[Mike Darancette]

"We hope to learn how often big rocks crash into the Moon since we're sending astronauts back,"

Could the answer be 5 or 6 times on some days?

[Robert A Cook PE]

Several thousand times a year? But - What size of impacting rocks should they worry about?

How big an area is the primary impact - and how big is the secondary (splashback) rock impact area?

Compare the area of the moon with the area of the landing craft and shelter itself: Probability of impact - even with an enhanced affected zone - is very very small.