Answer:
The movement of atoms in Soviet Union spacecraft would have been similar to that in any spacecraft or object in motion. In the absence of any external force or influence, atoms in an object will continue to move with the object in a straight line at a constant speed. However, in a spacecraft, the movement of atoms would also be affected by various factors such as the gravitational pull of celestial bodies, air resistance in the atmosphere, and the movement of the spacecraft itself, among other things.