry. Blunt shapes mean that less than 1% of the kinetic energy ends up as heat that reaches the vehicle and the heat energy instead ends up in the atmosphere.
Landing
Splashdown (spacecraft landing)
Splashdown is the method of landing a spacecraft by parachute in a body of water. It was used by American manned spacecraft prior to the Space Shuttle program. It is also possible for the Russian Soyuz spacecraft and Chinese Shenzhou spacecraft to land in water, though this is only a contingency...
in the sea. These capsules were designed to land at relatively slow speeds.
Russian capsules for Soyuz make use of braking rockets as were designed to touch down on land.
The Space Shuttle and Buran glide to a touchdown at high speed.
Recovery
After a successful landing the spacecraft, its occupants and cargo can be recovered. In some cases, recovery has occurred before landing: while a spacecraft is still descending on its parachute, it can be snagged by a specially designed aircraft. This mid-air retrievalMid-air retrieval
Mid-air retrieval is a technique used in atmospheric reentry when the reentering vehicle is incapable of a satisfactory unassisted landing. The vehicle is slowed by means of parachutes, and then a specially-equipped aircraft matches the vehicle's trajectory and catches it in mid-air.This is a risky...
technique was used to recover the film canisters from the 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...
spy satellites.
Human spaceflight
The first human spaceflight was Vostok 1Vostok 1
Vostok 1 was the first spaceflight in the Vostok program and the first human spaceflight in history. The Vostok 3KA spacecraft was launched on April 12, 1961. The flight took Yuri Gagarin, a cosmonaut from the Soviet Union, into space. The flight marked the first time that a human entered outer...
on April 12, 1961, on which cosmonaut
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....
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....
of the USSR made one orbit around the Earth. In official Soviet documents, there is no mention of the fact that Gagarin parachuted the final seven miles. The international rules for aviation records stated that "The pilot remains in his craft from launch to landing". This rule, if applied, would have "disqualified" Gagarin's spaceflight. Currently the only spacecraft regularly used for human spaceflight are Russian Soyuz 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...
and the U.S. 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...
fleet. Each of those space programs have used other craft in the past. Recently, the Chinese Shenzhou spacecraft
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...
has been used three times for human spaceflight, and SpaceShipOne twice.
Sub-orbital spaceflight
On a sub-orbital spaceflightSub-orbital spaceflight
A sub-orbital space flight is a spaceflight in which the spacecraft reaches space, but its trajectory intersects the atmosphere or surface of the gravitating body from which it was launched, so that it does not complete one orbital revolution....
the spacecraft reaches space and then returns to the atmosphere after following a (primarily) ballistic trajectory. This is usually because of insufficient specific orbital energy
Specific orbital energy
In the gravitational two-body problem, the specific orbital energy \epsilon\,\! of two orbiting bodies is the constant sum of their mutual potential energy and their total kinetic energy , divided by the reduced mass...
, in which case a suborbital flight will last only a few minutes, but it is also possible for an object with enough energy for an orbit to have a trajectory that intersects the Earth's atmosphere, sometimes after many hours. Pioneer 1
Pioneer 1
On October 11, 1958, Pioneer 1 became the first spacecraft launched by NASA, the newly formed space agency of the United States. The flight was the second and most successful of the three Thor-Able space probes.- Spacecraft design :...
was NASA's first space probe
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
intended to reach the Moon. A partial failure caused it to instead follow a suborbital trajectory to an altitude of 113854 kilometres (70,745.8 mi) before reentering the Earth's atmosphere 43 hours after launch.
The most generally recognized boundary of space is the Kármán line
Karman line
The Kármán line lies at an altitude of above the Earth's sea level, and is commonly used to define the boundary between the Earth's atmosphere and outer space...
(actually a sphere) 100 km above sea level. (NASA alternatively defines an astronaut as someone who has flown more than 50 miles (80.5 km) or 80 km above sea level.) It is not generally recognized by the public that the increase in potential energy required to pass the Kármán line is only about 3% of the orbital energy (potential plus kinetic energy) required by the lowest possible earth orbit (a circular orbit just above the Kármán line.) In other words, it is far easier to reach space than to stay there.
On May 17, 2004, Civilian Space eXploration Team
Civilian Space eXploration Team
The Civilian Space eXploration Team, known as CSXT, is a team of around 30 civilians interested in private spaceflight. The team was created by Ky Michaelson. It has conducted multiple rocket launches in an attempt to establish altitude records...
launched the GoFast Rocket on a suborbital flight, the first amateur spaceflight. On June 21, 2004, SpaceShipOne was used for the first privately-funded
Private spaceflight
Private spaceflight is flight above Earth altitude conducted by and paid for by an entity other than a government. In the early decades of the Space Age, the government space agencies of the Soviet Union and United States pioneered space technology augmented by collaboration with affiliated design...
human spaceflight
Human spaceflight
Human spaceflight is spaceflight with humans on the spacecraft. When a spacecraft is manned, it can be piloted directly, as opposed to machine or robotic space probes and remotely-controlled satellites....
.
Orbital spaceflight
A minimal orbital spaceflight
Orbital spaceflight
An orbital spaceflight is a spaceflight in which a spacecraft is placed on a trajectory where it could remain in space for at least one orbit. To do this around the Earth, it must be on a free trajectory which has an altitude at perigee above...
requires much higher velocities than a minimal sub-orbital flight, and so it is technologically much more challenging to achieve. To achieve orbital spaceflight, the tangential velocity around the Earth is as important as altitude. In order to perform a stable and lasting flight in space, the spacecraft must reach the minimal orbital speed
Orbital speed
The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body...
required for a closed orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
.
Interplanetary spaceflight
Travel
Travel is the movement of people or objects between relatively distant geographical locations. 'Travel' can also include relatively short stays between successive movements.-Etymology:...
between planets within a single planetary system
Planetary system
A planetary system consists of the various non-stellar objects orbiting a star such as planets, dwarf planets , asteroids, meteoroids, comets, and cosmic dust...
. In practice, the use of the term is confined to travel between the planets of the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
.
Interstellar spaceflight
Five spacecraft are currently leaving the Solar SystemSolar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
on escape trajectories. The one farthest from the Sun is Voyager 1
Voyager 1
The Voyager 1 spacecraft is a 722-kilogram space probe launched by NASA in 1977, to study the outer Solar System and eventually interstellar space. Operating for as of today , the spacecraft receives routine commands and transmits data back to the Deep Space Network. At a distance of as of...
, which is more than 100 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
distant and is moving at 3.6 AU per year. In comparison Proxima Centauri
Proxima Centauri
Proxima Centauri is a red dwarf star about 4.2 light-years distant in the constellation of Centaurus. It was discovered in 1915 by Robert Innes, the Director of the Union Observatory in South Africa, and is the nearest known star to the Sun, although it is too faint to be seen with the naked eye...
, the closest star other than the Sun, is 267,000 AU distant. It will take Voyager 1 over 74,000 years to reach this distance. Vehicle designs using other techniques, such as nuclear pulse propulsion
Nuclear pulse propulsion
Nuclear pulse propulsion is a proposed method of spacecraft propulsion that uses nuclear explosions for thrust. It was first developed as Project Orion by DARPA, after a suggestion by Stanislaw Ulam in 1947...
are likely to be able to reach the nearest star significantly faster.
Another possibility that could allow for human interstellar spaceflight is to make use of time dilation
Time dilation
In the theory of relativity, time dilation is an observed difference of elapsed time between two events as measured by observers either moving relative to each other or differently situated from gravitational masses. An accurate clock at rest with respect to one observer may be measured to tick at...
, as this would make it possible for passengers in a fast-moving vehicle to travel further into the future while aging very little, in that their great speed slows down the rate of passage of on-board time. However, attaining such high speeds would still require the use of some new, advanced method of propulsion
Spacecraft propulsion
Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research. However, most spacecraft today are propelled by forcing a gas from the...
.
Intergalactic spaceflight
Intergalactic travel involves spaceflight between galaxies, and is considered much more technologically demanding than even interstellar travel and, by current engineering terms, is considered science fictionScience fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...
.
Point-to-point sub-orbital spaceflight
Point-to-point sub-orbital spaceflight is a category of spaceflight in which a spacecraft uses a sub-orbital flight for transportation. This can provide a two-hour trip from London to Sydney. Today, no company offers this type of spaceflight for transportation. However, Virgin Galactic is planning to build a spaceplane called SpaceShipThree, which will offer this service in the future.Spacecraft and launch systems
The first 'true spacecraft' is sometimes said to be Apollo Lunar Module
Apollo Lunar Module
The Apollo Lunar Module was the lander portion of the Apollo spacecraft built for the US Apollo program by Grumman to carry a crew of two from lunar orbit to the surface and back...
, since this was the only manned vehicle to have been designed for, and operated only in space; and is notable for its non aerodynamic shape.
Spacecraft propulsion
Spacecraft today predominantly use rocketRocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
s for propulsion
Spacecraft propulsion
Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research. However, most spacecraft today are propelled by forcing a gas from the...
, but other propulsion techniques such as ion drives are becoming more common, particularly for unmanned vehicles, and this can significantly reduce the vehicle's mass and increase its delta-v
Delta-v
In astrodynamics a Δv or delta-v is a scalar which takes units of speed. It is a measure of the amount of "effort" that is needed to change from one trajectory to another by making an orbital maneuver....
.
Expendable launch systems
All current spaceflight except NASANASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
's 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...
and the SpaceX
SpaceX
Space Exploration Technologies Corporation, or more popularly and informally known as SpaceX, is an American space transport company that operates out of Hawthorne, California...
Falcon 1
Falcon 1
The Falcon 1 is a partially reusable launch system designed and manufactured by SpaceX, a space transportation company in Hawthorne, California. The two-stage-to-orbit rocket uses LOX/RP-1 for both stages, the first powered by a single Merlin engine and the second powered by a single Kestrel engine...
use multi-stage
Multistage rocket
A multistage rocket is a rocket that usestwo or more stages, each of which contains its own engines and propellant. A tandem or serial stage is mounted on top of another stage; a parallel stage is attached alongside another stage. The result is effectively two or more rockets stacked on top of or...
expendable launch systems to reach space.
Reusable launch systems
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....
's flight, on April 12, 1981. During the Shuttle era, six orbiters were built, all of which have flown in the atmosphere and five of which have flown in space. The Enterprise
Space Shuttle Enterprise
The Space Shuttle Enterprise was the first Space Shuttle orbiter. It was built for NASA as part of the Space Shuttle program to perform test flights in the atmosphere. It was constructed without engines or a functional heat shield, and was therefore not capable of spaceflight...
was used only for approach and landing tests, launching from the back of a Boeing 747
Boeing 747
The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...
and gliding to deadstick landings at Edwards AFB, California. The first Space Shuttle to fly into space was the Columbia
Space Shuttle Columbia
Space Shuttle Columbia was the first spaceworthy Space Shuttle in NASA's orbital fleet. First launched on the STS-1 mission, the first of the Space Shuttle program, it completed 27 missions before being destroyed during re-entry on February 1, 2003 near the end of its 28th, STS-107. All seven crew...
, followed by the Challenger
Space Shuttle Challenger
Space Shuttle Challenger was NASA's second Space Shuttle orbiter to be put into service, Columbia having been the first. The shuttle was built by Rockwell International's Space Transportation Systems Division in Downey, California...
, Discovery
Space Shuttle Discovery
Space Shuttle Discovery is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States, and was operational from its maiden flight, STS-41-D on August 30, 1984, until its final landing during STS-133 on March 9, 2011...
, Atlantis
Space Shuttle Atlantis
The Space Shuttle Atlantis is a retired Space Shuttle orbiter in the Space Shuttle fleet belonging to the National Aeronautics and Space Administration , the spaceflight and space exploration agency of the United States...
, and Endeavour
Space Shuttle Endeavour
Space Shuttle Endeavour is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States. Endeavour was the fifth and final spaceworthy NASA space shuttle to be built, constructed as a replacement for Challenger...
. The Endeavour was built to replace the Challenger, which was lost
STS-51-L
STS-51-L was the twenty-fifth flight of the American Space Shuttle program, which marked the first time an ordinary civilian, schoolteacher Christa McAuliffe, had flown aboard the Space Shuttle. The mission used Space Shuttle Challenger, which lifted off from the Launch Complex 39-B on 28 January...
in January 1986. The Columbia broke up
Space Shuttle Columbia disaster
The Space Shuttle Columbia disaster occurred on February 1, 2003, when shortly before it was scheduled to conclude its 28th mission, STS-107, the Space Shuttle Columbia disintegrated over Texas and Louisiana during re-entry into the Earth's atmosphere, resulting in the death of all seven crew members...
during reentry in February 2003.
The first (and so far only) automatic partially reusable spacecraft was the Buran
Shuttle Buran
The Buran spacecraft , GRAU index 11F35 K1 was a Russian orbital vehicle analogous in function and design to the US Space Shuttle and developed by Chief Designer Gleb Lozino-Lozinskiy of Energia rocket corporation...
(Snowstorm), launched by the USSR on November 15, 1988, although it made only one flight. This spaceplane
Spaceplane
A spaceplane is a vehicle that operates as an aircraft in Earth's atmosphere, as well as a spacecraft when it is in space. It combines features of an aircraft and a spacecraft, which can be thought of as an aircraft that can endure and maneuver in the vacuum of space or likewise a spacecraft that...
was designed for a crew and strongly resembled the U. S. Space Shuttle, although its drop-off boosters used liquid propellants and its main engines were located at the base of what would be the external tank in the American Shuttle. Lack of funding, complicated by the dissolution of the USSR, prevented any further flights of Buran.
Per the Vision for Space Exploration
Vision for Space Exploration
The Vision for Space Exploration is the United States space policy which was announced on January 14, 2004 by President George W. Bush. It is seen as a response to the Space Shuttle Columbia disaster, the state of human spaceflight at NASA, and a way to regain public enthusiasm for space...
, the Space Shuttle is due to be retired in 2011 due mainly to its old age and high cost of the program reaching over a billion dollars per flight. The Shuttle's human transport role is to be replaced by the partially reusable 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...
(CEV) no later than 2014. The Shuttle's heavy cargo transport role is to be replaced by expendable rockets such as the Evolved Expendable Launch Vehicle (EELV) or a Shuttle Derived Launch Vehicle.
Scaled Composites
Scaled Composites
Scaled Composites is an aerospace company founded by Burt Rutan and currently owned by Northrop Grumman that is located at the Mojave Spaceport, Mojave, California, United States...
SpaceShipOne was a reusable suborbital spaceplane
Spaceplane
A spaceplane is a vehicle that operates as an aircraft in Earth's atmosphere, as well as a spacecraft when it is in space. It combines features of an aircraft and a spacecraft, which can be thought of as an aircraft that can endure and maneuver in the vacuum of space or likewise a spacecraft that...
that carried pilots Mike Melvill
Mike Melvill
Michael Winston "Mike" Melvill is one of the test pilots for SpaceShipOne, the experimental spaceplane developed by Scaled Composites. Melvill piloted SpaceShipOne on its first flight past the edge of space, flight 15P on June 21, 2004, thus becoming the first commercial astronaut and the 434th...
and Brian Binnie
Brian Binnie
William Brian Binnie is a former United States Navy officer and is one of the test pilots for SpaceShipOne, the experimental spaceplane developed by Scaled Composites.-History:...
on consecutive flights in 2004 to win the Ansari X Prize
Ansari X Prize
The Ansari X Prize was a space competition in which the X Prize Foundation offered a US$10,000,000 prize for the first non-government organization to launch a reusable manned spacecraft into space twice within two weeks...
. The Spaceship Company
The Spaceship Company
The Spaceship Company is a spacecraft manufacturing company formed by Burt Rutan and Richard Branson in mid-2005, jointly owned by Virgin Group and Scaled Composites, which will own the technology created by Scaled for Virgin Galactic's Virgin SpaceShip program...
will build its successor SpaceShipTwo. A fleet of SpaceShipTwos operated by Virgin Galactic
Virgin Galactic
Virgin Galactic is a company within Richard Branson's Virgin Group which plans to provide sub-orbital spaceflights to the paying public, along with suborbital space science missions and orbital launches of small satellites...
planned to begin reusable private spaceflight
Private spaceflight
Private spaceflight is flight above Earth altitude conducted by and paid for by an entity other than a government. In the early decades of the Space Age, the government space agencies of the Soviet Union and United States pioneered space technology augmented by collaboration with affiliated design...
carrying paying passengers (space tourists
Space tourism
Space Tourism is space travel for recreational, leisure or business purposes. A number of startup companies have sprung up in recent years, hoping to create a space tourism industry...
) in 2008, but this was delayed due to an accident in the propulsion development.
Space disasters
All launch vehicles contain a huge amount of energy that is needed for some part of it to reach orbit. There is therefore some risk that this energy can be released prematurely and suddenly, with significant effects. When a Delta IIDelta II
Delta II was an American space launch system, originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and was in service from 1989 until November 1, 2011...
rocket exploded 13 seconds after launch on January 17, 1997, there were reports of store windows 10 miles (16.1 km) away being broken by the blast.
Space is a fairly predictable environment, but there are still risks of accidental depressurisation and the potential failure of equipment, some of which may be very newly developed.
In 2004 the International Association for the Advancement of Space Safety
International Association for the Advancement of Space Safety
The International Association for the Advancement of Space Safety is a non-profit organization committed to furthering international cooperation and scientific advancement in space systems safety. Its aim is to advance the science and application of space safety. IAASS was legally established on...
was established in the Netherlands to further international cooperation and scientific advancement in space systems safety.
Weightlessness
Space adaptation syndrome
Space adaptation syndrome or space sickness is a condition experienced by around half of space travelers during adaptation to weightlessness. It is related to motion sickness, as the vestibular system adapts to weightlessness.- Cause and remedy :...
, a self-limiting nausea caused by derangement of the vestibular system
Vestibular system
The vestibular system, which contributes to balance in most mammals and to the sense of spatial orientation, is the sensory system that provides the leading contribution about movement and sense of balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of...
. Long-term exposure causes multiple health issues. The most significant is bone loss, some of which is permanent, but microgravity also leads to significant deconditioning
Deconditioning
Deconditioning is adaptation of an organism to less demanding environment, or, alternatively, the decrease of physiological adaptation to normal conditions...
of muscular and cardiovascular tissues.
Radiation
Once above the atmosphere, radiation due to the Van Allen belts, solar radiation and cosmic radiation issues occur and increase.Further away from the Earth, solar flare
Solar flare
A solar flare is a sudden brightening observed over the Sun surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy . The flare ejects clouds of electrons, ions, and atoms through the corona into space. These clouds typically reach Earth a day...
s can give a fatal radiation dose in minutes, and the health threat from cosmic radiation
Health threat from cosmic rays
The health threat from cosmic rays is the danger posed by galactic cosmic rays and solar energetic particles to astronauts on interplanetary missions.Galactic cosmic rays consist of high energy protons and other nuclei with extrasolar origin...
significantly increases the chances of cancer over a decade exposure or more.
Life support
In human spaceflightHuman spaceflight
Human spaceflight is spaceflight with humans on the spacecraft. When a spacecraft is manned, it can be piloted directly, as opposed to machine or robotic space probes and remotely-controlled satellites....
, the life support system is a group of devices that allow a human being to survive in outer space. NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
often uses the phrase Environmental Control and Life Support System or the acronym ECLSS when describing these systems for its human spaceflight
Human spaceflight
Human spaceflight is spaceflight with humans on the spacecraft. When a spacecraft is manned, it can be piloted directly, as opposed to machine or robotic space probes and remotely-controlled satellites....
missions. The life support system may supply: air, water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
and food
Food
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...
. It must also maintain the correct body temperature, an acceptable pressure on the body and deal with the body's waste products. Shielding against harmful external influences such as radiation and micro-meteorites may also be necessary. Components of the life support system are life-critical
Life-critical system
A life-critical system or safety-critical system is a system whose failure ormalfunction may result in:* death or serious injury to people, or* loss or severe damage to equipment or* environmental harm....
, and are designed and constructed using safety engineering
Safety engineering
Safety engineering is an applied science strongly related to systems engineering / industrial engineering and the subset System Safety Engineering...
techniques.
Space weather
Space weather is the concept of changing environmental conditions in outer spaceOuter space
Outer space is the void that exists between celestial bodies, including the Earth. It is not completely empty, but consists of a hard vacuum containing a low density of particles: predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, and neutrinos....
. It is distinct from the concept of weather
Weather
Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...
within a planetary atmosphere, and deals with phenomena involving ambient plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
, magnetic fields, 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...
and other matter
Matter
Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...
in space (generally close to Earth but also in interplanetary, and occasionally interstellar medium
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...
). "Space weather describes the conditions in space that affect Earth and its technological systems. Our space weather is a consequence of the behavior of the sun, the nature of Earth's magnetic field, and our location in the solar system."
Space weather exerts a profound influence in several areas related to space exploration and development. Changing geomagnetic conditions can induce changes in atmospheric density causing the rapid degradation of spacecraft altitude in 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...
. Geomagnetic storms due to increased solar activity can potentially blind sensors aboard spacecraft, or interfere with on-board electronics. An understanding of space environmental conditions is also important in designing shielding and life support systems for manned spacecraft.
Environmental considerations
Rockets as a class are not inherently grossly polluting. However, some rockets use toxic propellants, and most vehicles use propellants that are not carbon neutralCarbon neutral
Carbon neutrality, or having a net zero carbon footprint, refers to achieving net zero carbon emissions by balancing a measured amount of carbon released with an equivalent amount sequestered or offset, or buying enough carbon credits to make up the difference...
. Many solid rockets have chlorine in the form of perchlorate
Perchlorate
Perchlorates are the salts derived from perchloric acid . They occur both naturally and through manufacturing. They have been used as a medicine for more than 50 years to treat thyroid gland disorders. They are used extensively within the pyrotechnics industry, and ammonium perchlorate is also a...
or other chemicals, and this can cause temporary local holes in the ozone layer. Re-entering spacecraft generate nitrates which also can temporarily impact the ozone layer. Most rockets are made of metals that can have an environmental impact during their construction.
In addition to the atmospheric effects there are effects on the near-Earth space environment. There is the possibility that orbit could become inaccessible for generations due to exponentially increasing space debris
Space debris
Space debris, also known as orbital debris, space junk, and space waste, is the collection of objects in orbit around Earth that were created by humans but no longer serve any useful purpose. These objects consist of everything from spent rocket stages and defunct satellites to erosion, explosion...
caused by spalling of satellites and vehicles (Kessler syndrome
Kessler syndrome
The Kessler syndrome , proposed by NASA scientist Donald J...
). Many launched vehicles today are therefore designed to be re-entered after use.
Applications of spaceflight
Current spaceflights are frequently, but not invariably paid for by governments; but there are strong launch markets such as satellite televisionSatellite television
Satellite television is television programming delivered by the means of communications satellite and received by an outdoor antenna, usually a parabolic mirror generally referred to as a satellite dish, and as far as household usage is concerned, a satellite receiver either in the form of an...
that is purely commercial, although the launchers themselves are often at least partly funded by governments.
Uses for spaceflight include:
- Earth observation satelliteEarth observation satelliteEarth observation satellites are satellites specifically designed to observe Earth from orbit, similar to reconnaissance satellites but intended for non-military uses such as environmental monitoring, meteorology, map making etc....
s such as Spy satelliteSpy satelliteA spy satellite is an Earth observation satellite or communications satellite deployed for military or intelligence applications....
s, weather satelliteWeather satelliteThe weather satellite is a type of satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be either polar orbiting, seeing the same swath of the Earth every 12 hours, or geostationary, hovering over the same spot on Earth by orbiting over the equator while...
s - Space explorationSpace explorationSpace 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....
- Space tourismSpace tourismSpace Tourism is space travel for recreational, leisure or business purposes. A number of startup companies have sprung up in recent years, hoping to create a space tourism industry...
is a small market at present - Communication satellites
- Satellite navigation
There is growing interest in spacecraft and flights paid for by commercial companies and even private individuals
Private spaceflight
Private spaceflight is flight above Earth altitude conducted by and paid for by an entity other than a government. In the early decades of the Space Age, the government space agencies of the Soviet Union and United States pioneered space technology augmented by collaboration with affiliated design...
. It is thought that some of the high cost of access to space is due to governmental inefficiencies; and certainly the costs of the governmental paperwork surrounding NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
is legendary. If a commercial company were able to be more efficient, costs could come down significantly. Space launch vehicles such as Falcon I have been wholly developed with private finance, and the quoted costs for launch are lower.
See also
- Aerial landscape artAerial landscape artAerial landscape art includes paintings and other visual arts which depict or evoke the appearance of a landscape from a perspective above it—usually from a considerable distance—as it might be viewed from an aircraft or spacecraft. Sometimes the art is based not on direct observation but on aerial...
- Manned mission to MarsManned mission to MarsA manned mission to Mars has been the subject of science fiction, engineering, and scientific proposals throughout the 20th century and into the 21st century...
- Space logisticsSpace logisticsAccording to the AIAA Space Logistics Technical Committee, space logistics isHowever, this definition in its larger sense includes terrestrial logistics in support of space travel, including any additional "design and development, acquisition, storage, movement, distribution, maintenance,...
- US space exploration history on US stamps
External links
- Aerospace engineering at Wikiversity
- Basics of Spaceflight
- Uses of Nanotechnology in Spaceflight
- International Spaceflight Museum
- Robert H. Goddard—Pioneer of Space Flight
- ALTA-SPACE