The Olympus Mons mountain on Mars is so tall and yet so gently sloped that, were you suited and supplied correctly, ascending it would allow you to walk most of the way to space. Mars has a big, puffy atmosphere, taller than ours, but there’s barely anything to it at that level. 30 Pascals of pressure, which is what we get in an industrial vacuum furnace here on Earth. You may as well be in space. Imagine that. Imagine a world where you could quite literally walk to space.