William Atkins
Thursday, 27 November 2008 19:49
Science -
Space
Page 2 of 3
The Hansen-lead research strongly suggests that the plumes being ejected from the surface of Saturn’s moon contains liquid-water vapor because of the very fast speeds at which they are being spewed out.
The researchers state that they used an occultation of a star by a plume seen on October 24, 2007. The plume ejected four “
high-density gas jets,” which were
“superimposed on the background plume.”
They state,
“The maximum water column density in the plume is about twice the density reported earlier. The density ratio does not agree with predictions—we should have seen less water than was observed in 2005."
And,
"The ratio of the jets' bulk vertical velocities to their thermal velocities is 1.5 [+/-] 0.2, which supports the hypothesis that the source of the plume is liquid water, with gas accelerated to supersonic velocity in nozzle-like channels.” [Nature abstract]
The researchers found that the speeds are faster than the speed of sound, specifically over 1,360 miles (2,190 kilometers) per hour.
According to the NASA article
Enceladus Jets: Are They Wet or Just Wild?,
“At the heart of the search is the question of whether the jets originate from an underground source of liquid water. Some theories offer models where the jets could be caused by mechanisms that do not require liquid water. Painstaking detective work by Cassini scientists is testing the possibilities to get closer to an answer.”
However, the Hansen team disputes this theory, saying they think, from the data they have analyzed, that the plumes are liquid water, and are not ice.
Page three talks more about Hansen's ideas.
