No sodium in the vapour plumes of Enceladus.
Nature
; 459(7250): 1102-4, 2009 Jun 25.
Article
em En
| MEDLINE
| ID: mdl-19553993
ABSTRACT
The discovery of water vapour and ice particles erupting from Saturn's moon Enceladus fuelled speculation that an internal ocean was the source. Alternatively, the source might be ice warmed, melted or crushed by tectonic motions. Sodium chloride (that is, salt) is expected to be present in a long-lived ocean in contact with a rocky core. Here we report a ground-based spectroscopic search for atomic sodium near Enceladus that places an upper limit on the mixing ratio in the vapour plumes orders of magnitude below the expected ocean salinity. The low sodium content of escaping vapour, together with the small fraction of salt-bearing particles, argues against a situation in which a near-surface geyser is fuelled by a salty ocean through cracks in the crust. The lack of observable sodium in the vapour is consistent with a wide variety of alternative eruption sources, including a deep ocean, a freshwater reservoir, or ice. The existing data may be insufficient to distinguish between these hypotheses.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Sódio
/
Lua
/
Gases
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article