|
 April 10, 2000 -- Can you imagine what
might happen if your car broke down while you were driving ...
on the Moon?
No, Triple-A is not a cell-phone call away. A concerned motorist
is not going to stop and lend a hand. And forget about walking
home.
If this sounds silly, don't forget that about 30 years ago people
actually were driving around on Earth's satellite. During three
of the Apollo missions to the Moon in the early '70s, astronauts
in bulky white space suits cruised the Moon's rugged gray terrain
in their custom-designed "moon car."
Right: Pictured here during the Apollo 17 landing, the
Lunar Roving Vehicle (LRV) (better known as the Moon Buggy) carried
astronauts across the surface of the Moon during the Apollo 15,
16, and 17 missions. You can see the lunar rover in action by
clicking on this
RealVideo introduction (126kB) to NASA's Great Moonbuggy
Race. credit NASA
Designing a car up to the task was quite a challenge
for the engineers at NASA and General Motors who built the car
-- which they called the "Lunar Roving Vehicle."
The moon rover had to be large enough to drive over big rocks
and in and out of craters, but small enough to be tucked into
the astronauts' spaceship. It had to be strong enough to support
the astronauts and their heavy equipment, but light enough to
send to the Moon. And it must not break down -- the astronauts
couldn't risk getting stranded.
"We had all kinds of things we had to think about
-- what might, could happen," said Otha "Skeet"
Vaughan Jr., a retired NASA engineer who worked on the project.
The importance of safety and reliability ruled out some of the
more unusual designs. To find the best way to get around on the
Moon, the engineers played with ideas for vehicles that walked,
crawled, jumped and even flew over the Moon's surface, according
to Vaughan.
"We had all kinds of different concepts, but it eventually
came down to [this] -- we had to have something simple,"
Vaughan said. "And something simple was something like a
Jeep."
But a regular Jeep would be far too heavy to launch into space.
"The other big crunch was weight," said Randy Simpson,
a mechanical engineer who was fresh out of college when he was
assigned to the lunar rover project. "It cost a lot of money
to put something on the moon, so every ounce you could get out
of that structure (saved money)."
The finished lunar rover weighed only about 450 pounds, or just
75 pounds in the Moon's one-sixth strength gravity. At the same
time, the rover could carry up to about 1000 Earth-pounds --
more than twice its own weight.
"If you visualize your own automobile, it had to carry the
equivalent of two more of your automobiles on top of your current
car," said Saverio Morea, who was the project manager for
the lunar roving vehicle at the Marshall Space Flight Center.
"And it still had to be stable on a 45 degree slope."
To keep from tipping over on the Moon's hilly terrain, the rover's
wheels needed to be as far apart as possible. But the rover also
had to take up very little space when stowed aboard the lunar
module, the astronauts' spaceship. To meet both challenges, the
engineers designed the rover to fold up like a Transformer toy.
"A large automobile the size of a Lincoln today had to be
folded into something smaller than a Volkswagen," Morea
said. "It had to be very large yet very light."
Being light solved some problems, but created others.
CONTINUES AFTER SIDEBAR
|
 The original lunar
rovers may be hundreds of thousands of miles away, but the spirit
of the moon buggy was alive and well this weekend right here
on Earth. On April 7 and 8, 2000, students from all over the
United States and Puerto Rico converged on Huntsville, Alabama
to compete in NASA's 7th annual Great Moonbuggy Race. Each team
of students brought along a homemade moon rover designed to solve
some of the same engineering challenges as the original Lunar
Roving Vehicle. Twenty-five teams in all raced their buggies
around a course at the US Space & Rocket Center, navigating
obstacles on a simulated lunar terrain. For a complete list of
winners, click
here.
Above: A RealVideo
(126kB) introduction for the Great Moonbuggy Race, with some
nice footage of the real Lunar Rover. credit NASA
 |
 |
|
Above, left:
A team from the College of
New Jersey in Ewing heads for the finish line to win the college
division of this year's Great Moonbuggy Race. (Photo: NASA Marshall Space Flight Center) |
Above, right: A team from
Pittsburg High School in Pittsburg, Kan., rumbled through "lunar"
terrain win the high school division of the Great Moonbuggy Race.
(Photo: NASA Marshall Space
Flight Center) |
The Great Moonbuggy Race is sponsored by the NASA Marshall
Space Flight Center, the U.S. Space & Rocket Center, American
Institute of Aeronautics and Astronautics, Sci-Quest, and the
Alabama Aerospace Teachers' Association. For more information
see http://moonbuggy.msfc.nasa.gov. |
Traction was an issue. With so little weight pressing the
rover's wheels into the Moon's dusty soil, the engineers weren't
sure the rover could get enough traction to climb slopes with
the astronauts on board. To solve this problem, the engineers
put cleats on the wheels, and then put fenders on the rover to
control the moon dust that the cleats would kick up.
It didn't help the traction problem that people weren't certain
what the lunar soil was like.
"Back in the early '60s they didn't know whether they would
sink down into the moon when they landed on it," Simpson
said. "There were some early probes that went to try and
get an idea of the consistency of the surface, but nobody really
knew whether that was the same all over the moon or whether it
was just a particular place."
By the early '70s, though, information from the probes together
with data from thermal, optical and radar studies of the Moon's
surface allowed the engineers to make a good guess about the
soil's texture, Vaughan said.
 "Myself,
I felt very confident that we would land fine and wouldn't have
any problems," Vaughan said, "and I felt that once
we got the rover there we wouldn't have any problems either."
For the most part, he was right.
The lunar rover performed beautifully on the whole, allowing
the astronauts to venture further from the landing sites and
broadcasting panoramic shots of mountains, boulders and craters
back to televisions on Earth.
A couple of unforeseen curve balls served as reminders of the
importance of careful planning for missions into space.
"One of the scariest things that we had was on Apollo 15,
when they went to take (the rover) out of the (lunar module)
it wouldn't come out right," Vaughan said. "We were
down there at Marshall trying to figure out how in the world
we were going to get that thing out."
The rover was supposed to slide out of its holder on the lunar
module using a little mechanism that wasn't working right. Engineers
at Marshall Space Flight Center worked with a model rover for
about an hour trying to figure out how the astronauts could get
the rover free.
"The beauty of it is that the vehicle weighed [so little]
that the astronauts were able to man-handle it down," Morea
said.
The astronauts didn't have to worry about folding the rover back
up, though. They left it behind on the Moon.
Today, three abandoned lunar rovers still sit on the Moon. With
the exception of their plastic parts, they will probably be sitting
there thousands of years from now -- a silent testament to 20th
century engineering.
"It's been very meaningful to me over the years to see the
rover in pictures and photographs and on the television -- it's
still sitting up there on the moon," Simpson said. "I
had a little bitty part in putting it on the moon for who knows
how long." |
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