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I’m looking for a book I remember. A girl her father and brother (?) leave earth on an ark ship headed to another planet. After several years (?) they arrive on the new planet, but it is much harder to survive than anyone thought.
I specifically remember crops not growing the way everyone thought they would and their animals dying. Wheat is crystalline and practically inedible, etc.
There were also some kind of moth people.
The kids end up helping everybody because they are more adventurous than the timid adults and try new foods etc.
They get through the first year and realize they should be recording their history in some way.
They find out the girl had been keeping a diary and begin reading it aloud. The first sentences are the first ones of the book.