This Lecture covers the effect of forces in space on the elliptic orbit of the spacecraft - focusing on changes in the quasi-static orbital elements. We then specifically focus on the effect of atmospheric drag on mission planning and lifetime.

CORRECTIONS:
1. In the third line of \dot a, we should have = - \sqrt{a\mu}\frac{\rho}{B}
2. In the expression for a(t), there should be a 2 in front of the \sqrt{\mu}