Enceladus, the Europa of Saturn

[vogon13]

Yeah, sorry about that. Also been in a persistent snit about the crappy antenna on Galileo ever since Cassini got to Saturn and showed everyone what a good down link could do from orbiting a gas giant. I have so much more Voyager material on hand than Galileo, too. Seemed like in that time frame, books, magazines, etc. were either more plentiful or easier to find. Is there a definitive, affordable 'coffee table' book about the Galileo mission? <br /><br />Would actually like to see Galileo mission re-flown with a good antenna. And a little more of the mission conducted outside of Jupiter's equatorial plane.<br /><br />Feel free to point things out if it seems I have not got the drift of a question or something, I try to be as helpful as I can (outside of Free Space). <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[chew_on_this]

I would bet all the Gallileo science isn't even complete yet. Seems like a short time ago they crashed it into Jupiter.

 

[CalliArcale]

Regarding Galileo's antenna, strictly speaking, it wasn't crappy. It was actually an extremely good antenna. The problem was that its dish could not fully deploy, and consequently the really good antenna was completely wasted. The problem still isn't fully understood; there's only so much you can do to study a problem like that from millions of miles away. The artist's conceptions of the spacecraft aren't even neccesarily accurate -- they're just an estimation based on sensor readings from the unsuccessful deployment of the dish.<br /><br />This probably played a major role in giving Cassini a rigid dish, of course. A rigid dish doesn't have to be deployed, and consequently won't break down when you try to do so.<br /><br />It is truly amazing what engineers were able to get out of Galileo. It far surpassed its original mission objectives, and with an antenna never meant to do more than make routine telemetry communications with Earth during the earliest part of the mission. It was never meant to transmit significant amounts of data, and not meant to be used at all at such a large distance. It's a huge acheivement, mainly on the software side. Of course, being a software engineer I love to bring that up as an example of how software can save hardware's bacon. <img src="/images/icons/tongue.gif" /><br /><br />The JIMO mission, if it happens, will do a lot more maneuvering than Galileo did. There are four big moons; it seems a shame not to use all that mass to get some interesting orbits, a la Cassini. (Cassini has a much smaller orbit than Galileo did, and consequently makes a lot more moon encounters. It will also be making much more dramatic changes to its orbit over the course of its primary mission to study Saturn from different vantages. It's mostly using Titan's mass to acheive this. Titan will get a lot of flybys.) <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>I would bet all the Gallileo science isn't even complete yet. Seems like a short time ago they crashed it into Jupiter.<p><hr /></p></p></blockquote><br /><br />The Pioneer science isn't even complete, and those probes are no longer capable of communicating with Earth! Studies of old data continue for decades. Galileo data will be studied for many years to come.<br /><br />Galileo was, however, at the end of its useful lifespan when it was deliberately deorbited. It was running perilously low on propellant. Once propellant is exausted, a probe is effectively dead because even if it does still work, it cannot point its antenna towards Earth. From that point on, it is dead to humanity. Pioneer 10 and 11 lasted as long as they did mainly because they were spin-stablized; this greatly reduced the amount of propellant required to maintain communications. Galileo did have a spun section, but it also had to cope with the gravitational influence not just of Jupiter but of the four massive Galilean moons. It had to tweak its attitude regularly, or it would lose contact with Earth. This also meant that its orbit was very chaotic. Over the short term, scientists could predict where Galileo would go, but not over the long term. There was a chance it could hit Europa, and a small but non-zero chance that terrestrial organisms had survived the journey aboard it. To avoid contaminating what is at present a fairly pristine scientific resource, Galileo was disposed of in the atmosphere of Jupiter.<br /><br />By that time, it was becoming quite erratic; the radiation environment near Jupiter is very harsh, and although the electronics had faired far better than required, they were beginning to succumb. One of the final straws was when it failed to take any pictures of Io during its last flyby of the tortured moon; the computer controlling the camera had reset itself due to radiation-induced faults. Some lamented NASA's decision <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[vogon13]

I am happy Galileo worked as well as it did, even with the 'impaired' antenna (really like saying crappy, though) I just lament the mission it could have been for lack of a little grease on the antenna deployment pins. Also, IIRC, lube probably would have been sufficient had launch not been delayed by Challenger accident. Sigh.<br /><br />I really really wanted some close-ups of Amalthea, too............... <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[CalliArcale]

I will admit, "crappy" is a good word. <img src="/images/icons/wink.gif" /> I just wanted to point out how nice a piece of equipment it was originally. Actually, that just makes it sadder. It was such a waste. <img src="/images/icons/frown.gif" /><br /><br />Amalthea pics would've been great, but there's a very good chance it would've failed anyway. Remember, the camera was failing out by Io at that point! The radiation is worse the further in you go. (I seem to recall they did get spectroscopy from Amalthea at least, but you're right -- pics would've been awesome.) <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[gpurcell]

"It is truly amazing what engineers were able to get out of Galileo. It far surpassed its original mission objectives."<br /><br />Well, true and not so true. On some measuement indices, Galileo did indeed exceed expectations. But try asking the atmospheric scientists about how well THEIR expectations for the mission were met! And while it is true that we do have some high resolution pictures of the Jovian moon system, the amount Galileo was able to deliver was a small fraction of what was intended.<br /><br />Yes, Galileo was a success. But the loss of the HGA was a bitter, bitter blow.

 

[chew_on_this]

Bump for closest encounter of any object so far in the Saturnian system (July 14)!

 

[chew_on_this]

T-1 day and counting! Some very light reading also.<br /><br />http://saturn.jpl.nasa.gov/news/events/enceladus20050802/index.cfm

 

[chew_on_this]

Map of planned coverage. More at:<br /><br />http://ciclops.org/view.php?id=1219

 

[thechemist]

A worthy crosspost: you can see boulders in this baby <img src="/images/icons/shocked.gif" /> <img src="/images/icons/shocked.gif" /> <img src="/images/icons/shocked.gif" /><br /><br />link to image <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>

 

[thechemist]

And here is the context of the above image (N00037070.jpg) in the larger one (W00009337.jpg):<br /><br /> <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>

 

[silylene old]

Interesting image, for sure. I don't think the "lumps" are boulders, because they all look rounded and merged with the surface substrate. I would expect some boulders to lie on top of the surface, but I see very few if any that look like this. This makes the surface all the more interesting. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[centsworth_II]

"I would expect some boulders to lie on top of the surface..." -- silylene<br /><br />Boulders, not from impacts but broken off from the edges of raised fracture faces -- ice cliffs? <div class="Discussion_UserSignature"> </div>

 

[silylene old]

The "boulders" are not arranged preferntially at the edges of the fractures. rather they are preferentially in the middle of the mounds between the fractures. And individually they don't look like boulders, but either some kind of slumped ice-lumps, or some kind of upwelled bumps. It's really an odd-looking bumpy surface. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[thechemist]

Being a non-native english speaker, I used the term "boulders" in the general sense. Whatever the local geology is, I was blown away by this image,<br />a bit like with the very first MER images.<br />It made Enceladus appear as a real world in my head. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>

 

[thalion]

I have to agree that they probably aren't boulders, for two reasons:<br /><br />1.) Where could they all have possibly come from? If they are part of some ejecta deposit, that would be difficult to explain with their relatively regular shape.<br /><br />2.) If they are boulders, then they are truly enormous, even with the close flyby distance--I'd guess some tens of meters across, and would make the famous "Apollo boulder" look like so much grit.<br /><br />But I have to agree with The Chemist here: these pictures make Enceladus feel like a real world. <img src="/images/icons/smile.gif" />

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>It's really an odd-looking bumpy surface.<p><hr /></p></p></blockquote><br /><br />My husband took one look at it and pronounced it a "cottage cheese" surface. That's actually strangely apt. It is bizarre. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[astrophoto]

I accidentally created a duplicate thread on this, so I will voice my opinion here instead. They look like bubbles to me, probably caused by upwelling gases from within. Looks to me like a snapshot of time if you were to boil water and then instantly freeze it.

 

[silylene old]

astrophoto - you may be right, it does look like that <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[astrophoto]

Giant concretion blueberries?<br /><br />Unfortunately the images are just short of being resolvable to any definitive level. I have a feeling that scientists will come to a near consensus on one theory or another but in the end we'll all need to correct that once we explore further.<br /><br />Has any guesstimate ever been made on the thickness of the surface as has been made about Europa?

 

[yurkin]

I think calling Enceladus the Europa of Saturn is bit like calling Titan and early Earth. It seems accurate only at first glance. Enceladus is clearly its own world and trying to learn about Encaldus by comparing it to Europa isn’t going to work.

 

[astrophoto]

I never compared it. I asked if anyone had come up with any analysis on possible thickness of the surface -- that could mean it's solid to the core or only mm thick. The patterns and color of the terrain certainly lend credence to the possibility of being a dynamic icy world, these 'boulders' definitely add something to that equation.

 

[yurkin]

I wasn’t referring to you directly it was just a general thought I had.

 

[yurkin]

I think the boulders were once part of the Saturn’s Rings. Enceladus orbits much closer to Saturn then its other major moons. So some of the moonlets from the initial debris field may have fell down on Enceladus before forming into the neat ring system. They didn’t form a crater because Enceladus doesn’t have much mass and the difference in orbital velocities between the moon and moonlets was small.