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Reading Selection

Just imagine that you a.re an astronaut.Suppose you are flyrng a spacecraft to theMoon. Your goal is to learn about the Moon ssurface. What kind of vehicle would you liketo have there?

Engineers have already answered thisquestion. In the Apollo space program, fJ.S.astronauts flew to the Moon. On many ofthese flights, the astronauts landed andwalked on the Moon s surface. They tooksamples of Moon rocks and performed manyscientific experiments. But since their oxygensupply was limited, they could only walkabout 1 km (% rnrle) away from their

52 / Designing Vehicles to Meet Requirements

\-,

spacecraft. Many places they wanted toinvestigate were too far away.

To help the astronauts in their work on themoon, engineers designed a vehicle called theLunar Rover. It was big enough to hold twoastronauts, their equipment, and manysamples of Moon rocks. What were the LunarRover's deslgn requirements?

First of all, the Lunar Rover had to be lightenough so that a rocket could lift it off Earth.The Rover weighed 21o kg (462 lb) on Earth.It only weighed 35 kg (77 lb) on the Moon. VDo you know whylz

\-/

Lunar Rover: Making Tlacks on the Moon

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How did the Lunar Rover get its energ/ to, move? Most cars on Earth burn gasoline to\/ drive their engines. Burning g""otine requires

o)rygen and o>rygen comes from the air.Because there is no air on the Moofi, ? gasolineengine would not work. Instead, the Roverused electric motors, one for each wheel.Energr for the motors came from batteries.

The Rover had to move over the Moon ssurface. Some of thatsurface is rough anduneven. The engineersmade the tires bigenough so that theRover could roll oversmall bumps andcracks. To save onweight, engineers madethese tires of wire. The

\-/

tires looked like round metal cages, just likethe cage around a small electric fan.

The Lunar Rover's top speed was about12 km (7 mrles) per hour. It needed to moveslowly to save on the battery. The slow speedalso helped astronauts control the vehicle onthe rough terrain.

Engineers made careful records of theirdesign for the Lunar Rover. They also recorded

the results of all tests.Suppose engineersneeded to build avehicle to explore thesurface of anotherplanet, like Mars. Whatmight this vehicle looklike? Do some researchand find out!

Close-up oJ Lunar Rouer's tire

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STC' / Motton and Design Designing Vehicles to Meet Requirements / 53

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