how do satellites stay at the same elevations and speed in orbit?
In: Engineering
For the most part there is no atmosphere to slow down a satellite, it is purely under the influence of gravity so the orbit will remain the same for many years as long as it doesn’t get too low, but that doesn’t mean they always stay at the same elevation and speed.
Geostationary satellites always stay a certain distance away from Earth and travel in a circular orbit once every 24 hours, but many imaging satellites will have a very elliptical orbit which brings them very close to Earth at high speeds for part of it and then launches them far away at low speed until they slow down and fall back in for another pass. This gives a nice mix of close approaches to get detailed images, and not spending too much time in the thin atmosphere causing them to slow down and burn up in the atmosphere
Satellites in a [Molniya orbit](https://en.wikipedia.org/wiki/Molniya_orbit) will change their elevation and speed constantly throughout their orbit to keep them moving in that very elliptical shape.
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