How will the acceleration of gravity change on the planet when a spacecraft launched

How will the acceleration of gravity change on the planet when a spacecraft launched from it rises to an altitude equal to the radius of the planet?

Let’s write down the law of universal gravitation:

F = m * M / R ^ 2, where m is the mass of the body, M is the mass of the planet, R is its radius.

According to Newton’s second law, we get the equation:

G * m * M / R ^ 2 = m * a, where a is the acceleration of gravity, G is the gravitational constant.

a = G * M / R ^ 2.

Then the acceleration a1 at the height R will be equal to:

a1 = G * M / 4R ^ 2.

The acceleration ratio will be:

a1 / a = G * M / 4R ^ 2: G * M / R ^ 2 = 1/4.

Answer: the acceleration of gravity will decrease by 4 times.