Shuttle and ISS?

Question

I've been watching the Shuttle and ISS orbit for years now, it's a hobbie of mine. One thing eludes me; Why do they zigzag North and South while they orbit?
I've asked NASA but they must be too busy to answer.

An answer for an answer. i.e. STS-115. STS stands for, Space Transportation System.

Thank you,
Loser

Very good Chris. not sure weather to belive or not. they both have tha ability to adjust. why not just fly around the equator?

Answer 1

Because the transporters were launched from points not on the equator, and the fuel burns to put the craft into an equatorial orbit would not accomplish anything useful. For minimum fuel burn, the plane of the orbit must pass through the launch point, the equator at 90 degrees longitude away from the launch point, and the center of the earth. If one were going to pick an orbit, an ecliptic plane orbit might be preferable, and that could be achieved with relatively small additional fuel, given that the launch points are fairly near the Tropic of Cancer.

Answer 2

First of all, the plane of the orbit must cut through the center of the earth (center of mass of the earth actually, but no need to be picky!). Without getting clever, the only way to launch into an equatorial orbit is to launch from a point on the equator. Launching from any location not on the equator will result in an orbit that is inclined to the equator by an angle equal to the latitude.

The earth rotates once in 24 hours but the shuttle orbits a lot quicker than that because it is in a low earth orbit (look up Kepler's laws to relate orbital period and orbital altitude. If you now think of what is going on........if the shuttle orbits once, by the time it gets back to where it started the earth has rotated a bit and so it will pass over a different location on the earth's surface. When you plot this out on a flat map, it looks just like the curves that you see on NASA's giant displays.

To get the shuttle into an equatorial orbit would basically mean that it would have to fly south a bit during liftoff. This would use up a large amount of fuel and really serve no purpose.

The European Space agency mainly launches to geostationary orbit which is an equatorial orbit. For this reason their launch site is much closer to the equator to make the launches more fuel efficient..

Answer 3

It's because they don't orbit directly over the Equator. And that's because they don't start at the equator - they start at Florida or Star City.

The shuttle/ISS orbit in a circle around Earth, the center of which is the center of Earth. Since Earth is rotating under the shuttle/ISS, the orbit mapped on a *stationary* Earth looks like it oscillates north and south. But it's all because Earth is rotating.

Answer 4

Because the earth is turning on a tilted axis.Try it with a globe of the earth.

Answer 5

It is surely so they can cover most of the globe.