Glossary — F
16 terms
Fuel
The propellant component that reacts with the oxidizer, providing chemical energy.
Example: RP-1 is a refined kerosene fuel used in many first stages.
Flyby
A mission that passes near a body to observe it without entering orbit.
Example: The probe made a close flyby of the comet's nucleus.
Fairing
The protective nose shell enclosing the payload during ascent.
Example: The fairing jettisoned after the rocket left the atmosphere.
First stage
The lowest stage firing from liftoff through the early ascent.
Example: The first stage's nine engines ignited simultaneously.
Feedback control
Control that uses measured output to correct errors.
Example: Feedback control held the vehicle on course despite winds.
Full-flow staged combustion
A cycle where both fuel-rich and oxidizer-rich preburners drive separate turbopumps.
Example: Raptor is a full-flow staged combustion engine using methane.
Film cooling
Injecting a cool fluid layer along the wall to shield it from hot gas.
Example: Film cooling adds a protective boundary layer in high-heat regions.
Formation flying
Several spacecraft flying in a coordinated configuration.
Example: The satellites flew in close formation for interferometry.
Flight termination system
A system that destructs or shuts down an errant vehicle to protect the public.
Example: The flight termination system is armed before liftoff.
FDIR
Fault Detection, Isolation, and Recovery: systems that detect, isolate, and respond to failures.
Example: FDIR re-routed a failed sensor to a backup.
Frozen orbit
An orbit chosen so eccentricity and argument of perigee stay stable despite perturbations.
Example: Lunar mapping missions use frozen orbits to keep a steady altitude.
Flight azimuth
The compass direction of the launch trajectory.
Example: The flight azimuth targeted the desired orbital inclination.
Flagship mission
A large, high-cost, high-priority science mission.
Example: The flagship mission carried multiple instruments to the outer solar system.
Full thrust
The operating state producing maximum rated thrust.
Example: Engines ramped to full thrust before clamp release.
Fuel-rich
A combustion mixture with more fuel than oxidizer, used for cooling or performance.
Example: A slightly fuel-rich mixture keeps chamber temperatures within limits.
Flight profile
The planned sequence of phases, attitudes, and events along a flight.
Example: The flight profile included a coast phase before the final burn.