In an attempt to better understand their daughters better, their parents bring them to the observatory. With this newly equipped information, Riley sets her sights on building and completing a full-scale rocket which the girls use to go on an out-of-this-world journey. (15th or 16th book in the Snow Day series)

After Dr. Tenma's son, Toby surprising shows up back home after the peacekeeper's big explosion. The father of Toby and now Toby's robotic identical-looking twin Astro. The Doc surprisingly suggests the three of them go on a trip... to the surface of Mars.

Donna has taken her friends mini-golfing on Mars, that's when they uncover the first human born on Mars, "Gardner Elliott". Wanting to visit Earth and meet his real father for the first time. They snook him on the millennium falcon. Now they must follow clues to figure out the father's identity.