Envisat is a large Earth-observing satellite which has been inactive since 2012. It is still in orbit and considered space debris. Operated by the European Space Agency (ESA), it was the world's largest civilian Earth observation satellite.
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 laser broom is a proposed ground-based laser beam-powered propulsion system that sweeps space debris out of the path of artificial satellites to prevent collateral damage to space equipment. It heats up one side of the debris to shift its orbit trajectory, altering the path to hit the atmosphere sooner. Space researchers have proposed that a laser broom may help mitigate Kessler syndrome, a runaway cascade of collision events between orbiting objects. Additionally, laser broom systems mounted on satellites or space station have also been proposed.
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 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.
A supersynchronous orbit is either an orbit with a period greater than that of a synchronous orbit, or just an orbit whose major axis is larger than that of a synchronous orbit. A synchronous orbit has a period equal to the rotational period of the body which contains the barycenter of the orbit.
Strictly speaking, a satellite collision is when two satellites collide while in orbit around a third, much larger body, such as a planet or moon. This definition is typically loosely extended to include collisions between sub-orbital or escape-velocity objects with an object in orbit. Prime examples are the anti-satellite weapon tests. There have been no observed collisions between natural satellites, but impact craters may show evidence of such events. Both intentional and unintentional collisions have occurred between man-made satellites around Earth since the 1980s. Anti-satellite weapon tests and failed rendezvous or docking operations can result in orbital space debris, which in turn may collide with other satellites.
Progress M1-5 was the Progress spacecraft which was launched by Russia in 2001 to deorbit the fifteen-year-old Mir space station in a controlled fashion over a remote ocean area, far away from shipping lanes - otherwise Mir's orbit would have decayed uncontrolled over time, with debris potentially landing in a populated area. The Russian Aviation and Space Agency, Rosaviakosmos, was responsible for the mission.
A number of space tethers have been deployed in space missions. Tether satellites can be used for various purposes including research into tether propulsion, tidal stabilisation and orbital plasma dynamics.
Busek Company Incorporated is an American spacecraft propulsion company that builds thrusters, electronics, and various systems for spacecraft.
Space Tethered Autonomous Robotic Satellite II or STARS-II, was a nanosatellite built by Japan's Kagawa University to test an electrodynamic tether in low Earth orbit, a follow-on to the STARS mission.
SpaceX CRS-14, also known as SpX-14, was a Commercial Resupply Service mission to the International Space Station launched on 2 April 2018. The mission was contracted by NASA and was flown by SpaceX. This mission reused the Falcon 9 first stage booster previously flown on CRS-12 and the Dragon capsule flown on CRS-8.
The Space Safety Programme, formerly the Space Situational Awareness (SSA) programme, is the European Space Agency's (ESA) initiative to monitor hazards from space, determine their risk, make this data available to the appropriate authorities and where possible, mitigate the threat.
The ClearSpace-1 mission is an ESA Space debris removal mission led by ClearSpace SA, a Swiss startup company. The mission's objective is to remove the PROBA-1 satellite from orbit. The mission aims to demonstrate technologies for rendezvous, capture, and deorbit for end-of-life satellites and to build a path to space junk remediation. Destructive reentry will destroy both the captured satellites and itself.
David A. Spencer is the Mars Sample Return Campaign Mission Manager at the Jet Propulsion Laboratory. As an aerospace engineer, Spencer designs and operates planetary spacecraft.
Sentinel-1B is a European radar imaging satellite launched on 25 April 2016. It is the second of two original satellites in the Sentinel-1 constellation, part of the European Union's Copernicus programme on Earth observation. The satellite carries a C-SAR sensor, capable of providing high-resolution imagery regardless of weather conditions.
RemoveDEBRIS was a satellite research project intending to demonstrate various space debris removal technologies. The mission was led by the Surrey Space Centre from the University of Surrey with the satellite's platform manufactured by Surrey Satellite Technology Ltd (SSTL). Partners on the project included Airbus, ArianeGroup, Swiss Center for Electronics and Microtechnology, Inria, Innovative Solutions In Space, Surrey Space Centre, and Stellenbosch University.
Astroscale Holdings Inc. is a private orbital debris removal company headquartered in Tokyo, Japan. The company is developing satellite end-of-life and active debris removal services to mitigate the growing and hazardous buildup of debris in space.
ION Satellite Carrier is a satellite platform developed, manufactured, and operated by Italian company D-Orbit. The platform features a customizable 64U satellite dispenser capable of hosting a combination of CubeSats that fits the volume. Throughout a mission, ION Satellite Carrier can release the hosted satellites individually, changing orbital parameter between one deployment and the next. Each of the miniature CubeSats weighs a few kilograms.
Space sustainability aims to maintain the safety and health of the space environment.
