Chapter 6 -10

10 astronomy

listen to a discussion in an astronomy class. Fill in the diagram with the information that you hear.

W: We’re been talking about the lunar landscape and lunar soil, today I want to pose an interesting question to you, one that scientists are grappling with as we speak.

Is there water on the moon? Or, theoretically, could there be water on the moon? It would seem that yes, water could be on the moon.

We just haven’t found it yet. Especially since we’ve talked about how the moon likely shared a similar origin with Earth.

M: But how can there be water on the moon if there is no atmosphere and little gravity?

Wouldn’t any water that may have been on the moon have evaporated a long time ago?

W: Yes, Earth and the moon share similar origins, but scientists think that if there is water on the moon, it likely came from comets and meteors that contained ice and crashed into the moon.

This is also a theory of how Earth got its water, but what you said is correct. Any water on the moon’s surface would evaporate quickly.

That’s why scientists think any water on the moon would have to be in the form of ice, specifically underground ice deposits. These can be in the form of crystals or perhaps larger bodies of ice.

W: You mean like an underground ice lake or something?

M: Exactly. That’s exactly what we are talking about, possible frozen underground ranks. Now, if ice were on the moon, where would you start looking?

M: The polls. They are the coldest. That’s where they are looking for water on Mars too, and it’s where ice is found on Earth.

W: Right. You’d look for ice in the polar regions. Well, when investigating any theory, as you all know, scientists make the best guesses they can possibly make, and then seek evidence to support or disprove the theory.

Let’s take a look at the evidence in support of there being ice on the moon.

Now, scientists have been thinking about this problem since the 1960s, but it wasn’t until 1996 when they got their first solid evidence.

A spacecraft called Clementine was sent to investigate the lunar South Pole and sent back the first evidence of potential water.

Its radar suggested that it had found deposits of water ice a few meters under the moon’s surface.

Then in March 1998, a second spacecraft, Lunar Prospector, confirmed what Clementine had found. Even more, confirmed that there are large deposits of water ice at both the moon’s north and south poles.

M: Hoe did they know the ice was there if it was underground? That’s what you said, right?

W: Good question. They know because they found indirect evidence in the form of hydrogen.

M: What do you mean by that?

W: What I mean is that instruments on the spacecraft detected hydrogen. Hydrogen, as you know, combines with oxygen to form water, the chemical formula being H2O, for two hydrogen atoms joining an oxygen atom with water being the result.

The instruments on Lunar Prospector could not detect H2O, but it could say if there was or wasn’t any hydrogen present, and what the instruments showed was lots of hydrogen, enough for perhaps trillions of tons of water ice.

But the scientists, being scientists, were not satisfied with indirect evidence. So guess what they did next?

M: They got samples of ice to bring back?

W: That would be ideal, but at present it’s too expensive and difficult. They had a simpler solution. When Lunar Prospector was ending its lifetime, the scientist crashed into one of the craters where ice was expected to be located.

They had hoped that the crash would cause water vapor to be released. If that happened, they could see the water vapor with powerful telescopes, and it would give direct evidence for the presence of water ice.

However, they knew the chances were very slim, less than ten percent.

M: So, did they find the water vapor?

W: Unfortunately, no. They did not detect water vapor from the impact, but that does not mean that there is no water on the moon since there are many uncertainties. For the time being, we’ll just have to stay tuned and see what the scientists could up next.

1) Based on information from the discussion, to which spacecraft does each statement relate? Place a checkmark in the correct box.