SoylentNews is people
SoylentNews
from the forget-the-puncture-kit,-give-me-a-welding-torch dept.
Chainmail tires re-invent the wheel to get future NASA rovers rolling.
NASA has developed chainmail tires with a memory and thinks they'll do the trick for future rovers.
As readers of The Register's coverage of the Curiosity Rover may recall, the vehicle has experienced considerable wheel damage that has led to changes to its route in 2014 and a 2017 software update to preserve the wheels and provide better grip.
Throw in the fact that it's not yet possible to send a spare wheel to Mars and have it fitted, and NASA has a clear need for more robust tires.
Enter a technology called "spring tires" that use a tubular structure of steel mesh – think tire-shaped chainmail - to cushion rovers as they roll. Spring tires have many fine qualities as the mesh forms a pattern that provides good grip on many surfaces. Mesh is also light by nature and can survive some damage. But spring tires don't deform well: if one rolls over a sharp rock, it can acquire a dent - or "plastic deformation" as NASA boffins put it.
The tires use a nickel titanium alloy that can endure plastic deformation.
(Score: 2) by frojack on Saturday November 25 2017, @09:27PM (1 child)
Wheel damage has pretty much tapered off in the second half of the mission.
The guy who wrote the hand-wringing wail of the wheels has pretty much admitted he was mistaken. [soylentnews.org]
I'm also sure that if YOU yourself look at the wheels (with all your engineering credentials,) you will the damage shown is NOT from the things you seem to quote. Corrosion is almost nil at those temperatures. None of the wheel damage is occurring at the inside corners, and fatigue is not the source of these problems. (lots of recent pictures at the link posted above).
The photos show damage, but since they started driving sensibly, (around instead of over things) it has dramatically tapered off. Like a teenager with a new hot rod, the first set of tires go quickly. Then sticker shock makes the next set last 4 times as long.
No, you are mistaken. I've always had this sig.
(Score: 0) by Anonymous Coward on Sunday November 26 2017, @09:23AM
First of all, your link is broken.
The pictures that would be needed are microscopic, preferably scanning electron microscope pictures of properly treated surfaces. Those pictures don't exist.
Anyway, fatigue is obvious. Aluminum does not have a fatigue limit. This is a fatal flaw. Any repeated flexing, no matter how minor, will cause aluminum to fail. Titanium and spring steel have fatigue limits; flexing that is minor enough can be repeated forever without causing damage.
Regular corrosion isn't the issue. This isn't about wheels being simply eaten through. It's about crack propagation that is promoted by corrosion that is invisible to the human eye. The temperature may be low, but this isn't friendly garden soil. Perchlorates are nasty.
Mars has iron oxide and perchlorates to go with the rover's aluminum wheels. Can you remember where else NASA mixed those components? It was the fuel of the Space Shuttle's solid rocket boosters. The fuel was literally that, plus a rubbery binder holding it together. These chemicals are anything but peaceful when you put them together. Aluminum strongly takes oxygen and would spontaneously ignite in Earth atmosphere if not for the hard layer of aluminum oxide that forms on the surface. Chlorine tends to disrupt that layer; chlorine is found in the perchlorate ion. Without being silly (liquid mercury perhaps) it would be hard to come up with a worse chemical environment for aluminum wheels.