Re: What are some details about when a spacecraft reenters our atmosphere?

I'm a little fuzzy on exactly what your question is, but here's some info that may help.

First, I did a Web search on the words

atmospheric reentry of spacecraft

and, as usual, Altavista came back with a zillion and three hits. Luckily, the first hit may be on the track of what you're looking for. It concerns spacecraft reentry and it discuss some of the basic physics involved. Plus, it has some cool photos.

The bottom line is this: atmospheric reentry is a fancy way of saying that atmospheric drag causes a fast moving object to slow. Drag is a form of friction, and friction causes heat.

An orbiting satellite stays in orbit because there's little or no atmospheric drag to impede its forward motion. But even a couple of hundred miles up the satellite is bumping into air molecules, slowing it down ever so slightly, causing it decrease orbit bit by bit. This is called "orbital decay". Eventually, the satellite gets low enough where it begins to run into a more significant amount of atmosphere, and amount of drag skyrockets, causing a heating of the air surrounding the object to thousands of degrees even as the object decelerates quickly (several g's).

In the case of the Space Shuttle, the main engine is fired intentionally to cause the Shuttle to brush against the upper part of the atmosphere and begin slowing.

I'd suggest trying a Web search of your own using the same phrase as above. Another good term to look for might be "ablative heat shield". Good luck and happy hunting.

Steve Czarnecki