Explore topic-wise fullforms in Space Science

INFO: Full form for ERA is Electrical Replaceable Assembly in Space Science category
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INFO: Full form for ERA is Environmental Research Aircraft in Space Science category
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INFO: Full form for TOI is Transfer Orbit Insertion in Space Science category
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INFO: Full form for DAE is Data Acquisition Equipment in Space Science category
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INFO: Full form for FCT is Flight Control Team in Space Science category
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INFO: Full form for FCT is Fuel Cell Test in Space Science category
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INFO: Full form for FCT is Flight Crew Trainer in Space Science category
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An emergency position-indicating radio beacon (EPIRB) is a type of emergency locator beacon, a portable, battery-powered radio transmitter used in emergencies to locate airplanes, vessels, and persons in distress and in need of immediate rescue. In the event of an emergency, such as a ship sinking or an airplane crash, the transmitter is activated and begins transmitting a continuous radio signal, which is used by search-and-rescue teams to quickly locate the emergency and render aid. The signal is detected by satellites operated by an international consortium of rescue services, COSPAS-SARSAT, which can detect emergency beacons anywhere on Earth transmitting on the COSPAS distress frequency of 406 MHz. The consortium calculates the position of the beacon and quickly passes the information to the appropriate local first responder organization, which performs the search and rescue. The basic purpose of this system is to help rescuers find survivors within the so-called "golden day" (the first 24 hours following a traumatic event) during which the majority of survivors can usually be saved. The feature distinguishing a modern EPIRB, often called GPIRB, from other types of emergency beacon is that it contains a GPS receiver and broadcasts its position, usually accurate within 100 m (330 ft), to facilitate location. Previous emergency beacons without a GPS can only be localized to within 2 km (1.2 mi) by the COSPAS satellites.

The standard frequency of a modern EPIRB is 406 MHz. It is an internationally regulated mobile radiocommunication service that aids search-and-rescue operations to detect and locate distressed watercraft, aircraft, and people. It is distinct from a satellite emergency position-indicating radiobeacon station.

The first form of these beacons was the 121.500-MHz ELT, which was designed as an automatic locator beacon for crashed military aircraft. These beacons were first used in the 1950s by the U.S. military, and were mandated for use on many types of commercial and general-aviation aircraft beginning in the early 1970s. The frequency and signal format used by the ELT beacons was not designed for satellite detection, which resulted in a system with poor location detection abilities and long delays in detection of activated beacons. The satellite detection network was built after the ELT beacons were already in general use, with the first satellite not being launched until 1982, and even then, the satellites only provided detection, with location accuracy being roughly 20 km (12 mi). The technology was later expanded to cover use on vessels at sea (EPIRB), individual persons (PLB), and starting in 2016, maritime survivor locating devices (MSLD). All have migrated from using 121.500 MHz as their primary frequency to using 406 MHz, which was designed for satellite detection and location.

Since the inception of Cospas-Sarsat in 1982, distress radio beacons have assisted in the rescue of over 28,000 people in more than 7,000 distress situations. In 2010 alone, the system provided information used to rescue 2,388 persons in 641 distress situations.

INFO: Full form for BUR is Back-up Rate in Space Science category
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INFO: Full form for ETD is Estimated Turnover Date in Space Science category
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INFO: Full form for SQT is Software Quality Training in Space Science category
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INFO: Full form for SQT is System Qualification Testing in Space Science category
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INFO: Full form for ETD is Electrical Terminal Distributor in Space Science category
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INFO: Full form for ETD is External Tank Door in Space Science category
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INFO: Full form for ELL is Early Lunar Lander in Space Science category
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INFO: Full form for HMV is Hydrogen Manual Valve in Space Science category
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INFO: Full form for FTE is Forced Test End in Space Science category
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INFO: Full form for FTE is Factory Test Equipment in Space Science category
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INFO: Full form for FTE is Flight Test Engineer in Space Science category
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INFO: Full form for SPR is Software Problem Report in Space Science category
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INFO: Full form for SPR is Subcontractor Performance Review in Space Science category
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INFO: Full form for EMO is Engineering Management Office in Space Science category
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INFO: Full form for EBD is Eyeballs Down (+gz) in Space Science category
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INFO: Full form for BIU is Buffer Interface Unit in Space Science category
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INFO: Full form for MIR is Malfunction Investigation Report in Space Science category
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A mirror is an object that reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the image in an equal yet opposite angle from which the light shines upon it. This allows the viewer to see themselves or objects behind them, or even objects that are at an angle from them but out of their field of view, such as around a corner. Natural mirrors have existed since prehistoric times, such as the surface of water, but people have been manufacturing mirrors out of a variety of materials for thousands of years, like stone, metals, and glass. In modern mirrors, metals like silver or aluminum are often used due to their high reflectivity, applied as a thin coating on glass because of its naturally smooth and very hard surface.

A mirror is a wave reflector. Light consists of waves, and when light waves reflect off the flat surface of a mirror, those waves retain the same degree of curvature and vergence, in an equal yet opposite direction, as the original waves. This allows the waves to form an image when they are focused through a lens, just as if the waves had originated from the direction of the mirror. The light can also be pictured as rays (imaginary lines radiating from the light source, that are always perpendicular to the waves). These rays are reflected at an equal yet opposite angle from which they strike the mirror (incident light). This property, called specular reflection, distinguishes a mirror from objects that diffuse light, breaking up the wave and scattering it in many directions (such as flat-white paint). Thus, a mirror can be any surface in which the texture or roughness of the surface is smaller (smoother) than the wavelength of the waves.

When looking at a mirror, one will see a mirror image or reflected image of objects in the environment, formed by light emitted or scattered by them and reflected by the mirror towards one's eyes. This effect gives the illusion that those objects are behind the mirror, or (sometimes) in front of it. When the surface is not flat, a mirror may behave like a reflecting lens. A plane mirror will yield a real-looking undistorted image, while a curved mirror may distort, magnify, or reduce the image in various ways, while keeping the lines, contrast, sharpness, colors, and other image properties intact.

A mirror is commonly used for inspecting oneself, such as during personal grooming; hence the old-fashioned name looking glass. This use, which dates from prehistory, overlaps with uses in decoration and architecture. Mirrors are also used to view other items that are not directly visible because of obstructions; examples include rear-view mirrors in vehicles, security mirrors in or around buildings, and dentist's mirrors. Mirrors are also used in optical and scientific apparatus such as telescopes, lasers, cameras, periscopes, and industrial machinery.

The terms "mirror" and "reflector" can be used for objects that reflect any other types of waves. An acoustic mirror reflects sound waves. Objects such as walls, ceilings, or natural rock-formations may produce echos, and this tendency often becomes a problem in acoustical engineering when designing houses, auditoriums, or recording studios. Acoustic mirrors may be used for applications such as parabolic microphones, atmospheric studies, sonar, and seafloor mapping. An atomic mirror reflects matter waves, and can be used for atomic interferometry and atomic holography.