Relive Apollo 11 Twitter Feed

Here is a list of Apollo 11 key terms and abbreviations used in the @ReliveApollo11 twitter feed.

Abbreviations and Acronyms
Source: Apollo 11 Mission Operations Report, Pre-Launch Information

Apollo 11 Key Terms/Glossary

Acquisition of Signal (AOS) – During each lunar orbit, Mission Control in Houston loses radio contact with Apollo 11 as it passes around the far side of the Moon; AOS marks the time when this contact is regained.
Apogee – In an elliptical orbit of Earth, the point during orbit that is farthest from the center of the Earth
Apolune/Apocynthion – In an elliptical orbit of the Moon, the point during orbit that is farthest from the center of the Moon
Bingo fuel – A critically low level of fuel; a ‘Bingo’ fuel call means ‘land in 20 seconds or abort’.  5.6% fuel in the LM started a 94-second countdown to Bingo fuel.
Black Team – One of the four shifts of flight control teams at Mission Control during the Apollo 11 mission.  Led by Flight Director Glynn Lunney.
BTU – British Thermal Unit, a unit of energy equivalent to 1,060 Joules or 253 calories.
CAPCOM – Capsule Communicator.  This is the one position at Mission Control directly in contact with the astronauts in the spacecraft.  Charles Duke, Ron Evans, Owen Garriott, and Bruce McCandless primarily attend to CAPCOM duties, although other astronauts, including the entire Apollo 11 backup crew, rotated through the position.
CDR – Commander.  Neil Armstrong is the Commander for Apollo 11.
CMP – Command Module Pilot.  Michael Collins is the Command Module Pilot for Apollo 11.
CSM – Command-Service Module.  During most of the mission, the Command Module and Service Module remain docked; the combined spacecraft is referred to as the CSM.
Columbia – Call sign of the Command Module of Apollo 11
Command Module (CM) – One of three parts of the Apollo 11 spacecraft, used as spacecraft control center for the mission
Docking – A maneuver in which two spacecraft are physically joined together.
Drogue parachutes – Thin parachutes deployed during entry to gain control of the spacecraft at speeds that would destroy larger parachutes; used as precursors to main parachutes.
Eagle – Call sign of the Lunar Module of Apollo 11.
Equal potential point – The location between the Moon and the Earth where Apollo 11 will have the same velocity with respect to both objects.
Extra-Vehicular Activity (EVA) – Work done by an astronaut away from the Earth and outside of spacecraft.  On Apollo 11, astronauts performed an EVA on the surface of the Moon for the first time.
Feet per second (ft/s) – A unit of speed/velocity equivalent to 0.68 miles per hour.
Gimbal – A ring that can rotate about an axis.  For space travel, three gimbals (for three degrees of freedom) are needed to compensate for rotation in 3-dimensional space. http://history.nasa.gov/alsj/lm_imu.gif
Gimbal lock – When the axes of two gimbals are in the same direction, so changes about one direction are not compensated for.
Green Team - One of the four shifts of flight control teams at Mission Control during the Apollo 11 mission.  Led by Flight Director Cliff Charlesworth.
Ground Elapsed Time (GET) – Time measured since liftoff/start of mission.  From liftoff until splashdown, Apollo 11 took 8 days, 3 hours, 18 minutes 35 seconds; GET at splashdown was 195:18:35.
Hatch – A “door” providing a complete seal on the spacecraft; hatches on Apollo 11 include the CM main hatch, the LM hatch, and one on either end of the tunnel between the two.
LMP – Lunar Module Pilot.  Buzz Aldrin is the Lunar Module Pilot for Apollo 11.
Loss of Signal (LOS) – During each lunar orbit, Mission Control in Houston loses radio contact with Apollo 11 as it passes around the far side of the Moon; LOS marks the time when this contact is lost.
Lunar Equipment Conveyor (LEC) – A pulley-like system used to transfer equipment between the Lunar Module and the lunar surface.
http://history.nasa.gov/alsj/alsj-lec.html
Lunar Module (LM) - One of three parts of the Apollo 11 spacecraft, used only in lunar orbit and for landing on the Moon.  Has 2 components: descent stage (left on the Moon) and ascent stage (used to rendezvous with Command Module after landing).
Lunar Orbit Insertion (LOI) – A rocket burn that will move the Apollo 11 spacecraft into orbit around the Moon.
Maria – The “lunar seas” or dark regions; smooth plains with few craters on the Moon.
Maroon Team – One of the four shifts of flight control teams at Mission Control during the Apollo 11 mission.  Led by Flight Director Milt Windler.
Manned Space Flight Network (MSFN) – A group of tracking stations across the Earth’s surface used to maintain contact with the spacecraft.  A “Unified S Band” system allows the MSFN to use one transmitter for tracking, ranging, telemetry, and voice communications.
Midcourse correction – A series of rocket burns allowing Apollo 11 to maintain an appropriate flight path.
Modularized Equipment Stowage Assembly (MESA) – Part of the LM descent stage that contains equipment for use on the lunar surface, including geology equipment, storage containers, and film equipment.
Nautical Miles – A unit of length, used primarily in navigation, equivalent to 1,852 meters or 1.15 miles.
Nominal – According to plan.
Orbital parameters – The measures that identify a specific orbit.  Orbital parameters for Apollo 11, as given by the PAO, include two elements: Apolune and Perilune.
PAO – Public Affairs Office/Officer.  The PAO provides commentary on the NASA transmissions of communications between Apollo 11 astronauts and Mission Control staff.
Passive Seismometer Experiment (PSEP) – A piece of equipment, deployed and left on the Moon, designed to analyze lunar structure and detect moonquakes.
Passive Thermal Control (PTC) – A system used to keep the spacecraft within a certain temperature range, using coatings on the spacecraft or rotating the spacecraft to maintain even temperature.  This is in contrast to Active Thermal Control systems, like heaters or coolers.
Perigee – In an elliptical orbit of Earth, the point during orbit that is closest to the center of the Earth
Perilune/Pericynthion – In an elliptical orbit of the Moon, the point during orbit that is closest to the center of the Moon
Period – The time required to complete one full revolution or cycle.
Portable Life Support System (PLSS) – The ‘backpacks’ of the astronauts’ EVA suits.  A PLSS regulates suit pressure and temperature, provides breathable oxygen while filtering out carbon dioxide, and provides communications for the astronaut.
Rendezvous – A maneuver between two spacecraft where the two enter the same orbit, match velocities, and bring them together.  The first rendezvous between US spacecraft occurred during the Gemini 6A and 7 missions, although there was no physical contact between the spacecraft.
Revolutions per hour – A unit of angular velocity where an object rotates through 360 degrees in the span of an hour. 
Roll rate – Rate at which the spacecraft rotates about one axis.  Used in Passive Thermal Control mode and measured in revolutions per hour.
Saturn V – A 3-stage liquid fuel rocket used to launch the Apollo 11 spacecraft towards the Moon.
Service Module – One of three parts of the Apollo 11 spacecraft, housing the power and other components used by the spacecraft during the mission.  Not entered by the astronauts.
Sextant – An instrument of navigation that measures the altitude of a celestial object (e.g. a star) above the horizon.
Slide rule – A mathematical tool used for design calculations; a precursor to the modern calculator.
Solar corona – An “atmosphere” of the sun, usually seen during a total solar eclipse.
Solar wind experiment – A foil sheet exposed to the Sun, allowing solar-wind particles to embed themselves into the foil.  The Earth’s atmosphere prevents the charged solar particles from reaching the surface, but the particles can reach the surface of the Moon.
Sphere of influence – The area around an object where that object is the primary gravitational force on an orbiting body.  The Earth’s Sphere of Influence has a radius of 925,000 kilometers.
Stage – One component of a multi-stage rocket.  The Saturn V has 3 stages: S-IC, S-II, and S-IVB.
Staging – The maneuver during which a used rocket stage is jettisoned from the spacecraft.
Stationkeeping – Maneuvers designed to keep a spacecraft in a fixed orbit.
Telemetry – Technology that allows for remote measurement, transmitting, and receiving information.
Thrust – A mechanical force that moves a vehicle forward.  In spaceflight, the thrust must overcome the weight of a rocket.
Tranquility Base – Name given to the Apollo 11 landing site within the Sea of Tranquility (Mare Tranquilitatis).
Transearth Injection – A rocket burn that will move the Apollo 11 spacecraft out of lunar orbit and on a trajectory towards the Earth.
Translunar Injection – A rocket burn that will move the Apollo 11 spacecraft out of Earth orbit and on a trajectory towards the Moon.
Trajectory – The path that a moving object follows through space.
Velocity – The rate of change of position.  Often used interchangeably with “speed” by PAO, even though speed is just the magnitude of velocity, which also specifies direction.
White Team - One of the four shifts of flight control teams at Mission Control during the Apollo 11 mission.  Led by Flight Director Gene Kranz.

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