Re: More GEO questions

From: Bjoern Gimle (
Date: Fri Oct 12 2001 - 14:33:48 EDT

  • Next message: Bjoern Gimle: "Re: NOSS"

    I think Bill missed a crucial point, mentioned only briefly:
    We are talking about normal satellites staying in a "fixed" orbit without
    using any fuel - not a Buck Rogers type starship. Such an orbit is defined
    by the position and speed at a SINGLE moment. If the speed is correct, and
    perpendicular to the radius, it is a circle, and has a resulting period. If
    it is lower, the period and perigee (closest point) is smaller, unless the
    decrease is exactly at the perigee. If higher, the period and apogee is
    higher, unless the increase is exactly at apogee. If more than 1.414...
    times the circular speed, it will escape Earth gravity. If very low, what
    perceive as a "parabola of throw" (?) is the tip of a very narrow ellipse,
    with a perigee near the Earth's centre. To keep a 24h period closer to
    Earth, it would have to hover like a VTOL aircraft, farther away it would
    reverse the thrust to counteract the centrifugal force.
    So, the formulae that have appeared are ONLY valid for the standard
    geostationary orbit.
    Arthur C. Clarke did not invent this formula, or those that describe other
    "free-flight" orbits, they have been known since the days of Newton. But he
    was the first to realize how they could be used for communication
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