What the other answers fail to mention is that the mass of your orbiting object actually cancels out. It does not matter. See these two equations:

(1) F1 = F2 = Gm1m2 / r^2

(2) F1 = m1 * a1

Where F is force, G is the universal gravitational constant, m is mass, and r is distance between centers of mass of the orbiting and orbited bodies in question. The 1 and 2 represent the object in question, for example m1 is the mass of object 1 and F1 is the force exerted on object 1.

Thus,

a1 = G*m2 / r^2

i.e., the mass of the orbiting object does not influence its acceleration in any way.

edit: added an index of 1 to a.

What the other answers fail to mention is that the mass of your orbiting object actually cancels out. It does not matter. See these two equations:

(1) $F_1 = F_2 = G m_1 m_2 / r^2$

(2) $F_1 = m_1 a_1$

Where F is force, G is the universal gravitational constant, m is mass, and r is distance between centers of mass of the orbiting and orbited bodies in question. The 1 and 2 represent the object in question, for example $m_1$ is the mass of object 1 and $F_1$ is the force exerted on object 1.

Thus,

$a_1 = G m_2 / r^2$

i.e., the mass of the orbiting object does not influence its acceleration in any way.

edit: added an index of 1 to a.