The total mass of the propellant or reaction material that a spacecraft or rocket accelerates and expels to produce thrust. In chemical rockets, this is the combusted fuel and oxidizer. In electric propulsion like ion engines, it is the ionized gas. The efficiency of a propulsion system depends heavily on how fast it can eject this mass.
Heard on the job
The mission profile leaves us with very little working mass for orbital corrections once we reach Mars.
Also heard as
- reaction mass
- propellant mass