Yes, the International Space Station (ISS) is constantly changing its vector due to its orbit around the Earth. It orbits the Earth at an altitude of approximately 400 kilometers (250 miles) and completes roughly 15.5 orbits per day. This means that the ISS is constantly accelerating towards the center of the Earth due to the gravitational force acting upon it.
The acceleration of the ISS is always directed towards the center of the Earth, causing it to continuously change its direction of motion. However, despite this continuous change in velocity and direction, the magnitude of the velocity of the ISS remains relatively constant, resulting in a nearly constant speed.
When astronauts are inside the ISS, they are in a state of freefall, just like the ISS itself. They experience microgravity because they are falling towards the Earth along with the space station, essentially in orbit around the Earth. As a result, the astronauts and objects inside the ISS are in a state of apparent weightlessness.
Since the astronauts and objects inside the ISS are also in freefall, they do not experience the sensation of acceleration or feel a force of acceleration due to the continuous change in velocity or direction. They are essentially floating inside the space station, experiencing weightlessness.
In summary, while the ISS does constantly change its vector due to its orbit, the astronauts inside the ISS do not feel a force of acceleration or experience any significant effects of the changing velocity. They remain in a state of apparent weightlessness due to being in freefall along with the space station.