American Girl in Space: Amelia Takes Command by Marissa Moss (Middletown, WI: Pleasant Publications/American Girl, 1999)
A bit sad because the "frame" of this book is a girl dealing with a bully, but the central part--spent at space camp--is not skimped on so the book does work as sf.
Amelia is being bullied at school. When her friend Nadia asks her to come to Space Camp she decides to go. She competes with three boys for the place of commander on the simulator and wins, to the boys's shock because they hadn't thought her in the running. We get a lot of description of what she has to learn, in such a way that we can choose to learn it too, and when things go wrong on their "flight" Amelia takes command and makes decisions about how to maneouver the rocket.
The book ends with a return home, a maths test, and telling off the bully. This seems the most important bit, but I did find the time at space camp well done, and I can imagine some girls getting hooked on that bit, even though Amelia doesn't seem to carry it home with her (her last thoughts are of her grandma's Depression diary).