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Author Topic: How do the lunar rovers gain sufficient traction?  (Read 4603 times)

Offline L_D

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I am wondering how the Lunar Rovers got enough traction to operated on the moons loose surface with only 1/6th the gravity of Earth.

A Lunar Rover with 2 astronauts weighs approximately 700kgs here on Earth so on the Moon it will only weigh approx 120kgs, but it will still have a 700kg mass.

On the moons loose surface with only 30-odd kgs of weight on each tyre, and a 700kg mass to move, it would seem that traction should be a huge problem and yet the rovers operated as well as anyone would expect them to here on Earth.


In the above video some have commented that it looks like it could have been shot on Earth and then just slowed down, the rovers seem to have no more problems than would be expected on Earth WRT getting bogged, or stopping, or steering (even though steering on the Moon requires that a moving 700kg mass have it's direction changed by 2 wheels operating on a loose surface with only 30kgs of downward force on each).

It's very hard to imagine a 4WD here on Earth getting enough traction to go anywhere on a sandy/grainy surface if 80+ percent of it's weight were suspended, I think I need an off road version of the skidcar to test this:


Any thoughts?

[MOD EDIT - PLEASE ENSURE THAT YOU PHRASE YOUR THREAD TITLES AS QUESTIONS. CHRIS]

 
« Last Edit: 27/08/2009 10:53:31 by chris »


 

lyner

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How do the lunar rovers gain sufficient traction?
« Reply #1 on: 27/08/2009 11:12:21 »
I think they got away with it because they never needed to get up steep slopes * and were going very slowly, so cornering would not have been a problem. The torque was very low so wheel spin would not have happened, either.
I imagine that the terrain would be more uniform than on Earth - without wind, there would not be the  dunes or dust bowls which you find on Earth.  Absence of atmospheric  erosion might mean that you would expect less dust, in any case. Though the Earth's atmosphere eliminates spaceborne dust from getting down here. Which effect would dominate, I wonder?

*But there would have been less weight to lift up a slope or over a boulder so I think the effect of reduced weight would tend to cancel out. The skidcar test is not quite a fair one. They didn't exactly use racing slicks, did they?
 

Offline Chemistry4me

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How do the lunar rovers gain sufficient traction?
« Reply #2 on: 27/08/2009 11:25:54 »
I am wondering how the Lunar Rovers got enough traction to operated on the moons loose surface with only 1/6th the gravity of Earth.
Ha! The simple answer would be: They never landed on the moon!!
 

Offline DrChemistry

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How do the lunar rovers gain sufficient traction?
« Reply #3 on: 27/08/2009 11:29:40 »
I am wondering how the Lunar Rovers got enough traction to operated on the moons loose surface with only 1/6th the gravity of Earth.
Ha! The simple answer would be: They never landed on the moon!!

Conspiracy! Biggest cover-up in history.
 

lyner

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How do the lunar rovers gain sufficient traction?
« Reply #4 on: 27/08/2009 13:48:54 »
It won't be long before you will see pictures from the orbiter. It will show tracks and all. SO SHADDUPAYAFACE! (With respect, that is)
 

Offline DrChemistry

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How do the lunar rovers gain sufficient traction?
« Reply #5 on: 27/08/2009 17:02:18 »
If the respectful remark was for me, it was pointless. :) While some think it was a conspiracy, I am very certain that we did land on the moon.  Shadows in multiple directions and a waving flag is not evidence that we never landed on the moon.
 

Offline JimBob

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How do the lunar rovers gain sufficient traction?
« Reply #6 on: 27/08/2009 18:23:29 »
And the shaddows are easily explained by a single light source. The optics of the wide angle lens used, the distances separating the objects and their geometry are all factored to make it appear that there is a multiple light source. All shadows can be explained using a single light source when the lens optics are  factored in.

I have looked at moon rock. I have seen these rocks in thin-section in Professor Muehlberger's  lab. (His full name is William Rudolph Muehlberger if you want to look up him and his vast body of work. See also http://www.jsc.nasa.gov/history/oral_histories/MuehlbergerWR/WRM_BIO.pdf - See NASA INVOLVEMENT) These are so distinctive, with characteristics unseen on earth, that I have no doubt that they are from the Moon. Trying to produce the huge amount of these in existence by artificial means is simply impossible. Just the budget to build enough furnaces capable of making the amount of rocks artificially would cost more than was spent on the whole Apollo program.


As to the subject of this thread. If you listen to the astronaut's transmission form the moon,it is obvious that most, if not all, of the concerns discussed by the first poster are discussed by the astronauts in the clip - if you have it with audio - see this link

http://video.google.com/videoplay?docid=1502962445208997168   (The audio only is edited for television broadcast, eliminating the 8 second gap between earth and the moon.)

I have known Bill since I was 19 years old - back in the dark ages. I was a student when Bill was training the Apollo astronauts to do geologic sampling during their moon landings. He remains one of the most brilliant people I know and, MOST importantly, one of the most principled person I have ever met. He would never have participated in a hoax.

Two of the most telling remarks made in the audio of the first ever moon rover mission, The Google video clip above, are "Is he on the ground at all?" and "when he turns, the back end breaks loose just like on snow."

It wasn't easy driving on the moon.
« Last Edit: 28/08/2009 02:37:32 by JimBob »
 

lyner

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How do the lunar rovers gain sufficient traction?
« Reply #7 on: 27/08/2009 18:40:22 »
Did you notice this thread got started by cunning and stealth. It was an innocent and reasonable question and we just all took off on it.

But I do wish people wouldn't talk of "Kg of force"!!!!!
 

lyner

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How do the lunar rovers gain sufficient traction?
« Reply #8 on: 27/08/2009 20:11:49 »
Quote
I have known Bill since I was 19 years old - back in the dark ages. I was a student when Bill was training the Apollo astronauts to do geologic sampling during their moon landings. He remains one of the most brilliant people I know and, MOST importantly, one of the most principled person I have ever met. He would never have participated in a hoax.
And there were hundreds just like him, involved.
Imagine you're on your death bed and had been involved in a scandal like that. You'd spill the beans, just to get your own back. Well, wouldn't you?

None of the conspiracy theorists ever quote a death bed confession. I wonder why.
 

Offline L_D

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How do the lunar rovers gain sufficient traction?
« Reply #9 on: 30/08/2009 04:16:45 »

As to the subject of this thread. If you listen to the astronaut's transmission form the moon,it is obvious that most, if not all, of the concerns discussed by the first poster are discussed by the astronauts in the clip - if you have it with audio - see this link

http://video.google.com/videoplay?docid=1502962445208997168 [nofollow]   (The audio only is edited for television broadcast, eliminating the 8 second gap between earth and the moon.)..

..Two of the most telling remarks made in the audio of the first ever moon rover mission, The Google video clip above, are "Is he on the ground at all?" and "when he turns, the back end breaks loose just like on snow."

It wasn't easy driving on the moon.


The link above doesn't work for me, it is the first trouble that I've heard of them having controlling the Rovers, normally when you look at the tracks or watch vid's of the Rovers there is no signs of less control than would be expected on Earth (on a simailarly loose surface).

This NASA report says that they performed well and that the major difference was just a twofold increase in braking distance and less reponsive steering at 8-10kph..

Quote
What was different between training and actual EVA?
The Earth trainer had rubber tires and could support its own weight in 1 g. The flight article would have collapsed in 1 g if the crew sat on it. Since the handling characteristics of the LRV could not be fully tested on Earth, a "grand prix" test was performed by the CDR on A-15 & 16. The trainer provided adequate simulation, the major difference was the necessity to pay constant attention to the lunar terrain in order to have adequate warning of obstacles, especially in adverse lighting situations. Braking required ~2 x the 1 g distance. Steering was not as responsive between 8 - 10 kph with hard-over inputs.

http://ares.jsc.nasa.gov/HumanExplore/Exploration/EXLibrary/docs/ApolloCat/Part1/LRV.htm [nofollow]



If they had roads on the moon it would be very easy to test on Earth what driving in 1/6g would be like, the skidcar set-up taking just over 80% of the vehicles weight would be pretty accurate ..

All the testing I've seen for Lunar Rovers (past and future) just involves driving in the desert in 1g without any skidcar-type testing to simulate traction expected under 1/6g, this would seem to be a major oversight.
 
 

lyner

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How do the lunar rovers gain sufficient traction?
« Reply #10 on: 30/08/2009 11:59:04 »
If I remember right, the treads on the tyres were very deep. What were the speeds involved?

I'm still not sure whether this thread is trying to explain something or just to prove they couldn't have done it.
 

Offline pacman77

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How do the lunar rovers gain sufficient traction?
« Reply #11 on: 17/11/2009 21:48:43 »
if going over hills or bumps they could put spikes on the tyres like a cars ice tyre but longer they would act like fingers so no wheel spin and work best at low speed a spoon shaped tip would negate gravity as the digging effect would create artificial gravity.
 

Offline doppler1

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How do the lunar rovers gain sufficient traction?
« Reply #12 on: 13/01/2010 07:56:38 »
 :D, this is an interesting and hotly debated topic it seems. I have a question which may seem silly but when watching the real time videos of the moon buggy in action, why does the dirt sent up behind the buggy by the rotation of the wheels return to the surface so quickly, I would have thought that the dust particles should remain airborne for a longer time frame???? or am I missing something her as well? I am not a conspiracy theorist at all but found this interesting.
 

Offline Bored chemist

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How do the lunar rovers gain sufficient traction?
« Reply #13 on: 13/01/2010 10:25:04 »
:D, this is an interesting and hotly debated topic it seems. I have a question which may seem silly but when watching the real time videos of the moon buggy in action, why does the dirt sent up behind the buggy by the rotation of the wheels return to the surface so quickly, I would have thought that the dust particles should remain airborne for a longer time frame???? or am I missing something her as well? I am not a conspiracy theorist at all but found this interesting.
Airborne? there's no air there.
 

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How do the lunar rovers gain sufficient traction?
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