Concept
Outer space
Related concepts (98)
Oort cloud
The Oort cloud (ɔːrt,_ʊərt), sometimes called the Öpik–Oort cloud, is theorized to be a vast cloud of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years). The concept of such a cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose honor the idea was named. Oort proposed that the bodies in this cloud replenish and keep constant the number of long-period comets entering the inner Solar System—where they are eventually consumed and destroyed during close approaches to the Sun.
Apollo 8
Apollo 8 (December 21–27, 1968) was the first crewed spacecraft to leave low Earth orbit and the first human spaceflight to reach the Moon. The crew orbited the Moon ten times without landing, and then departed safely back to Earth. These three astronauts—Frank Borman, James Lovell, and William Anders—were the first humans to witness and photograph the far side of the Moon and an Earthrise. Apollo 8 launched on December 21, 1968, and was the second crewed spaceflight mission flown in the United States Apollo space program after Apollo 7, which stayed in Earth orbit.
Extravehicular activity
Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmental support. EVA includes spacewalks and lunar or planetary surface exploration (commonly known from 1969 to 1972 as moonwalks). In a stand-up EVA (SEVA), an astronaut stands through an open hatch but does not fully leave the spacecraft.
Kármán line
The Kármán line (or von Kármán line vɒn_ˈkɑrmɑːn) is a proposed conventional boundary between Earth's atmosphere and outer space set by the international record-keeping body FAI (Fédération aéronautique internationale) at an altitude of above mean sea level. However, such definition of the edge of space is not universally adopted. The Kármán line has no particular physical meaning, in that there is no noticeable change in the characteristics of the atmosphere across it, but is important for legal and regulatory purposes, since aircraft and spacecraft are subject to different jurisdictions and legislations.
Low Earth orbit
A 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.
Space station
A space station is a spacecraft capable of supporting a human crew in orbit for an extended period of time and is therefore a type of space habitat. It lacks major propulsion or landing systems. An orbital station or an orbital space station is an artificial satellite (i.e., a type of orbital spaceflight). Stations must have docking ports to allow other spacecraft to dock to transfer crew and supplies. The purpose of maintaining an orbital outpost varies depending on the program.
Reconnaissance satellite
A reconnaissance satellite or intelligence satellite (commonly, although unofficially, referred to as a spy satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications. The first generation type (i.e., Corona and Zenit) took photographs, then ejected canisters of photographic film which would descend back down into Earth's atmosphere. Corona capsules were retrieved in mid-air as they floated down on parachutes.
Interplanetary medium
The interplanetary medium (IPM) or interplanetary space consists of the mass and energy which fills the Solar System, and through which all the larger Solar System bodies, such as planets, dwarf planets, asteroids, and comets, move. The IPM stops at the heliopause, outside of which the interstellar medium begins. Before 1950, interplanetary space was widely considered to either be an empty vacuum, or consisting of "aether". The interplanetary medium includes interplanetary dust, cosmic rays, and hot plasma from the solar wind.
V-2 rocket
The V-2 (Vergeltungswaffe 2), with the technical name Aggregat 4 (A-4), was the world's first long-range guided ballistic missile. The missile, powered by a liquid-propellant rocket engine, was developed during the Second World War in Nazi Germany as a "vengeance weapon" and assigned to attack Allied cities as retaliation for the Allied bombings of German cities. The V-2 rocket also became the first artificial object to travel into space by crossing the Kármán line (edge of space) with the vertical launch of MW 18014 on 20 June 1944.
Radiative cooling
In the study of heat transfer, radiative cooling is the process by which a body loses heat by thermal radiation. As Planck's law describes, every physical body spontaneously and continuously emits electromagnetic radiation. Radiative cooling has been applied in various contexts throughout human history, including ice making in India and Iran, heat shields for spacecraft, and in architecture. In 2014, a scientific breakthrough in the use of photonic metamaterials made daytime radiative cooling possible.