Richard Penn is a retired ergonomic software designer who now writes hard science fiction set in a near-future version of the asteroid belt. Freedom at Feronia is a close sequel to Dark Colony (2014). In this one, the Terpsichorean team modifies a small ship for a potential trip to Mars. But first, they must raid a colony of religious extremists that is not playing nicely with others. Penn is not a great stylist, but it is refreshing to read a science fiction novel that pays attention to such engineering details as orbital dynamics and spacecraft design. ( )