Have you ever thought about what it must be like in space? That shit is scary. We take for granted that we have an atmosphere to disperse light, as well as a ground for light to reflect off of. In space, some shit could be right in front of you and you would have no idea. If there were an asteroid between you and the sun, you wouldn’t realize until it was so close that there was a huge black spot covering the sun up.

Because of the soildier attempting to hide behind the rock (middle right)

Perhaps because you can see mountains at the same scale that allows you to clearly see the object's horizon/curvature. It would be like if Earth had mountains thousands of miles high. It's a landscape that feels deeply unnatural.

Immediately made me think of Lake Mungo

It is a very safe place, as all people are extremely far away.