July 28, 2014
On this polar stereographic map of Enceladus' south polar terrain, all 100 geysers have been plotted whose source locations have been determined in Cassini's imaging survey of the moon's geyser basin. The uncertainty attached to each location is given by the size of the surrounding circle.
Five sources are indicated by dashed circles. Each of these jets appeared only in images taken very close together in time; in other words, the source locations have been confidently determined, but their tilts are uncertain.
The two crosses -- one on Alexandria and one at the end of Baghdad -- indicate two jets. Each was observed in one image only but each was intersected by the shadow of Enceladus, as in Encroaching Shadow, allowing a determination of the fracture on which they lie.
This map and the information it contains were used to compare geysering activity with enhanced thermal emission observed by Cassini's heat-measuring instruments and with the distribution of tidal stresses across the region. Those comparisons yielded the clues needed to ascertain the mechanisms underlying the geysering process.
This map was part of a paper by Porco, DiNino, and Nimmo, and published in the online version of the Astronomical Journal in July 2014:
A companion paper, by Nimmo et al. is available at:
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.
Credit: NASA/JPL-Caltech/Space Science Institute