And even better: suppose the cause of Tunguska was simply an asteroid. Then it would still be a great place to test the first time-travel device to, because the

And even better: suppose the cause of Tunguska was simply an asteroid. Then it would still be a great place to test the first time-travel device to, because the place is already associated with weird things. No one would be able to distinguish between readings and hypotheses of the original event and anything added by the time-travel device.