Orbital spacecraft may be recoverable or not. Most are not. Recoverable spacecraft may be subdivided by a method ofreentry to Earth into non-wingedspace capsules and wingedspaceplanes. Recoverable spacecraft may bereusable (can be launched again or several times, like theSpaceX Dragon and theSpace Shuttle orbiters) or expendable (like theSoyuz). In recent years, more space agencies are tending towards reusable spacecraft.
A GermanV-2 became the first spacecraft when it reached an altitude of 189 km in June 1944 inPeenemünde, Germany.[11]Sputnik 1 was the firstartificial satellite. It was launched into an ellipticallow Earth orbit (LEO) by theSoviet Union on 4 October 1957. The launch ushered in new political, military, technological, and scientific developments; while the Sputnik launch was a single event, it marked the start of theSpace Age.[12][13] Apart from its value as a technological first, Sputnik 1 also helped to identify the upperatmospheric layer's density, by measuring the satellite's orbital changes. It also provided data onradio-signal distribution in theionosphere. Pressurizednitrogen in the satellite's false body provided the first opportunity formeteoroid detection. Sputnik 1 was launched during theInternational Geophysical Year fromSite No.1/5, at the 5thTyuratam range, inKazakh SSR (now at theBaikonur Cosmodrome). The satellite travelled at 29,000 kilometres per hour (18,000 mph), taking 96.2 minutes to complete an orbit, and emitted radio signals at 20.005 and 40.002 MHz
While Sputnik 1 was the first spacecraft to orbit the Earth, other human-made objects had previously reached an altitude of 100 km, which is the height required by the international organizationFédération Aéronautique Internationale to count as a spaceflight. This altitude is called theKármán line. In particular, in the 1940s there wereseveral test launches of theV-2 rocket, some of which reached altitudes well over 100 km.
As of 2016, only three nations have flown crewed spacecraft: USSR/Russia, USA, and China.The first crewed spacecraft wasVostok 1, which carried Soviet cosmonautYuri Gagarin into space in 1961, and completed a full Earth orbit. There were five other crewed missions which used aVostok spacecraft.[14] The second crewed spacecraft was namedFreedom 7, and it performed asub-orbital spaceflight in 1961 carrying American astronautAlan Shepard to an altitude of just over 187 kilometers (116 mi). There were five other crewed missions usingMercury spacecraft.
Except for the Space Shuttle and theBuran spaceplane of the Soviet Union, the latter of which only ever had one uncrewed test flight, all of the recoverable crewed orbital spacecraft werespace capsules.
Crewed spacecraft
American Mercury, Gemini, and Apollo spacecraft
Soviet Vostok capsule
Soviet Voskhod (variant of Vostok)
1967 Soviet/Russian Soyuz spacecraft
Chinese Shenzhou spacecraft
TheInternational Space Station, crewed since November 2000, is a joint venture between Russia, the United States, Canada and several other countries.
Uncrewed spacecraft are spacecraft without people on board. Uncrewed spacecraft may have varying levels of autonomy from human input; they may beremote controlled, remote guided or evenautonomous, meaning they have a pre-programmed list of operations, which they will execute unless otherwise instructed.
Many space missions are more suited to telerobotic rather thancrewed operation, due to lower cost and lower risk factors. In addition, some planetary destinations such asVenus or the vicinity ofJupiter are too hostile for human survival. Outer planets such asSaturn,Uranus, andNeptune are too distant to reach with current crewed spaceflight technology, so telerobotic probes are the only way to explore them. Telerobotics also allows exploration of regions that are vulnerable to contamination by Earth micro-organisms since spacecraft can be sterilized. Humans can not be sterilized in the same way as a spaceship, as they coexist with numerous micro-organisms, and these micro-organisms are also hard to contain within a spaceship or spacesuit. Multiple space probes were sent to study Moon, the planets, the Sun, multiple small Solar System bodies (comets and asteroids).
Some spacecrafts can operate as both a crewed and uncrewed spacecraft. For example, theBuran spaceplane could operate autonomously but also had manual controls, though it never flew with crew onboard.[15][16]
A communications satellite is anartificial satellite that relays and amplifiesradio telecommunication signals via atransponder; it creates acommunication channel between a sourcetransmitter and areceiver at different locations onEarth. Communications satellites are used fortelevision,telephone,radio,internet, andmilitary applications.[25] Many communications satellites are ingeostationary orbit 22,300 miles (35,900 km) above theequator, so that the satellite appears stationary at the same point in the sky; therefore thesatellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others formsatellite constellations inlow Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently.
The high frequencyradio waves used for telecommunications links travel byline of sight and so are obstructed by the curve of the Earth. The purpose of communications satellites is to relay the signal around the curve of the Earth allowing communication between widely separated geographical points.[26] Communications satellites use a wide range of radio andmicrowavefrequencies. To avoid signal interference, international organizations have regulations for which frequency ranges or "bands" certain organizations are allowed to use. This allocation of bands minimizes the risk of signal interference.[27]
A collage of automated cargo spacecraft used in the past or present to resupply theInternational Space Station
Cargo or resupply spacecraft are robotic spacecraft that are designed specifically to carrycargo, possibly to supportspace stations' operation by transporting food, propellant and other supplies.
Space probes are robotic spacecraft that are sent to explore deep space, orastronomical bodies other than Earth. They are distinguished fromlanders by the fact that they work in open space, not on planetary surfaces or in planetary atmospheres. Being robotic eliminates the need for expensive, heavy life support systems (theApollo crewed Moon landings required the use of theSaturn V rocket that cost over a billion dollars per launch, adjusted for inflation) and so allows for lighter, less expensive rockets. Space probes have visited every planet in the Solar System andPluto, and theParker Solar Probe has an orbit that, at its closest point, is in theSun's chromosphere. There are five space probes that areescaping the Solar System, these areVoyager 1,Voyager 2,Pioneer 10,Pioneer 11, andNew Horizons.
The identicalVoyager probes, weighing 721.9 kilograms (1,592 lb),[28] were launched in 1977 to take advantage of a rare alignment ofJupiter,Saturn,Uranus andNeptune that would allow a spacecraft to visit all four planets in one mission, and get to each destination faster by usinggravity assist. In fact, the rocket that launched the probes (theTitan IIIE) could not even send the probes to the orbit ofSaturn, yetVoyager 1 is travelling at roughly 17 km/s (11 mi/s) andVoyager 2 moves at about 15 km/s (9.3 mi/s) kilometres per second as of 2023. In 2012,Voyager 1 exited the heliosphere, followed byVoyager 2 in 2018.Voyager 1 actually launched 16 days afterVoyager 2 but it reached Jupiter sooner becauseVoyager 2 was taking a longer route that allowed it to visit Uranus and Neptune, whereasVoyager 1 did not visit Uranus or Neptune, instead choosing to fly past Saturn’s satelliteTitan. As of August 2023,Voyager 1 has passed 160astronomical units, which means it is over 160 times farther from theSun than Earth is. This makes it the farthest spacecraft from the Sun.Voyager 2 is 134 AU away from the Sun as of August 2023. NASA provides real time data of their distances and data from the probe’s cosmic ray detectors.[29] Because of the probe’s declining power output and degradation of theRTGs over time,NASA has had to shut down certain instruments to conserve power. The probes may still have some scientific instruments on until the mid-2020s or perhaps the 2030s. After 2036, they will both be out of range of theDeep Space Network.
A lander is a type of spacecraft that makes a soft landing on the surface of anastronomical body other thanEarth. Some landers, such asPhilae and theApollo Lunar Module, land entirely by using their fuel supply, however many landers (and landings of spacecraft onEarth) useaerobraking, especially for more distant destinations. This involves the spacecraft using a fuel burn to change its trajectory so it will pass through a planet (or a moon's) atmosphere.Drag caused by the spacecraft hitting the atmosphere enables it to slow down without using fuel, however this generates very high temperatures and so adds a requirement for aheat shield of some sort.
Space capsules are a type of spacecraft that can return from space at least once. They have a blunt shape, do not usually contain much more fuel than needed, and they do not possess wings unlikespaceplanes. They are the simplest form of recoverable spacecraft, and so the most commonly used. The first such capsule was theVostok capsule built by the Soviet Union, that carried the first person in space,Yuri Gagarin. Other examples include theSoyuz andOrion capsules, built by the Soviet Union andNASA, respectively.
Spaceplanes are spacecraft that are built in the shape of, and function as,airplanes. The first example of such was theNorth American X-15 spaceplane, which conducted two crewed flights which reached an altitude of over 100 kilometres (62 mi) in the 1960s. This first reusable spacecraft was air-launched on a suborbital trajectory on July 19, 1963.
The first reusable orbital spaceplane was theSpace Shuttle orbiter. The first orbiter to fly in space, theSpace ShuttleColumbia, was launched by the USA on the 20th anniversary ofYuri 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.Enterprise was used only for approach and landing tests, launching from the back of aBoeing 747 SCA and gliding to deadstick landings atEdwards AFB, California. The first Space Shuttle to fly into space wasColumbia, followed byChallenger,Discovery,Atlantis, andEndeavour.Endeavour was built to replaceChallenger when it waslost in January 1986.Columbiabroke up during reentry in February 2003.
The first autonomous reusable spaceplane was theBuran-class shuttle, launched by the USSR on November 15, 1988, although it made only one flight and this was uncrewed. Thisspaceplane 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 thedissolution of the USSR, prevented any further flights of Buran. The Space Shuttle was subsequently modified to allow for autonomous re-entry in case of necessity.
Per theVision for Space Exploration, the Space Shuttle was retired in 2011 mainly due to its old age and high cost of program reaching over a billion dollars per flight. The Shuttle's human transport role is to be replaced bySpaceX'sSpaceX Dragon 2 andBoeing'sCST-100 Starliner. Dragon 2's first crewed flight occurred on May 30, 2020.[30] The Shuttle's heavy cargo transport role is to be replaced by expendable rockets such as theSpace Launch System andULA'sVulcan rocket, as well as the commercial launch vehicles.
TheSpace Shuttle is a retired reusable Low Earth Orbital launch system. It consisted oftwo reusable Solid Rocket Boosters that landed by parachute, were recovered at sea, and were the most powerful rocket motors ever made until they were superseded by those ofNASA’sSLS rocket, with a liftoff thrust of 2,800,000 pounds-force (12 MN), which soon increased to 3,300,000 pounds-force (15 MN) per booster,[31] and were fueled by a combination ofPBAN andAPCP, theSpace Shuttle Orbiter, with 3RS-25 engines that used aliquid oxygen/liquid hydrogen propellant combination, and the bright orange throwawaySpace Shuttle external tank from which the RS-25 engines sourced their fuel. The orbiter was a spaceplane that was launched at NASA’sKennedy Space Centre and landed mainly at theShuttle Landing Facility, which is part of Kennedy Space Centre. A second launch site,Vandenberg Space Launch Complex 6 inCalifornia, was revamped so it could be used to launch the shuttles, but it was never used. The launch system could lift about 29 tonnes (64,000 lb) into an eastwardLow Earth Orbit. Each orbiter weighed roughly 78 tonnes (172,000 lb), however the different orbiters had differing weights and thus payloads, withColumbia being the heaviest orbiter,Challenger being lighter thanColumbia but still heavier than the other three. The orbiter structure was mostly composed of aluminium alloy. The orbiter had seven seats for crew members, though onSTS-61-A the launch took place with 8 crew onboard. The orbiters had 4.6 metres (15 ft) wide by 18 metres (59 ft) long payload bays and also were equipped with a 15.2 metres (50 ft)CanadaArm1, an upgraded version of which is used on theInternational Space Station. The heat shield (orThermal Protection System) of the orbiter, used to protect it from extreme levels of heat duringatmospheric reentry and the cold of space, was made up of different materials depending on weight and how much heating a particular area on the shuttle would receive during reentry, which ranged from over 2,900 °F (1,600 °C) to under 700 °F (370 °C). The orbiter was manually operated, though an autonomous landing system was added while the shuttle was still on service. It had an in orbit maneouvreing system known as the Orbital Manoeuvring System, which used the hypergolic propellantsmonomethylhydrazine (MMH) anddinitrogen tetroxide, which was used for orbital insertion, changes to orbits and the deorbit burn.
Refurbishing the orbiters and the solid rocket boosters after flight was very complex, expensive and slow. The shortest time between landing and reflight for a Space Shuttle was 54 days for the Space ShuttleAtlantis.
Though the shuttle’s goals were to drastically decrease launch costs, it did not do so, ending up being much more expensive than similar expendable launchers. This was due to expensive refurbishment costs and the external tank being expended. Once a landing had occurred, the SRBs and many parts of the orbiter had to be disassembled for inspection, which was long and arduous. Furthermore, the RS-25 engines had to be replaced every few flights. Each of the heat shielding tiles had to go in one specific area on the orbiter, increasing complexity more. Adding to this, the shuttle was a rather dangerous system, with fragile heat shielding tiles, some being so fragile that one could easily scrape it off by hand, often having been damaged in many flights. After 30 years in service from 1981 to 2011 and 135 flights, the shuttle was retired from service due to the cost of maintaining the shuttles, and the 3 remaining orbiters (the other two were destroyed in accidents) were prepared to be displayed in museums.
Starship is a spacecraft andsecond stage[32] under development by American aerospace companySpaceX. Stacked atop its booster,Super Heavy, it composes the identically namedStarshipsuper heavy-liftspace vehicle. The spacecraft is designed to transport both crew and cargo to a variety of destinations, including Earth orbit, the Moon, Mars, and potentially beyond. It is intended to enable long durationinterplanetary flights for a crew of up to 100 people.[32] It will also be capable of point-to-point transport on Earth, enabling travel to anywhere in the world in less than an hour. Furthermore, the spacecraft will be used torefuel other Starship vehicles to allow them to reach higher orbits to and other space destinations.Elon Musk, the CEO of SpaceX, estimated in a tweet that 8 launches would be needed to completely refuel a Starship inlow Earth orbit, extrapolating this from Starship's payload to orbit and how much fuel a fully fueled Starship contains.[33] To land on bodies without an atmosphere, such as the Moon, Starship will fire its engines and thrusters to slow down.[34]
The Mission Extension Vehicle is a robotic spacecraft designed to prolong the life on another spacecraft. It works by docking to its target spacecraft, then correcting its orientation or orbit. This also allows it to rescue a satellite which is in the wrong orbit by using its own fuel to move its target to the correct orbit. The project is currently managed by Northrop Grumman Innovation Systems. As of 2023, 2 have been launched. The first launched on aProton rocket on 9 October 2019, and did a rendezvous withIntelsat-901 on 25 February 2020. It will remain with the satellite until 2025 before the satellite is moved to a final graveyard orbit and the vehicle does a rendezvous with another satellite. The other one launched on anAriane 5 rocket on 15 August 2020.
A spacecraftastrionics system comprises different subsystems, depending on the mission profile. Spacecraft subsystems are mounted in thesatellite bus and may includeattitude determination and control (variously called ADAC, ADC, or ACS),guidance, navigation and control (GNC or GN&C), communications (comms), command and data handling (CDH or C&DH), power (EPS),thermal control (TCS), propulsion, and structures. Attached to the bus are typicallypayloads.
Life support
Spacecraft intended for human spaceflight must also include alife support system for the crew.
A spacecraft needs an attitude control subsystem to be correctly oriented in space and respond to externaltorques and forces properly. This may usereaction wheels or it may use small rocket thrusters. The altitude control subsystem consists ofsensors andactuators, together with controlling algorithms. The attitude-control subsystem permits proper pointing for the science objective, sun pointing for power to the solar arrays and earth pointing for communications.
GNC
Guidance refers to the calculation of the commands (usually done by the CDH subsystem) needed to steer the spacecraft where it is desired to be. Navigation means determining a spacecraft'sorbital elements or position. Control means adjusting the path of the spacecraft to meet mission requirements.
Command and data handling
The C&DH subsystem receives commands from the communications subsystem, performs validation and decoding of the commands, and distributes the commands to the appropriate spacecraft subsystems and components. The CDH also receives housekeeping data and science data from the other spacecraft subsystems and components, and packages the data for storage on adata recorder or transmission to the ground via the communications subsystem. Other functions of the CDH include maintaining the spacecraft clock and state-of-health monitoring.
Spacecraft need an electrical power generation and distribution subsystem for powering the various spacecraft subsystems. For spacecraft near theSun,solar panels are frequently used to generate electrical power. Spacecraft designed to operate in more distant locations, for exampleJupiter, might employ aradioisotope thermoelectric generator (RTG) to generate electrical power. Electrical power is sent through power conditioning equipment before it passes through a power distribution unit over an electrical bus to other spacecraft components. Batteries are typically connected to the bus via a battery charge regulator, and the batteries are used to provide electrical power during periods when primary power is not available, for example when a low Earth orbit spacecraft iseclipsed by Earth.
Thermal control
Spacecraft must be engineered to withstand transit throughEarth's atmosphere and thespace environment. They must operate in avacuum with temperatures potentially ranging across hundreds of degreesCelsius as well as (if subject to reentry) in the presence of plasmas. Material requirements are such that either high melting temperature, low density materials such asberyllium andreinforced carbon–carbon or (possibly due to the lower thickness requirements despite its high density)tungsten orablative carbon–carbon composites are used. Depending on mission profile, spacecraft may also need to operate on the surface of another planetary body. Thethermal control subsystem can be passive, dependent on the selection of materials with specific radiative properties. Active thermal control makes use of electrical heaters and certainactuators such as louvers to control temperature ranges of equipments within specific ranges.
Spacecraft may or may not have apropulsion subsystem, depending on whether or not the mission profile calls for propulsion. TheSwift spacecraft is an example of a spacecraft that does not have a propulsion subsystem. Typically though, LEO spacecraft include a propulsion subsystem for altitude adjustments (drag make-up maneuvers) andinclination adjustment maneuvers. A propulsion system is also needed for spacecraft that perform momentum management maneuvers. Components of a conventional propulsion subsystem include fuel, tankage, valves, pipes, andthrusters. The thermal control system interfaces with the propulsion subsystem by monitoring the temperature of those components, and by preheating tanks and thrusters in preparation for a spacecraft maneuver.
Structures
Spacecraft must be engineered to withstand launch loads imparted by the launch vehicle, and must have a point of attachment for all the other subsystems. Depending on mission profile, the structural subsystem might need to withstand loads imparted by entry into theatmosphere of another planetary body, and landing on the surface of another planetary body.
Payload
The payload depends on the mission of the spacecraft, and is typically regarded as the part of the spacecraft "that pays the bills". Typical payloads could include scientific instruments (cameras,telescopes, orparticle detectors, for example), cargo, or ahuman crew.
Theground segment, though not technically part of the spacecraft, is vital to the operation of the spacecraft. Typical components of a ground segment in use during normal operations include a mission operations facility where the flight operations team conducts the operations of the spacecraft, a data processing and storage facility,ground stations to radiate signals to and receive signals from the spacecraft, and a voice and data communications network to connect all mission elements.[35]
Launch vehicle
Thelaunch vehicle propels the spacecraft from Earth's surface, through theatmosphere, and into anorbit, the exact orbit being dependent on the mission configuration. The launch vehicle may beexpendable orreusable. In asingle stage to orbit rocket, the rocket can be considered a spacecraft itself.
^Swenson, L. Jr.; Grimwood, J. M.; Alexander, C. C.This New Ocean, A History of Project Mercury. pp. 66–62424.On October 4, 1957 Sputnik I shot into orbit and forcibly opened the Space Age.
_drawing.svg)
.jpg)
