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Orbital elements
Orbital elements, also called Keplerian or classical orbital elements, are the six parameters defining an orbit's size, shape, orientation, and the orbiting body's position, standard in satellite catalogs.
Orbital Express
Orbital Express was a DARPA mission launched in 2007 that demonstrated autonomous robotic satellite refueling, completing seven rendezvous and dockings and 14 refuelings in orbit.
Orbital inclination
Orbital inclination is the angle between an orbit's plane and a reference plane, one of six Keplerian elements: 0° rides the equator, 90° passes over the poles.
Orbital inclination change
An orbital inclination change, also called a plane change, is a maneuver that rotates a spacecraft's orbital plane and is among the most expensive in orbital mechanics.
Orbital Maneuvering System
The Orbital Maneuvering System (OMS) was the Space Shuttle orbiter's primary in-space propulsion system, two AJ10 rocket engines that performed orbital insertion, orbit changes, rendezvous, and the de-orbit burn.
Orbital Marine Power
Orbital Marine Power is a Scottish engineering company, headquartered in Orkney, that develops floating tidal stream turbines; its O2 turbine has generated grid power at EMEC since 2021.
Orbital mechanics
Orbital mechanics, also known as astrodynamics or orbital dynamics, is the branch of mechanics that studies the motion of spacecraft and planets under gravity to plan space missions.
Orbital rendezvous
Orbital rendezvous is the set of maneuvers by which a chaser spacecraft matches a target's position and velocity in orbit, a required step for docking and space station missions.
Orbital Sciences Corporation
Orbital Sciences Corporation was an American aerospace company founded in 1982 and based in Dulles, Virginia, that built the Pegasus rocket, the Antares rocket, and the Cygnus cargo spacecraft before merging into Orbital ATK in 2015.
Orbital spaceflight
Orbital spaceflight, or orbital flight, is flight in which a spacecraft travels fast enough to fall freely around a celestial body instead of back to its surface.
Orbital station-keeping
Orbital station-keeping is the propulsive maneuvers that keep a spacecraft within its designated orbital position or window despite perturbations such as drag, gravity irregularities, and solar radiation pressure.
Orbitz
Orbitz, also known as Orbitz.com, is an American online travel agency founded in 2000 by five major U.S. airlines and owned by Expedia Group since 2015.
OrbView-2
OrbView-2, originally named SeaStar, was a commercial Earth-observation satellite launched by Orbital Sciences in 1997 whose SeaWiFS instrument measured ocean chlorophyll for more than 13 years.
Orca (language models)
Orca is a family of small instruction-tuned language models from Microsoft Research that learns reasoning from GPT-4's explanation traces; its successor, Orca 2, released in November 2023, picks its own reasoning strategy per task.
Orca Energy Group
Orca Energy Group, until 2020 Orca Exploration Group, is a natural gas company incorporated in the British Virgin Islands that operates the Songo Songo gas field offshore Tanzania.
OrCAD
OrCAD is a suite of electronic design automation software for printed circuit board design, first released in 1985 and owned by Cadence Design Systems since 1999.
Order analysis
Order analysis is a signal processing method that extracts harmonic components, or orders, from vibration measurements of rotating machinery as a function of rotational speed rather than time.
Order cycle time
Order cycle time is the elapsed time between when a customer places an order and receives the product or service, covering transmittal, processing, picking, and delivery.
Order of Daedalians
The Order of Daedalians is an American fraternal organization of military aviators founded by World War I pilots in 1934 and headquartered at Joint Base San Antonio-Randolph, Texas.
Order of Railroad Telegraphers
The Order of Railroad Telegraphers (ORT) was a North American labor union for railroad telegraphers, train dispatchers, and station agents, founded in 1886 and peaking at about 100,000 members.
Order-n formulation
The Order-n formulation is a recursive method for computing the dynamics of articulated multibody systems whose computational cost grows linearly with the degrees of freedom, using algorithms introduced by Roy Featherstone.
Ordered statistics CFAR
Ordered statistics CFAR (OS-CFAR) is a radar detection scheme proposed by Hermann Rohling in 1983 that estimates background noise by sorting reference cells, tolerating multiple interfering targets.
Ordinary seaman
An ordinary seaman is the entry-level, unlicensed deck rating on a merchant ship, ranking below able seaman, performing maintenance, cleaning, and helm and lookout watches under supervision.
Ordine degli Ingegneri
The Ordine degli Ingegneri (Order of Engineers) is the Italian professional order for engineers, a network of 106 provincial bodies that maintains the register of engineers and controls access to the profession.
Ordnance QF 17-pounder
The Ordnance QF 17-pounder was a British 76.2 mm anti-tank gun of the Second World War, named for its 17-pound projectile and mounted in Sherman Firefly tanks.
Ordnance QF 18-pounder
The Ordnance QF 18-pounder was the standard quick-firing field gun of British and Commonwealth artillery in the First World War, with more than 10,000 guns produced from 1904.
Ordnance QF 25-pounder
The Ordnance QF 25-pounder, or 25-pdr, was a British quick-firing 87.6 mm gun-howitzer that served as the standard field gun of British and Commonwealth forces during the Second World War.
Ordnance QF 6-pounder
The Ordnance QF 6-pounder was a British 57 mm anti-tank gun of the Second World War that entered service in 1942 and first saw action in North Africa.
Ordnance Survey
Ordnance Survey (OS), Great Britain's national mapping agency founded 21 June 1791 by the Board of Ordnance, maintains over 600 million geospatial features, the National Grid, and OSGB36 mapping data.
Ordos Power Qipanjing power station
Ordos Power Qipanjing power station is a coal-fired power station in Qipanjing Town, Ordos, Inner Mongolia, China, built from 2003 as the captive power supply for the Qipanjing Industrial Park.