The crew saw some thing that appeared to have come off the shuttle. they are breaking out the gear to study the outside to see if it was a tile or something that would cause the shuttle to be destroyed or if it is something like a bag of trash that came off or a lump of ice. there is no way of knowing until they get the equipment off. one of the sensors indicated a mild impact, but it could have been vibrations.
the more man learns, the more he realises, he really does not know anything.