R.L. said:

>But, despite its failures, NASA has proven remarkably capable
>when designing for alien environments. It is VERY unlikely we will
>see the fireball, and I have no say on what instruments will be
>used- (not complaining, mind you, I am not an astronomer and I
>wouldnt be qualified to make such decisions- our Titan expert
>across the hall from me will probably make those decisions)
>Also, Titan does not require the laser to observe it, so alas I will
>be out of the loop mostly."

The Huygens probe is actually ESA and not NASA. If it was NASA,
I'd be more comfortable about success.

>I assume your reference to cyanide emission lines is because the
>methane and nitrogen when broken down in a plasma will
>form HCN...?

No it's actually CN. The shocklayer of the Huygens probe gets very
hot and generates weird species that you'd normally not find in a
CRC handbook.

----- Important ----

Please tell your Titan expert across the hall that the main CN shocklayer emission wave length is centered on 384 nanometers
and the second peak is centered on 358 nanometers. A transmission filter that admits the range 340 - 400 nanometers
would be ideal for observing Huygens' entry. This information is
based upon unpublished nitrogen/methane shocktube data.

The data should be acquired as intensity versus universal time synchronized to a recognized time standard. Normally we model radiative heat flux as a function of nose radius, free stream atmospheric density and free stream velocity. During entry,
Huygens will gather data though its inertial measurement unit (IMU) indicating free stream density and velocity. However Huygens
does NOT have a calorimeter on its heat shield and will not be running a photometer during actual hypersonic entry (we're
not happy about that). Keck telescope data about the shocklayer CN radiation intensity coupled with Huygens' IMU data might
enable us to reconstruct an accurate radiative heat flux model. Also
I believe(?) Huygens is not transmitting real time telemetery while
the heat shield is still attached. If Huygens augers-in, we won't
know what killed it. However if you folks show a complete CN radiative heat flux time history then it's probably a safe bet that the
heat shield didn't fail and Huygens augered-in due to something bone-headed like putting a switch in backwards, an EDL software glitch, etc. This observation by Keck could potentially be very important to the Space Program and future Titan exploration.

Gary