So NOAA does have some space missions (like the GOES weather satellites), but instead of standing up a whole new space design, acquisition, and management arm within NOAA, NASA tends to manage the day to day construction and operations of these missions. This ensures the taxpayers aren’t paying for two separate civilian agencies with redundant capabilities. NOAA gets to work on earth science (their expertise) and NASA builds and flys spacecraft (their expertise). It’s a win-win