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The planet Mars is the closest and most similar planet to Earth. It is veryto scientists. For example, Mars has seasons withweather, but other planets have the same temperatures all year round. Was thereon Mars?
To find out, scientists needif Mars ever had water. In 2004. two robot explores (探测器), or 'rovers', called Spirit and Opportunity were sent to look forof water. These rovers can drive over rocksall kind of rough ground. They can also use cameras and send photos to Earth. First, the two rovers found chemicals and patterns (图文) in the rocks that were probably made by water. Then, they moved to another area andother rocks which may have been created by water. Now scientists think there was probably water on the planet long ago. Today are still not sure if there was life on the mars. Theyneed more information to decide. The discoveries of the two rovers answered some old questions, but they also brought up many new ones.
