NASA stumped
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Titanium is considerably heavier than aluminum.
Ti = 4.54 g/cm3
Al = 2.702 g/cm3
The last estimate I heard was $1,000,000/pound to put something into space. Changing the wheels to Ti would add a bunch of extra weight to the rover and might put the launch craft over its maximum weight. Since they used solid wheels the craters in the surface doesn't really hurt their function.
EDIT: Something else to consider is Al has a memory of its original shape and will take a small hit deform some and bounce back undamaged whereas Ti will not do this. The problem is once Al takes too much of a pop it will crack as you can see in some of the larger dents in the wheels.
Ti = 4.54 g/cm3
Al = 2.702 g/cm3
The last estimate I heard was $1,000,000/pound to put something into space. Changing the wheels to Ti would add a bunch of extra weight to the rover and might put the launch craft over its maximum weight. Since they used solid wheels the craters in the surface doesn't really hurt their function.
EDIT: Something else to consider is Al has a memory of its original shape and will take a small hit deform some and bounce back undamaged whereas Ti will not do this. The problem is once Al takes too much of a pop it will crack as you can see in some of the larger dents in the wheels.
Yessum - I'm sure they researched the everluvin' Jeebus outta the available materials - wif Unobtanium being hoarded by the Borg 'n all. Er wuz it the Ferengi? Shoot - cain't 'member.
Lookin' at those wheels I cain't hep but think of the 2015's AL panels
How aboot bamboo then?
MGD
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Joined: Apr 2003
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From: Central NJ
A litle off topic but still NASA related;
Nasa spent an incredidle amount of money during the Apollo misions to develope a pen which would write in the zero gravity of space. When the Russians were asked why the did not do the same, they said "we use pencils"
Nasa spent an incredidle amount of money during the Apollo misions to develope a pen which would write in the zero gravity of space. When the Russians were asked why the did not do the same, they said "we use pencils"
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And it turned out that the excess graphite from the pencils shorted out some equipment
MGD
Rover finds Martian Love - together they Prank Mission Control
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I wonder why they didn't use a Lthium Alumium alloy?
Every 1% by weight of lithium added to aluminium reduces the density of the resulting alloy by 3% and increases the stiffness by 5%.
from <http://en.wikipedia.org/wiki/Al%E2%80%93Li>
Every 1% by weight of lithium added to aluminium reduces the density of the resulting alloy by 3% and increases the stiffness by 5%.
from <http://en.wikipedia.org/wiki/Al%E2%80%93Li>
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Now - I KNOW bamboo is elastic
Waitin' fer the other Joe to show up, lol ...
MGD
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From: Cabot, AR
But based on another site I would bet a lot of it has to do with this:
The principal disadvantages of peak-strength aluminum-lithium alloys are reduced ductility and fracture toughness in the short transverse direction, anisotropy of in-plane properties, the need for cold work to attain peak properties, and accelerated fatigue crack extension rates when cracks are micro structurally small.
All of these are bad for a wheel, especially when in it will be used with the heat extremes of Mars. The rover is obviously disposable since there isn't a plan to transport it back to earth for some retreads, so if the wheels are worn out when the mission is over it’s no big deal. If a wheel gets beat up and dented it will still roll. If it takes a hard hit and fractures then it won't roll and the mission is over. Ideally the wheel will be rather weak so that it can be beat on and still roll. The more heat treatment Al receives the more brittle it becomes. It's all a balancing act of getting the properties you need the most and giving up the ones you want but don't need.