Testing
They didn't test reverse before sending to Mars?
Putting a nuclear-powered, laser-armed space tank on Mars is one of humanity’s most remarkable achievements, and now we've even figured out how to make it go backwards! Curiosity, the space tank in question, last week shifted into “R” and travelled just over 100 metres in a single day. That's the longest distance the rover has …
Maybe there's a loose part rubbing on the wheel that flaps against the wheel when going forward, but rides on top in reverse. I've seen that happen in auto accidents, where the fender is pushed in just the right way and only one direction works without grinding the crap out of the tire.
I don't understand why the wheels would sustain less damage when moving in reverse. Can anyone suggest reasons?
The rover's wheels are heavily ribbed, presumably to improve the level of grip. You see from the tracks it leaves behind that those ribs do cut into the surface. It's possible that they have an asymmetric profile - e.g. more sawtoothed shaped than straight up and down, to cut into the surface and provide a positive key. On the other hand if that level of grip isn't needed (or you can switch direction again if you get stuck) running the "saw" backwards may well allow smoother operation and avoid relentlessly cutting into the surface when it isn't needed.
No actual evidence to support that hypothesis but it seems eminently plausible.
They're not only ribbed, but they appear to be unidirectional: http://cdn1.sbnation.com/entry_photo_images/5008228/rover_13_large_verge_medium_landscape.jpg
and
http://graphics8.nytimes.com/newsgraphics/2013/06/26/curiosity/assets/411-177-leftwheel-after.jpg
The ribbing doesn't go all the way around: http://upload.wikimedia.org/wikipedia/commons/9/9d/PIA16134-Mars_Curiosity_Rover_Wheels.jpg
So perhaps it's a wear thing.
http://graphics8.nytimes.com/newsgraphics/2013/06/26/curiosity/assets/411-177-leftwheel-after.jpg
Questions that come to mind when I look at that picture.
Why didn't they route that cable bundle through the (presumably) hollow leg? It could be damaged by stones kicking up or by a stone trapped in the wheel.
The thickness of the wheel metal is not enough to avoid tears and punctures. I wonder if they knew this would happen or not. Did it happen because of unforeseen conditions or did they not test it on Earth sufficiently or some other reason.
No criticisms should be implied. I'm just curious.
Why didn't they route that cable bundle through the (presumably) hollow leg? It could be damaged by stones kicking up or by a stone trapped in the wheel.
To make it possible to hotwire it. If astronauts finally get there after 2+ years in a rocket it would be damn embarrassing to have forgotten the key. Just theorising...
Why would Mars rover tyres need to be inflatable? We have run flat and durable hard rubber tyres on earth.
It's also common practice to remove air from inflatable tyres when venturing off road.
Curiosity has only travelled 3.5 miles and it's tyres have gaping holes and gashes.
Presumably NASA would just need to develop a suitable material to withstand extreme cold.
Is there a vehicle on earth that operates on rough terrain with Aluminium wheels?