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."

Pictures available later

[sighted]

I should add that although the closest approach to Enceladus is happening as I type this, Cassini won't have a chance to turn its antenna toward Earth until later this evening (U.S. time). The downlink will take several hours, so the first pictures probably won't be publicly available until tomorrow.

Re:It really has the sensors for this?

[rijrunner]

    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.

 

Re:Pictures available later

[CheshireCatCO]

Early afternoon is, I believe, the plan. JPL (http://jpl.nasa.gov) and CICLOPS (http://ciclops.org) are both planning releases that I know of.

*Tops* of the Plumes!?

[CheshireCatCO]

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.

Re:Where's Google...?

[icebrain]

Yes, it has thrusters. Midcourse corrections happen every now and then.

It's not so much that orbital mechanics is hard; a lot of it is just brute-force computation. The hard part is getting reliable data to base said computation on.

Re:Arthur C Clarke reference

[rbanffy]

For 2001, Clarke picked up Saturn. The monolith was in Iapetus.

Only the movie (and subsequent books) mentions Jupiter. It makes sense, as more people watched the movie than read the book. In the book, they use Jupiter to accelerate Discovery towards Saturn, but Kubrick (IIRC) thought this would confuse the audience (like the Bowman meeting with the monolith in the hotel room after the psychedelic trip would be readily understood) and Saturn was dropped. Douglas Trumbull used the techniques developed during this in Silent Running.

It's all fairly well explained in 2010 (the book).

And, BTW, when Cassini passes through the plume, it will be close to vacuum, barely detectable.

Re:It really has the sensors for this?

[K. S. Kyosuke]

It can really analyse the water samples? Wow, I'm impressed.

This...is...Star Trek! ;-)

Actually, you can do quite a lot with computer-controlled devices that the original manufacturer did not intend originally. Galileo, for one thing, was capable of transmitting a huge amount of data even though it was crippled so much that anyone except the JPL people would probably give up [wikipedia.org]. I bow to those guys. Perhaps they are going to use this [nasa.gov]?

Re:Pictures available later

[sighted]

Definitely, but there should be some interesting shots from other portions of the flyby, especially of the north polar region, not to mention the other kinds of data that is expected to come down.

Re:Where's Google...?

[Tablizer]

Very true, although it's a bit more complicated still: chaos pretty well guarantees that even if you plan out a great trajectory in advance, you'll drift and end up in trouble down-stream. Plus there are inevitable changes required due to problems (like with Huygens or changing models of the Titan atmosphere) ...

It's not so much "trouble", but rather using up more course adjustment fuel to compensate for errors in reality versus the model. After every moon pass-by they can use the cameras to check the probe's orbit against the model, and make adjustments with small rocket firings. The less fuel you have, the shorter the mission and/or less chances to change your mind.

But Cassini is on an amazing pinball ride.
     

Re:Pictures available later

[Peter Lake]

Cassini started sending the data back to Earth few hours ago (around 7:00 pm PDT). Hopefully we'll get to see the first images by thursday morning about 5:00 AM PTD.

Here's an animation of the flyby, you can see the spacecraft's close trajectory and how various instruments in their turn take measurements of Enceladus: http://www.youtube.com/watch?v=9Pfz1n6tMUg [youtube.com]