Considering $\boldsymbol{R}$ as the radius of the moon, the ratio of the velocities of two spacecraft orbiting moon in circular orbit at altitudes $\boldsymbol{R}$ and $2 \boldsymbol{R}$ above the surface of the moon is_____________
Considering $\boldsymbol{R}$ as the radius of the moon, the ratio of the velocities of two spacecraft orbiting moon in circular orbit at altitudes $\boldsymbol{R}$ and $2 \boldsymbol{R}$ above the surface of the moon is_____________