answer: #Person1# and #Person2# talk about the existence of water, the quality of soils, the presence of life, and the possibility of humans living on Mars.
documents: #Person1#: I'm reading an interesting report on Mars.
  #Person2#: Oh, what does it say? Does it say water could still exist under the surface of Mars?
  #Person1#: Absolutely! It says there is water on Mars buried beneath the surface. It's just a matter of how deep it is.
  #Person2#: Then could the soil on Mars somehow be fertile enough to grow simple plants?
  #Person1#: The soil would need quite a bit of fertilizer to grow anything. And it would need to be protected from the UV radiation.
  #Person2#: Actually, we are doing a project in school that involves landing a ship and staying on Mars for an extended period of time. Does NASA have any type of portable habitats that could be used to stay on the planet?
  #Person1#: I'm not sure NASA has built any portable habitats for extended stays on Mars, but they have looked at various designs.
  #Person2#: One of the most exciting things about Mars is that there could have bean life on it. What are your personal opinions on the life on Mars theory?
  #Person1#: Well, I'm not really an expert in this area, but my understanding is that anything is possible. It's just that it is so hard to determine what went on 4. 5 billion years ago.
  #Person2#: But maybe there is a chance of gradually improving the surface and atmosphere of Mars so it may be inhabitable by humans.
  #Person1#: I'm skeptical. Mars is made of rocks containing silicon, iron, and various minerals. It also has an atmosphere of carbon dioxide. It is so different from what we have on earth, you know.
  #Person2#: I'd still like to hope that some day we could set up a human colony there.
  #Person1#: But there are still other big problems we need to solve such as prolonged weightlessness, food storage, and a series of physiological effects.