Lights
I'm pretty sure the
Mars Exploration Rovers 
don't have or require lights. I've added them just in case I do some testing at night or into the short winter evenings. On the front of the chassis are two MR16 12V 20W halogen lamps because that was what I had handy. 40W at 12V represents quite a large current drain so at some later time, these will be swapped over to LED equivalents. They can be switched on and off via the
I/O board and are powered by the associated relay board.