The Watering Hole: April 7 - GeoSynchronous Orbits

People sometimes wonder why we can place objects in orbits where they always seem to be at the same point in the sky. If a nearly circular orbit is assumed, the first obvious answer is that the orbit be very have to be near the equator since, otherwise, it would bobble up and down as it orbited. An extreme case would be a polar orbit where the wobble would be ±90 degrees. Also the orbit would have to equal an Earth day because the orbital period may not be an exact product or sub product of a day on Earth. This is exemplified by the ISS which orbits the Earth in about 90 minutes while the Moon takes a bit over 28 days.

There has to be a happy medium!

This is why geosynchronous orbits work! Distance and the relative masses of two bodies come into play when they orbit about one another, but the mass of the lesser body dries out in the wash.

If you are actually into physics, you can look here.

I might note that a science fiction writer came up with this concept – Arthur C. Clark.

At this point, I might note that most modern Earth synchronous satellites are placed in slightly inclined orbits in order to allow more space in the equatorial region. The inclination allows for the placement of hundreds of satellites that orbit along the same longitude and latitude area and altitude without fear of collision, human error excepted. The combined drift represents a directional drift if less than 1 second (1/3600 of a degree) in a volume of about a million cubic meters.

This is our Open Thread. Where do your ideas come from?

About these ads