The reading and the lecturer are both about " Asteroids ".

The reading and the lecturer are both about " Asteroids " . The professor in the lecture totally disagrees with the three reasons in the reading passage. In fact, the professor believes that these three reasons won't lead to satisfaction consequences at all. First of all, the author suggests that the asteroids are often much smaller than planets, so they have lower gravity. This argument is challenged by the lecture. The professor says that people who live in a low-gravity environment would suffer from muscle loss and lower bone density. Even those astronauts who just spend a short period of time in the spaceship would also have muscle and bone density loss. Secondly, the writer contends that Mining Valuable Metals Next some asteroids are rich in valuable elements and precious metals that are relatively rare on Earth, such as gold and platinum. The lecturer, however, rebuts this by asserting that points out one potential problem in it. The costs of mining and transporting these materials back to earth would be so high that the profit could be quite minimal. Finally, it is stated in the article that asteroids are a good option for colonization because some of them would be very easy to reach. The lecturer, on the other hand, posits that asteroids are easy to reach but not that easy to return from. When an asteroid comes near to the Earth, it is indeed convenient to get onto it. But some orbital paths of asteroids are not predictable, they could get quite far away from the Earth. Under this circumstance, getting back from there would be a challenge.