Why do airplanes have this hole? Check out the typical commercial jetliner. It has main engines on either side to generate thrust. But there's another engine hidden int he back of the tail.

All the equipment for the care and feeding of uprated Space Shuttle Main Engines (SSME), adapted for SLS by Aerojet Rocketdyne as the RS-25, is repackaged from the backend of Space Shuttle ...

Discover how Firefly's Blue Ghost lander executed a flawless Lunar Orbit Insertion burn, entering an elliptical orbit, ...