Aerobrakes

Part of speech: noun

Definitions

1. A mechanism used in spacecraft to slow down by using atmospheric drag during re-entry
2. A device that generates aerodynamic resistance as a vehicle descends through an atmosphere to reduce speed
3. An engineering feature that allows vehicles to decelerate efficiently by converting speed into heat through air contact

Etymology: "Aerobrakes" is the plural of "aerobrake", a compound of the combining form "aero-", from Greek "aēr" meaning air, and "brake", a device for slowing or stopping motion. Together they name a structure that slows a craft by pushing against the air as it falls through an atmosphere, rather than by firing rockets. The noun was formed by back-formation from "aerobraking", the practice of using atmospheric drag to shed speed. In other words, speakers first coined the process name, then extracted the device name from it by dropping the "-ing" ending. The method is most associated with spacecraft that dip into a planet's upper air to lose velocity before settling into orbit, saving the fuel that a braking burn would require.