Posted by ztech on December 25, 1999 at 19:33:34:
In Reply to: What keeps Hubble up posted by Spotted1 on December 25, 1999 at 12:58:09:
> WHat keeps the HST orbit intact, should'nt it decay over time from gravity from earth ?
Spotted1;
Hubble, and all "things" in orbit, are actually continuously falling towards the earth due to gravity. However, the velocity (or speed) of the "thing" in orbit is such that it always remains at a relatively constant distance above earth. Let's take a bullet fired from a gun. The bullet fired from the gun has an initial velocity when it leaves the barrel. However, gravity acts on the bullet (also the air acts to slow it down) so as to make it fall at certain speed starting at zero and increasing at a rate of 32 feet per second every second. Imagine that the bullets initial speed (velocity) is high enough to allow it to "fall" constantly due to the curvature of the earth. Hubble is that bullet "falling" continuously towards a curved earth and because of this remains in "orbit.
Best Regards
Ztech.