NEOWatcher

2008-Sep-22, 12:34 PM

This weekend I was hearing radio talk of the upcoming HST mission and heard a common misconception repeatedly voiced.

"The ISS can not be used because the HST is at a much higher orbit."

But; It got me thinking about the energy needed to change the orbit from one inclination to another.

I started picturing the two orbits as vectors with direction as a delta in direction, and the length as the amount of energy needed to achieve orbit. (both vectors originating at rest at (0,0))

In the simple case*, would the amount of energy needed be as simple as vector made by subtracting one from the other?

*Same altitude, circular orbit. Not actually HST to ISS.

"The ISS can not be used because the HST is at a much higher orbit."

But; It got me thinking about the energy needed to change the orbit from one inclination to another.

I started picturing the two orbits as vectors with direction as a delta in direction, and the length as the amount of energy needed to achieve orbit. (both vectors originating at rest at (0,0))

In the simple case*, would the amount of energy needed be as simple as vector made by subtracting one from the other?

*Same altitude, circular orbit. Not actually HST to ISS.