Enceladus' Water Vapor Plume

Hansen, C. J.; Esposito, L. W.; Stewart, A. I. F.; Colwell, J. E.; Hendrix, Amanda; Pryor, W. R.; Shemansky, D. E.; West, Robert A.

doi:10.1126/science.1121254

Cited by 515 publications

(401 citation statements)

References 21 publications

Supporting

Mentioning

377

Contrasting

Order By: Relevance

“…The south polar region of Saturn's satellite Enceladus has attracted recent attention due to its large, internally generated thermal anomaly (Spencer et al, 2006), plumes of water and other material jetting from cracks in the surface (Porco et al, 2006;Hansen et al, 2006;Spahn et al, 2006;Waite et al, 2006), and the young fractured terrain surrounding the pole (Porco et al, 2006). These observations imply a thin ice lithosphere and possibly a source of liquid near the surface.…”

Section: Introductionmentioning

confidence: 99%

Enceladus' south polar sea

Collins

Goodman

2007

Icarus

113

109

View full text Add to dashboard Cite

Recent observations of the south pole of Saturn's moon Enceladus by the Cassini spacecraft have revealed an active world, powered by internal heat. In this paper, we propose that localized subsurface melting on Enceladus has produced an internal south polar sea. Evidence for this localized sea comes from the shape of Enceladus, which does not match a differentiated body at its current orbital position. We show that melting induced by the observed heat flow at the south pole produces a large enough pit to match the shape of Enceladus with a differentiated rock and ice interior. Numerical modeling of melting and ice flow shows that the sea produced beneath the south pole is stable against inflow of ductile ice from its surroundings for the duration of the heating. The shape modification due to melting also produces a negative degree-two gravity anomaly, which can reorient the spin axis of Enceladus in order to place the sea at the pole.

show abstract

Section: Introductionmentioning

confidence: 99%

Enceladus' south polar sea

Collins

Goodman

2007

Icarus

113

109

View full text Add to dashboard Cite

show abstract

“…[3] Cassini observations in 2005 [Dougherty et al, 2006;Hansen et al, 2006;Porco et al, 2006;Waite et al, 2006] discovered water emanating from the south pole of Enceladus, verifying Enceladus as the source of the observed OH and predicted H 2 O neutrals. This discovery also provided evidence that the neutrals are unlikely to be azimuthally symmetric.…”

Section: Introductionmentioning

confidence: 99%

Cassini INMS observations of neutral molecules in Saturn's E‐ring

et al. 2010

View full text Add to dashboard Cite

[1] In 2008, the Cassini ion neutral mass spectrometer (INMS) investigation made in situ measurements of neutral species near Saturn's equatorial plane within 0.5 Saturn radii (R S ) of the orbit of Enceladus. After removing the large background and modeling to interpret instrumental effects, the data provide rough constraints on the neutral distribution and composition. These data show an azimuthal asymmetry in the neutral densities and provide measurements used to compare to simulations of neutral H 2 O emitted from Enceladus. Far from Enceladus, the neutral water densities, at a few times 10 3 molecules/cm 3 , are near the detection limit of INMS. Near Enceladus, but outside of the plumes and north of the equatorial plane, the INMS detects particles within 5000 km of Enceladus, with the density increasing to approximately 10 5 molecules/cm 3 at the equatorial plane. The observations also show CO 2 in the form of its dissociated product, CO. On the basis of the spatial distribution of CO 2 counts, the scale height of the neutral cloud above and below the equatorial plane is less than 7000 km. Far from Enceladus, the concentration of CO 2 with respect to H 2 O increases, a consequence of the predicted decline in H 2 O density. Relatively high counts at 2 amu are infrequently observed. These measurements indicate H 2 released during ice-grain impacts and provide a constraint on the frequency and distribution of small ice grains.

show abstract

“…Tidal heating is responsible for the volcanic activity on Io (Peale et al, 1979) and probably the geysers of Enceladus (Hansen et al, 2006;Porco et al, 2006;Hurford et al, 2007). Tidal theory has a long and established body of work; however, tidal processes remain poorly understood.…”

Section: Tidal Heatingmentioning

confidence: 99%

Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating

et al. 2013

View full text Add to dashboard Cite

Traditionally, stellar radiation has been the only heat source considered capable of determining global climate on long timescales. Here, we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at highenough levels to induce a runaway greenhouse for a long-enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets ''Tidal Venuses'' and the phenomenon a ''tidal greenhouse.'' Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits (i.e., with negligible tidal heating) in the habitable zone (HZ). However, these planets are not habitable, as past tidal heating desiccated them, and hence should not be ranked highly for detailed follow-up observations aimed at detecting biosignatures. We simulated the evolution of hypothetical planetary systems in a quasi-continuous parameter distribution and found that we could constrain the history of the system by statistical arguments. Planets orbiting stars with masses < 0.3 M Sun may be in danger of desiccation via tidal heating. We have applied these concepts to Gl 667C c, a *4.5 M Earth planet orbiting a 0.3 M Sun star at 0.12 AU. We found that it probably did not lose its water via tidal heating, as orbital stability is unlikely for the high eccentricities required for the tidal greenhouse. As the inner edge of the HZ is defined by the onset of a runaway or moist greenhouse powered by radiation, our results represent a fundamental revision to the HZ for noncircular orbits. In the appendices we review (a) the moist and runaway greenhouses, (b) hydrogen escape, (c) stellar mass-radius and mass-luminosity relations, (d) terrestrial planet mass-radius relations, and (e) linear tidal theories.

show abstract

Enceladus' Water Vapor Plume

Cited by 515 publications

References 21 publications

Enceladus' south polar sea

Enceladus' south polar sea

Cassini INMS observations of neutral molecules in Saturn's E‐ring

Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating

Contact Info

Product

Resources

About