The Lion of Mars by Jennifer Holm is spot-on for this grade level, and timely with Mars in the news.
The Boy Who Harnessed the Wind is available in a variety of "for younger readers" versions: picture book, grade 5-8ish, and adult.
See You in the Cosmos by Jack Cheng is good--lots of meat there for discussion, and an unusual (podcast trnascripts) format.
Space Case by Stuart Gibbs--murder mystery on the Moon, featuring a 12-year-old
Cathy Andronik
(Retired) Brien McMahon HS/Presenter, Bureau of Education & Research