Spacecraft communication

A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, 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).

On a sub-orbital spaceflight, a space vehicle enters space and then returns to the surface without having gained sufficient energy or velocity to make a full Earth orbit. For orbital spaceflights, spacecraft enter closed orbits around the Earth or around other celestial bodies. Spacecraft used for human spaceflight carry people on board as crew or passengers from start or on orbit ( space stations) only, whereas those used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft used to support scientific research are space probes. Robotic spacecraft that remain in orbit around a planetary body are artificial satellites. To date, only a handful of interstellar probes, such as ''Pioneer 10'' and '' 11'', ''Voyager 1'' and '' 2'', and '' New Horizons'', are on trajectories that leave the Solar System.

Orbital spacecraft may be recoverable or not. Most are not. Recoverable spacecraft may be subdivided by a method of reentry to Earth into non-winged space capsules and winged spaceplanes. Recoverable spacecraft may be reusable (can be launched again or several times, like the SpaceX Dragon and the Space Shuttle orbiters) or expendable (like the Soyuz). In recent years, more space agencies are tending towards reusable spacecraft.

Humanity has achieved space flight, but only a few nations have the technology for orbital launches: Russia ( RSA or "Roscosmos"), the United States (NASA), the member states of the European Space Agency (ESA), Japan ( JAXA), China (CNSA), India ( ISRO), Taiwan National Chung-Shan Institute of Science and Technology, Taiwan National Space Organization (NSPO), Israel ( ISA), Iran ( ISA), and North Korea (NADA). In addition, several private companies have developed or are developing the technology for orbital launches independently from government agencies. The most prominent examples of such companies are SpaceX and Blue Origin.

History

A German V-2 became the first spacecraft when it reached an altitude of 189 km in June 1944 in Peenemünde, Germany. Sputnik 1 was the first artificial satellite. It was launched into an elliptical low Earth orbit (LEO) by the Soviet 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 the Space Age.Dougall, Walter A. (Winter 2010
"Shooting the duck"
'' American Heritage'' Apart from its value as a technological first, Sputnik 1 also helped to identify the upper atmospheric layer's density, through measuring the satellite's orbital changes. It also provided data on radio-signal distribution in the ionosphere. Pressurized nitrogen in the satellite's false body provided the first opportunity for meteoroid detection. Sputnik 1 was launched during the International Geophysical Year from Site No.1/5, at the 5th Tyuratam range, in Kazakh SSR (now at the Baikonur Cosmodrome). The satellite traveled at , 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 man-made objects had previously reached an altitude of 100 km, which is the height required by the international organization Fédération Aéronautique Internationale to count as a spaceflight. This altitude is called the Kármán line. In particular, in the 1940s there were several test launches of the V-2 rocket, some of which reached altitudes well over 100 km.

Spacecraft types

Crewed spacecraft

As of 2016, only three nations have flown crewed spacecraft: USSR/Russia, USA, and China.
The first crewed spacecraft was Vostok 1, which carried Soviet cosmonaut Yuri Gagarin into space in 1961, and completed a full Earth orbit. There were five other crewed missions which used a Vostok spacecraft. The second crewed spacecraft was named ''Freedom 7'', and it performed a sub-orbital spaceflight in 1961 carrying American astronaut Alan Shepard to an altitude of just over . There were five other crewed missions using Mercury spacecraft.

Other Soviet crewed spacecraft include the Voskhod, Soyuz, flown uncrewed as Zond/L1, L3, TKS, and the Salyut and ''Mir'' crewed space stations. Other American crewed spacecraft include the Gemini spacecraft, the Apollo spacecraft including the Apollo Lunar Module, the Skylab space station, the Space Shuttle with undetached European Spacelab and private US Spacehab space stations-modules, and the SpaceX Crew Dragon configuration of their Dragon 2. US company Boeing also developed and flown a spacecraft of their own, the CST-100