From: "Travis Watkins" <[EMAIL PROTECTED]>
But in this case the hyperbolic orbit is not around the object with which we wish to have a similar speed. The orbit is around the sun, just like the orbit of Earth.
I'm not clear on why it has to be a hyperbola.
Would it not be possible to find a trajectory that comes past inside the height of a geosynchronous orbit but traveling at a relative speed similar to the rotational velocity of the planet?
No, because GEO orbit is by definition the only place rotation speed matches orbital speed. Inside this orbit and below that height, rotation -matched speed is best good for an elliptical orbit. Elliptal orbits are closed, meaning an object form the outside can't enter one without thrust.
We could even change the angle of approach by using the moon if needs be, and we only need to get close enough to be dominated by earth's gravitational pull if we can get the speed close enough.
True, you could do that, hiding the burn behind the moon, and mimic the free return orbit as explained in _Apollo 13_, but that still requires a minimum of several minutes of ionized aerobraking.
We could even use an orbital path that would pass through the sun or one of the other planets because we need not use the entire orbit, just enough of it that we are outside of the active detection radius of the planet when we make our final adjustments.
Maybe your best bet would be a Hohmann transfer orbit from the inner system, rising up to meet Earth in an tangential ellipse. This eliminates the 30 km/s solar orbit velocity, leaving only the infalling 11.2 km/s earth escape velocity, and a slingshot of the moon can subtract it's 1km/s earth orbit velocity from that, so you've only got 10.2 km/s to get rid of.
-- Jeff Wilson - [EMAIL PROTECTED] < http://www.io.com/~jwilson > _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
