Three Characteristics?

Question

List three characteristics of th emoon that had to be known before a manned landing was possible.

1.

2.

3.

(Please help me with this..!! It would mean a lot!)

Answer 1

The surface had to be mapped sufficiently to be able to locate primary and secondary landing sites.

The exact distance and location in space had to be known and predicted, based on the time of year.

There had to be evidence that the surface was solid and not a 100-foot layer of dust (or green cheese I suppose).