Posts tagged ‘International Space Station’

Help Help, We Are All Going to Die! Oh, Wait, Never Mind

I don't know why I have so much fun fact checking the "science" at green blog "the Thin Green Line," but I do.  Today's exercise:

There are, right now, at least half a million pieces of junk in orbit around our cosmic Pig Pen of a planet. Space junk isn't just an aesthetic problem, either: Even tiny pieces of junk orbit at speeds above 15,000 miles per hour, so even the tiniest bit of debris can cause serious damage to anything it comes into contact with. Space junk threatens satellites, manned space missions and even the International Space Station.

While certainly space junk can be a problem in certain instances, I am constantly left helpless with laughter at the absolute urgency this type of blog approaches every problem.  Here are a couple of things that might help you sleep better at night:

  • The speed space junk is traveling is largely irrelevant.  It could be 15,000 mph or 50,000.  The important variable is the closing speed of two objects, not their absolute speed.  And (thanks to our friend Newton) we know that objects in the same stable orbits have to be moving at the same speed.  Now, orbits don't all have to parallel and can cross, yielding real relative velocities, but recognize that since over 95% of these half million objects are less than 4 inches in diameter, its a bit like you and your friends firing guns and having the bullets meet in mid-air.
  • The drawing he shows makes the sky seem really cluttered.  But let's just take a small portion of this space.  Let's consider the volume of space between 100 and 500 miles above the Earth's surface.  Using a bit of geometry, this space works out to be 93 trillion cubic miles of volume.  Which means one object, generally less than 4 inches in diameter, in space per every 186,000 cubic miles, which for scale is the equivalent volume to a building 40 stories tall that covers the entire continental United States.

Certainly avoiding these objects is a navigation concern for powered spacecraft, which is why all these pieces of junk are watched in the first place.  But the idea of a space superfund to clean this stuff up is so hilariously expensive (given current tech) and such a staggering waste of resources compared to other uses of those funds that one would only expect to find it on, well, an environmental blog.