A satellite or artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. Satellites have a variety of uses, including communication relay, weather forecasting, navigation (GPS), broadcasting, scientific research, and Earth observation. Additional military uses are reconnaissance, early warning, signals intelligence and, potentially, weapon delivery. Other satellites include the final rocket stages that place satellites in orbit and formerly useful satellites that later become defunct.
A geosynchronous orbit is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds. 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. Over the course of a day, the object's position in the sky may remain still or trace out a path, typically in a figure-8 form, whose precise characteristics depend on the orbit's inclination and eccentricity. A circular geosynchronous orbit has a constant altitude of 35,786 km (22,236 mi).
A geostationary orbit, also referred to as a geosynchronous equatorial orbit (GEO), is a circular geosynchronous orbit 35,786 km (22,236 mi) in altitude above Earth's equator, 42,164 km (26,199 mi) in radius from Earth's center, and following the direction of Earth's rotation.
Space debris are defunct human-made objects in space – principally in Earth orbit – which no longer serve a useful function. These include derelict spacecraft, mission-related debris, and particularly-numerous in-Earth orbit fragmentation debris from the breakup of derelict rocket bodies and spacecraft. In addition to derelict human-made objects left in orbit, space debris includes fragments from disintegration, erosion, or collisions; solidified liquids expelled from spacecraft; unburned particles from solid rocket motors; and even paint flecks. Space debris represents a risk to spacecraft.
Space Exploration Technologies Corp., commonly referred to as SpaceX, is an American spacecraft manufacturer, launch service provider, defense contractor and satellite communications company headquartered in Hawthorne, California. The company was founded in 2002 by Elon Musk with the goal of reducing space transportation costs and ultimately developing a sustainable colony on Mars. The company currently operates the Falcon 9 and Falcon Heavy rockets along with the Dragon and Starship spacecraft.
Atlas V is an expendable launch system and the fifth major version in the Atlas launch vehicle family. It was originally designed by Lockheed Martin, now being operated by United Launch Alliance (ULA), a joint venture between Lockheed Martin and Boeing. It is used for DoD, NASA, and Commercial payloads. It is America's longest-serving active rocket. After 87 launches, in August 2021 ULA announced that Atlas V would be retired, and all 29 remaining launches had been sold. As of January 2024, 17 launches remain. Other future ULA launches will use the new Vulcan Centaur rocket.
The Kessler syndrome, proposed by NASA scientist Donald J. Kessler in 1978, is a scenario in which the density of objects in low Earth orbit (LEO) due to space pollution is numerous enough that collisions between objects could cause a cascade in which each collision generates space debris that increases the likelihood of further collisions. In 2009, Kessler wrote that modeling results had concluded that the debris environment was already unstable, "such that any attempt to achieve a growth-free small debris environment by eliminating sources of past debris will likely fail because fragments from future collisions will be generated faster than atmospheric drag will remove them". One implication is that the distribution of debris in orbit could render space activities and the use of satellites in specific orbital ranges difficult for many generations.
The year 2007 contained several significant events in spaceflight, including a Chinese ASAT test, the launches of the US Phoenix and Dawn missions to study Mars and Asteroid belt respectively, Japan's Kaguya Lunar orbiter, and the first Chinese Lunar probe, Chang'e 1.
Kosmos-2251 was a Russian Strela-2M military communications satellite. It was launched into Low Earth orbit from Site 132/1 at the Plesetsk Cosmodrome at 04:17 UTC on 16 June 1993, by a Kosmos-3M carrier rocket.· The Strela satellites had a lifespan of 5 years, and the Russian government reported that Kosmos-2251 ceased functioning in 1995. Russia was later criticised by The Space Review for leaving a defunct satellite in a congested orbit, rather than deorbiting it. In response, Russia noted that they were not required to do so under international law. In any case, the KAUR-1 satellites had no propulsion system, which is usually required for deorbiting.
Iridium 33 was a communications satellite launched by Russia for Iridium Communications. It was launched into low Earth orbit from Site 81/23 at the Baikonur Cosmodrome at 01:36 UTC on 14 September 1997, by a Proton-K rocket with a Block DM2 upper stage. The launch was arranged by International Launch Services (ILS). It was operated in Plane 3 of the Iridium satellite constellation, with an ascending node of 230.9°.
The Iridium satellite constellation provides L band voice and data information coverage to satellite phones, satellite messenger communication devices and integrated transceivers. Iridium Communications owns and operates the constellation, additionally selling equipment and access to its services. It was conceived by Bary Bertiger, Raymond J. Leopold and Ken Peterson in late 1987 and then developed by Motorola on a fixed-price contract from July 29, 1993, to November 1, 1998, when the system became operational and commercially available.
The year 2012 saw a number of significant events in spaceflight. In May and October, the first Commercial Orbital Transportation Services resupply missions took place, during which the SpaceX Dragon became the first private spacecraft to dock with the International Space Station (ISS). In June, China launched the crewed Shenzhou 9 orbital mission, and North Korea achieved its first successful orbital launch in December. 2012 also saw China's first successful asteroid exploration mission, and the landing of NASA's Curiosity rover on Mars. The Vega and Unha-3 rockets made their maiden flights in 2012, while the Proton-K made its last.
A space tug is a type of spacecraft used to transfer spaceborne cargo from one orbit to another orbit with different energy characteristics. The term can include expendable upper stages or spacecraft that are not necessarily a part of their launch vehicle. However, it can also refer to a spacecraft that transports payload already in space to another location in outer space, such as in the Space Transportation System concept. An example would be moving a spacecraft from a low Earth orbit (LEO) to a higher-energy orbit like a geostationary transfer orbit, a lunar transfer, or an escape trajectory.
In 2015, the maiden spaceflights of the Chinese Long March 6 and Long March 11 launch vehicles took place.
Several new rockets and spaceports began operations in 2016.
In 2013, the maiden spaceflight of the Orbital Sciences' Antares launch vehicle, designated A-ONE, took place on 13 April. Orbital Science also launched its first spacecraft, Cygnus, that docked with the International Space Station in late September 2013.
This article documents notable spaceflight events during the year 2019.
The year 2021 broke the record for the most orbital launch attempts till then (146) and most humans in space concurrently (19) despite the effects of COVID-19 pandemic.
The year 2022 witnessed the number of launches of SpaceX's Falcon rocket family surpassing the CNSA's Long March rocket family, making the United States the country with the highest number of launches in 2022 instead of China. This year also featured the first successful launch of Long March 6A, Nuri, Angara 1.2, Vega-C, Kinetica-1, and Jielong-3. National space agencies' activities in this year is also marred by the Russian invasion of Ukraine, leading to tension between Roscosmos and Western space agencies, threats of ending collaboration on the International Space Station (ISS), and delays on space missions.
Sputnik 99 launched on April 2, 1999 from the Baikonur Cosmodrome on board a Soyuz-U-PVB launch vehicle. The nano-satellite was created in a joint-venture by Rosaviakosmos, Aéro-Club de France, and the Radio Amateur Satellite Corporation (AMSAT) as a marketing effort financially backed by The Swatch Group. Sputnik 99 was deployed from the Mir space station on April 16, 1999, even though its primary mission package, an amateur radio broadcast system (AR), had been purposely disabled, immediately rendering the satellite a piece of space flotsam.
