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That CAN'T be true! / Were the Lunar Rovers faked?
« on: 06/03/2013 05:06:26 »
There are so any problems associated with the Lunar Rover that it would seem almost farcical to believe they could possibly be real.
The construction:
It is often said that if astronauts could not even sit on a Lunar Rover here on Earth because the Rovers were built of such lightweight construction that they "would have collapsed in 1 g if the crew sat on it." (1), and that the " The vehicle could support its own weight on earth, but no more" (2).
It would seem to defy basic physics to build a weak design because the astronauts on the moon are not just gently putting their weight onto the vehicles, they are also imparting their considerable momentum onto the vehicles and that momentum will be the same on earth as it is on the moon, the mass of the astronauts and their suits do not change. If we take as an example the method the astronauts supposedly used for getting onto the Rovers we can see that they jump up and onto the vehicles:
p=mv tells us that the momentum that the astronauts have, and therefore the forces they will impart, are the same on the Earth as they are on the Moon as long as they are traveling at the same speed. This means that if the astronauts, in the final stage of jumping onto the rover, fall from a height of 6 inches on the moon then the forces they impart onto the rover will be the same as if they fell from a height of 1 inch here on earth.
Once we understand that the forces of momentum are independent of weight then it is nonsensical to suggest you cannot even sit on a rover on earth, but you can jump on one on the moon. The astronauts and their suits have the same mass on earth as they do on the moon and it is very hard to imagine that jumping onto the rovers on the moon they would have less velocity than sitting on them here on earth.
Similarly, driving the rovers on an uneven terrain where the chassis is often forced to change directions vertically, the forces will be very similar, if not the same as here on Earth. Hitting a mound at 10kph will impart the same forces on the vehicle as hitting a mound at 10kph here on earth, the mass and velocity are the same. If you can't hoon around a crater filled terrain here on earth with the vehicles then you can't do it on the moon. If you can't sit on a rover on earth then you can't jump onto one on the moon.
Traction:
To take a 4WD onto a loose ungroomed surface here on Earth would not be counter-intuitive to most people, however, most people would balk at the idea of taking a 2wd vehicle onto a loose ungroomed terrain here on earth because, quite sensibly, it is unlikely a 2wd, with half the traction of a 4WD, would have enough traction. Well, on the Moon a 4WD does not have anywhere near half the traction of a 4WD on earth, it has only a piddly 1/6 the traction and that is true for steering, braking, and accelerating.
Fully loaded the rovers on the moon have a mass of approx 1,500lbs, yet they only have approx 250lbs of weight on the ground to try and accelerate, steer, and brake the 1500lb mass, and they are on a loose surface. The suggestion anyone can go 4WD driving on a loose surface in 1/6g is ludicrous.
I know defenders of the apollo missions will say that the lunar dust binds together so it is not loose, and will quote astronauts as saying they had big trouble controlling the rovers. The problem with both these excuses is that it is not what we see in the video and photographic footage, instead we see a surface that is very loose with dust being disturbed very easy by the astronauts moving around in it, and we see no control problems with the rovers either in driving or the photos of the tracks. It would appear as though they are merely paying homage to the physics while, at the same time, not bothering to fake any traction difficulties for TV.
Power:
The rovers would appear to be massively underpowered, they have 4 x 1/4hp motors giving a grand total of 1hp to drive a 1,500lb vehicle. One horsepower is low powered even for a mobility scooter, imagine putting seven big blokes on a low powered mobility scooter and seeing what performance you get out of it, yet on the moon they hooned around no problems at all.
Uphill there would be some benefits from being on the moon but driving on a flat surface on the moon you would get the same performance as on earth, simply because it is the same mass that has to be accelerated.
Balance:
The rovers are horribly unbalance vehicles, they weigh approximately 460lbs and the astronauts weigh approx 400lbs each fully suited (3), this means when one astronaut is driving there is approximately 3/4 of the weight on one side of the vehicle:
I doubt many of us would want to drive such an unbalanced vehicle over an uneven terrain here on earth, but on the moon where 1/6 g means it is much more likely to roll the suggestion becomes untenable. If the driver were to hit a rise on the unweighted side of the vehicle then the rover will rise 2, 3, or 4 times higher than it will hitting the same bump on earth (depending on the degree of the slope).
In conclusion:
We are supposed to believe they took a 4WD to the moon that was of such a lightweight design that they couldn't sit on it on earth, but they could jump on it on the moon?
They had no traction problems on a loose surface in 1/6g even though 1/6g equals a whooping 1/6th of the traction?
They had ample power driving a 1500lb mass with a 1hp vehicle?
They could hoon around with one astronaut on one side of the vehicle (approx 3/4 the weight on one side), on an uneven terrain hitting bumps in 1/6g, with no worries at all about rolling?
(1) http://ares.jsc.nasa.gov/HumanExplore/Exploration/EXLibrary/docs/ApolloCat/Part1/LRV.htm
(2) http://www.hq.nasa.gov/office/pao/History/SP-4204/ch23-3.html
(3) http://www.hq.nasa.gov/alsj/a17/A17_LunarRover2.pdf
The construction:
It is often said that if astronauts could not even sit on a Lunar Rover here on Earth because the Rovers were built of such lightweight construction that they "would have collapsed in 1 g if the crew sat on it." (1), and that the " The vehicle could support its own weight on earth, but no more" (2).
It would seem to defy basic physics to build a weak design because the astronauts on the moon are not just gently putting their weight onto the vehicles, they are also imparting their considerable momentum onto the vehicles and that momentum will be the same on earth as it is on the moon, the mass of the astronauts and their suits do not change. If we take as an example the method the astronauts supposedly used for getting onto the Rovers we can see that they jump up and onto the vehicles:
Quote
Getting to sit on the Rover seat in a stiff pressure suit from the lurain was not so easy. The astronauts found they had to stand facing forward, then with an upward and sideways kick, jump up with their legs and arms stretched out ahead to hopefully land in the middle of their seat.
http://www.honeysucklecreek.net/msfn_missions/Apollo_15_mission/hl_Apollo15.html
p=mv tells us that the momentum that the astronauts have, and therefore the forces they will impart, are the same on the Earth as they are on the Moon as long as they are traveling at the same speed. This means that if the astronauts, in the final stage of jumping onto the rover, fall from a height of 6 inches on the moon then the forces they impart onto the rover will be the same as if they fell from a height of 1 inch here on earth.
Once we understand that the forces of momentum are independent of weight then it is nonsensical to suggest you cannot even sit on a rover on earth, but you can jump on one on the moon. The astronauts and their suits have the same mass on earth as they do on the moon and it is very hard to imagine that jumping onto the rovers on the moon they would have less velocity than sitting on them here on earth.
Similarly, driving the rovers on an uneven terrain where the chassis is often forced to change directions vertically, the forces will be very similar, if not the same as here on Earth. Hitting a mound at 10kph will impart the same forces on the vehicle as hitting a mound at 10kph here on earth, the mass and velocity are the same. If you can't hoon around a crater filled terrain here on earth with the vehicles then you can't do it on the moon. If you can't sit on a rover on earth then you can't jump onto one on the moon.
Traction:
To take a 4WD onto a loose ungroomed surface here on Earth would not be counter-intuitive to most people, however, most people would balk at the idea of taking a 2wd vehicle onto a loose ungroomed terrain here on earth because, quite sensibly, it is unlikely a 2wd, with half the traction of a 4WD, would have enough traction. Well, on the Moon a 4WD does not have anywhere near half the traction of a 4WD on earth, it has only a piddly 1/6 the traction and that is true for steering, braking, and accelerating.
Fully loaded the rovers on the moon have a mass of approx 1,500lbs, yet they only have approx 250lbs of weight on the ground to try and accelerate, steer, and brake the 1500lb mass, and they are on a loose surface. The suggestion anyone can go 4WD driving on a loose surface in 1/6g is ludicrous.
I know defenders of the apollo missions will say that the lunar dust binds together so it is not loose, and will quote astronauts as saying they had big trouble controlling the rovers. The problem with both these excuses is that it is not what we see in the video and photographic footage, instead we see a surface that is very loose with dust being disturbed very easy by the astronauts moving around in it, and we see no control problems with the rovers either in driving or the photos of the tracks. It would appear as though they are merely paying homage to the physics while, at the same time, not bothering to fake any traction difficulties for TV.
Power:
The rovers would appear to be massively underpowered, they have 4 x 1/4hp motors giving a grand total of 1hp to drive a 1,500lb vehicle. One horsepower is low powered even for a mobility scooter, imagine putting seven big blokes on a low powered mobility scooter and seeing what performance you get out of it, yet on the moon they hooned around no problems at all.
Uphill there would be some benefits from being on the moon but driving on a flat surface on the moon you would get the same performance as on earth, simply because it is the same mass that has to be accelerated.
Balance:
The rovers are horribly unbalance vehicles, they weigh approximately 460lbs and the astronauts weigh approx 400lbs each fully suited (3), this means when one astronaut is driving there is approximately 3/4 of the weight on one side of the vehicle:
I doubt many of us would want to drive such an unbalanced vehicle over an uneven terrain here on earth, but on the moon where 1/6 g means it is much more likely to roll the suggestion becomes untenable. If the driver were to hit a rise on the unweighted side of the vehicle then the rover will rise 2, 3, or 4 times higher than it will hitting the same bump on earth (depending on the degree of the slope).
In conclusion:
We are supposed to believe they took a 4WD to the moon that was of such a lightweight design that they couldn't sit on it on earth, but they could jump on it on the moon?
They had no traction problems on a loose surface in 1/6g even though 1/6g equals a whooping 1/6th of the traction?
They had ample power driving a 1500lb mass with a 1hp vehicle?
They could hoon around with one astronaut on one side of the vehicle (approx 3/4 the weight on one side), on an uneven terrain hitting bumps in 1/6g, with no worries at all about rolling?
(1) http://ares.jsc.nasa.gov/HumanExplore/Exploration/EXLibrary/docs/ApolloCat/Part1/LRV.htm
(2) http://www.hq.nasa.gov/office/pao/History/SP-4204/ch23-3.html
(3) http://www.hq.nasa.gov/alsj/a17/A17_LunarRover2.pdf
