"Space shuttle fly as a Child" very odd word choices too make here. No one usually says space shuttle and generally use rockets and usually people see launches not flights and enjoy rocket launches. It is just very intentful and specific I think for ET to specifically say "space shuttle fly as a child"

"Two boosters fly back down to earth" is also notable because if the use of two. Usually people would naturally just say the. "It is truly incredible watching THE boosters fall back down to Earth"

So there is something being communicated with intent here for sure in my opinion. The intent has to do with

Whatever a space shuttle represents to children

Two of something

And whatever the boosters represent, returning.