8/22 practice The reading passage explores the benefits of colonizing asteroids. The professor's lecture deals with the same issue. However, he thinks that the ideas of the reading passage are not practical. And in the lecture, He uses three specific points to support his idea. First, the reading passage suggested that the low-gravity environment would make landing and taking off easier and allowed a spaceship to carry less fuel for the trip back to Earth. The professor rebuts in the lecture that the low-gravity could also present certain risks. For example, astronauts may lose their muscle mass, and their bone density would be lower as a result of settling in a low-gravity environment a few months. He mentions that we should not ignore the health risks from a low-gravity experience. Obviously, the professor's argument disproves its counterpart in the reading. Moreover, contrary to the statement in the reading that an asteroid could be significantly profitable in providing some rare metals, the professor contends that abundant resources do not directly result in profitable mining. First, he supports this point with the fact that the costs of mining and transporting these metals to Earth would be extremely high. Besides, he argues that no one can guarantee that the price would remain at a profitable level with the increased supply. Finally, the author of the reading asserts that asteroids would be easier to reach since some of them are near Earth's orbit periodically. In contrast, the professor claims that it may cause a problem when colonists come back to Earth. This is because the asteroids will not stay close. The distance from the asteroids to Earth is changing all the time. Therefore, there is a high possibility that an asteroid could be far away from Earth when a spaceship wants to get back. Consequently, it could be a considerable challenge for the spacecraft to travel in such a long distance.