leJOS is a firmware replacement for Lego Mindstorms programmable bricks. Different variants of the software support the original Robotics Invention System, the NXT, and the EV3. It includes a Java virtual machine, which allows Lego Mindstorms robots to be programmed in the Java programming language. It also includes 'iCommand.jar' which allows you to communicate via bluetooth with the original firmware of the Mindstorm. It is often used for teaching Java to first-year computer science students. The leJOS-based robot Jitter flew around on the International Space Station in December 2001.