[X] My Assistant

[paxdan]

Nasa Watch is reporting that we shoud expect a large announcement from the Cassini team today:

My wild speculation is that it will be a subsurface ocean confirmed on enceladus. Hence more potentially habitable real eastate in the solar system.

Heads up anyone?

[Anne Verbiscer]

I wouldn't be too quick to dismiss ammonia on the surface of Enceladus just yet. Models of Earth-based spectral observations support the inclusion of modest amounts (as much as 20%) of ammonia hydrate (1% NH3 H2O) in an intimate (salt and pepper type) mixture and 15% and 10% ammonia hydrate in areal (checkerboard) mixtures on the leading and traiiling hemispheres, respectively.

[volcanopele]

I wouldn't be too quick to dismiss ammonia on the surface of Enceladus just yet. Models of Earth-based spectral observations support the inclusion of modest amounts (as much as 20%) of ammonia hydrate (1% NH3 H2O) in an intimate (salt and pepper type) mixture and 15% and 10% ammonia hydrate in areal (checkerboard) mixtures on the leading and traiiling hemispheres, respectively.

Wonder how your spectra reconcile with the lack of ammonia (or at least less than 1%) found in the plume by INMS?

I read your paper about a month on the Icarus website. I'll give it another read.

BTW, welcome to the forum!

[Anne Verbiscer]

Wonder how your spectra reconcile with the lack of ammonia (or at least less than 1%) found in the plume by INMS?

I read your paper about a month on the Icarus website. I'll give it another read.

BTW, welcome to the forum!

First of all, our spectra measured the surface of Enceladus, not the plume, as measured by INMS. (Or were you
asking how the spectra of the surface can be reconciled with the composition of the plume as measured by INMS?)
Second, INMS is measuring pure ammonia rather than ammonia hydrate. The amount (by weight) of pure ammonia in
the hydrate used in our spectral models is only 1%, so the two measurements may be more similar than they appear.

Still, particles in the plumes and the surface particles may differ in ways other than (or in addition to) composition.
If the plumes are indeed the source of E-ring particles, then they may not coat much of the surface of Enceladus since
the spectrum of the E-ring does not match that of Enceladus. (If I recall correctly, Joe Knapp already showed how
much of the surface gets coated by plume particles in this forum some time ago.)
Also in the paper, we compare our spectra to those of E-ring particles and find that the crystallinity of water ice on the
surface of Enceladus is remarkably distinct from that of the E-ring which is comprised primarily of amorphous water ice.
Amorphous ice can be produced by flash freezing of water, as occurs in the plumes.

Thanks for the welcome, BTW. I've been lurking for a while... And I enjoyed reading your article on UMSF in the
current LPI Bulletin.