Even more space

 Here's another book I looked up while I'm in the children's sci-fi frame of mind - Space Trap, by Monica Hughes!

I didn't remember the title, or the writer - I thought it might possibly have been another Nicholas FIsk, though it's not entirely his kind of style. Luckily, I remembered that there's a slightly tetchy robot called Mr Isnek Ansnek, so it was easy to google. All books should be so convenient - I'm still drawing a blank with "the one with a talking dog, possibly called Bob, and a plot involving the hole in the ozone layer"...

But Space Trap comes with a description on Open Library saying "When twelve-year-old Valerie and her brother and sister fall through a space trap and are transmitted to an alien planet, they seek ways to return to the thirty-second century." - which isn't exactly what happens. They're still in the thirty-second century, they're just on a different planet. And really, it's all about seeking the one unique way to get back to the planet they started out on, but that's just being pedantic.