Page 93 - Apollo Moonships

91
MISSION PROFILE
Flight plan that shows all scheduled events and phases of a mission.
NAUTICAL MILE
Unit of distance that is approximately one minute of arc measured along any meridian. By international agreement it has been set at 1852 metres exactly (about 6 076 feet).
NEAR SIDE OF THE MOON
Lunar hemisphere that is permanently turned towards the Earth, whereas the opposite side is the far side of the Moon.
NITROGEN TETROXIDE
Powerful oxidizer that is hypergolic (spontaneously reacts) upon contact with various forms of hydrazine, which makes the pair a popular bipropellant for rockets.
OMNIDIRECTIONAL ANTENNA
In radio communication, an omni antenna or omnidirectional antenna is a class of antenna which radiates radio wave power uniformly in all directions in one plane, with the radiated power decreasing with elevation angle above or below the plane, dropping to zero on the antenna’s axis. This radiation pattern is often described as “doughnut shaped”.
ORBIT
Gravitationally curved path of an object around a point in space (for example the orbit of a planet around a star such as the Sun).
OXIDIZER
Element or compound in an oxidation-reduction (redox) reaction that accepts an electron from another species. Substance that supplies the chemical reactant necessary for burning (the most common oxidizer on Earth is the free oxygen in the atmosphere).
PARKING ORBIT
Temporary orbit used during the launch of an spacecraft, satellite or space probe. A launch vehicle boosts into the parking orbit, then coasts for a while, then fires again to enter the final desired trajectory.
PITCH AXIS
Lateral axis running from the pilot’s left to right in piloted aircraft or spaceship, and parallel to the wings of a winged aircraft. Normally was represented by the letter Y.
PROPELLANT
Chemical used in the production of energy
or pressurized gas that is subsequently used
to create movement of a fluid or to generate propulsion of a vehicle, projectile, rocket, missile or other object. Common propellants are energetic materials and consist of a fuel like gasoline, jet fuel, rocket fuel, and an oxidizer.
In rockets and aircraft, propellants are used to produce a gas that can be directed through a nozzle, thereby producing thrust. In rockets, rocket propellant produces an exhaust, and the exhausted material is usually expelled under pressure through a nozzle.
RADIATOR
Heat exchanger used to transfer thermal energy from one medium to another for the purpose of cooling and heating.
REACTION ENGINE
Engine that derives thrust by expelling of stream o moving particles to the rear.
REDUNDANCY
In engineering, redundancy is the duplication
of critical components or functions of a system with the intention of increasing reliability of the system, usually in the form of a backup or fail- safe. In many safety-critical systems, such as fly- by-wire and hydraulic systems in aircraft, some parts of the control system may be triplicated, which is formally termed triple modular redundancy (TMR).
REENTRY
See atmospheric reentry.
RENDEZVOUS
See space rendezvous.
RETROROCKET
Rocket engine that provide thrust in opposite direction to the motion of a vehicle, thereby causing it to decelerate.
ROLL AXIS
Axis drawn through the body of the vehicle from tail to nose in the normal direction of flight, or the direction the pilot faces. This axis also is known as Longitudinal axis.
RP–1 (REFINED PETROLEUM–1)
Highly refined form of kerosene outwardly similar to jet fuel, used as rocket fuel. Refined petroleum is most commonly burned with LOX (liquid oxygen) as the oxidizer.
S–BAND
Part of the microwave band of the electromagnetic spectrum. It is defined by an standard for radio waves with frequencies that range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. The S band is used by weather radar, surface ship radar, and some satellites and spacecrafts, especially used by NASA.
SPACE RENDEZVOUS
Orbital maneuver during which two spacecraft, one of which is often a space station, arrive at the same orbit and approach to a very close distance (e.g. within visual contact). Rendezvous requires a precise match of the orbital velocities of the two spacecraft, allowing them to remain
at a constant distance through orbital station- keeping. Rendezvous may or may not be followed by docking or berthing, procedures which bring the spacecraft into physical contact and create a link between them.
SERVICE MODULE
Spacecraft compartment containing a variety of support systems used for spacecraft operations. Usually located in the uninhabited area of
the spacecraft, the Service Module (SM) was jettisoned upon the completion of the mission, and usually burns up during atmospheric reentry. The Service Module (SM) of the Apollo mother ships was an unpressurized cylindrical structure, measuring 24.17 (7.4 m) long and 12.83 feet (3.9 m) in diameter. The interior
was a simple structure metallic consisting of a central tunnel section about 44 inches (1.1 m) in diameter, surrounded by six pie-shaped sectors. The pie-shaped sectors were topped
by a forward bulkhead and fairing, separated
by six radial beams, covered on the outside
by four honeycomb panels, and supported by an aft bulkhead and engine heat shield. The sectors were not all equal 60° angles, but varied according to required size.
TELEMETRY
Highly automated communications process
by which measurements are made and other data collected at remote or inaccessible points, frequently in space, and transmitted to receiving equipment for monitoring.
THROTTLEABLE ENGINE
Engine equipped with a valve system that regulates the flow of propellant (fuel and oxidizer) into the combustion chamber to control and vary the rate of thrust produced.
THRUST
Reaction force described quantitatively by Newton’s second and third movement laws. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction on that system. The force applied on a surface in a direction perpendicular or normal to the surface is known as thrust.
THRUSTER
Propulsive device used by spacecraft and watercraft for station keeping, attitude control, in the reaction control system, or long-duration, low-thrust acceleration.
TRAJECTORY
Path that a moving object follows through space as a function of time.
UMBILICAL
Cable which supplies required consumables to an apparatus. It is named by analogy with an umbilical cord. An umbilical can for example supply air and power to a pressure suit or hydraulic power to a subsea equipment.
VHF–BAND
Very high frequency (VHF) is the designation for the range of radio frequency electromagnetic waves between 30 MHz and 300 MHz, with corresponding wavelengths of ten to one meters.
VELOCITY
Rate of change of the position of an object, equivalent to a specification of its speed and direction of motion. Velocity is a vector physical quantity; both magnitude and direction are required to define it. The scalar absolute value (magnitude) of velocity is called “speed”, a quantity that is measured in metres per second
ULLAGE
Also known as headspace, ullage is the unfilled space in a container, particularly with a liquid.
WATER–GLYCOL
Mixture of water and ethylene glycol used as refrigerant. In the Apollo spaceships cooled the cabin atmosphere the spacesuits, and critical components of many systems.
YAW AXIS
Axis drawn from top to bottom, and perpendicular to the other two rotational axes (pitch and roll).