Section D Robots are useful in exploring space because they can work in the conditions which exist in space. Such robots usually look like boxes with wheels. Though these robots are useful, however, they are extremely expensive—they break easily and they cannot do very many tasks. Because of these problems, scientists have been working on a new and unusual kind of robot. These new robots will look and move like snakes, so they have been given the name ‘snakebots'. The way a snake is shaped allows it to do special things, such as getting into very small spaces, like cracks in rocks. Snakes can also push themselves underground, and climb up different kinds of objects, like rocks and trees. Such abilities account for the usefulness of robots designed like snakes, because they will be able to do these things, too. Such robots would be much more effective than regular robots with wheels. Wheeled robots easily get stuck and fall over, but snakebots would not have these problems. They could go almost anywhere and so would be useful for exploring the different environments of other planets. Since they can carry tools, snakebots would be able to work in space, as well. They could, for example, help repair the International Space Station. How do you make a robot shaped like a snake? A snakebot is put together like a chain, made of about thirty parts, or modules. Each module is basically the same—they all contain a computer and a wheel to aid movement. The computer in the ' head' of the snake makes the modules work together. If one module fails, another can easily take its place. Snakebot modules can also carry different kinds of tools, as well as cameras. Since each module is actually a robot in itself, each module can work apart from the rest if necessary. The snakebot design is much simpler than that of most common robots. Thus, snakebots will be much less expensive to build. One of the robots sent to Mars cost over a hundred million dollars to build. However, snakebots cost as little as a few hundred dollars to make and could therefore save enormous amounts of money on future space missions. With their versatility and affordability, snakebots will be the way of the future; at least as far as space robots are concerned. Summary: It is much easier to send robots, rather than people, into space, but scientists have found that robots with wheels are not the most【46】______ones. This is because there are many problems associated with today’s robots: they are very expensive, they【47】______and cannot do many tasks. In fact, for exploring places with lots of obstacles to go over or under,【48】______work better than wheeled robots. They are made of separate parts, or【49】______, each of which is actually a robot in itself. Snakebots can go almost anywhere and do many different kinds of tasks. It looks as though robots shaped like snakes will be the way of the future owing to their【50】______. (46)