Children's/YA Sci-Fi novel where kids steal spaceship

Question

I'm trying to remember a sci-fi novel, probably from the 80's or 90's, I read the first few chapters of in 5th grade. In it two kids, a girl and a boy, steal a spaceship from their school. They go into space and get held-up and captured by some aliens with freeze rays, this was as far as I got in the book. The book was written in first person from the perspective of the girl, and it had a comedic tone. The two kids had a crush on each other.

Some other things I remember:

• The parents of the girl were either astronauts of some other kind of scientists
• The parents worked for some organization that's name was NASA but with one or two extra letters, like CNASA or something
• Ganymede had been turned into a retirement community
• I think the school was in Mexico, but I might be conflating this with some other book
• The kids took the spaceship on the last day of school before vacation
• Earth had established diplomatic relations with alien life forms
• Shortly after being captured, the girl tries using an alien toilet but is confused how it works

Answer 1

I believe this would be I Spent my Summer Vacation Kidnapped into Space by Martyn N. Godfrey. The name of the space organization was NASA-O (the "O" probably standing for "offworld;" I don't have the book on hand at the moment to check). I do recommend it, a lot of interesting stuff happens after the point you stopped reading.