MESSENGER Mercury Updates.

[jsmoody]

Interesting article on Mercury's odd rotation, with simulation and cool graphics:<br /><br />The Rotation of Mercury<br /><br /> <div class="Discussion_UserSignature"> No amount of belief makes something a fact" - James Randi </div>

 

[rlb2]

Hi Andrew<br /><br />Thanks. Good stuff, it would be cool if those tiny dots were moons or planets from afar. The dots could also be stars as mentioned or just plain old fashion artifact. It would be difficult for Mercury to hold on to any moon because of its location next to the sun.<br /> <div class="Discussion_UserSignature"> Ron Bennett </div>

 

[richalex]

<blockquote><font class="small">In reply to:</font><hr /><p>It would be difficult for Mercury to hold on to any moon because of its location next to the sun.<p><hr /></p></p></blockquote>?? How hard could it be? I mean, we are about to drop a moon into Mercury's orbit.

 

[centsworth_II]

<font color="yellow">"...we are about to drop a moon into Mercury's orbit."</font><br /><br />A "moon" with a powered attitude control system to maintain its orbit. <div class="Discussion_UserSignature"> </div>

 

[3488]

Hi centsworth_II.<br /><br />That is very true. MESSENGER is controllable, a natural Hermian satellite would not be.<br /><br />A Hermian moon, very close in would be possible, but as yet we do not know<br />anything of the nature of the Mercury mass concentrations, if they exist. <br /><br />They would destabilise a low orbiting moon, where as a high orbiting one, would be <br />subject to solar pertabations.<br /><br />Hi all,<br /><br />A nice article below from: Spaceflightnow.com. <br /><br />I think MeteorWayne & myself have already covered the points contained, but is is well written. <img src="/images/icons/smile.gif" /><br /><br />I am having to use the work's computer now, as my own internet connection has <br />crashed (disastrous given the return of MESSENGER data). <br /><br />I hope it is a British Telecom problem & not mine.<br /><br />So I may be out of the loop for a while after this afternoon. <img src="/images/icons/frown.gif" /><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>

 

[franontanaya]

It can be interesting to see if there's a sharp cut between filled, shallow craters and empty craters, or if it is a linear continuum. I know volcanic eruptions, gravity (specially for icy crusts) and ejecta can bury craters or make them more shallow. A sharp cut could mean volcanic activity or maybe be related with the origin of Caloris Basin. <br /><br />Mercury seems to have many almost erased big impacts, but few if any very recent. Could that show a record of how the orbits got cleared over time? <div class="Discussion_UserSignature"> </div>

 

[3488]

Hi FranOntanaya,<br /><br />The Caloris Basin forming event, certainly sent shock waves around the entire planet,<br />hence the antipodal weird terrain, as imaged from Mariner 10, where said <br />shockwaves focussed, after the gigantic impact.<br /><br />Do not forget, there is evidence of an even larger impact basin, the suspected <br />Skinakas Basin, a crop of the possible outer rim.<br /><br />I also suspect that when the iron sank to form the huge massive core, the heat from <br />that separation, would have caused widespread melting of silicate rock. Also I suspect<br />that there was a peiod of more general volcanism, which has since waned to zero <br />or may not be quite extinct (perhaps some of the very dark patches were <br />from more recent fire fountains).<br /><br />Until we get even higher resolution images, it is difficult to say. I would expect from imagery <br />seen from both Mariner 10 & MESSENGER, the volcanic outpourings do seem to be a continuum from<br />more to a less active events.<br /><br />I should have time this weekend to look properly at the images to make a more informed <br />statement.<br /><br />Your last sentence, yes most definately, I think there is a record of how the orbit was <br />cleared of impacting bodies. <br /><br />I do not know if there are also clues as to wether or not Mercury has kept the same <br />orbit since formation, or if Mercury has migrated inwards.<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]

That was a great (if brain painful) read jsmoody, thanx! <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]

<font color="orange">These just in</font> <br /><br />Mercury's complex cratering history. <font color="orange">First mosaic. Till now single frames have been released</font><br /><br />Overview of MESSENGER approach to Mercury.<br /><br /><font color="yellow">If my internet connection is working when I get home, I will have a go at cropping some <br />features on the crater image</font><br /><br /><font color="orange">There are some dark patches. Perhaps further ancient fire fountains</font><br /><br /><font color="yellow">Just a cursory glance has suggested, some interesting features</font> <img src="/images/icons/laugh.gif" /><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>

 

[brellis]

Emily Lakdawalla's Jan. 18 Roundup of the Flyby for the Planetary Society <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>

 

[franontanaya]

Will temperatures be noticeablely lower in the ground under those bright patches? Mercury's mean albedo is 12%. The maximum daytime temperature there can be around 600K. If the albedo of the patches cut half the radiation and the underground can keep some of the nightly cold, maybe there are relatively cold points there all year round.<br /><br />Sorry my ignorant question but, if Enceladus with its 99% albedo was placed at Mercury orbit, would it reach 270K? <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

Todays releases:<br /><br /> MESSENGER Radar Altimeter Data <br /><br />and<br /> First WAC Image after closest approach (9 minutes) <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]

you have an incoming flux at perihelion of:<br />1366 W/m² / 0.307² = 14500 W/m²<br />If you could really have a 99% albedo body, you would absorb only 1% ie 145 W/m2 and have, assuming an IR emissivity epsilon of 0.98 (smooth clean ice), a radiative flux balance:<br />145 W/m2 = absorbed flux = reemitted flux = epsilon.sigma.T4<br />(assuming no heat flux from the interior)<br />Hence T=226K.<br /><br />For people in doubt, note that the same calculation with 12% Bond albedo and an epsilon of 0.9 gives 707K.<br /><br />The point is to keep an actual 99% albedo! This may be possible on Enceladus only because of ultra-flat surface of ice thanks to resurfacing. Ageing of your surface will quickly increase the absorptivity (decrease the albedo).<br /><br />273K corresponds to an albedo of 0.9825! <br /><br />Also, 226K is "above" sublimation of ice in vacuum. To get a reasonably negligible sublimation rate, you should be below 170K.<br />You would satisfy this condition on your "instantly teleported Enceladus" above 71° latitude at perihelion, and above 43° latitude at aphelion.<br /><br />Best regards.<br /><br />

 

[franontanaya]

Wow.<br /><br />So, if an impact of an icy body on the night side and near the poles left a very pure ice area, when day came it would have evaporated by the transfer of heat from the surrounding terrain, not so much by the direct heat of the sunlight.<br /><br />What if the ice was thick and the base of it evaporated, creating an umbrella that shadows the ground, keeping most of the ice from having direct contact with heated terrain but at dawn and sunset? And if that ice is in a crater which walls shadow the dawn and sunset? Would that allow some ice to survive a whole hermian day? <div class="Discussion_UserSignature"> </div>

 

[alokmohan]

MESSENGER to heaven is intersting.

 

[h2ouniverse]

IIRC, we had also this kind of speculation about Ceres. The only reservation is that it should logically apply to the Moon too (Mercury, Moon and Ceres are the three airless inner system bodies with a low axial tilt). And yet, there seems to be no ice on the surface on Moon so far... (signature of hydrogen in poler craters, maybe hydrated rocks?)

 

[MeteorWayne]

Today's releases:<br /> MESSENGER Views an Intriguing Crater <br />and<br /> Ridges and Cliffs on Mercury's Surface <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]

Thanks MeteorWayne, for the updates.<br /><br />Still out of the loop, till Wednesday, my router has broke. <img src="/images/icons/frown.gif" /><br /><br />The ridges & cliffs image is most interesting. I've had a go at blowing the earlier <br />release of that one up, but a higher resolution one, closer in was obviously taken. <br /><br />Like the first WAC image after closest approach too. <img src="/images/icons/smile.gif" /><br /><br />I will be back later hopefully, during break time.<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>

 

[Philotas]

<font color="yellow">MESSENGER Views an Intriguing Crater </font><br /><br />Dare I say the most intriguing feature so far? <img src="/images/icons/smile.gif" /><br /><br /> <br /><br />9 days till press release. <div class="Discussion_UserSignature"> </div>

 

[3488]

Just a quick log in.<br /><br />Also this is most interesting: Ridges & Cliffs on Mercury's surface.<br /><br />There could well be evidence of past volcanism here.<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]

Looks like only one Today:<br /><br /> Looking Towards the South Pole of Mercury <br /><br />This image was acquired about 98 minutes after MESSENGER's closest approach to Mercury, when the spacecraft was at a distance of about 33,000 kilometers (21,000 miles) with the Narrow Angle Camera.<br /><br /> <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]

Thank you very much MeteorWayne.<br /><br />That is a very interesting image. Notice the comparitively 'smooth area' <br />very close to the actual south pole.<br /><br />Hopefully I will be back properly from Wednesday or Thursday at the latest. <br /><br />Just awaing a new router to arrive, as mine has failed.<br /><br />Thank you again MeteorWayne for your very valuable updates.<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>

 

[Philotas]

The bright feature at the terminator appears to be pretty tall and does not have the typical shape of a crater. <br /><br />Good to hear Andrew. You were lucky it did not break down at the date of closest encounter. <img src="/images/icons/smile.gif" /><br /> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

Most likely it's one of the ridges or scarps that seem to be fairly common in the planet. <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]

Thanks Philotas, it was good timing in that it did not break down then. <br /><br />If it had I would have been most upset. Hopefully, my new piece of kit (which I do not <br />have to pay for, as it is still under guarantee) will arrive in a couple of days or so.<br /><br />MeteorWayne is correct in my opinion. To me that streak looks like a scarp wall too.<br /><br />It looks as if it is so tall, that the top of the wall, is catching the morning sun, <br />before the base of it does.<br /><br />These scarps as MeteorWayne says are very common all over Mercury. <br /><br />The current school of thought being, as the iron core began to cool, it shrank, causing <br />the silicate crust above to wrinkle & crack, due to compressional forces.<br /><br />It is very likely, that this could still be happening now, as the giant core continues to cool.<br /><br />Seismometers would be interesting to land on the surface.<br /><br />That is a WOW image. Scarp, smoothish area, craters of all sizes, the south polar <br />region of Mercury is an interesting place. <br /><br />I will dig out a Mariner 10 image of the other side of the south polar region & compare.<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>