Ah, I see... Or, more exactly, I saw. That is, I previously saw a dark cavity in that very photo, whereas turning up the brightness does indeed show a row of black rectangles instead.
Doesn't mean it wouldn't be a row of nine shuttlebay or cargo hold hatches, though.
After all, this feature never glows, and it does have that fancy approach control booth thing atop. This would naturally leave us wondering where the impulse engines are if not there, but the underside has some applicable features.