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Spacecraft to Fly Through Geyser Plumes On Saturn Moon
Riding with Robots writes "Today the robotic Saturn probe Cassini will make its closest buzz ever over the surface of the enigmatic ice moon Enceladus, whose surprising giant water geysers hint at a hidden ocean of liquid water. The spacecraft will fly right through the tops of the geyser plumes in order to sample the material that originated beneath the surface. NASA is offering a video, interactive guide and image gallery in advance of the event."
The probe was going to be flying around the rings of Saturn, so they added the Cosmic Dust Analyzer, which can analyze dust particles. For the type of thing they are doing here, they can treat water as a dust particle as it will freeze. It is particulate matter.
Well, the initial plans called for wipers, but that would have required another .4 kg of expensive plutonium pellets in the RTG, and the added mass of the motor, intermittent-wipe controller, and the mechanism for changing spare wiper blades would have meant that the hermetically sealed capsule containing the Blob (frozen by Steve McQueen in the 1950s) would have been bumped to another deep-space probe.
The spacecraft is flying 200 km from the south pole of Enceladus. The plume extends *thousands* of kilometers into space. We're not passing through the top of the plume by any means. We're getting right into it.