A floating rock that holds two astronauts is not stable at all; it is a controlled fall disguised as stillness. Around any large body, orbital mechanics dictate that an object must constantly accelerate toward the center while its tangential velocity bends that fall into a closed path, a balance expressed by the equality of gravitational acceleration and the required centripetal acceleration for that orbit.
The odd truth is that those astronauts never stop falling, yet they feel planted because the rock, their bodies and even loose tools share one identical trajectory. In a circular orbit, the orbital velocity sets the pace: match that sideways speed and you share the same geodesic in spacetime; miss it, and gravity either drags you inward or lets you drift away, breaking the illusion of standing on a solid floor.
The real trick is local gravity. If the rock is small, its own gravitational field is negligible, so contact forces and friction alone keep boots in place while the whole system free falls together under the dominant pull of the nearby planet or moon. Give the rock just the right orbital velocity vector, align the astronauts with it, and their perch exists only as long as that invisible equation keeps balancing.
