Odyssey (Academy - Book 5) by Jack McDevitt
'Why read Jack McDevitt? The question should be: Who among us is such a slow pony that s/he isn't reading McDevitt?' Harlan Ellison
To boost waning interest in interstellar travel, a mission is sent into deep space to learn the truth about 'moonriders', the strange lights supposedly being seen in nearby systems.
But the team soon discovers that their odyssey is no mere public-relations ploy, for the moonriders are no harmless phenomenon. They are very, very dangerous ... in a way that no one could possibly have imagined.
'McDevitt's energetic, character-driven prose serves double duty by exploring Earth's future political climate and forecasting the potential dangers awaiting humanity among the stars' Booklist