A Plethora of Plumes
Cassini Finds Plethora of Plumes, Hotspots at Enceladus
The new images from the imaging science subsystem and the composite infrared spectrometer teams also include the best 3-D image ever obtained of a “tiger stripe,” a fissure that sprays icy particles, water vapor and organic compounds. There are also views of regions not well-mapped previously on Enceladus, including a southern area with crudely circular tectonic patterns.
The images and additional information are online:
“Enceladus continues to astound,” said Bob Pappalardo, Cassini project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “With each Cassini flyby, we learn more about its extreme activity and what makes this strange moon tick.”
For Cassini’s visible-light cameras, the Nov. 21, 2009, flyby provided the last look at Enceladus’s south polar surface before that region of the moon goes into 15 years of darkness, and includes the most detailed look yet at the jets.
Scientists planned to use this flyby to look for new or smaller jets not visible in previous images. In one mosaic, scientists count more than 30 individual geysers, including more than 20 that had not been seen before. At least one jet spouting prominently in previous images now appears less powerful.
A new map that combines heat data with visible-light images shows a 40-kilometer (25-mile) segment of the longest tiger stripe, known as Baghdad Sulcus. The map illustrates the correlation, at the highest resolution yet seen, between the geologically youthful surface fractures and the anomalously warm temperatures that have been recorded in the south polar region. The broad swaths of heat previously detected by the infrared spectrometer appear to be confined to a narrow, intense region no more than a kilometer (half a mile) wide along the fracture.
“The fractures are chilly by Earth standards, but they’re a cozy oasis compared to the numbing 50 Kelvin (-370 Fahrenheit) of their surroundings,” said John Spencer, a composite infrared spectrometer team member based at Southwest Research Institute in Boulder, Colo. “The huge amount of heat pouring out of the tiger stripe fractures may be enough to melt the ice underground. Results like this make Enceladus one of the most exciting places we’ve found in the solar system.”
Some of Cassini’s scientists infer that the warmer the temperatures are at the surface, the greater the likelihood that jets erupt from liquid. “And if true, this makes Enceladus’ organic-rich, liquid sub-surface environment the most accessible extraterrestrial watery zone known in the solar system,” Porco said. Water is an essential ingredient for life as we know it, and studying environments in the solar system where water persists is important in identifying potential habitats for life.
The Nov. 21 flyby was the eighth targeted encounter with Enceladus. It took the spacecraft to within about 1,600 kilometers (1,000 miles) of the moon’s surface, at around 82 degrees south latitude.