I worked at NASA (AMES) on a project to put small mobile robots on the moon. Our biggest goal was to create a tele-operated mode where from earth we could actively roam around the moon. The hardest part was that factoring in a 4 second delay from our commands to the network stacks to the rover on the moon, and then that video from the moon back to our computers and then creating good judgement. A 4 second delay seems insignificant but is in fact detrimental to intuitive controlling.