Spaceflight Wiki
Spaceflight (or space flight) is an application of astronautics to fly objects, usually spacecraft, into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such as satellites in orbit around Earth, but also includes space probes for flights beyond Earth orbit. Such spaceflights operate either by telerobotic or autonomous control. The first spaceflights began in the 1950s with the launches of the Soviet Sputnik satellites and American Explorer and Vanguard missions. Human spaceflight programs include the Soyuz, Shenzhou, the past Apollo Moon landing and the Space Shuttle programs. Other current spaceflight are conducted to the International Space Station and to China's Tiangong Space Station.
Spaceflights include the launches of Earth observation and telecommunications satellites, interplanetary missions, the rendezvouses and dockings with space stations, and crewed spaceflights on scientific or tourist missions.
Spaceflight can be achieved conventionally via multistage rockets, which provide the thrust to overcome the force of gravity and propel spacecraft onto suborbital trajectories. If the mission is orbital, the spacecraft usually separates the first stage and ignites the second stage, which propels the spacecraft to high enough speeds that it reaches orbit. Once in orbit, spacecraft are at high enough speeds that they fall around the Earth rather than fall back to the surface.
Most spacecraft, and all crewed spacecraft, are designed to deorbit themselves or, in the case of uncrewed spacecraft in high-energy orbits, to boost themselves into graveyard orbits. Used upper stages or failed spacecraft, however, often lack the ability to deorbit themselves. This becomes a major issue when large numbers of uncontrollable spacecraft exist in frequently used orbits, increasing the risk of debris colliding with functional satellites. This problem is exacerbated when large objects, often upper stages, break up in orbit or collide with other objects, creating often hundreds of small, hard to find pieces of debris. This problem of continuous collisions is known as Kessler syndrome.
