flateric said:'Test and lab equipment' looks very suspicious...could it be pre-MOL?
Orionblamblam said:You know where to go for more data... ;D
Post #1, left, that is indeed the McDonnell one-man space station, civilian version, derived from the military test space station (MTSS).
Details in "McDonnell’s Military Test Space Station (MTSS)"
https://thespacereview.com/article/5176/1
...Actually, old buddy, this begs the question as to whether you've ever come across any concept diagrams of how McD was going to handle the EVA hatch on a Mercury. It would *have* to be outward-opening, but the real issue is whether the hinges would have to be outside due to space constraints.