Editing List of Acronyms and Abbreviations

This list contains definitions for [[Orbiter]] or important [[spaceflight]] acronyms or abbreviations, especially those appearing in [[MFD|MFDs]] and various [[HUD]] modes.

One entry in this list consists of a term with one or more definitions, like:

;Term:Definition
<pre>
;Term:Definition
</pre>

Don't use links in the term part of a entry, please do so in the definition part, for keeping a consistent look-and-feel and don't putting to much emphasis on a single definition.

Terms without definitions will get moved to the talk page into the section "Wanted definitions". If you have multiple definitions for a term, the definition part should turn into a numbered list, like:
;Term:
#Definition 1
#Definition 2
#Definition 3

<pre>
;Term:
#Definition 1
#Definition 2
#Definition 3
</pre>

The order of the definitions should be like that:
#Orbiter HUD definitions
#Orbiter MFD definitions
#General Orbiter definitions
#Orbiter [[Add-on]] definitions
#General spaceflight definitions

If you don't agree to a ordering of definitions, please complain in the [[Talk:List_of_Acronyms_and_Abbreviations|talk]] page about the entry.

==See also==

* [[Russian glossary]]
* [[List of Acronyms and Abbreviations/ISS|List of Acronyms and Abbreviations for the ISS]]

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=A=
;ACC: Acceleration, used in [[Surface MFD]] to indicate increasing or decereasing horizontal speed of the ship in m/s<sup>2</sup>
;ACT: Activate, command button in [[RCS attitude MFD]] in docking mode to activate the programmed orientation to the target dock
;AgP:[[Argument of periapsis]]:The angle in the orbit from the point of the ascending node to the point of periapsis, displayed in [[Orbit MFD]]
;ALT or Alt:[[altitude]], distance from the body surface 
#Used in [[Orbit MFD]] when Alt mode is selected to indicate distance from the surface of the body
#Used in [[Surface MFD]] to indicate altitude in km from the body surface
;AN:[[ascending node]]:a vector in an orbit where the body passes from south to north of the plane of reference (i.e. ecliptic or equatorial). Shown in [[Align MFD]] and [[Orbit MFD]] as a dotted vector line connecting to a solid square on the orbit.
;AOA: Angle of attack, the difference between the ship's direction of travel and the pitch of its nose
#Used in [[Surface MFD]] to indicate the angle of attack
;AORP:'''A'''utonomous '''O'''rbiter '''R'''apid '''P'''rototype, a system to allow a [[STS|shuttle]] orbiter to land without [[crew]].
;AP: Used in [[Surface MFD]], a red rectangle with white "AP" in the altitude tape to indicate the altitude of the ship's apoapsis
;ApA:[[apoapsis]] apoapsis altitude, the lowest altitude of an orbit, displayed in [[Orbit MFD]].
;ApD:[[apoapsis]] apoapsis distance
;ApR:[[apoapsis]] apoapsis radius, displayed in [[Orbit MFD]]
;ApT:time to [[apoapsis]] in seconds, displayed in [[Orbit MFD]]
;AR:
#'''A'''utomatic '''R'''eference, used in [[Align MFD]], [[Orbit MFD]] as a command button for Align to select a reference body automatically based on highest gravity
#'''A'''ltitude '''R'''ange, used to manually set the range in the altitude graph in [[Ascent profile MFD]]
#'''a'''cceptance '''r'''eview
;atmo:[[atmosphere]]
;ATM DATA: Atmospheric data in [[Surface MFD]] readouts
;ATV:
#'''A'''utonomous '''T'''ransfer '''V'''ehicle, an unmanned cargo spacecraft, see [[ATV]].
#'''A'''utomated '''T'''ransfer '''V'''ehicle[http://www.orbiterwiki.org/wiki/ATV#The_ATV]
;AU:[[astronomical unit]]
;AX: '''Ax'''is, command button in [[RCS attitude MFD]] to change the selected axis beetween pitch/yaw/roll

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=B=
;BAS: Basemode, command button to select programmed attitude (prograde, orbit normal, perpendicular in, radial down) in [[RCS attitude MFD]]
;BMW:'''B'''ate, '''M'''ueller, '''W'''hite - authors of ''Fundamentals of Astrodynamics'' (1971)
;BRG: '''B'''ea'''r'''in'''g''', used in the [[Horizontal Situation Indicator MFD]] to indicate the compass direction of the ILS or VOR transmitter

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=C=
;CaLV:'''Ca'''rgo '''l'''aunch '''v'''ehicle, see [[Ares V]]
;CDI:[[course deviation indicator]]
;CDR:
#commander
#'''c'''ritical '''d'''esign '''r'''eview
;CEV:'''C'''rew '''e'''xpedition '''v'''ehicle, see [[CEV]]
;CFD:computational fluid dynamics
;CFG: command button in [[RCS attitude MFD]] to switch to configuration page
;CLV:'''C'''rew '''l'''aunch '''v'''ehicle, see [[Ares I]]
;CNC: Cancel, used in [[RCS attitude MFD]] in the docking mode to cancel the docking mode program
;COAS:'''C'''rew '''O'''ptical '''A'''lignment '''S'''ight
;COM:communication or communicator
;CRS: '''C'''ou'''rs'''e, indicates the ship's course (heading) in the [[Horizontal Situation Indicator MFD]]
;CTD:[[crash to desktop]]
;CTRL:Control
;CTV:
#'''C'''rew '''T'''ransfer '''V'''ehicle, a manned spacecraft derived from the [[ATV]], see [[CTV]]
#'''C'''ompatibility '''T'''est '''V'''an, '''NASA'''
;CUR: Command button in [[RCS attitude MFD]] to set the programmed attitude to the current attitude
;CVEL:
#[[closing velocity]]
#'''C'''ommon '''V'''essel '''E'''xtensions '''L'''ight, see [[CVEL]]

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=D=
;D3D9:refers to the advanced graphics client in [[Orbiter]]
;Da: Deviation, displayed in [[RCS attitude MFD]] to indicate how many degrees the ship has to go in Roll to reach programmed attitude
;DCK: command button in [[RCS attitude MFD]] to set the MFD into Docking mode
;DDT&E:'''d'''esign, '''d'''evelopment, '''t'''est and '''e'''valuation
;DEV:'''Dev'''iation, in the [[Horizontal Situation Indicator MFD]], it indicates how far the OBS is adjusted left or right of the radial
;DG:[[Delta-glider]]
;DG4:Orbiter's stock '''DG'''
;DGIII:[[DeltagliderIII]], a famous enhanced version of the [[Delta-glider]].
;DGIV:[[DeltaGliderIV]], an improved version of the [[DeltaGliderIII]].
;DG-S:[[Delta-glider]] equiped with two [[scramjet|scramjets]].
;Dir:'''dir'''ection
;Dist:'''dist'''ance
#Displayed in [[Sync MFD]], distance ship to target
;DIV:[[divergent]], i.e. [[yaw]] [[gimbal]] mode.
;DLng:difference in longitude between ship and target, displayed in [[Sync MFD]]
;DN:
#'''Down''', used in [[Map MFD]] when Tracking mode is off and map zoomed in to scroll the map down so you can see farther South
# Command button in [[RCS attitude MFD]] to change the selected modification up so you can edit it
#[[descending node]]
;DNP:dynamic [[pressure]], given in Pa
#Displayed in [[Surface MFD]] to indicate atmospheric pressure
;DNS:atmospheric density, given in kg m<sup>-3</sup>, symbol ρ
#displayed in [[Surface MFD]]
;DPS:'''D'''ata '''P'''rocessing '''S'''ystem. Term describing the general purpose computers and their interfaces onboard various manned spacecraft
;Dr: Deviation, displayed in [[RCS attitude MFD]] to indicate how many degrees until the ship reaches pitch and yaw alignment with the programmed attitude
;DSP: '''D'''i'''sp'''lay, used in [[Map MFD]] to switch between Ground Track Display and Orbital Plane Display
;DST or Dst:
#Distance (to target), used in the [[Horizontal Situation Indicator MFD]] to indicate distance to the selected ILS or VOR transmitter
#Distance, used in [[Orbit MFD]] to select between Rad, ApR, PeR (distance from body center) and Alt, ApA, PeA (distance from body surface)
;DTe:time to [[ejection]], as seen on the [[transfer MFD]]
;DTi:time to intercept, as seen on the [[transfer MFD]]
;DTmin:time of arrival difference
#Displayed in [[Sync MFD]] to indicate difference in time between ship and target passing the intersection point
;Dv:delta [[velocity]], as seen on the [[transfer MFD]], see also [[Delta-V]]

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=E=
;Ecc:[[eccentricity]] of orbit, displayed in [[Orbit MFD]]
;ECL:plane of the [[ecliptic]]
;ECLSS:'''E'''nvironmental '''c'''ontrol and '''l'''ife '''s'''upport '''s'''ystem
;ECSS:'''e'''uropean '''c'''ooperation for '''s'''pace '''s'''tandardization
;EELV:Evolved Expendable Launch Vehicle
;ELS: '''EL'''ements, custom '''S'''elect, used in [[Align MFD]] to select a custom orbital elements to which to align
;END: command button in [[RCS attitude MFD]] to stop the programmed attitude mode
;EQU:plane of the [[equator]]
;EQU POS: Equatorial position, given as longitude and latitude
#Displayed in [[Surface MFD]] given as position and rate of change
;ESA:[[European Space Agency]]
;ESAS:[[w:Exploration Systems Architecture Study|Exploration Systems Architecture Study]]
;ET:[[external tank]]
;EVA:'''E'''xtra '''v'''ehicular '''a'''ctivity, see [[EVA]]

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=F=
;FGB:Russian abbreviation for Functional Cargo Block. See [[FGB]]
;FoV:field of view, as seen in the [[general information display]]
;FPS:[[frame rate]] (frames per second), as seen in the [[general information display]]
;FRF:'''F'''light '''R'''eadiness '''F'''iring, a launch countdown test of the Shuttle running all except SRB ignition and lift-off.
;FRM: '''Fr'''a'''m'''e of reference, used in [[Orbit MFD]] to change the orbital display and parameters between Equatorial or Ecliptic

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=G=
;G or g:
#used in [[Orbit MFD]], indicates what fraction of gravity is exerted on the ship by the reference body (0 to 1)
#unit of acceleration. 1g equals the gravity acceleration on earths surface, 9.81 m/s²
;GET:'''G'''round '''E'''lapsed '''T'''ime [http://history.nasa.gov/SP-4029/Apollo_00c_Introduction.htm]
;GL:Used often as vehicle name prefix for a [[Delta-glider]]
;GLOC:'''G'''ravity-induced '''L'''oss '''o'''f '''C'''onsciousness  
;GMT:Greenwich Mean Time.See [[w:Universal Time|Universal Time on Wikipedia]]
;GO: '''Go''', command button in [[RCS attitude MFD]], once the desired orientation and modifications are set, to activate the program
;GPDS:[[GPDS|Generic Payload Description System]]
;GPS:'''G'''lobal '''P'''ositioning '''S'''ystem
;GS: [[w:Ground speed|Ground speed]]
#Command button in [[Surface MFD]] to set the speed tape to GS
;GTO:[[GTO|'''g'''eostationary '''t'''ransfer '''o'''rbit]]

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=H=
;H:Horizon
;HAC:[[Heading Alignment Cone]]
;HLLV:'''h'''eavy '''l'''ift '''l'''aunch '''v'''ehicle
;HSI:[[horizontal situation indicator]]
;HST:[[Hubble Space Telescope]]
;HTO:[[hypothetical transfer orbit]], as seen on the [[transfer MFD]]
;HUD:[[heads up display]], used in [[Docking MFD]], [[Orbit MFD]], [[Surface MFD]] to copy the current parameters to the HUD

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=I=
;IAS:indicated air speed [[w:Indicated airspeed|Indicated airspeed]]
#Command button in [[Surface MFD]] to set the speed tape to IAS
;IDS:[[IDS|instrument docking system]], used in [[Docking MFD]]
;ILS:
#[[instrument landing system]]
#also used in [[Horizontal Situation Indicator MFD]] to indicate which runway at which Spaceport is selected by the NAV system
#'''I'''nternational '''l'''aunch '''s'''ervices, a US-russian joint venture marketing [[Atlas]] and [[Proton]] launches
;Inc: [[Inclination]], angular difference between one orbit with respect to another, usually the ecliptic, equatorial, body orbit, or target orbit, displayed in [[Align MFD]], [[Orbit MFD]] 
;INV: Inverse, command button in [[RCS attitude MFD]] to change the programmed attitude to the inverse (retrograde, orbit antinormal, perpendicular out, radial up)
;ISP:[[specific impulse]]
;ISS:[[International Space Station]]

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=J=
;JD:[[Julian date]]
;JSC:  Lyndon B. '''J'''ohnson '''S'''pace '''C'''enter
;JWST:'''J'''ames '''W'''ebb '''S'''pace '''T'''elescope


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=K=
;KISS:"Keep it simple, stupid!" Famous engineering dogma.[http://en.wikipedia.org/wiki/KISS_principle] 
;KSC:[[Kennedy Space Center]]

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=L=
;LAN:
#Longitude of the [[ascending node]], used in [[Align MFD]], [[Orbit MFD]]
#local-area network
;LCC:
#'''l'''aunch '''c'''ontrol '''c'''enter
#'''l'''ife '''c'''ycle '''c'''ost
;LDEF:[[Long Duration Exposure Facility]]
;LEN: List Length
#Command button in [[Sync MFD]] to select number of orbits to display (lines 0-18)
;LEO:[[Low earth orbit]]
;LH2:Liquid Hydrogen
;LOCV: Loss of crew and vehicle
;LOX:Liquid Oxygen
;LPe:longitude of [[periapsis]], displayed in [[Orbit MFD]]
;L/R:'''L'''eft/'''R'''ight, used in [[Horizontal Situation Indicator MFD]] to switch MFD mode focus to the left or right graphic display

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=M=
;m:metre
;M:
#Mega (SI prefix for 10<sup>6</sup>). 
#Mass, given in kg
#[[mach]] number or multiples of speed of sound in a given medium
##Used in [[Surface MFD]] ship's speed is given in mach number as well as m/s
;MCC:
#'''m'''id '''c'''ourse '''c'''orrection
#'''m'''ission '''c'''ontrol '''center'''
;MCC-H:'''m'''ission '''c'''ontrol '''c'''enter '''H'''ouston
;MCC-M:'''m'''ission '''c'''ontrol '''c'''enter '''M'''oscow
;MDR:'''m'''ission '''d'''efinition '''r'''eview
;MECO:'''m'''ain '''e'''ngine '''c'''ut'''o'''ff
;MET:'''M'''ission '''E'''lapsed '''T'''ime. See [[w:Mission Elapsed Time|Mission Elapsed Time on Wikipedia]].
;MFD:'''M'''ulti'''f'''unctional '''D'''isplay, see [[MFD]]
;MHz: '''M'''ega'''H'''er'''z''', same as the old term megacycles/second, radio and transponder frequency, used in [[COMNAV MFD]]
;MJD:[[modified Julian date]]
;MLP:[[Mobile Launcher Platform]]
;MMOD:'''M'''icro'''m'''eteorites and '''o'''rbital '''d'''ebris
;MMU:'''m'''anned '''m'''aneuvering '''u'''nit, see [[MMU]]
;MnA:[[mean anomaly]], displayed in [[Orbit MFD]]
;MnL:[[mean longitude]], displayed in [[Orbit MFD]]
;MOD: used in [[Orbit MFD]] and [[Sync MFD]] to cycle the display between parameters only, orbital display only, or both
;m/s:meters per second, the SI base unit of [[velocity]]
;MSx:Mission Specialist x


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=N=
;NAV:
#Navigatonal receiver, 
##in [[COMNAV MFD]] it is used to identify up to four receivers in the stack
##in [[Horizontal Situation Indicator MFD]], it is used to select which receiver an HSI display is tuned to
##in [[RCS attitude MFD]] command button in Docking mode to slave one of the Nav receivers to this MFD
#navigation
#[[navigation aid]]
;NT: '''N'''o '''t'''arget, used in [[Orbit MFD]] to deselect the target

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=O=
;OAT:outside air temperature, displayed in [[Surface MFD]] given in Kelvins (K)
;Ob:
#Obliquity of ecliptic (tilt of axis of rotation against plane of ecliptic)
#Orbit, displayed in [[Sync MFD]] indicates how many orbits remaining until rendezvous
;OB+ and OB-: '''O'''mni'''B'''earing, used to change the offset of the course arrow to left or right of the beam
;OBS:[[omni bearing selector]]
;OBT:[[orbit]], as seen on the [[orbit MFD]]
;OMBUU: '''O'''rbiter '''M'''id'''b'''ody '''U'''mbilical '''U'''nit
;[[OMP]]:'''O'''rbiter '''M'''ultiplayer '''P'''roject, an ongoing program to create a multiplayer server in Orbiter.
;OMS:'''O'''rbital '''M'''aneuvering '''S'''ystem, the 'main engines' of the [[space shuttle]] orbiter
;OS:[[w:Orbital speed|Orbital speed]]
#Command button in [[Surface MFD]] to set the speed tape to OS

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=P=
;P:position (sometimes radius) vector, as seen on the [[align orbital plane MFD]]
;p0:atmospheric pressure at sea level
;PAM:'''P'''ayload '''A'''ssist '''M'''odule, a family of solid upper stages for the [[Space Shuttle]]
;PAPI:'''P'''recision '''A'''pproach '''P'''ath '''I'''ndicators, lit runway centerline.
;PB:[[Shuttle PB]]
;PDR:'''p'''reliminary '''d'''esign '''r'''eview
;PDRS:'''P'''ayload '''D'''eployment and '''R'''etrieval '''S'''ystem, the official name of the robot arm of the Space Shuttle
;PeA:[[periapsis]] altitude. Altitude of periapsis above the surface of the orbited body, used in [[Orbit MFD]]
;PeD:[[periapsis]] distance. See PeR. 
;PeR:[[periapsis]] radius. Distance of periapsis from the center of the orbited body, used in [[Orbit MFD]]
;PeT:time to [[periapsis]] in seconds, displayed in [[Orbit MFD]]
;PG:
#Page, switching displayed pages in an MFD mode, used in [[Align MFD]]
#[[prograde]]
;PLT:Pilot
;PMI:'''P'''rincipal '''m'''oments of '''i'''nertia, see [[PMI]]
;Pos:position
;PRJ: Projection, used in the [[Orbit MFD]] to switch orbital display between Ecliptic, Equatorial, Ship's orbit, Target orbit
;PRR:'''p'''reliminary '''r'''equirements '''r'''eview
;PSx:Payload Specialist x

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=Q=
;QR: '''q'''ualification '''r'''eview

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=R=
;R:
#mean radius
#specific gas constant
;+R and -R: 
#Command buttons in [[RCS attitude MFD]] (R+) to add a line (pitch, yaw, roll) to the programmed attitude, or R- to remove the last line
#Command buttons in [[Sync MFD]] to rotate intersection points
;r0:atmospheric density at sea level
;Rad:
#Displayed in [[Orbit MFD]] when Radius mode is selected to indicate distance from the center of the body in meters
#radial distance
#angular unit ''radians''
;RAnm:[[true anomaly]] of reference axis, displayed in [[synchronise orbit MFD]]
;Rate: How fast the current orbital plane is changing, degrees per second, used in [[Align MFD]]
;RCS:[[reaction control system]], spacebourne orientation rocket system.
;R&D:'''r'''esearch and '''d'''evelopment
;RDT&E:'''r'''esearch, '''d'''evelopment, '''t'''esting and '''e'''valuation
;REF: '''Reference'''
#used in [[Align MFD]], [[Map MFD]], [[Orbit MFD]] to select a reference body.
#'''Ref''': Reference displayed in [[Sync MFD]] to switch Reference axis
;RG:[[retrograde]]
;RInc:[[relative inclination]], relative inclination between the ship and target orbits, used in [[Align MFD]] and [[Sync MFD]]
;RKA:Russian Space Agency
;RMS:'''R'''emote '''M'''anipulator '''S'''ystem
;RS:Russian-side, used as prefix for orientation when describing ISS components.
;RSLS:'''R'''edundant '''s'''et '''l'''aunch '''s'''equencer, the computer systems responsible for the ignition of the SSMEs in the [[Space Shuttle]] orbiter.
;RTFM:'''R'''ead '''t'''he '''f'''ine (or many other '''f'''-words) '''m'''anual, a typical forum answer for questions already answered extensivly in the manual.
;RTLS:'''R'''eturn '''t'''o '''l'''aunch '''s'''ite, a [[Space Shuttle]] abort mode.
;RTN: Return, command button in [[RCS attitude MFD]] to return the display to the Active mode page
;RVel:relative [[velocity]]
#Displayed in [[Sync MFD]], Relative speed between ship and target

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=S=
;SAR:
#'''S'''earch '''a'''nd '''r'''escue.
#'''S'''yntetic '''a'''perture '''r'''adar, a [[radar]] mode used for creating navigation maps or detect slowly moving ground vehicles.
;S/C: [[spacecraft|'''s'''pace'''c'''raft]]
;SC< and SC>:'''SC'''an frequency up or down in the currently selected receiver, used in [[COMNAV MFD]]
;SDK:Software Development Kit [http://en.wikipedia.org/wiki/SDK]
;SDHLV:'''S'''huttle '''D'''erived '''H'''eavy '''L'''aunch '''V'''ehicle, see [[Ares V]] 
;SDLV:'''S'''huttle '''D'''erived '''L'''aunch '''V'''ehicle, see [[Ares]]
;SECO:
#'''S'''econdary '''E'''ngine '''C'''ut'''o'''ff
#'''S'''ustainer '''E'''ngine '''C'''ut'''o'''ff
;SET: Set, used in [[RCS attitude MFD]] to set the desired attitude
;SHP: Ship, used in [[Map MFD]] to indicate your ship's name, position, altitude, course of your ship
;Sim:
#simulation time (in seconds), as seen in the [[general information display]]
#a common abbreviation for "simulator"
;Sh-ToR:ship [[time-on-reference]], as seen on the [[synchronise orbit MFD]]
;SI unit: The metric system of measurement, the modern name, see [[SI unit]]
;SL+ and SL-: '''S'''e'''l'''ect, change which receiver to next or previous receiver to adjust frequency, used in [[COMNAV MFD]]
;SLF:shuttle landing facility, see [[Cape Canaveral]]
;SMa: [[semi-major axis]], used in [[Orbit MFD]]
;SMi:[[semi-minor axis]], used in [[Orbit MFD]]
;SRB:'''S'''olid '''R'''ocket '''B'''ooster [http://en.wikipedia.org/wiki/Solid_rocket_booster]
;SRTM:'''S'''huttle '''r'''adar '''t'''opography '''m'''ission, see [[SRTM]].
;SSME:Space Shuttle Main Engines [http://en.wikipedia.org/wiki/SSME_%28rocket_engine%29]
;SSTO:[[Single_Stage_To_Orbit | Single Stage to Orbit]]
;STOVL:Short take-off, vertical landing. As performed by the DG on full fuel employing hover thrusters during takeoff.
;STP:static [[pressure]], given in Pa
#Displayed in [[Surface MFD]] to indicate atmospheric pressure
;STS:'''s'''pace '''t'''ransportation '''s'''ystem, AKA space shuttle, see [[space transportation system]]
;SUS: command button in [[RCS attitude MFD]] to suspend programmed attitude temporarily

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=T=

;T:orbit period, measured in seconds, displayed in [[Orbit MFD]]
;TAEM:Terminal Area Energy Management
;TAS:true air speed [[w:True airspeed|True airspeed]]
#Command button in [[Surface MFD]] to set the speed tape to TAS
;TEI:'''T'''rans '''E'''arth '''I'''njection[http://en.wikipedia.org/wiki/Trans_Earth_Injection] 
;TGT:'''T'''ar'''G'''e'''T''' 
#command button used in [[Align MFD]], [[Docking MFD]], [[Map MFD]], [[Orbit MFD]], and [[Sync MFD]] to select a target
#used in the [[Map MFD]] display to indicate target name, position, altitude of the target
;Tg-ToR:target [[time-on-reference]], as seen on the [[synchronise orbit MFD]]
;TKS:russian spacecraft for the Almaz program, see [[TKS]]
;TLA:Three letter acronym for a '''t'''hree '''l'''etter '''a'''cronym.
;TLE:two-line elements 
;TLe:eject longitude, as seen on the [[transfer MFD]]
;TLi:intercept longitude, as seen on the [[transfer MFD]]
;TLI:Trans Lunar Injection
;Tn:'''T'''ime to '''n'''ode, used in [[Align MFD]]
;TOFS:tangential offset [[docking MFD]]
;ToR: time on reference axis, displayed in [[Sync MFD]] to indicate number of seconds until ship or target passes the intersection point
;TrA:[[true anomaly]], displayed in [[Orbit MFD]]
;TRK:Track, used in [[map MFD]] to keep the ship centered in the map display
;TrL:[[true longitude]], displayed in [[Orbit MFD]]
;TRL:'''t'''echnology '''r'''eadiness '''l'''evel
;Ts:length of siderial day
;TthA: Estimated thrust time at the ascending node to align planes, used in [[Align MFD]]
;TthD: Estimated thrust time at the descending node to align planes, used in [[Align MFD]]
;TVEL:tangential [[velocity]]

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=U=
;UMMU:'''U'''niversal '''m'''anned '''m'''aneuvering '''u'''nit, popular add-on, see [[Universal MMU]].
;UNKS:unknown problems, you are aware of.
;UNK-UNKS:unknown problems, you are not aware of.
;UP: 
#'''UP''', used in [[Map MFD]] when Track mode is off and map is zoomed in to scroll the map up to see farther North
#Command button in [[RCS attitude MFD]] to change the selected modification up so you can edit it
;UT:'''u'''niversal '''t'''ime, GMT. Not to be confused with [[UTC]] (Universial Time Co-ordinated). The latter is based on atomic clocks not astronomy, hence the occasional ''leap-second'' to correct UTC to GMT.

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=V=
;+V and -V: Used in [[RCS attitude MFD]] to add or subtract one degree each click the programmed attitude mode
;VACC: Vertical acceleration, used in [[Surface MFD]] how fast rate of ascent or descent is increasing or decreasing in m/s<sup>2</sup>
;VASI:'''V'''isual '''A'''pproach '''S'''lope '''I'''ndicator, the glideslope lighting system ajacent to runways to guide pilots onto the correct angle of glideslope (normally 3 degrees).
;VC:
#virtual cockpit
#Visual C++, an IDE and C++ compiler by Microsoft. 
;Vel:[[velocity]], displayed in [[Orbit MFD]]
;VOR:
#[[very high frequency omnidirectional radio]]
# used in the [[Horizontal Situation Indicator MFD]] to indicate which VOR transmitter is selected by a NAV radio, if it's selected to a VOR transmitter
;VRR: '''V'''elocity '''R'''adial '''R'''ange, used to manually set the range in the Radial Velocity graph in [[Ascent profile MFD]]
;VS:vertical speed
#Used in [[Surface MFD]] to indicate rate of ascent or descent in meters per second
;VSA: [[Virtual Space Agency]]
;VSI: Vertical Speed Indicator, used in [[Surface MFD]], the VS tape reading rate of ascent or descent, in m/s
;VTOL:'''V'''ertical '''T'''ake '''O'''ff and '''L'''anding
;VTR: '''V'''elocity '''T'''angential '''R'''ange, used to manually set the range in the Tangential Velocity Range graph in [[Ascent profile MFD]]

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=W=
;WBS:'''w'''ork '''b'''reakdown '''s'''tructure
;WPD:'''w'''ork '''p'''ackage '''d'''escription
;Wrp:time acceleration factor, seen in the [[general information display]]
=X=
;XPDR:[[transponder]], used in [[Docking MFD]]
=Y=
;YSC:Yokohama Science Center
=Z=
;ZM+ and ZM-: zoom,used in [[Map MFD]] to zoom the map display in and out

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