Due to changing requirements, several versions of the Dyna-Soar were considered, all sharing the same basic shape and layout. A single pilot sat at the front, with an equipment bay situated behind. This bay contained data-collection equipment, weapons, reconnaissance equipment, or a four-person mid-deck in the case of the X-20X "shuttle space vehicle". A Martin Marietta Transtage upper stage attached to the aft end of the craft would allow orbital maneuvers and a launch abort capability before being jettisoned before descent into the atmosphere. While falling through the atmosphere an opaque heat shield made from a refractory metal would protect the window at the front of the craft. This heat shield would then be jettisoned after aerobraking so the pilot could see, and safely land.