DESTINATION MOON: A History of the Lunar Orbiter Program
 
 
APPENDIX A
 
GLOSSARY
 
 
 
[361] albedo
The ratio of the amount of electromagnetic radiation reflected by a body to the amount incident upon it. This concept is identical with reflectance but should be distinguished from spectral reflectance.
 
anomaly
In general, a deviation from the norm, an irregularity, a malfunction.
 
apolune
That point in a lunar&endash;centric orbit which is most distant from the Moon.
 
Bimat web
The continuous processing film used in the Lunar Orbiter photographic subsystem to process the camera film.
 
deboost
A velocity control engine burn to allow a spacecraft to decelerate and go into orbit around a planetary body, or to leave an orbit and descend to a landing on that body.
 
delta V
A change in velocity.
 
flux
The rate of flow of some quantity, often used in reference to the flow of some form of energy.
 
gimbal
A device with two mutually perpendicular and intersecting axes of rotation. It provides free angular movement in two directions and serves as an engine mount.
 
Greenwich Mean Time (GMT)
The local mean time at the Greenwich, England meridian. Some of the Lunar Orbiter post&endash;launch operations reports used the local time at the Kennedy Space Center, expressed either in Eastern Standard Time (EST, 5 hours behind GMT) or Eastern Daylight Time (EDT, 4 hours behind GMT), depending on the time of year when a launch took place.
 
ground resolution
The degree to which an optical or photographic system can reproduce fine detail of the surface being imaged, as measured against a photographic scale. It is the product of a combination of capabilities of the film (graininess, sensitivity, etc.) and the lens (type, resolving, power, etc.) and is usually expressed in line pairs per millimeter. Photographic scale is found by dividing the altitude at which the picture is taken by the focal length of the camera. For Lunar Orbiter, the [362] effective film resolution was 76 line pairs per millimeter, which gave 1-meter resolution through the 610 mm lens and 8-meter resolution through the 80 mm lens under predetermined contrast conditions on the lunar surface.
 
hypergolic
A term used to describe propellants that ignite spontaneously on contact with an oxidizer; a self-igniting fuel, propellant, or propulsion system.
 
launch window
The postulated opening in a continuum of time or space through which a spacecraft must be launched to achieve a desired encounter, rendezvous, or impact.
 
noise level
The level of any undesired disturbance within a useful frequency band.
 
nominal
Occurring or performing as intended in pre-mission planning.
 
oxidizer
A substance that combines with another to produce heat and, in a rocket, hot gases of combustion thrust.
 
parking orbit
A temporary orbit in which a vehicle coasts before transfer into final orbit or trajectory.
 
perilune
The point in a lunar-centric orbit which is closest to the Moon.
 
pitch
An angular movement (of a spacecraft) about an axis parallel to the lateral axis of the vehicle.
 
roll
The rotational or oscillatory movement of a spacecraft or similar body about a longitudinal axis through the spacecraft.
 
software
(Computer) programs and formulation of programs.
 
yaw
The rotational or oscillatory movement of a spacecraft or the like about a vertical axis.
 

Sources:
- Charles McLaughlin Space Age Dictionary (Princeton: D. Van Nostrand Co., 1959).
- William H. Allen, ed., Dictionary of Technical Terms for Aerospace Use, NASA SP-7 Washington., D.C.: GPO, 1965).
- J. L. Nayler, A Dictionary of Astronautics (New York: Hart Publishing Co., 1964 )
- Woodford A. Heflin, ed. The United States Air Force Dictionary (Air University Press, 1956).
 

 
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