The factor that is not needed when calculating the velocity of a satellite orbiting a planet is the mass of the satellite.
When calculating orbital velocity, the formula used is:
\[ v = \sqrt{\frac{GM}{r}} \]
where \( v \) is the orbital velocity, \( G \) is the universal gravitational constant, \( M \) is the mass of the planet, and \( r \) is the orbital radius (distance from the center of the planet to the satellite). The mass of the satellite does not appear in this equation, as it cancels out in the derivation of the orbital velocity.