When he navigates away from the shuttle it doesnt accelerate off into the distance. It is not under any force of acceleration. Its like if you get out of a car while its moving super fast. You move with the car until the air or ground slow you down. Theres no air or ground out there. So he just moves with the shuttle. The reason the shuttle moves relative to earth rather than relative to the sun along with earth is due to the exponential nature of gravity. The suns gravity is not nearly as strong as the earths gravity when youre so far from the sun and so close to the earth. And so the shuttle and the astronaught outside the shuttle just orbit the earth. Maintaining their paths until some force acts on them. He could float next to the shuttle for hours without any propulsion at all. But im sure you have read and failed to understand basic physics explanations like this countless times in your quest to remain retarded.