2 Pallas.

3488 · Jul 15, 2008

I was not actually looking for 2 Pallas in particular, I was looking for 1 Ceres stuff, from the last opposition (which I cannot find), but guess what. I came across this instead (I had looked for 2 Pallas Hubble stuff a while back, but could not find any. It has just been released). 2 Pallas imaged by Hubble Space Telescope in September 2007. <img src="http://sitelife.space.com/ver1.0/Content/images/store/11/14/6bf120de-4a6a-43b8-bec9-e65384b4e8c1.Medium.jpg" alt="" />  2 Pallas appears to rotate with a tilt of approx 62 degrees, therefore has very extreme seasons, prograde, (Sun rises in the east & sets in the west as on Earth),  once every 7 Hours, 48 minutes & 7 seconds.Below a high contrast Hubble Space Telescope image of 2 Pallas. A few surface features can be made out, particularly at the bottom of the 'disk'. <img src="http://sitelife.space.com/ver1.0/Content/images/store/13/4/2db50d44-e5c4-468e-b4cd-d03801ddbf92.Medium.jpg" alt="" />  Andrew Brown.  <div class="Discussion_UserSignature"> "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". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

Philotas · Jul 16, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I was not actually looking for 2 Pallas in particular, I was looking for 1 Ceres stuff, from the last opposition (which I cannot find), but guess what. I came across this instead (I had looked for 2 Pallas Hubble stuff a while back, but could not find any. It has just been released).2 Pallas imaged by Hubble Space Telescope in September 2007.  2 Pallas appears to rotate with a tilt of approx 62 degrees, therefore has very extreme seasons, prograde, (Sun rises in the east & sets in the west as on Earth),  once every 7 Hours, 48 minutes & 7 seconds.Below a high contrast Hubble Space Telescope image of 2 Pallas. A few surface features can be made out, particularly at the bottom of the 'disk'.  Andrew Brown.  Posted by 3488</DIV> Much of a round thing. <div class="Discussion_UserSignature"> </div>

h2ouniverse · Jul 16, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Much of a round thing. Posted by Philotas</DIV> Apparently they say the roundness is illusory. Would be kind of an octahedron.Does anyone know whether Dawn will finally go there or not? The latest news I had were that Dawn would stop at Ceres.

MeteorWayne · Jul 17, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Apparently they say the roundness is illusory. Would be kind of an octahedron.Does anyone know whether Dawn will finally go there or not? The latest news I had were that Dawn would stop at Ceres. Posted by h2ouniverse</DIV> The Dawn primary mission is to Vesta and Ceres, in that order. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

h2ouniverse · Jul 17, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>The Dawn primary mission is to Vesta and Ceres, in that order. Posted by MeteorWayne</DIV> Hi MW, Yes, I knew. But there were initial plans to extend the mission to Pallas after Vesta and Ceres. And I was wondering whether this was still possible.

3488 · Jul 17, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Hi MW, Yes, I knew. But there were initial plans to extend the mission to Pallas after Vesta and Ceres. And I was wondering whether this was still possible. Posted by h2ouniverse</DIV>Hi Joel, it is still possible given current engineering data & fuel margins. As Wayne says, the 4 Vesta & 1 Ceres orbital mission are the top priority. The option to go for a close slow pass of 2 Pallas, if the primary mission & perhaps an extended mission at 1 Ceres (would be ideal as the distance between 1 Ceres & 2 Pallas reduces after the end of the Primary Mission) must be kept open & that chance siezed should engineering factors allow, for a close pass in December 2018.It seems after the HST observations last September, that 2 Pallas is as important as 1 Ceres & 4 Vesta in understanding the early Solar System, as almost certainly all three are embryonic planets.Lets hope the option is not forgotten & I will not forget. 2 Pallas is an interesting object, no doubting it, worth a visit by a spacecraft & it could well be possible with DAWN.Andrew Brown.  <div class="Discussion_UserSignature"> "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". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

h2ouniverse · Jul 17, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Hi Joel, it is still possible given current engineering data & fuel margins. As Wayne says, the 4 Vesta & 1 Ceres orbital mission are the top priority. The option to go for a close slow pass of 2 Pallas, if the primary mission & perhaps an extended mission at 1 Ceres (would be ideal as the distance between 1 Ceres & 2 Pallas reduces after the end of the Primary Mission) must be kept open & that chance siezed should engineering factors allow, for a close pass in December 2018.It seems after the HST observations last September, that 2 Pallas is as important as 1 Ceres & 4 Vesta in understanding the early Solar System, as almost certainly all three are embryonic planets.Lets hope the option is not forgotten & I will not forget. 2 Pallas is an interesting object, no doubting it, worth a visit by a spacecraft & it could well be possible with DAWN.Andrew Brown.  Posted by 3488</DIV> Hi Andrew, I had found this in a paper ( http://128.97.94.42/dawn/pdf/ACMConferencePaper&nbsp

written by most of the scientists of the team"We now know much about Ceres and Vesta. They are two of three remaining large asteroids, the other being Pallas, which is much more difficult to reach. Tables 1 and 2 give some of the physical parameters of these bodies. Pallas is dark, resides in the same region of the asteroid belt as Ceres and has relatively low density approaching that of  eres. Although measurements at Pallas are highly desirable, exploring Vesta and Ceres may be sufficient to bracket the properties of large "minor" planets."So no opportunity before 2018? Hmmm. Food for thought. 10 Hygiea is a large body too. Could they catch it instead?

3488 · Jul 18, 2008

Hi Joel,10 Hygeia?? Ummmm very interesting prospect.I had not really thought about 10 Hygeia, but is the fourth largest member of the Asteroid Belt. At one time it was considered for the Deep Impact spacecraft to encounter 8 Flora, but that idea was scrapped in favour to chase another comet as 8 Flora was eventually considered to be too far from the Sun for Deep Impact's solar panels. Found the below. <img src="http://sitelife.space.com/ver1.0/Content/images/store/12/1/3c793113-5f10-49b7-8150-72e9ca752d1e.Medium.jpg" alt="" />  Had Galileo launched in May 1986, as planned, then we would have seen the very large Asteroid 29 Amphitrite close up. In the end & following a 1989 launch, we got to see much smaller main belt asteroids 243 Ida & 951 Gaspra instead, but they have been of immense interest, so do not feel cheated.It would be great to see a real big one, the first being 21 Lutetia in July 2010 by the ESA Rosetta, the second largest M Type asteroid known, with only 16 Psyche being any larger of that type. 2867 Steins, in September, although rather small, is of a very rare Basalt type, (similar to Earth's mantle or the surface of Mercury) a chunk from the 4 Vesta south polar crater perhaps? Andrew Brown.  <div class="Discussion_UserSignature"> "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". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

h2ouniverse · Jul 20, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Hi Joel,10 Hygeia?? Ummmm very interesting prospect.I had not really thought about 10 Hygeia, but is the fourth largest member of the Asteroid Belt. Posted by 3488</DIV> Hi AndrewThe patch you pasted identifies Hygiea as spherical, whereas in this article http://www.rni.helsinki.fi/~mjk/IcarPIII.pdf it is modelled as an oblate potato 500×385×350 km  Excerpt: "10 Hygiea (Figs. 5 and 6). Hygiea (C-type, 430 km) has a very long period, so only a small part of the period can be covered during one night. This does not preclude a good solution, but a twofold ambiguity remains in the pole result as Hygiea moves close to the plane of the ecliptic. The shape results (a/b=1.3, b/c=1.1) are very similar for the same reason. "Best regards

vogon13 · Jul 22, 2008

I confess a desire to see Chiron up close someday.  Nice to see some Jupiter leading and trailing Trojans, too. Maybe the same mission could 'do' all three . . . .      <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

vogon13 · Jul 22, 2008

OK, thought about that some more. Launch from earth on a NH style trajectory, but a bit slower (Not quite solar escape velocity) with a solar orbital period of 20 years.  (worked this out in my head, might be off a bit) Pass a trailing Trojan (or two) on outbound path to Chiron and then pass Chiron at the 10 year mark (and at solar aphelion, so moving pretty slow relative to Chiron for a nice leisurely look over).  On way back to earth (yeah, make sure orbital period is an exact multiple of 365.25 days) catch a leading Trojan (or 2) (note in interim, Jupiter has lapped the probe around the sun). Might be able to catch 1 or 2 main belt asteroids outbound and inbound too, btw.  Then 20 years after launch, flyby earth, and if probe is still in good shape, arrange flyby to accel, and go back out to outer solar system and check out something in the TransNeptunian  area on the way out of solar system, or flyby Uranus, or Neptune. For propulsion, use an 'off the shelf' Deep Space One style ion drive, and for power, either some RTGs, or maybe the new Rankine cycle power Stern has proposed.     <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

h2ouniverse · Jul 23, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>OK, thought about that some more. Launch from earth on a NH style trajectory, but a bit slower (Not quite solar escape velocity) with a solar orbital period of 20 years.  (worked this out in my head, might be off a bit) Pass a trailing Trojan (or two) on outbound path to Chiron and then pass Chiron at the 10 year mark (and at solar aphelion, so moving pretty slow relative to Chiron for a nice leisurely look over).  On way back to earth (yeah, make sure orbital period is an exact multiple of 365.25 days) catch a leading Trojan (or 2) (note in interim, Jupiter has lapped the probe around the sun). Might be able to catch 1 or 2 main belt asteroids outbound and inbound too, btw.  Then 20 years after launch, flyby earth, and if probe is still in good shape, arrange flyby to accel, and go back out to outer solar system and check out something in the TransNeptunian  area on the way out of solar system, or flyby Uranus, or Neptune. For propulsion, use an 'off the shelf' Deep Space One style ion drive, and for power, either some RTGs, or maybe the new Rankine cycle power Stern has proposed.     Posted by vogon13</DIV> Hi VogonThis kind of mission is being reviewed. Solutions with a closer aphelion are being consideredWhy do you want to go back to Earth?

3488 · Jul 23, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I confess a desire to see Chiron up close someday.  Nice to see some Jupiter leading and trailing Trojans, too. Maybe the same mission could 'do' all three . . . .      Posted by vogon13</DIV>You know what vogon? I do too. The Jovian trojans, how about the large D Type (same type as the Mars moons Phobos & Deimos) 624 Hektor, a suspected gigantic dumb bell shaped leading trojan asteroid, complete with a 15 KM diameter moon?Another interesting Centaur would be 5145 Pholus, very red. Andrew Brown.  <div class="Discussion_UserSignature"> "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". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Oct 15, 2008

2 Pallas, new HST imagery & update. <img src="http://sitelife.space.com/ver1.0/Content/images/store/15/13/df897d44-1d9c-458c-9daf-1c10340189e1.Medium.png" alt="" />2 Pallas, enlarged & sharpened images.2 Pallas has been the scene of absolute carnage. Huge chunks blasted off, leaving a formally fairly spherical body, looking beaten & dented. The scene of unimaginable violence & devastation.The HST views above are centred on 30 degrees south latitude with 60 degrees north at the top of the rotating gigantic, almost dwarf planet sized asteroid. I really, really hope, DAWN can do a slow encounter post 1 Ceres. Andrew Brown.  <div class="Discussion_UserSignature"> "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". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

h2ouniverse · Oct 17, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>2 Pallas, new HST imagery & update. .  Posted by 3488</DIV> Hi Andrew,If there is a mission extension for Dawn, I would prefer that Dawn focuses on Ceres and monitors transient phenomena over a longer time => we need to prepare for future landers and to understand our closest icy body! Let's have a Dawn-2 to seriously study Pallas and Hygiea, rather than just a fly-by. It seems that they have not made their mind yet for a potential post-Ceres fly-by, and might select a non-Pallas target.Btw, if you have a look at the third diagram I posted on the thread "extant water on TNOs", you'll see that I placed a Pallas-like TNO on the chart. The stunning thing is that if the authors are right, Pallas should have had liquid water pockets for several billion years before they froze. Provided of course that a giant impact has not excavated the regolith and vaporized such water ammonia layers into space as your pictures might point to!Regards.

3488 · Dec 16, 2008

Mithridates has created this very interesting article on his blog regarding 2 Pallas oppositions.Mithridates blog article on 2 Pallas. Hopefully the HST & other large observatories will / have observed today.Andrew Brown.  <div class="Discussion_UserSignature"> "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". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

h2ouniverse · Dec 16, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Mithridates has created this very interesting article on his blog regarding 2 Pallas oppositions.Mithridates blog article on 2 Pallas. Hopefully the HST & other large observatories will / have observed today.Andrew Brown.  Posted by 3488</DIV> Thanks Andrew (and Mithridates!) for the link!BTW, it's now more than one year since the latest opposition of Ceres. It was supposed to be observed by major observatories. Still no news, no papers... Did you see one?

3488 · Dec 16, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Thanks Andrew (and Mithridates!) for the link!BTW, it's now more than one year since the latest opposition of Ceres. It was supposed to be observed by major observatories. Still no news, no papers... Did you see one?  Posted by h2ouniverse</DIV>Good point Joel,I have not seen a thing. You can bet that either Jon Clarke, Wayne, Silylene or myself would have bought anything here & I would certainly have tipped you off.I will investigate, but as you say, its over a year now, about 13 months IIRC, November 2007.Something should be made available, but I can appreciate it takes time to sort & sift through the info (like Phoenix, Cassini, etc), but a few decent images could be made available IMO.Andrew Brown.  <div class="Discussion_UserSignature"> "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". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

silylene old · Dec 16, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Good point Joel,I have not seen a thing. You can bet that either Jon Clarke, Wayne, Silylene or myself would have bought anything here & I would certainly have tipped you off.I will investigate, but as you say, its over a year now, about 13 months IIRC, November 2007.Something should be made available, but I can appreciate it takes time to sort & sift through the info (like Phoenix, Cassini, etc), but a few decent images could be made available IMO.Andrew Brown.  Posted by 3488</DIV>The next opposition is Feb. 25 2009, when Ceres will be magnitude +6.9.  Ceres will be (by far) the brightest of all asteroid oppositions in 2009.  Vesta, and Pallas do not have any oppositions in 2009;  and Juno's opposition is rather far away.The Dawn Mission was launched on approximately the date of the 2007 Ceres opposition.  I am unaware of any particular new result from the 2007 opposition. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

3488 · Apr 2, 2009

Update on Hubble Space Telescope observations of the giant Main Belt Asteroid 2 Pallas.

Andrew Brown.

h2ouniverse · Apr 3, 2009

hi Andrew

I am puzzzled by the statement "Initially, we derive a triaxial mean shape model of 291 x 278 x 250 +/- 9 km". This seems way too small.

This being said, Pallas looks rounder than what had been said before.

3488 · Apr 3, 2009

h2ouniverse":x9y1xotg said:
hi Andrew

I am puzzzled by the statement "Initially, we derive a triaxial mean shape model of 291 x 278 x 250 +/- 9 km". This seems way too small.

This being said, Pallas looks rounder than what had been said before.

Hi Joel,

Yes I agree, that does seem way too small, 2 Pallas has at least a diameter of 550 KM, possibly more. I wonder if they mean radius's of a triaxial body, not diameters. That would fit.

Yes 2 Pallas does look a lot rounder than initially depicted, but the dimensions they gave, assuming diameters are far too small, that much is for sure.

2 Pallas imagery & shape models.

K Band albedo map of 2 Pallas. To me looks like there are two giant craters just north of the equator approx 270 Longnitude, eastward.

Andrew Brown.

2 Pallas.

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