This is a remarkable picture. I think(?), the heatshield is laying with its interior surface up. An undamaged separated forebody heatshield looks a little bit like a frisbee. The heatshield has a big thick lip that goes around its circumference. The edge of this lip is where the flow expansion starts and is the second hottest part of the heatshield during peak heat flux. The hottest part is at the stagnation point which is dead center on the exterior. The interior of the heatshield appears to be silvery in color while the exterior appears to be black. The exterior of MER's heatshield was made out of SLA-561V which had a tan/orange color before it charred black. During fabrication, the SLA-561V was packed by hand as a paste into a graphite composite honeycomb (Hexcel is the manufacturer on the graphite composite honeycomb). This graphite composite honeycomb was glued to a graphite polyimide face sheet. The face sheet was next glued onto an aluminum honeycomb. The backside of the aluminum honeycomb was also glued to a graphite polyimide face sheet of the same thickness, 0.0148 inches. This backside is what we should be seeing. Here's a mystery: The polyimide face sheet should be black but I see a silvery color. Did Lockheed-Martin put a layer of Mylar on top of the polyimide to line the interior of the heatshield? It's not in the speicification. The Mylar would have protected MER from outgassing. I'm not comfortable with this theory. Another possibility is the polyimide face sheet blew off when the heatshield slammed into the Martian surface (the heatshield would have been going pretty fast). If the face sheet blew off then we're looking at the aluminum honeycomb. There were also six explosive nut, kick off spring assemblies that attached the forebody heatshield to the back shell. Metal flanges would would have stayed with the forebody while the kick off springs would have flown off. If you look at the pan shot of Bonneville crater, you'll see a small perfectly round crater in the dust. My guess is there's a kick off spring in the middle of that round crater. I wish we could get a closer look.

Gary