The mesosphere is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as altitude increases. This characteristic is used to define limits: it begins at the top of the stratosphere, and ends at the mesopause, which is the coldest part of Earth's atmosphere, with temperatures below −143 °C. The exact upper and lower boundaries of the mesosphere vary with latitude and with season, but the lower boundary is usually located at altitudes from 47 to 51 km above sea level, and the upper boundary is usually from 85 to 100 km.
A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, peaking in number at an altitude around 800 km (500 mi), while the farthest in LEO, before medium Earth orbit (MEO), have an altitude of 2,000 kilometers, about one-third of the radius of Earth and near the beginning of the inner Van Allen radiation belt.
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.
A graveyard orbit, also called a junk orbit or disposal orbit, is an orbit that lies away from common operational orbits. One significant graveyard orbit is a supersynchronous orbit well beyond geosynchronous orbit. Some satellites are moved into such orbits at the end of their operational life to reduce the probability of colliding with operational spacecraft and generating space debris.
The Aerospace Corporation is an American nonprofit corporation that operates a federally funded research and development center (FFRDC). The corporation provides technical guidance and advice on all aspects of space missions to military, civil, and commercial customers. As the FFRDC for national-security space, Aerospace works closely with organizations such as the United States Space Force (USSF) and the National Reconnaissance Office (NRO) to provide "objective technical analyses and assessments for space programs that serve the national interest". Although the USSF and NRO are primary customers, Aerospace performs work for civil agencies such as NASA and NOAA as well as international organizations and governments in the national interest. Aerospace, as part of its charter, also provides expertise to commercial entities, both established companies and startups, domestically and abroad.
The Kessler syndrome, also known as the Kessler effect, collisional cascading, or ablation cascade, is a scenario proposed by NASA scientists Donald J. Kessler and Burton G. Cour-Palais in 1978. It describes a situation in which the density of objects in low Earth orbit (LEO) becomes so high due to space pollution that collisions between these objects cascade, exponentially increasing the amount of space debris over time. This proliferation of debris poses significant risks to satellites, space missions, and the International Space Station, potentially rendering certain orbital regions unusable and threatening the sustainability of space activities for many generations. In 2009, Kessler wrote that modeling results indicated the debris environment had already become unstable, meaning that efforts to achieve a growth-free small debris environment by eliminating past debris sources would likely fail because fragments from future collisions would accumulate faster than atmospheric drag could remove them. The Kessler syndrome underscores the critical need for effective space traffic management and collision avoidance strategies to ensure the long-term viability of space exploration and utilization.
The NASA Orbital Debris Program Office is located at the Johnson Space Center and is the lead NASA center for orbital debris research. It is recognized world-wide for its leadership in addressing orbital debris issues. The NASA Orbital Debris Program Office has taken the international lead in conducting measurements of the environment and in developing the technical consensus for adopting mitigation measures to protect users of the orbital environment. Work at the center continues with developing an improved understanding of the orbital debris environment and measures that can be taken to control its growth.
The Orbital Debris Co-ordination Working Group (ODCWG) is one of the working groups of the International Organization for Standardization's Technical Committee 20/Subcommittee 14 TC20/SC14 "Spacecraft Systems and Operations".
Cartosat-2 was an Earth observation satellite in a Sun-synchronous orbit and the second of the Cartosat series of satellites. The satellite was built, launched and maintained by the Indian Space Research Organisation (ISRO). Weighing around 680 kg at launch, its applications were mainly be towards cartography. It was launched by the Polar Satellite Launch Vehicle PSLV C7 launch vehicle on 10 January 2007.
Space policy is the political decision-making process for, and application of, public policy of a state regarding spaceflight and uses of outer space, both for civilian and military purposes. International treaties, such as the 1967 Outer Space Treaty, attempt to maximize the peaceful uses of space and restrict the militarization of space.
Tiangong-1 was China's first prototype space station. It orbited Earth from September 2011 to April 2018, serving as both a crewed laboratory and an experimental testbed to demonstrate orbital rendezvous and docking capabilities during its two years of active operational life.
The Review of United States Human Space Flight Plans Committee, better known as the HSF Committee, Augustine Commission, or Augustine Committee, was a group convened by NASA at the request of the Office of Science and Technology Policy (OSTP), to review the nation's human spaceflight plans to ensure "a vigorous and sustainable path to achieving its boldest aspirations in space." The review was announced by the OSTP on May 7, 2009. It covered human spaceflight options after the time NASA had planned to retire the Space Shuttle. A summary report was provided to the OSTP Director John Holdren, White House Office of Science and Technology Policy (OSTP), and NASA Administrator on September 8, 2009. The estimated cost associated with the review was expected to be US$3 million. The committee was scheduled to be active for 180 days; the report was released on October 22, 2009.
INSAT-4B was an Indian communications satellite which forms part of the Indian National Satellite System. Launched in 2007, it was placed in geostationary orbit at a longitude of 93.48° East.
The NASA Authorization Act of 2014 is a bill that would authorize the appropriation of $17.6 billion in fiscal year 2014 to the National Aeronautics and Space Administration (NASA). NASA would use the funding for human exploration of space, the Space Launch System, the Orion spacecraft, the Commercial Crew Program, the International Space Station (ISS), and various technological and educational projects.
National Aerospace Technology Administration is the official space agency of the Democratic People's Republic of Korea, succeeding the Korean Committee of Space Technology (KCST). It was founded on 1 April 2013. Formerly called the National Aerospace Development Administration (NADA), it changed its name in September 2023 following the 9th Session of the 14th Supreme People's Assembly. The current basis for the activities of NATA is the Law on Space Development, passed in 2014 during the 7th session of the 12th Supreme People's Assembly. The act sets out the DPR Korean principles of the development of space capabilities as it relates to the principles of the DPR Korean Juche ideology and independence, as well as the aim of solving scientific and technological problems of space exploration to improve its economy, science, and technology.
Space traffic management is defined by the International Academy of Astronautics (IAA) as "the set of technical and regulatory provisions for promoting safe access into outer space, operations in outer space and return from outer space to Earth free from physical or radio-frequency interference."
The space policy of the Donald Trump administration, as of December 2020, comprises six Space Policy Directives and an announced "National Space Strategy", representing a directional shift from the policy priorities and goals of his predecessor, Barack Obama. A National Space Policy was issued on December 9, 2020.
Space sustainability aims to maintain the safety and health of the space environment, as well as planetary environments.
Space diplomacy refers to the integration of the collaboration of the knowledge, technology, and legislation involved in science diplomacy as applied to the expanded exploration of space. As diplomatic relationships are integral to the mitigation of various health, scientific, natural or technological issues across nations, space diplomacy is a growing field in which various nations can come to a consensus on what is fair when it comes to the exploration and commercialization of space travel.
Space ethics, astroethics or astrobioethics is a discipline of applied ethics that discusses the moral and ethical implications arising from astrobiological research, space exploration and space flight. It deals with practical contemporary issues like the protection of the space environment and hypothetical future issues pertaining to our interaction with extraterrestrial life forms.
