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Home Demo 04

When planning a mission to Mars there's a lot for scientists to consider. The Red Planet is, after all, a long way off-and a small target compared to the vast Universe surrounding it. One false move, and you miss your target completely and are cast off into space. To make things even more complicated, Mars is moving at about 15 miles per second around the Sun! Here's a way to try out your targeting skills-will you make a proper landing, or will you get lost in outer space?

What You Do

  1. Tie the string to the washer, and suspend it from a table using books as a weight, or tape, so that it swings like a pendulum on a clock.
  2. Tear up the paper towel and create marble-sized wads good for throwing.
  3. Start the washer swinging.
  4. Sitting a leg's length away, try to hit the swinging washer by throwing the wads of paper at it.

What Did You Find?

It is difficult to hit a moving target. Why exactly? In the time it takes for the paper wad to travel to the point you were aiming at, the washer has moved already! Scientists face a similar problem when planning a mission to Mars, so they plan ahead - with careful calculations. Careful observation and measurement predict the exact location of Mars at a certain time in the future, and the speed and path of the spacecraft is adjusted to arrive at the same point at the same time. Try hitting the washer again - only this time, predict where the washer is going to be given how long it takes your wad of paper to travel. Can you make a successful landing on the red planet-er, the red washer?

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  What You Need

  • Paper towels
  • A metal washer
  • String

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Figure 1