Over the years, NASA has studied the moon in various ways: through orbiting satellites and even by astronauts landing on the moon! But some scientists have considered the option of building a base on the moon. This would be a permanent station on the surface of the moon, which would allow scientists to gather even more information. What Model Should Be Used?
Years ago, scientists built a permanent station in the icy region of Antarctica. Since we've already had this experience, it makes sense to use the Antarctica base to model a moon base in certain ways. For example, at first, several countries claimed those parts of Antarctica that they explored. However, over time, those countries agreed to share. And in 1959, they wisely agreed to collaborate and avoid individual claims to parts of Antarctica.
Since then, Antarctica became a continent without countries. It is open to all countries for scientific work, but no country may take its resources, build a military base, or put weapons there. Our moon base should be similar. It should be a cooperative effort of all the countries of Earth. All countries should be given the right to join if they wish to. The moon should be set aside as a preserve. No country should be allowed to claim any part of it. Like Antarctica, the moon should be open to all countries for peaceful work. For Which Purpose?
| A permanent moon base would offer great opportunities for scientists to study outer space. For one thing, telescopes built at a moon base would be much more powerful than telescopes that are put into orbit. Telescopes launched into space can have fragile parts altered, moved, or broken as a result of being launched. A telescope built on the moon would not have to survive a space launch; therefore, a telescope built on the moon could be more complex.
In addition, the moon's gravity is much weaker than Earth's gravity. Space vehicles launched from the moon could be smaller, lighter, and more cost-effective than those launched from Earth. That means that space vehicles could be launched from the moon to travel to other planets, such as Mars or Venus, for less money than if they were launched from the surface of Earth. Why Permanent?
Today, our space program is costly. This is due to many factors. Building advanced technology such as a space shuttle is a very costly process. In addition, sometimes a rocket is used for a single trip and then discarded-never to be used again! We launch a satellite into orbit and then allow it to burn up on re-entry. NASA's current practices are wasteful. In the long run, permanent equipment is cheaper than temporary equipment. A permanent base would make better use of our resources, our energies, and our money. A permanent base can grow, expand, and improve over time. Why Robots?
Not only should we build a permanent base on the moon, but it should be installed with a plethora of robotic equipment. Yes, granted, some human scientists would be necessary to manage and maintain the robotic equipment and moon station. But overall, having a supply of robotic equipment on a moon base may be more important than having a lot of human astronauts.
First of all, it is easier to send a machine out into space than a human. A machine doesn't need an oxygen supply and can roam over difficult terrain better than a human astronaut can do in a space suit. Second, machines can be used under very harsh conditions, such as in sub-zero freezing temperature—whereas such conditions can pose a real threat to human astronauts. Lastly, all human astronauts must eventually return home. This is due to many factors. Astronauts can develop health issues in space, or they may want to return to see their family. No matter what, a prolonged stay in space wears on the human body. On the other hand, machines can operate in space for very long periods of time. When NASA sent the robotic explorers Spirit and Opportunity to Mars in 2003, they were expected to survive ninety days. More than six years later, these helpful robots were still sending useful data back to Earth. A human mission may do some things that a robotic one cannot, but outlasting its planned stay is not one of them.
| All in all, establishing a permanent international robotic base on the moon seems to be a logical course of action. Humans can maintain the base and analyze the data brought back by advanced machines. Such a well-organized base will surely result in major scientific discoveries!

21. In what way does this passage contain
incomplete information?
A. The author does not provide any
data about the cost or time involved
in building a moon base.
B. The author does not explain how a
moon base would decrease the costs
of space exploration.
C. The author does not say who would
live on the moon base.
D. The author does not support his
opinion with facts.