Analysis of the ejection mechanism for Martian meteorites is proceeding, but in the meantime it needs to be noted that the most likely mechanism is that of relatively tangential impacts, instead of direct impacts.

In the case of direct impacts, the pressures seem to be enough to fracture or pulverize the rock instead of ejecting it; for tangential impacts, the forces seem to be quite adequate for ejection without pulverization. The search for these tangential impact features is continuing.

Take a body in space, in a field of debris from the formation of its solar system. If the shape of that body changes, as in the formation of a large volcano, it will now intersect debris which formerly missed it.

EP