[X] My Assistant

[jsheff]

Have you seen these stunning descent images from Huygens?

Huygens views

[Guest_BruceMoomaw_*]

Here's the peculiarity noted after landing by the electrical sensors of HASI -- mentioned in two places on the Web. First, Emily mentions it in her blog entry on the first day of last September's DPS meeting ( http://www.planetary.org/blog/article/00000227/ ):

"There were two little mysteries that Marcello [Fulchignoni] mentioned, but didn't explain. First, his instrument included a permittivity sensor. Permittivity is one physical property you can measure for a substance, having to do with how much it resists the flow of an electric charge. Well, HASI recorded an increase in the permittivity of the Titan surface at 12 minutes after impact. They don't know what it means, and are working first to rule out anything that might be coming from within Huygens to cause that observation. Second, he mentioned that they MAY be seeing some electrical discharge events (read: lightning) in their data. Again, though, they must first rule out anything that was happening aboard the spacecraft as the cause."

The same thing is mentioned on a Powerpoint slide at last September's Titan Conference ( http://www.lpl.arizona.edu/titanconference...ts2/wrk.062.ppt ), with a graph:

"The study of the dielectric properties of materials in the ELF range provides useful information about the surface of planetary environments. Furthermore, the permittivity of many solids and liquids is function of frequency and temperature. From Figure 4, it is possible to identify the impact on the surface and the variation of both amplitude and phase shift. Furthermore, 12 min after landing, a sudden variation both in phase shift and amplitude has been observed, more visible on the phase shift and at lower frequencies...

"The nature of the event observed 12 min after impact on the surface is not understood. Several possibilities are studied, namely mechanical, electrical and surface properties variations."

OK. Was any other event seen by Huygens at that time? Well, there seems to have been no shift in the rate of the very slight, slow change in the craft's post-landing tilt angle at that time -- and, while, the methane level sensed by the GCMS rose dramatically during the first 2 minutes after landing, it then levelled off completely again for the rest of the probe's stay on the surface ( http://www.nature.com/nature/journal/v438/...nature04122.pdf , Fig. 3).

But: there is one other change that does show up at about the same time -- which can be seen on pg. 21 of Dan Harpold's presentation on the GCMS results at last September's Harsh-Environment Mass Spectrometry Workshop ( http://cot.marine.usf.edu/hems/workshop/Wo...day/Harpold.pdf ): the amount of ethane detected started rising at about the same time, and the amount of CO2 just a few minutes later. I have no idea what this might signify, but it is definitely worthy of note.