Strange quark matter in cosmic ray flux and exotic events

There have been several reports of exotic nuclear fragments, with highly un usual charge to mass ratio, in cosmic ray experiments. Although there exist experimental uncertainties which make them, at best, only candidate `exoti c' events, it is important to understand what they could be, if they are ev entually confirmed. Among other possible explanations, some authors have in terpreted them to be lumps of strange quark matter (strangelets). A major p roblem with such an interpretation is that to reach the earth's surface, th ey must possess an unusually high penetrability through the terrestrial atm osphere. We show that a recently proposed mechanism for the propagation of strangelets through the earth's atmosphere, together with a proper account of charge capture and ionisation loss, would solve this problem. We also ar gue that this could lead to viable strategies for definitive detection of s trange quark matter in cosmic ray flux using a ground based large area arra y of passive detectors.