The Outer Space Mystery

The Boxcar Children are going to college! That is, they are going to Mountvale College to help Grandfather at a convention of young astronomers. The Aldens learn many interesting things, and get to look at the stars and planets through a telescope at the observatory. But then some valuable information disappears - along with one of the students at the convention. What's going on? It's another mystery for the Boxcar Children!