The others

This prize was the sum of 100,000 francs, to be given to a person who succeeded in communicating with extraterrestrials. Mars was ruled out as being too close, and too easy because life definitely exists on Mars! Grandma has a competitor, the evil professor Pinfield. Reuben isn't allowed to leave the observatory but one day he sneaks out and discovers an alien whom he calls Blue. Professor Pinfield wants to capture Blue and put her in a cage. Can Reuben save Blue? And who is Reuben and why did Grandma never allow him out of the observatory?