Rogue Colony. Galaxy Mavericks, #6

She was just a nonprofit volunteer trying to figure out her life. Then the disappearances began.  Michiko Lins is a Galaxy Corps volunteer, a disaster response team assembled to help after emergencies. She joined to take her mind off dropping out of nursing school, and to avoid her parents' wrath. When a moon in the galaxy mysteriously disappears after an alien attack, she signs up to help the survivors.
She makes some good friends along the way. But it turns out that moons aren't the only things disappearing. V1.0