The Cassini Orbiter has made an amazing discovery that the 300 mile diameter satellite moon of Saturn, named Enceladus has an atmosphere that must be
constantly replenishing itself. The gravity on the moon is not considered strong enough to hold an atmosphere and it is believed that the unusual
phenomenon is caused by geysers or volcanic activity on Enceladus. The magnetometer on the Orbiter Cassini found the anomaly when making passes twice
in the past month. The magnetometer is designed to measure the strength and direction of magnetic fields surrounding the saturn statellites during its
You see the field bending as though the lines are being draped over the moon," explained Cassini magnetometer team member Professor Stan Cowley, who
said if there was no atmosphere the lines should pass straight through the moon.
"You can infer the amount of mass from the moon that is being loaded on to the field lines from the amount of bending that is seen. This signal has
been measured twice, in the February and March encounters."
One alternative explanation might be sputtering - a phenomenon that sees energetic particles in the local space environment hit the moon, knocking off
atoms and molecules from its cold surface. But the amount of mass detected by Cassini suggests something far more significant is occurring on
If Enceladus does have ice volcanoes they probably get their energy from the contorting tidal effects of Saturn's strong gravity.
The moon is the most reflective object in the Solar System, throwing back about 90% of the sunlight that hits it.
Scientists say it is possible the high reflectivity could result from continuous deposition of icy particles originating from volcanoes.
"If there are ice flakes coming off, these could be a source for the E ring," Professor Cowley, from the University of Leicester, UK, told the BBC
"Enceladus sits in the middle of the outermost ring of Saturn. This is composed of tiny ice particles that only last for hundreds of years. There has
to be a source of them and that source is probably Enceladus.
"So, we're seeing here part of a wider story which is concerned with how the rings are formed and dissipated as well."
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The Voyager spaceship flew past the moon in 1981 at a distance of 90000 kilometres and did not detect any atmosphere at the time but that may have
been because of the limited technology at the time.
Scientist are hoping that this new information will aid them in figuring how the rings of saturn were formed.
[edit on 18-3-2005 by Mayet]