SOLVED: YA/Sci-fi book about girl living on huge spaceship, must live through rite-of-passage on supposedly deserted planet [s]

[Lorena]

This is a book I read probably somewhere in the mid-80s about a girl who lived on a massive spaceship, big enough to have enormous forests and other ecosystems on board. The children were taught basic survival skills, and when they were 12 or 13, they were left on an inhabitable planet with no intelligent life forms for some specific period of time to survive on their own as a rite of passage. It was up to the children whether they spent that time exploring around or just made a shelter and dug in for the duration (this was called "going turtle" or "tucking turtle" or some variation on that). The main character girl discovered something sinister on board her spaceship before her planet trip, and as a result her group was dropped off on a planet that was actually inhabited and unaware of other off-planet life, and she was captured and held past the time she needed to get to the pickup point to return to her ship. I believe one of her friends (a boy she liked/liked her) also stayed behind to rescue her, and then managed to escape the locals and were eventually rescued by a group from their spaceship, and revealed the sinister secret.

[Dawn]

Rite of Passage?

[Lorena]

That's it! Thanks, Dawn!

[Carolyn]

I recognized the plot from your description Simone - especially the 'going turtle'! I loved this book, must've read it when I was 13 or 14 (quite a while ago!)

Thanks for the title Dawn!