At least since the first manned missions to the moon in the 1960s and early 1970s, the general belief had been that the moon was totally dry. Then, about two years ago, several lunar missions showed that’s not absolutely true. Some lunar soil contains very small amounts of water molecules(分子). But where did the water on the moon come from? Answering that question can help us understand the moon’s history and evolution, and allow future engineers to potentially use this resource when building a sustainable moon base.
Chinese scientists have discovered that minerals in lunar soil might have got water from solar wind, which bombards(轰击)the moon’s surface with hydrogen ions(氢离子), according to a study published in the journal Nature Communication. The study found that lunar minerals may contain water content up to 179 ppm. One ppm of water would produce around 1 gram of water per ton of soil. The latest study confirms the estimates from the previous research, and those lunar minerals could contain even more water. Moreover, the new study identified solar wind as a key mechanism(途径)for the existence of the water on the moon’s surface. Solar wind resulted in at least 170 ppm of water content in lunar samples gathered by the Chang’e-5 mission.
Scientists around the world now propose three sources for the water on the moon:that it was created in the moon’s interior when it was full of volcanic activity, that it comes from solar wind, and that it was brought by comets and meteoroids crashing into the lunar surface.
Lunar samples collected during the Chang’e-5 mission may hold the keys to answering these questions, since they are much younger than the ones collected by US and Soviet moon missions. Because of this, the water content in the Chinese samples has had less time to be influenced by other factors, making these samples ideal for studying the moon’s water.
【小题1】What did people generally believe before the1970s?| A．The earth was going around the moon. |
| B．Some lunar soil contained water. |
| C．Engineers knew the moon’s history. |
| D．There was no water on the moon. |
| A．Solar wind could result in the water on the moon. |
| B．Other planets brought water to the moon. |
| C．The water on the moon was created in volcanoes. |
| D．The water on the moon is being used on the moon base. |
| A．It has been less influenced by other factors. |
| B．It contains more water than those collected by US. |
| C．It is the youngest sample influenced by the solar wind. |
| D．It was taken from the moon’s interior and less polluted. |
| A．China’s lunar samples contained most water from the moon. |
| B．Studies on how water got on the moon are still proceeding. |
| C．The water on the moon reflects the moon’s history and evolution. |
| D．Scientists are debating over the resource of the water on the moon. |
