While it's true that objects in space experience a lack of weight due to the absence of gravity, they still possess mass. The mass of an object determines its inertia, which is the resistance to changes in motion. Therefore, even though an object in space may not have weight, it still requires a significant force to slow down or stop its movement due to its mass.
When an external force is applied to an object in motion, such as an asteroid, it needs to overcome the object's inertia. In the case of a large asteroid, its mass can be substantial, making it more difficult to alter its motion. According to Newton's second law of motion, the force required to change the motion of an object is directly proportional to its mass and the rate of change of its velocity. Therefore, a large, massive object like an asteroid requires a considerable force to decelerate or bring it to a complete stop.
Keep in mind that weight is the force experienced by an object due to the gravitational attraction of another massive object, such as a planet or a star. In the absence of gravity or outside any gravitational field, an object's weight is zero, but its mass remains unchanged.