They probably sandbagged their lifespan by a factor of 2-3 (6-9 months design lifespan), but I doubt anyone expected them to last for 6+ years. Engineers don't often try to exceed design goals by more than a factor of 10, because that typically requires a completely different design.
Mechanical windshield wipers would probably get clogged and jammed by dust, for instance. I'm from New England; I usually had to manually clean the snow/salt/mud/ice off my windshield wipers every couple days or so during the winter. There's nobody who can step outside the Mars Rovers and run their fingers along the wiper blades.
Mechanical windshield wipers would probably get clogged and jammed by dust, for instance. I'm from New England; I usually had to manually clean the snow/salt/mud/ice off my windshield wipers every couple days or so during the winter. There's nobody who can step outside the Mars Rovers and run their fingers along the wiper blades.