There was a time when I was really worried about whether or not Huygens' heat shield would fail during its entry of Titan's atmosphere. Huygens aeroshell is covered with Thermal Protection System (TPS) tiles made out of a European TPS material called "AQ60" (It's a little bit like the SLA-561V used on MER's aeroshell). Titan's atmosphere is mostly nitrogen with about 3% methane. The shocklayer around Huygens' aeroshell is hot enough to decompose the methane and molecular nitrogen into atomic species that can then recombine into CN (cyanogen). CN is a very powerful radiator because it is a nonsymmetric molecule. There was concern the intense CN radidation would cause catastrophic spallation of the AQ60 TPS material. I have recently learned some new things that have reduced my original concerns. First, recent data from Cassini has shown there is less methane in Titan's atmosphere than originally thought (less than half as much). Next some recently finished shock tube studies have shown the CN emission to be intense but not as bad as some earlier theoretical models predicted. An AQ60 sample was subjected to radiation lamp tests and it held up well. A few days ago there was an arc jet test where an AQ60 sample was placed in a plasma beam set at roughly Huygens' entry enthalpy. I've seen other tests with different TPS materials where the sample immediately disintegrated as soon as it entered the plasma beam. However the AQ60 sample did very nicely and performed as expected.

Now assuming some ding-dong didn't install a switch in backwards, I think there is a very good chance that Huygens will survive entry (I hope I'm not jinxing it by saying this).

Gary