With more than a dozen volunteers gathered around him, geologist Chenzung Wang wheeled a cart across a small patch of grass on the outskirts of the former Loring Air Force Base. “Take a look,” he said, pointing to a blip on the cart’s computer screen. A white parabola appeared in sharp contrast to the soil around it. Picked up by ground-penetrating radar, the anomaly, as Wang referred to it, indicates that, 5 or 6 feet underground, are the remai…