# Launch to Orbit, Part 3

In Part 2, I found the velocity required for circular orbit was

$\displaystyle v = \sqrt{\frac{GM}{r}},$

where G is the gravitational constant, M is the mass of the body being orbited, and r is the distance to the center of that mass. I tested this on the ISS’s orbit and found the velocity matched quite well. Now, I’m interested in looking at orbital periods, and calculating aspects of some common orbits.

Problem: Calculate the velocity and periods for some typical circular orbits.