How fast would you need to shoot a cannon ball for it to completley circle the moon?

Question about Newton's cannon thought experiment- Used to picture how a sufficiently fast projectile could actually go into a circular orbit, but the drawback is that air resistance due to the Earth's atmosphere will slow the cannon ball down. But on the moon, where there is no resistance, a fired cannon ball could cirlce completley around the surface and smack into the cannon from behind. How fast would you need to shoot the cannonball to make this actually happen (in km/s)? (The m of the moon is 7.35 x 10^22 kg and the radius of the moon is 1737 km)