It’s extremely difficult to control a vehicle when there is a 15-24 minute delay between the time you that it needs a correction and when it receives that input.
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Because of the transmission delay between Earth and Mars, both the rover and helicopter are both semi-autonomous. Basically mission control gives them a plan, go from point A to B, and then the machine figures out how to achieve the objective using its onboard software. Once it completes its plan or mission, it relays its status back to mission control.
Yes I know. It’s basically a robot.