Friday, December 25, 2015

Trying to figure out falling

You are on Deimos [one of the small moons of Mars], space suited and bored. You decide to entertain yourself by seeing how far you can long jump. … Back on Earth you can jump a meter vertically. But here on Deimos, a moon with gravity a mere thousandth as strong, you can go 1,000 times higher. [With a running start] you fly so far that the surface of Deimos curves away below you as fast as you fall back toward it. Now you are falling for ever, in a circle. … You have jumped into orbit.

You are falling toward the moon below. You know it’s below because you are falling toward it. But you never fall all the way to it. You never fall all the way to it because it is “curv[ing] away … as fast as you fall.”

I’ve tried to make sense before of the idea that one can fall but never land on anything. It seems to me odd to use the word “fall” if one can’t land. Isn’t “fall” relative? I mean, if you pushed a toy car and it started to go down a slope, the gravity of planet drawing it forward, you wouldn’t say it was “falling.” You’d say it was traveling. Of course, if the slope became precipitous the toy car would certainly began to fall, probably tumbling. Is that it? The lack of control? The absence of impetus? You are drawn toward something beyond your control. You call that falling. 

Author Marcus Chown imagines not only jumping into orbit from the surface of Deimos, but being able to jump all the way beyond Deimos’ gravitation influence and on down to Mars. Given a good enough space suit and parachute (and opportunity) and somebody would do it. 

source: Solar System: a visual exploration of the planets, moons, and other heavenly bodies that orbit our sun by Marcus Chown


David Lee Ingersoll said...

There's a story to be written about that.

Glenn Ingersoll said...

You'd think!