The factor that is not needed when calculating the velocity of a satellite orbiting a planet is the mass of the satellite.
The formula for the orbital velocity \( v \) of a satellite in a circular orbit around a planet is given by:
\[ v = \sqrt{\frac{GM}{r}} \]
where:
- \( G \) 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).
As seen in this formula, the mass of the satellite does not appear, thus it is not needed for calculating the orbital velocity.