In 2004, NASA landed two rovers on Mars, Spirit and Opportunity. Both far surpassed expectations, operating much longer than their planned design lifetime of 6 months.
Spirit was ultimately lost in 2010, but Opportunity, having spent the last five months in hibernation during the Martian winter, is now driving again. It is amazing that this machine is still functioning. Imagine leaving a solar powered remote control toy in the sandy desert somewhere. How long would it survive and remain drivable?