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Satellite Orbits

Wikipedia claims that satellite orbits verify Einstein’s formulas for time dilation because the exact time and position of satellites are continuously adjusted. Their article makes it sound like Einstein’s equations are used to calibrate clocks and fine-tune positioning.

However, this cannot possibly be how things are done because there are other, more serious issues to consider, and these issues are of a kind that cannot be predetermined. Hence, adjustments to satellite orbits cannot be pre-calculated. They must be based on synchronization with Earth based stations.

Unpredictable factors

Satellites are subjected to a wide range of factors that would make them go off into space or drop down to Earth if not adjusted for. Unlike orbits of planets and moons, there’s no self regulating mechanism that kicks in to keep satellites in place. They must regularly adjust their orbits, or they will be lost.

There is for instance a solar wind that pushes things around. Like any other wind, it’s strength varies in unpredictable ways.

Earth’s gravitational field is not smoothly distributed across our planet. There are gravity anomalies that makes Earth’s gravitational field lumpy and irregular. Earth’s gravitational field is not even constant. It varies in 5.9 year cycles.

There’s also the fact that Earth’s rotational speed is irregular. It speeds up and slows down in unpredictable ways.

Continents drift. Earth may even be expanding. There are irregularities for which we have no good explanation.

South pole view of the expanding Earth
South pole view of the expanding Earth

None of this can be pre-calculated. The only practical solution is therefore to use ad-hoc algorithms based on feedback from known positions on Earth.

It follows from this that satellites do not verify time dilation directly, because any issue related to this phenomenon is taken care of by ad-hoc synchronization routines rather than careful calculations. Any verification that there may be is indirect, based on data collected from satellite logs.

This Post Has 3 Comments

  1. “..There is for instance a solar wind that pushes things around. Like any other wind, it’s strength varies in an unpredictable manner..”
    For ‘wind’ read ‘flow of charged particles’. That’s electric current in physics language! It is known as the Heliospheric Current Sheet.

  2. It’s an interesting thought that the Earth’s rotation is receive some impetus from the Sun’s charged particle supply. In other words it is acting more like an electric motor. This could account for the variations in speed, if the solar wind variations are synchronized with that? There obviously is some inertia/ angular momentum, which is the mechanical solution astronomers offer

    1. You’re right. The universe is much more interconnected than was generally believed a hundred years back. The Earth is not hanging in the middle of a void, only connected to the Sun through gravity. It’s part of a complex eco-system where things constantly change and stability is due to inertia and feedback loops of various kinds.

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