The Reaction Control System, commonly called RCS, is a method to control your spacecraft. It is used for pointing a direction, doing a rendezvous or even propelling in space / low gravity situation.
How it worksEdit
By pressing R on your keyboard you can activate your RCS. Like in real spacecrafts a jet of nitrogen or other gasses (monopropellent) is propelled out of some nozzles (usually placed at a 90° degree angle on the mass centre) to control the spacecraft. Obviously you need a monopropellent tank to make it work.
Other uses Edit
-RCS is used also by Kerbals in EVA activities.
-You can turn eccessive monopropellent into fuel with your Convert-O-Tron