A team of middle schoolers prepares for blastoff in this adventure from the author of the New York Times bestselling Mousetronaut, based on the childhoods of real-life astronauts Mark Kelly and his twin brother Scott.

It's a long, hot summer and Scott and Mark are in big trouble for taking apart (aka destroying) their dad's calculator. As a punishment, they're sent to their grandfather's house, where there's no TV and they have to do chores. And Grandpa is less tolerant of the twins' constant bickering. "Why don't you two work together on something constructive. What if you built a go-kart or something?" Grandpa suggests.

But it's not a go-kart the twins are interested in. They want to build a rocket. With the help of Jenny, nicknamed Egg, and a crew of can-do kids, they set out to build a real rocket that will blast off and orbit the Earth. The question soon becomes: which twin will get to be the astronaut?

Written by a NASA astronaut with four space flights under his belt, this exciting story includes extensive back matter on the space program with fantastic facts and details.