Low Earth orbitA low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never more than about one-third of the radius of Earth. The term LEO region is also used for the area of space below an altitude of (about one-third of Earth's radius). Objects in orbits that pass through this zone, even if they have an apogee further out or are sub-orbital, are carefully tracked since they present a collision risk to the many LEO satellites.
Elliptic orbitIn astrodynamics or celestial mechanics, an elliptic orbit or elliptical orbit is a Kepler orbit with an eccentricity of less than 1; this includes the special case of a circular orbit, with eccentricity equal to 0. In a stricter sense, it is a Kepler orbit with the eccentricity greater than 0 and less than 1 (thus excluding the circular orbit). In a wider sense, it is a Kepler orbit with negative energy. This includes the radial elliptic orbit, with eccentricity equal to 1.
Space ShuttleThe Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program name was Space Transportation System (STS), taken from a 1969 plan for a system of reusable spacecraft where it was the only item funded for development. The first (STS-1) of four orbital test flights occurred in 1981, leading to operational flights (STS-5) beginning in 1982.
Geosynchronous orbitA geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day.
Launch vehicleA launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage rocket, but the term is more general and also encompasses vehicles like the Space Shuttle. Most launch vehicles operate from a launch pad, supported by a launch control center and systems such as vehicle assembly and fueling.
Space Shuttle ColumbiaSpace Shuttle Columbia (OV-102) was a Space Shuttle orbiter manufactured by Rockwell International and operated by NASA. Named after the first American ship to circumnavigate the upper North American Pacific coast and the female personification of the United States, Columbia was the first of five Space Shuttle orbiters to fly in space, debuting the Space Shuttle launch vehicle on its maiden flight in April 1981.
Geocentric orbitA geocentric orbit, Earth-centered orbit, or Earth orbit involves any object orbiting Earth, such as the Moon or artificial satellites. In 1997, NASA estimated there were approximately 2,465 artificial satellite payloads orbiting Earth and 6,216 pieces of space debris as tracked by the Goddard Space Flight Center. More than 16,291 objects previously launched have undergone orbital decay and entered Earth's atmosphere. A spacecraft enters orbit when its centripetal acceleration due to gravity is less than or equal to the centrifugal acceleration due to the horizontal component of its velocity.
Space Shuttle EndeavourSpace Shuttle Endeavour (Orbiter Vehicle Designation: OV-105) is a retired orbiter from NASA's Space Shuttle program and the fifth and final operational Shuttle built. It embarked on its first mission, STS-49, in May 1992 and its 25th and final mission, STS-134, in May 2011. STS-134 was expected to be the final mission of the Space Shuttle program, but with the authorization of STS-135 by the United States Congress, Atlantis became the last shuttle to fly.
Space Shuttle programThe Space Shuttle program was the fourth human spaceflight program carried out by the U.S. National Aeronautics and Space Administration (NASA), which accomplished routine transportation for Earth-to-orbit crew and cargo from 1981 to 2011. Its official name, Space Transportation System (STS), was taken from a 1969 plan for a system of reusable spacecraft of which it was the only item funded for development. It flew 135 missions and carried 355 astronauts from 16 countries, many on multiple trips.
OrbitIn celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a planet, moon, asteroid, or Lagrange point. Normally, orbit refers to a regularly repeating trajectory, although it may also refer to a non-repeating trajectory.
Sea LaunchSea Launch was a multinational—Norway, Russia, Ukraine, United States—spacecraft launch company founded in 1995 that provided orbital launch services from 1999 to 2014. The company used a mobile maritime launch platform for equatorial launches of commercial payloads on specialized Zenit-3SL rockets from a former mobile/floating oil drilling rig renamed Odyssey. By 2014, it had assembled and launched thirty-two rockets, with an additional three failures and one partial failure.
SpacecraftA spacecraft (: spacecraft) is a vehicle that is designed to fly in outer space and operate there. Spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. All spacecraft except single-stage-to-orbit vehicles cannot get into space on their own, and require a launch vehicle (carrier rocket).
Space Shuttle ChallengerSpace Shuttle Challenger (OV-099) was a Space Shuttle orbiter manufactured by Rockwell International and operated by NASA. Named after the commanding ship of a nineteenth-century scientific expedition that traveled the world, Challenger was the second Space Shuttle orbiter to fly into space after Columbia, and launched on its maiden flight in April 1983. It was destroyed in January 1986 soon after launch in an accident that killed all seven crewmembers aboard.
Orbital propellant depotAn orbital propellant depot is a cache of propellant that is placed in orbit around Earth or another body to allow spacecraft or the transfer stage of the spacecraft to be fueled in space. It is one of the types of space resource depots that have been proposed for enabling infrastructure-based space exploration. Many different depot concepts exist depending on the type of fuel to be supplied, location, or type of depot which may also include a propellant tanker that delivers a single load to a spacecraft at a specified orbital location and then departs.
Rocket propellantRocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical rocket, or from an external source, as with ion engines. Rockets create thrust by expelling mass rear-ward, at high velocity. The thrust produced can be calculated by multiplying the mass flow rate of the propellants by their exhaust velocity relative to the rocket (specific impulse).
Space Shuttle EnterpriseSpace Shuttle Enterprise (Orbiter Vehicle Designation: OV-101) was the first orbiter of the Space Shuttle system. Rolled out on September 17, 1976, it was built for NASA as part of the Space Shuttle program to perform atmospheric test flights after being launched from a modified Boeing 747. It was constructed without engines or a functional heat shield. As a result, it was not capable of spaceflight. Originally, Enterprise had been intended to be refitted for orbital flight to become the second space-rated orbiter in service.
Medium Earth orbitA medium Earth orbit (MEO) is an Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level. The boundary between MEO and LEO is an arbitrary altitude chosen by accepted convention, whereas the boundary between MEO and HEO is the particular altitude of a geosynchronous orbit, in which a satellite takes 24 hours to circle the Earth, the same period as the Earth’s own rotation.
Launch padA launch pad is an above-ground facility from which a rocket-powered missile or space vehicle is vertically launched. The term launch pad can be used to describe just the central launch platform (mobile launcher platform), or the entire complex (launch complex). The entire complex will include a launch mount or launch platform to physically support the vehicle, a service structure with umbilicals, and the infrastructure required to provide propellants, cryogenic fluids, electrical power, communications, telemetry, rocket assembly, payload processing, storage facilities for propellants and gases, equipment, access roads, and drainage.
Liquid-propellant rocketA liquid-propellant rocket or liquid rocket utilizes a rocket engine that uses liquid propellants. Gaseous propellants may also be used but are not common because of their low density and difficulty with common pumping methods. Liquids are desirable because they have a reasonably high density and high specific impulse (Isp). This allows the volume of the propellant tanks to be relatively low.
Space explorationSpace exploration is the use of astronomy and space technology to explore outer space. While the exploration of space is carried out mainly by astronomers with telescopes, its physical exploration is conducted both by uncrewed robotic space probes and human spaceflight. Space exploration, like its classical form astronomy, is one of the main sources for space science. While the observation of objects in space, known as astronomy, predates reliable recorded history, it was the development of large and relatively efficient rockets during the mid-twentieth century that allowed physical space exploration to become a reality.
