Asteroids are large space objects made of rock and ice. There are hundreds of thousands of asteroids in our solar system. Though we often hear ideas about establishing colonies of humans to live and work on our Moon or our neighboring planet, Mars, some think that sending people to an asteroid

There are ( Asteroids are )some large space objects made of rock and ice called asteroids. Some people think they [ these objects could be] are better options for colonization than other planets like Mars [ in terms of colonization ]. However, in this lecture, the lecturer argued[s  ] it[ that living in asteroids ] is [may  ] not[ be ] as positive as this passage expected[assumes  ].

First of all, although low gravity can provide safe landing on asteroids, people’s health can be a problem. People will meet healthy proplems in a low-gravity environment, for example, their muscles would be weaker and bone density problem can risk their health.

First, extremely low gravity would pose a serious health threat to people in landing on asteroids. As scientists suggest, people’s muscles can become weaker and their bones can become less dense under this low-gravity environment. 

It is agreed that there are abundant metals in asteroids. However, they may not as valuable as people expected. The cost of exploring these metals can be huge, and when they are brought back on the earth, there is no guarantee that these metals will be more valuable than the money cost, especially when too many metals are explored.

Finally, as this passage said, it is actually easy to reach some asteroids because they sometimes come within of near Earth’s orbit. However, it is not easy to return. As asteroids run periodically, they can be close when reaching them, but they will go far after that. It may farther than the way to Mars when you want to go back.