What does OOS stand for?

OOS stands for "orbit-to-orbit stage"

How to abbreviate "orbit-to-orbit stage"?

"orbit-to-orbit stage" can be abbreviated as OOS

What is the meaning of OOS abbreviation?

The meaning of OOS abbreviation is "orbit-to-orbit stage"

What does OOS mean?

OOS as abbreviation means "orbit-to-orbit stage"