There were 6 kickoff springs that separated the forebody heat shield from the backshell. Down the axis of each kickoff spring was an explosive bolt that attached the forebody heatshield to the backshell. The kickoff spring insured that the forebody overcame the atmosphere's dynamic pressure and made a clean separation. The kickoff spring might have stayed with the forebody until impact and then bounced out or else fallen loose while in flight. I noticed some little fresh craters in the floor of Bonneville Crater not far from where MER-A's forebody heatshield impacted. I suspect those fresh little craters were from kickoff springs that fell out during flight.

Gary