A structure whose main function is to streamline and smooth the surface of an aircraft or space vehicle.

A crack or break in the crust of a planet along which slippage or movement can take place.

Algorithms, which reside in a spacecraft's subsystems, that insure the ability of the spacecraft to both prevent a mishap and to reestablish contact with Earth if a mishap occurs and contact is interrupted.

Satellite using electromagnetic surveillance techniques.

The release of energy through splitting atoms.

The phenomenon of emitting light upon absorbing radiation of an invisible wavelength.

The amount of radiation crossing a surface per unit of time, often expressed in "integral form" as particles per unit area per unit time.

Space flight past a heavenly body without orbiting.

A spacecraft which follows a continuous trajectory past a target object, never to be captured into an orbit. It must carry instruments that are capable of observing passing targets by compensating for the target's apparent motion.

Fractional Orbit Bombardment System. A Soviet method of delivering a warhead from partial satellite orbit and thus approaching from any direction.

A vector quantity that tends to produce an acceleration of a body in the direction of its application.

Reflecting light approximately away from the source.

Field Of View.

The motion of any unpowered body moving in a gravitational field.

Path of a spacecraft that provides for a return to Earth.

The number of oscillations per second of an electromagnetic (or other) wave.

A substance that when combined with an oxidizer burns to produce thrust in rockets.

A cell in which chemical reaction is used directly to produce electricity.

The release of nuclear energy through the uniting of atoms.

Fiscal Year.