WIn the context of spaceflight, a satellite is an object that has been intentionally placed into orbit. These objects are called artificial satellites to distinguish them from natural satellites such as Earth's Moon.
WThe footprint of a communications satellite is the ground area that its transponders offer coverage, and determines the satellite dish diameter required to receive each transponder's signal. There is usually a different map for each transponder, as each may be aimed to cover different areas.
WA global network is any communication network which spans the entire Earth. The term, as used in this article refers in a more restricted way to bidirectional communication networks, and to technology-based networks. Early networks such as international mail and unidirectional communication networks, such as radio and television, are described elsewhere.
WA ground track or ground trace is the path on the surface of a planet directly below an aircraft's or satellite's trajectory. In the case of satellites, it is also known as a suborbital track, and is the vertical projection of the satellite's orbit onto the surface of the Earth.
WA satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global coverage, such that at any time everywhere on Earth at least one satellite is visible. Satellites are typically placed in sets of complementary orbital planes and connect to globally distributed ground stations. They may also use inter-satellite communication.
WSatellite flare, also known as satellite glint, is a satellite pass visible to the naked eye as a brief, bright "flare". It is caused by the reflection toward the Earth below of sunlight incident on satellite surfaces such as solar panels and antennas. Streaks from satellite flare are a form of light pollution that can negatively impact ground-based astronomy, stargazing, and indigenous people.
WSatellite watching or satellite spotting is a hobby which consists of the observation and tracking of artificial satellites that are orbiting Earth. People with this hobby are variously called satellite watchers, trackers, spotters, observers, etc. Since satellites outside Earth's shadow reflect sunlight, those especially in low Earth orbit may visibly glint as they traverse the observer's sky, usually during twilight.
WThe space segment of an artificial satellite system is one of its three operational components. It comprises the satellite or satellite constellation and the uplink and downlink satellite links.
WSpace tethers are long cables which can be used for propulsion, momentum exchange, stabilization and attitude control, or maintaining the relative positions of the components of a large dispersed satellite/spacecraft sensor system. Depending on the mission objectives and altitude, spaceflight using this form of spacecraft propulsion is theorized to be significantly less expensive than spaceflight using rocket engines.
WA 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.
WSpace-based solar power (SBSP) is the concept of collecting solar power in outer space and distributing it to Earth. Potential advantages of collecting solar energy in space include a higher collection rate and a longer collection period due to the lack of a diffusing atmosphere, and the possibility of placing a solar collector in an orbiting location where there is no night. A considerable fraction of incoming solar energy (55–60%) is lost on its way through the Earth's atmosphere by the effects of reflection and absorption. Space-based solar power systems convert sunlight to microwaves outside the atmosphere, avoiding these losses and the downtime due to the Earth's rotation, but at great cost due to the expense of launching material into orbit. SBSP is considered a form of sustainable or green energy, renewable energy, and is occasionally considered among climate engineering proposals. It is attractive to those seeking large-scale solutions to anthropogenic climate change or fossil fuel depletion.
WSpire Global, Inc. is a space-to-cloud data and analytics company that specializes in the tracking of global data sets powered by a large constellation of nanosatellites, such as the tracking of maritime, aviation and weather patterns.
WUSA-235, also known as Advanced Extremely High Frequency 2 or AEHF-2, is a military communications satellite operated by the United States Air Force. It is the second of six spacecraft to be launched as part of the Advanced Extremely High Frequency program, which replaced the earlier Milstar system.
WUSA-304, also known as GPS-III SV03 or Matthew Henson, is a United States navigation satellite which forms part of the Global Positioning System. It was the third GPS Block III satellite to be launched.
WUSA-309, also known as GPS-III SV04 or Sacagawea, is a United States navigation satellite which forms part of the Global Positioning System. It was the fourth GPS Block III satellite to be launched.