Weightlessness on the ISS?

I think of it this way: Imagine firing a bullet from a gun that is aimed horizontally. That bullet will eventually fall to Earth, a hundred yards away or so. Now increase the bullet's velocity. The bullet will now fall to Earth a couple of miles away. But the Earth is not a flat surface. If you increase the speed of the bullet sufficiently, and remove the air so it is not encountering any resistance, the bullet will fall in a path that matches the curvature of the Earth. It will then continue to fall around the Earth, but it will never hit the ground. That is what an orbit is. The ISS is constantly falling toward the Earth, but it is moving horizontally at just the right speed so that it falls around the Earth instead of actually contacting the surface, or flying off into space. That is the tricky part about launching satellites. You have to get the speed and the altitude right, or the orbit will not work. Looks like they did a good job on the orbital parameters for the ISS.