Chad Cooper wrote: >
>Orbital Mechanics questions: >If you are travelling in the space Shuttle in space, and you want to >increase your altitude, do you increase or decrease your speed? > <ex-cathedra> The problem is that you can't do that _instantaneously_. Orbits are ellipses, so if you are in a circular orbit of height, say, 200 km, and you want to get to another orbit of height 250 km, you must _first_ spend half-orbit in a transfer orbit, with perigee 200 km high and apogee 250 high. In order to change from the 200 km circular orbit to the transfer orbit, you _add_ a Delta V to your rocket. After half-orbit, your rocket is _slower_ than it was, even slower than the circular orbit had been. Then, you _add_ another Delta V, to reach another speed that is still _lower_ than the initial speed for the 200 km-high circular orbit. So, you get this paradox: adding to the rocket speed makes its speed reduce. IF you want to play with figures, go to... http://www.geocities.com/albmont/hohtransf.htm ... and pray that the &^^(&*&&( geocities is on-line >Does this change when you are stationary in orbit vs orbiting? > You can't be stationary in orbit, because gravity pulls you down. Or do you mean _geostationary_? These orbits are such that you orbit the Earth in the same period as the Earth rotates. So, for a ground-based observer, your position doesn't change. </ex-cathedra> Alberto Monteiro
