Space Cowboys

It's too bad the Internet wasn't so well-developed during the bulk of my college career. I just ordered my two textbooks for the coming semester on-line, rather than via the only bookstore that services the campus. Did I save any money? Sorta. The American President was the same price at as well as the UNI bookstore, but since I routed the purchase through my associate link, I'll get 15% back on it. That covers shipping, and I avoid sales tax. Separate But Equal Branches is back-ordered at, the bookstore had used copies of this, but a brand new copy from was only five dollars more, and I'd rather have the new book, as all the used ones were in poor shape. All said, I probably came out even in terms of saving money, but now I get mail! If you're going to spend millions of dollars to make a space movie, check your physics. I saw Space Cowboys last night, and while it isn't the greatest movie in the world, it provided a relief from the heat and a much-needed distraction from work.

My physics training consists of one year of high school physics and a lot of Heinlein books. I am not an astrophysicist, but I know the basics of space travel. Anyone with a basic grasp of Newtonian Physics could spot some flaws in this movie.

One of the characters is about to blast to the moon, the others warn him that he'll only have enough fuel to get halfway there. Hmm, funny, I don't remember them blasting all the way to the moon in Apollo 13. Why not? Because an object in motion continues in motion until acted upon by an outside force. Physics 101 folks, you don't need enough fuel to blast all the way to the moon, nor would you want to! You just need enough to push you in that direction, the rest is a matter of time.

Running out of fuel halfway there wouldn't make for a very comfy landing if you were boosting for that entire length of time. You need fuel at the other end to slow yourself down, or you're going to splatter yourself across the lunar landscape. If you accelerate at 1 G for half the way to the moon, you've got to decellerate for the second half of the trip at the same rate or splat!

Not to mention that the character apparently navigates his way to the moon by dead-reckoning. If you want to go to the moon from Earth-orbit, you've got to do more than just "head that-a-way". The moon is in orbit around the earth, it moves, it's not like finding Des Moines. It'd be pretty inefficient to chase it around the globe rather than just plot a course for where it will be when you arrive in it's orbit.

I could go on about how apparently the astronauts just check in with NASA to let them know how things are going, never asking for guidance. I could also rant about why the geezers get to drive the shuttle, when they have a month's worth of training, when there are two fully-qualified astronauts in the cockpit, but I won't.

The Learning Channel makes bonehead mistakes too, I can't just blame Hollywood. Last night, as I was preparing for bed, I caught a documentary about traveling outside the solar system. One of the rocket scientists said something to the effect of "We'll never be able to get humans traveling anywhere near the speed of light, our bodies couldn't take the G forces". Wrong! He's leaving time out of the equation. How fast do you want to get to near-light speed? In 10 minutes? You're jelly. In 10,000 years? Now we're talking! You don't have to accelerate hard, you just have to do it for a long time. This was all part of a discussion that included "Space Arks" or ships carrying generations of humans, since the distances to be covered are so vast.

There is already the technology at NASA, being used in a space probe, called Deep Space One, that uses an "ion-drive" which spits ions out of the tail end of the probe, providing very light acceleration (about equal to the weight of a piece of paper on your palm) but does so for months at a time. In time, the probe will go much faster than anything we could launch with rockets!