Bade wrote:It looks like the firing of the LAM is not only increasing the apogee as it should but also the perigee (336 to 348 km). If the engine is fired at perigee as I think it normally should be, would that not only increase the apogee?
Perigee is a 'point' on the elliptical orbit, the engine was firing away for 9 minutes or so right ? The satellite must have moved a considerable distance beyond this 'point' during this firing. This will naturally lead to the idea of a dynamic perigee, won't it for all practical purposes increase the perigee, but will never decrease it with each impulse given.
To take a geometric view of the situation, draw a half-circle touching the perigee of the elliptical orbit. Any instantaneous engine firing will move the object at perigee to the space out of the circle. This automatically implies a larger distance from the reference center of the circle drawn or the foci of the elliptical orbit. A cumulative sequence of firings will leave the perigee growing in value.
If you could have given an instantaneous impulse at the perigee point rather than over the 9 minutes, then and only then can you have preserved the original perigee value.
Could it be more easily explainable by saying that the apogee and perigee values are related to each other thru an equation determined by mechanics of an elliptical orbit. So that vast increases in apogee result in corresponding miniscule changes in the perigee value.
found some relevant equations to elliptical orbit
e = eccentricity
a = half length of major axis of the ellipse.
(sum of apogee and perigee=2a=length of major axis of ellipse)
Note: apogee and perigee distances are on opposite sides of the earth with the earth being inside the elipse.