on nasa's worldmap, why does the space shuttles orbit form a sine wave?

Answer 1

because the astronauts are spaced out

Answer 2

Because the orbit of the space shuttle is "inclined" to the plane of the Earth's equator. This means that it's "tipped" a different amount than the Earth is. In 3d space, the orbit of the shuttle is a flat ellipse. The ellipse happens to pass over some places that are north of the equator, and others south of it.

The thing that makes it confusing is that maps are flat, and the Earth and the orbit of the shuttle are not. If you were to print out the image of the orbit path, and wrap the paper into a cylinder so that it makes the edges match up correctly, you'll see that the "sine wave" now looks like a circle tipped at an angle.

EDIT: thanks Gary - I'll try to make it a little easier to visualize.
If you want, try this: get a small globe. Put it on a table, but roll it over a little bit so that the south pole isn't touching the table - say, roll it enough to where you can see all of Antarctica. Now wrap a rubber band around it, but make the rubber band is parallel to the table. Be sure that the rubber band is around the widest part of the sphere, so that the center of the sphere is the same point as the center of the circle made by the rubber band.

Now look at how the rubber band passes over different points, and look at the path it takes. Now get a regular map and trace the same points on that flat map. Voila! Sine wave!

Answer 3

Above is correct but doesn't much help you visualize what's going on. Modelling shuttle orbits with a globe would help, provided the rotation of Earth and the speed of the shuttle were correctly scaled. Or try this - imagine a satelite launched into a low polar orbit where it crosses over the North and South poles once every 90 minutes. If Earth were not turning on its axis once every 24 hours, the satelite would fly over the same 2 points on the equator every loop. But due to the rotation, the satelite will fly over different points on the equator. To answer "which points" is simple. If Earth rotates once per 24 hours and the satelite polar orbits once per 1.5 hours, 24/1.5 = 16 satelite passes per day. So each time the satelite passes over the equator, the point it will pass over will be 360/16 = 22.5 degrees (about 1560 miles) west ("west" because Earth rotates toward the east) of the point it passed over 1.5 hours earlier. Got it? So every 16 passes, the satelite returns to the same points over the equator.

Now imagine the orbit is not quite polar but off the side of the poles, by a few degrees. Since both the satelite's and Earth's rotation haven't changed, the same situation of crossing the equator 22.5 degrees west still applies, tho now a map of the orbits looks like a 3D spirogram. As well, the northernmost and southernmost points also move in the same direction by the same amount. When this map is translated to a 2D map, the orbital path looks like a sinewave.

I know this is not easy to visualize or explain without a globe in front of us.... does this help?

Answer 4

An orbit is a great circle route. If you go from New york to Paris, along the shortest possible route, you end up flying more north than east and fly over nova scotia, go north close to Iceland before you turn east and then ultimately southeast flying over Ireland before you end up in Paris.

In order to follow this route, you don't need to turn. Point the initial direction and then fly a straight line. This is what orbiting things do. They fly without control changes and fly a "straight line" accross the globe, the center of the earth being the center of the orbit they follow.

If you slice thru the earth along the plane of the the orbit, you would get two perfect halves of the earth, each one being exactly the same size.

When you distort the globe to fit on a flat surface, the perfect circle you fly looks like a sine wave across this distorted map.

Answer 5

That depends on where u launch from. The near the equator when it is launched the lass the sign wave. The orbit that is 23,000 miles up is synchronous will make a small infinitive sign over the equator.

Answer 6

Because it launches from Florida, which isn't on the Equator. So, assuming it does no course-correcting in orbit - it MUST oscillate between the Northern & Southern hemispheres.

Answer 7

I think Zerobyte nailed it. Good job.