Explore topic-wise fullforms in Space Science

Urgent may refer to:

INFO: Full form for VAA is Vehicle Assembly Area in Space Science category
VAA also has other full forms in other categories mentioned below.

INFO: Full form for VAA is Viewpoint Adapter Assembly in Space Science category
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INFO: Full form for VRL is Vertical Recovery Line in Space Science category
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INFO: Full form for VRL is Vertical Reference Line in Space Science category
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INFO: Full form for VAK is Vertical Access Kit in Space Science category
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INFO: Full form for VAK is Vertical Assembly Kit in Space Science category
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INFO: Full form for LGP is Little Green People in Space Science category
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Lunar orbit rendezvous (LOR) is a key concept for efficiently landing humans on the Moon and returning them to Earth. It was utilized for the Apollo program missions in the 1960s and 1970s. In a LOR mission, a main spacecraft and a smaller lunar lander travel to lunar orbit. The lunar lander then independently descends to the surface of the Moon, while the main spacecraft remains in lunar orbit. After completion of the mission there, the lander returns to lunar orbit to rendezvous and re-dock with the main spacecraft, then is discarded after transfer of crew and payload. Only the main spacecraft returns to Earth.

Lunar orbit rendezvous was first known to be proposed in 1919 by Ukrainian engineer Yuri Kondratyuk, as the most economical way of sending a human on a round-trip journey to the Moon.

The most famous example involved Project Apollo's command and service module (CSM) and lunar excursion module (LEM), where they were both sent to a translunar flight in a single rocket stack. However, variants where the landers and main spacecraft travel separately, such as the lunar landing plan proposed for Shuttle-Derived Heavy Lift Launch Vehicle and Golden Spike, are also considered as Lunar Orbit rendezvous.

The kilowatt-hour (SI symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy equal to one kilowatt of power sustained for one hour or 3600 kilojoules (3.6 megajoules). It is commonly used as a billing unit for energy delivered to consumers by electric utilities.

INFO: Full form for MQN is Mission Quality Notice in Space Science category
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INFO: Full form for MJS is Manipulator Jettison System in Space Science category
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INFO: Full form for MOG is Management Oversight Group in Space Science category
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INFO: Full form for MIU is Mpe Interface Unit in Space Science category
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INFO: Full form for MIU is Multiplex Interface Unit in Space Science category
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INFO: Full form for MQS is Mission Quality Statistics in Space Science category
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INFO: Full form for MQG is Mission Quality Generation in Space Science category
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INFO: Full form for MQA is Mission Quality Assurance in Space Science category
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The maximum landing weight (MLW) is the maximum aircraft gross weight due to design or operational limitations at which an aircraft is permitted to land. The MLW is set in order to ensure safe landings; if an aircraft weighs too heavy during touchdown, it may suffer structural damage or even break apart upon landing. Aircraft also have a maximum take-off weight, which is almost always higher than the maximum landing weight, so that an aircraft can weigh less upon landing due to burning fuel during the flight.: 5:28 

The operation landing weight may be limited to a weight lower than the maximum landing weight by the most restrictive of the following requirements:

If the flight has been of short duration, usually due to an emergency just after takeoff, it may be necessary to dump fuel to reduce the landing weight. Some aircraft are unable to dump fuel, however. For example, on 3 February 2020, Air Canada Flight 837, a Boeing 767-300, suffered a rear tyre failure during take-off at Madrid–Barajas Airport on its way to Toronto, causing its left engine to catch fire. The pilots managed to extinguish it by shutting the engine down, but as 767-300s are not designed for fuel dumping, it had to stay in a single-engine holding pattern for over 4 hours to burn fuel and achieve its maximum landing weight, while an SAF fighter reported minimal damage to the landing gear. The plane landed safely and nobody was injured.

Sometimes the emergency may be so pressing that the aircraft has no time to dump or burn fuel in order to achieve its maximum landing weight before touchdown; in that case, a risky overweight landing may be permitted. In other cases, the flight crew may fail to dump fuel when it still had the time to do so before landing, leading to fatal accidents such as Aeroflot Flight 1492 on 5 May 2019, where an apparently needlessly overweight landing turned into a crash that killed 41 of the 78 people on board.

Where aircraft overweight landing is permitted, a structural inspection or evaluation of the touch-down loads before the next aircraft operation will be required in case damage has occurred.

INFO: Full form for MWG is Maintenance Analyzer Working Group in Space Science category
MWG also has other full forms in other categories mentioned below.

INFO: Full form for PHA is Preliminary Hazard Analyses in Space Science category
PHA also has other full forms in other categories mentioned below.

INFO: Full form for PHA is Pulse Height Analyzer in Space Science category
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A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and is large enough to cause significant regional damage in the event of impact. They are defined as having a minimum orbital intersection distance with Earth of less than 0.05 astronomical units (19.5 lunar distances) and an absolute magnitude of 22 or brighter. 99% of the known potentially hazardous objects are not an impact threat over the next 100 years. Only about 19 potentially hazardous objects are listed on the Sentry Risk Table as objects that are known not to be a threat over the next hundred years are excluded. Over hundreds if not thousands of years, "potentially hazardous" asteroids have the potential for their orbits to evolve to live up to their namesake.

Most of these objects are potentially hazardous asteroids (PHAs), and a few are comets. As of August 2021 there are 2,203 known PHAs (about 8% of the total near-Earth population), of which 159 are estimated to be larger than one kilometer in diameter (see list of largest PHAs below). Most of the discovered PHAs are Apollo asteroids (1,730) and fewer belong to the group of Aten asteroids (171).

A potentially hazardous object can be known not to be a threat to Earth for the next 100 years or more, if its orbit is reasonably well determined. Potentially hazardous asteroids with some threat of impacting Earth in the next 100 years are listed on the Sentry Risk Table. As of August 2021, only about 19 potentially hazardous asteroids are listed on the Sentry Risk Table. Most potentially hazardous asteroids are ruled out as hazardous to at least several hundreds of years when their competing best orbit models are sufficiently constrained, but recent discoveries whose orbital constraints are little-known have divergent or incomplete mechanical models until observation yields further data. After several astronomical surveys, the number of known PHAs has increased tenfold since the end of the 1990s (see bar charts below). The Minor Planet Center's website List of the Potentially Hazardous Asteroids also publishes detailed information for these objects.

In May 2021, NASA astronomers reported that 5 to 10 years of preparation may be needed to avoid a potential impactor based on a simulated exercise conducted by the 2021 Planetary Defense Conference.

INFO: Full form for POY is Pilot of The Year in Space Science category
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INFO: Full form for NEA is Near Earth Asteroid in Space Science category
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INFO: Full form for NEA is Noise Equivalent Angle in Space Science category
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INFO: Full form for SHE is Supercritical Helium in Space Science category
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INFO: Full form for SGV is Self Guided Vehicle in Space Science category
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Segment or segmentation may refer to:

INFO: Full form for SEG is System Engineering Groundrule in Space Science category
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Rocketdyne was an American rocket engine design and production company headquartered in Canoga Park, in the western San Fernando Valley of suburban Los Angeles, in southern California.

The Rocketdyne Division was founded by North American Aviation (NAA) in 1955, and was later part of Rockwell International (1967–1996) and Boeing (1996–2005). In 2005, the Rocketdyne Division was sold to United Technologies Corporation, becoming Pratt & Whitney Rocketdyne as part of Pratt & Whitney. In 2013, Pratt & Whitney Rocketdyne was sold to GenCorp, which merged it with Aerojet to form Aerojet Rocketdyne.

INFO: Full form for RDR is Raw Data Recorder in Space Science category
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A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other conveyance that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane. A rudder operates by redirecting the fluid past the hull (watercraft) or fuselage, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with hinges to the craft's stern, tail, or after end. Often rudders are shaped so as to minimize hydrodynamic or aerodynamic drag. On simple watercraft, a tiller—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be turned by a helmsman. In larger vessels, cables, pushrods, or hydraulics may be used to link rudders to steering wheels. In typical aircraft, the rudder is operated by pedals via mechanical linkages or hydraulics.

INFO: Full form for REI is Re Entry Interval in Space Science category
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INFO: Full form for REI is Runway End Identification in Space Science category
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INFO: Full form for REI is Range From Entry Interface (400 K) in Space Science category
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INFO: Full form for RUT is Resource Utilization Time in Space Science category
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INFO: Full form for RRI is Rendezvous Radar Indicator in Space Science category
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