To leave the gravitational pull of the Earth, and explore other planets, satellites must have at least:

To explore the other planets, the satellite must have the velocity more than the escape velocity.

Explanation:

The minimum velocity required by any object to escape from the earth gravitational pull is called the escape velocity.

The escape velocity for any planet depends on the mass of planet and radius of planet. It does not depends on the mass of object. The escape velocity is same for any mass for a particular planet.

So, to explore the other planets, the satellite must have the velocity more than the escape velocity.

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.