Our knowledge of Solar System: Dazzling statistics

[3488]

Hi Joel,<br /><br />No not at all. Dione is TBC. There is strong evidence, in fact very strong evidence of activity <br />(elevated dust emissions, some surface features & even an 'atmosphere' of sorts)<br />on Dione, but it has yet TBC 100%.<br /><br />I am very pleased to know that Dione does feature in Cassini's extended mission. I think<br />with that super close planned encounter, we will know for sure.<br /><br />IMO the same is true of the Uranus moon Ariel (which I believe to either be active <br />or at least very recently so), but notice the word believe, not I say that it is so, so must be so.<br /><br />So no problem there Joel.<br /><br />Thank you for your list, I agree with it 100%.<br /><br />Cheers. This is a most fascinating subject,<br />worthy of its own thread, <br />which I shall start.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[MeteorWayne]

TBC is To be confirmed?? <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[3488]

It is MeteorWayne.<br /><br />A lot of stuff on that list is To Be Confirmed.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

I would have put only Ceres, Eris, Dione and Iapetus in the TBC category.<br /><br />Andrew, do you have doubts on others?

 

[3488]

Sorry Joel,<br /><br />Perhaps I was not clear.<br /><br />I don't think there is any doubt on the others.<br /><br />The others are all evidenced in one way or another.<br /><br />The Cryovolcano Ganesa Macula on Titan, (the one you refer to in your list) I would love to see <br />something visit the central cryocaldera. A really interesting feature.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[rasun]

Exactly... how are we going to learn about the details of Quaoar, Sedna & friends? A few years before NASA officials may have thought, "only 2 to go now" - one costly probe to Uranus and Neptune each. Now it looks like we're discovering them faster than they can build probes.<br /><br />So what is going to happen? Build lots of New Horizons? Or a giant mega-probe, that'd orbit each interesting KBO for a while, and then get to the next one in 20-30 years? Give up the whole thing?<br />Or are we going to come up with something new?<br /><br />Like, we're going to have JWST, but I doubt that it would help a lot in mapping the surface of these objects...

 

[brellis]

Every comet has a cycle of venting as it approaches the sun <img src="/images/icons/cool.gif" /> <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>

 

[h2ouniverse]

in reply to<br />-----------<br />Every comet has a cycle of venting as it approaches the sun <br />-------------<br /><br />Hi Brad,<br /><br />That is true. But comets activity is short lived (just a few orbits). So does it really count? This is more the catastrophic consequence of a destabilized orbit than an intrinsic feature.<br /><br />Btw, if you want to add comets, then the exponential character of the number of recent discoveries is even more blatant... But I think that would distort my purpose.

 

[h2ouniverse]

In reply to:<br />------------<br />So what is going to happen? Build lots of New Horizons?<br />-----------<br /><br />Hi rasun,<br /><br />Why not? A relatively cheap way of proceeding would be<br />1) to miniaturize P/L so that spacecraft launch mass is reasonable<br />2) manufacture series of standardized probes and launch them in grapes.<br />3) get a very powerful ground network to receive signals without necessitating big commsystem on board<br /><br />3) is on going (SKA)<br />1) is achievable (being studied)<br />2) is a matter of will. The main difficulty is in the agencies' state of mind and their capability to resist de-standardization. Not an issue for industry. Series of tens of satellites have been and are being built.<br /><br />Best regards.

 

[brellis]

Update from the recent DPS meeting: Emily Lakdawalla's blog - she flew across the country to attend the meeting and write this report. Thanks Emily!<br /><br /><font color="yellow"> <br />The Planetary Society Weblog<br />By Emily Lakdawalla<br /><br />DPS: What's next with NEO searches<br />Oct. 11, 2007 | 16:16 PDT | 23:16 UTC<br />RSS 2.0 News Feed<br />Weblog Archive<br /><br />On Monday afternoon I went to a few of the sessions describing next steps in our efforts to locate all of the asteroids and comets that could possibly harm Earth, the near-Earth objects. Lindley Johnson, from NASA Headquarters, presented on "The State and Future Direction of NASA's NEO Program." In 1998, NASA was charged by Congress with the goal of discovering 90% of the asteroids above one kilometer in diameter within the next 10 years, which came to be known as the "Spaceguard goal." (A useful backgrounder by David Morrison on what exactly the Spaceguard goal is can be found here.) Various surveys, conducted by both professionals and amateurs, have combined efforts to help us reach this goal. As of October 1, 788 one-kilometer-and-larger objects had been found, including 64 near-Earth comets, and the discovery rate appears to be approaching an asymptote, indicating that we probably predicted the number of objects out there correctly, and have indeed found most of them; people seem to accept that the Spaceguard goal has either already been reached or will be reached by the end of 2008. </font><br /><br />H20: think how many 1km objects they'll find when they chart the entire asteroid belt in this much detail <img src="/images/icons/cool.gif" /> <div class="Discussion_UserSignature"> <p><font size="2" color="#ff0000"><em><strong>I'm a recovering optimist - things could be better.</strong></em></font> </p> </div>

 

[MeteorWayne]

Not sure what you mean by " a few " active orbits for a comet.<br /><br />Halley's comet has been active for at least 2250 years that we know of (about 30 orbits) and data derived from Giotto's 1986 encounter estimates that it will last 3000 more revolutions, or about 225,000 years.<br /><br />Can we call that "quite a few"? <img src="/images/icons/smile.gif" /> <br /><br />Edit: Shameless plug here....don't forget, for the next week or so we are plowing through the debris of Halley's comet.<br />See the 2007 Orionid Meteor Shwoer thread. <img src="/images/icons/wink.gif" /><br /><br />Meteor Wayne <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[h2ouniverse]

Hi MW,<br /><br />well a few hundreds of thousands of years is an eyeblink geologically speaking.<br /><br />Granted, interesting chemistry can occur anyway in the process. <br /><br />I still think however that comets should be counted separately from differentiated bodies (planets, large moons and dwarf planets).<br /><br />Cheers

 

[h2ouniverse]

Hi Brad,<br /><br />In reply to<br />---------<br />think how many 1km objects they'll find when they chart the entire asteroid belt in this much detail <br />--------------<br /><br />I had in mind a prediction between 1 and 2 millions for 1km+.<br />Small bodies distribution law seems consistent with comparable total mass per diameter class. (excluding Ceres that collects 30% of main belt mass).<br /><br />Will be interesting too for the Kuiper Belt... <br /><br />Best regards.

 

[MeteorWayne]

I agree 100%.<br /><br />Comets are in general very small, Halley is one of the largest, certainly one of the largest of the "short period" comets. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[h2ouniverse]

There are still these troubling observations of occultations, potentially by very small TNOs, reported:<br />http://www.nature.com/nature/journal/v442/n7103/abs/nature04941.html<br />If we are to believe HK Chang, that would mean trillions of objects in the classical KB!<br /><br />I wonder whether anybody has tried to reproduce the result recently.