Essential Space Launch Definitions

Apogee
The point in orbit where a body is farthest from Earth

Bi-propellant
A rocket propellant consisting of two unmixed or uncombined chemicals (fuel and oxidizer) fed separately into the combustion chamber

Cryogenic
A rocket fuel or oxidizer which is liquid only at very low temperatures, e.g. liquid hydrogen which has a boiling point of -217.2oC (-423oF)

DARPA
Defense Advanced Research Projects Agency

DOD
Department of Defense

Earth
Third planet from the Sun, a terrestrial planet.

ERV
Expendable Rocket Vehicle

Geostationary Orbit
A circular orbit in which a satellite moves from west to east at such velocity as to remain fixed above a particular point on the equator. Also called geosynchronous.

H2O2
Hydrogen Peroxide

Hohmann transfer orbit
A fuel efficient way to transfer from one circular orbit to another circular orbit that is in the same plane (same inclination), but a different altitude

LEO
Low Earth Orbit

Mach
The ratio of the speed of a vehicle (or of a liquid or gas) to the local speed of sound

MPV
MIPCC Powered Vehicle

MIPCC
Mass Injector Pre-Compressor Cooling

Microgravity
An environment of very weak gravitational forces, such as those within an orbiting spacecraft. Microgravity conditions in space stations may allow experiments or manufacturing processes that are not possible on Earth

Mono-propellant
A rocket propellant consisting of a single substance, especially a liquid containing both fuel and oxidizer, either combined or mixed together

Orbit
The path of an object that is moving around a second object or point

Nautical Mile
The distance spanned by one minute of arc in latitude, defined internationally as 1,852 meters (6,076.1033 feet)

Orbital Velocity
The velocity necessary to overcome the gravitational attraction of the Earth and so keep a satellite in orbit, about 17,450 mph (28,080 km/hr) close to the Earth

Oxidizer
An agent that releases oxygen for combination with another substance, creating combustion and gas for propulsion. Alternatively oxidants

Payload
Revenue-producing or useful cargo carried by a spacecraft; also, anything carried in a rocket or spacecraft that is not part of the structure, propellant, or guidance systems

Perigee
The point in a terrestrial orbit which is nearest to the Earth

RASCAL
Responsive Access Small Cargo Affordable Launch

Sun Sychronous Orbit
A walking orbit whose orbital plan precesses with the same period as the planet's solar orbital period. In such an orbit, a satellite crosses periapsis at about the same local time every orbit

Troposphere
The lower regions of a planetary atmosphere where convection keeps the gas mixed and maintains a steady increase of temperature with depth. Most clouds are in the troposphere