Monthly Archives: July 2013

Why space matters and explaining picture-taking (imaging) satellite operations, Part 1

Yes, it’s rocket science, but…

…it doesn’t take fancy non-English math symbols to explain a lot of the basics.

So, I’ll start with something I think people have asked lately:  “What can they see?”  (We’ll get to “What can they hear?” in a later post.)  Also, please note this will take a few posts to get there, as there are a lot of “basics” explained along the way (with a lot of assumptions).

It doesn’t matter who “they” are.  If they own a satellite, there’s the possibility they have a camera or other optical technology that can take pictures anywhere on the Earth’s surface (depending on the orbit).

Starting with the orbit, let’s assume a very basic low earth orbit (LEO).  This describes how closely the satellite can possibly complete a circle around the Earth without crashing into it.  If we believe Wikipedia, this orbit can range from 99 to 1200 miles from the surface of the earth, so there’s quite a range to work with.

“BUT WAIT!!” you shout, “Why do I want to assume a low earth orbit?”

Well, this merits an explanation.

Assume you’re on the freeway looking at a license plate of the car in front of you—is it easier to make out numbers of the plate if you’re closer, or further away?  What if you’re only inches away while the car is stationary in a parking lot?  If you’re normal, you will admit it’s much easier to see the numbers when you’re closer to the license plate.  Not only do you see the numbers, you might also see that they were raised, that there were dirt specks, and all the other details you would miss if you were further away.

It’s the same deal with satellites.  The further a satellite is away from the Earth while trying to observe a point on or close to its surface, the harder it is for the camera to make out the numbers and other details.

There is, as explained before, the problem of the wide range of orbits for a LEO satellite:  99-1200 miles from Earth’s surface.  But maybe it’s not a problem.  If you wanted to see as much detail as you can, then why not pick the 99-mile orbit?  After all, isn’t that the closest orbit you can pick without the Earth interrupting the satellite’s path?

Hmmmm!!?

Aside

Okay, so my company was told to cut our contract because the government was concerned about budget.  So, here I am as part of that cut, looking for work, cutting junipers, riding the motorcycle, and just trying to stay busy. … Continue reading