Air And Vacuum

In Poul Anderson's Satan's World, the giant quadrupedal Wodenite, Adzel, bounds across the Lunar surface in his armoured spacesuit. In sf, we have come a long way from a breathable atmosphere on the Lunar surface in HG Wells' The First Men In The Moon or inside the Moon in ERB's The Moon Maid.

David Falkayn, rescued by Adzel from Serendipity Inc.'s mountain castle, survives a brief passage through vacuum while he is hauled inside the trade pioneer crew's spaceship, Muddlin' Through. I had learned from Arthur C. Clarke that a human being would be able to survive a (very) short period in a vacuum. Before that, I had instead heard that the pressure of the Terrestrial atmosphere - 15 pounds per square inch? - on our bodies is counteracted by an equal and opposite pressure from within our bodies so that a human being placed in a vacuum would explode. Was this on a par with the also heard statement that a rocket would not be able to move a spaceship through a vacuum because it would have nothing to push against? I recently heard it claimed that astronauts cannot have reached the Moon for some such reason.