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In the Shadow of the Moon
March 3, 2008
While we were at Blockbuster on Sunday evening, my dear wife pointed out to me that a new documentary had just been release on DVD: In the Shadow of the Moon. We just watched it tonight and it was fantastic. It helped bridge the gap for me between the space age of my growing up years (the Space Shuttle) and what happened only 12 years before I was born: Mankind walking on the moon. Although the visuals in this movie were superb, what really struck me were the interviews with the astronauts, now in their late 70s. These men are likable, dramatic people who have learned over the past 40 years how to tell the story in a way that brings you to the moon's surface with them. Some highlights:
  | When in orbit around the Earth, the Earth's horizon only has a slight curvature to it. But as you move away from the Earth, that curvature quickly grows until eventually you see the whole circle of the planet's circumference. |
| While looking back at the Earth, it hanging there, completely surrounded by the blackness of space, the astronauts were overcome with a sense of how fragile our small plant is. |
| The moon as the most dramatic, beautiful, untouched dessert you've ever seen. |
| The biggest thrill of exhileration being on the way back to Earth. |
| An astronaut, after returning from the moon, going to a shopping mall, buying an ice cream, and then just sitting there appreciating all of the people. |
| Astronauts talking about there being "two moons" in their head. The first moon is what you see when you look up in the sky, and when astronauts who have been to the moon look up, they see the "first moon"... and they can't really relate that image to their experience on the surface of the moon, the "second moon", so to speak. |
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How far could you long jump on the moon? 88 feet?March 3, 2008
| On earth, people are able to long jump roughly 30 feet = 9 meters |
| How far a person can jump is a combination of how fast they are running when they leave the ground and how long they are in the air. |
| How long they are in the air depends on how high they jump |
| Said differently, the higher a person jumps, the longer they are in the air, and thus the further their forward speed caries them |
| I looked up some footage of the olympics on Google Video and it appears that jumpers are airborn for about 0.8 seconds |
| 9 metres / 0.8 seconds = 11.25 metres / second = 40 km/h. This speed feels a bit high to me, so perhaps they are airborn for longer than 0.8 seconds, but we can make a reasonable estimation using this figure. |
| How high do they jump? |
2*t = 0.8 (The total time airborn)
t = 0.4 (The time taken to fall from maximal height)
t = sqrt( 2 * d / 9.8 )
t^2 = 2*d / 9.8
d = ( 9.8 * t*t ) / 2
= ( 9.8 * 0.4*0.4 ) / 2
= 0.784 metres (2.57 feet) |
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| How fast are they moving upward when they leave the ground? |
v = t * a
= 0.4 * 9.8
= 3.92 metres/second = 14 km/h |
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| The force of gravity on the moon is 1/6th that of Earth's |
| 9.8 / 6 = approx 1.63 m/s/s |
| How long would it take a jumper to reach their apex if they jumped upward at 3.92 m/s on the moon? |
t = v / g
= 3.92 / 1.63
= 2.4 s |
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| How high would they go if they jumped upward at 3.92 m/s on the moon? |
d = ( 1.63 * t*t ) / 2
= ( 1.63 * 2.4*2.4 ) / 2
= 4.7 metres = 15 feet (!) |
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| In conclusion, how far, approximately, could a person jump on the moon given a 40 km/h running speed and 2.4s of air time? |
d = v * t
= 11.25 m/s * 2.4 s
= 27 meters
= 88 feet |
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First person to drive around the moon and other assorted funMarch 3, 2008
Although it's a little unclear whether the Bush administration's plan to return mankind to the moon will come to fruition, I think we all know that at some point it's inevitable. One of the more obvious developments is an extended stay there, perhaps several months at a time. And when you think of people being on a moon/planet, needing to move from one place to another is important just like it is on earth. I wonder when the first road will be laid on the moon. Looking forward a little further, I find it cute to think of the first person or team to strike out driving across the whole circumference of the moon. That would be quite a historic accomplishment -- and I expect it will be done long before there is a road around the moon. 10,000 km. That's a long, dusty drive. Here are some other interesting future events to consider relating to the moon: | First person to be buried on the moon |
| New games invented by people on the moon to take the lessened gravity into account |
| First baby born on the moon (I expect that pregnant women will return to earth to have their babies, but eventually I could see this being done) |
| World records that pertain to things done on the moon. Maybe they'd be called "Moon records" since their not really "World" records. I could see long jump being a good one. (Obviously this would require the development of space suits that are much less restrictive) It would be fun to make a mathematical model to predict what the limits of human long jump would be on the Moon. |
UPDATE: Hey cool, this article isn't too far off what I'm pondering here. older >>
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