The gravitational force between two objects is given by:
[tex]F=G \frac{m_1 m_2}{r^2} [/tex]
where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is the separation between the two objects
The distance of the telescope from the Earth's center is [tex]r=6940 km=6.94 \cdot 10^6 m[/tex], the gravitational force is [tex]F=9.21 \cdot 10^4 N[/tex] and the mass of the Earth is [tex]m_1=5.98 \cdot 10^{24} kg[/tex], therefore we can rearrange the previous equation to find m2, the mass of the telescope:
[tex]m_2 = \frac{Fr^2}{Gm_1}= \frac{(9.21 \cdot 10^4 N)(6.94\cdot 10^6)^2}{(6.67\cdot 10^{-11})(5.98\cdot 10^{24})} =11121 kg [/tex]
