Pass (spaceflight)
A pass, in spaceflight and satellite communications, is the period in which a satellite or other spacecraft is visible above the local horizon, and therefore available for radio communication with a particular ground station or satellite receiver (or, in some cases, for visual observation). The beginning of a pass is termed acquisition of signal; the end of a pass is termed loss of signal. The point at which the spacecraft comes closest to the ground observer is the time of closest approach.
The timing and duration of passes depends on the characteristics of the orbit a satellite occupies, as well as the topography and any occulting objects at the ground location. An observer directly on the ground track of the satellite will experience the greatest pass duration.Path loss and Doppler shifting are greatest toward the start and end of a pass.
Coverage
Satellites in geosynchronous orbit may be continuously visible from a single ground station, whereas satellites in low Earth orbit only offer short-duration passes.Satellite constellations, such as those of satellite navigation systems, may be designed so that a subset of the constellation is always visible from any point on the Earth, providing continuous coverage.
Spaceflight
Spaceflight (also written space flight) is ballistic flight into or through outer space. Spaceflight can occur with spacecraft with or without humans on board. Examples of human spaceflight include the U.S. Apollo Moon landing and Space Shuttle programs and the Russian Soyuz program, as well as the ongoing International Space Station. Examples of unmanned spaceflight include space probes that leave Earth orbit, as well as satellites in orbit around Earth, such as communications satellites. These operate either by telerobotic control or are fully autonomous.
Spaceflight is used in space exploration, and also in commercial activities like space tourism and satellite telecommunications. Additional non-commercial uses of spaceflight include space observatories, reconnaissance satellites and other Earth observation satellites.
A spaceflight typically begins with a rocket launch, which provides the initial thrust to overcome the force of gravity and propels the spacecraft from the surface of the Earth. Once in space, the motion of a spacecraft—both when unpropelled and when under propulsion—is covered by the area of study called astrodynamics. Some spacecraft remain in space indefinitely, some disintegrate during atmospheric reentry, and others reach a planetary or lunar surface for landing or impact.
Spaceflight (TV series)
Spaceflight is a 1985 American documentary miniseries about manned spaceflight, originally broadcast by PBS in four parts. It is narrated by Martin Sheen and features interviews with many former astronauts from the Mercury, Gemini, Apollo, and Space Shuttle programs. The series is a co-production of WETA-TV and WYES-TV. The final episode (Part 4) was redone after the Challenger explosion (the revision covered the inquiry and the return to flight as well).
Episodes
External links
Spaceflight (disambiguation)
Spaceflight is the act of traveling in outer space.
Spaceflight or Space flight may also refer to:
Pass
Pass, PASS, The Pass or Passed may refer to:
Permissions
- Boarding pass, allows a passenger to board an aircraft
- Continent pass, a pass allowing air travel within a continent
Arts and entertainment
- In contract bridge, to make no bid when it is one's turn to bid
Giovanni Passerini
Giovanni Passerini was an Italian botanist and entomologist, born on June 16, 1816 in Pieve di Guastalla. He died on April 17, 1893 in Parma .
Giovanni Passerini was a professor of botany at the University of Parma. He is the author of several works on the aphids. His collection, of 5, 500 specimens in 52 genera kinds and 89 species, is in the Natural history museum of the University of Parma.
In 1875, he was the first president of the Italian section of the Alpine Club .
Major works
References
