According to Dawn (who ought to know) the descent to the next mapping orbit is beginning now.
"NASA_Dawn NASA's Dawn Mission
I'm done with Survey science operations today!! Time for a several-week transfer down to High Altitude Mapping Orbit (HAMO)!!
20 hours ago"
Better pics on the way! Thanks, Dawn team, for the pictures so far. Will we learn of any preliminary nomenclature soon?
Phil
http://dawn.jpl.nasa.gov/mission/journal_09_01_11.asp on HAMO --
"...they have been able to detect variations in the gravity field that are due to the uneven distribution of mass within the protoplanet. With their improved charts of the waters around Vesta, they plotted the ship’s course, and it is now under sail. Thrusting with the ion propulsion system began on August 31 at 4:05 p.m. PDT, and this trip to the high altitude mapping orbit will take a month."
Thanks, Paul.
Phil
Thanks for updates, Paul!
Here below the updated velocity/distance plots, current transfer orbit is clearly elliptical.
I made by myself using http://dawn.jpl.nasa.gov/mission/live_shots.asp from JPL Dawn site. Obviously, not real-time data nor continuous coverage, if you have something better, pls give us!
First Message: Hello everybody
Answering dilo:
You can use SPICE data from NAIF: ftp://naif.jpl.nasa.gov/pub/naif/DAWN/kernels/
For example, I product this http://www.youtube.com/watch?v=qWZbcAKXu-s from theses data.
The problem is that you should have some (but little ) programming skill for using SPICE files.
But the good news is that the NAIF library (see upper node of link) is full of documentations and tools to learn and use it.
But maybe DrShank know a better way ?
Great pictures recently - not from HAMO yet or even the descent to HAMO, but really giving a taste of what the surface will look like in the weeks to come.
http://dawn.jpl.nasa.gov/multimedia/imageoftheday/archives.asp?month=2011-September
I'm especially interested at the moment in this area from the Sept. 3 release:
Dare I say those lobate margins look like flow features? Fun to think about, anyway!
> I'm especially interested at the moment in this area from the Sept. 3 release:
And why does this crater have an eccentric fill on the floor?
What a peculiar little world.
The eccentric fill may be a result of a local slope - the fill is horizontal, the crater's tilted. Of course, we need a proper shape model and interior mass distribution model to be sure, but that's my guess.
Phil
I considered this an, uh, occipital illusion, and briefly discounted a local slope phenomenon since this is not a grossly potato-shaped world, but the local slope phenomenon is likely the most tenable.
Still, ain't Kansas...
--Bill
Several of the recent images can be joined to make a rough mosaic - the first one (left end) in its raw form and the rest distorted to fit it, very uncontrolled.
Phil
...again. (That's why I've been hooked on UMSF since Mariner 9...)
Never gets old, not a bit. We NEVER find what we expect, and of course that's why we go.
Latest picture of the day - an unusual hill:
http://dawn.jpl.nasa.gov/multimedia/imageoftheday/image.asp?date=20110908
But they don't say what's unusual about it, so I'm forced to offer my own theory. It resembles a whale - eye, mouth, fin, tail... head at the top. I think it's the whale from the Hitchhikers Guide to the Galaxy. Of course it could be something boring like a volcano!
Phil
Assuming the magma chamber is not uranium powered - what is the smallest body that can support a volcano?
Wouldn't Vesta be below that limit?
it could be a shadow of an unknown moon ...
A whale-shaped moon!
Vesta is well known for its basalt crust, as shown by spectroscopy and the meteorites thought to have come from Vesta. So volcanoes can't be ruled out. The idea of a minimum size for volcanoes may crumble in the face of evidence. That's what Dawn is all about.
Phil
Dawn is approaaching to final orbit through a complicate set of maneuvers:
A glimpse of Vesta in colour!
http://photojournal.jpl.nasa.gov/catalog/PIA14697
(Alongside a visual/infrared false-colour image of the same bit of terrain.)
I wonder where on Vesta this is.
And today picture resized 400% and gamma corection for "best look"
From TIFF.
Simulator didn't update images in the last 14 hours!
Do someone knows the reason?
Have you tried sending them a friendly email rather than post an angry face here?
Good suggestion, Dough (I was hoping someone here was informed, but direct contact is better).
I received a kind answer after only 7 minutes by Judy Counley (Dawn site webmaster) telling that the responsible for simulator is already working on the issue!
Yes, we'ev got a lot of puzzle-pieces to fit and assemble. The duck-feet look like chicken-feet which are starting to look like talons...
--Bill
Many great new pics at the Photojournal today including this new map:
http://photojournal.jpl.nasa.gov/catalog/PIA14703
including a gridded version. The coordinate system does not match the old one derived from Hubble images, a point that is causing some controversy, but I have little doubt that this will become the official coordinate system eventually. Another image in the new set defines the prime meridian marker:
http://photojournal.jpl.nasa.gov/catalog/PIA14715
Phil
This is a montage of frames from the shape model rotation movie also included in this release.
Phil
Also cataloged here:
http://dawn.jpl.nasa.gov/multimedia/vesta_dawn_gallery.asp
It's amazing how there are some very distorted ancient basins in the more tropical latitudes. And perhaps another giant basin that creates a gap in the south polar crater "rim." And the grooves aren't equidistant from the center of the southern crater, are they?
http://www.dawn.mps.mpg.de/index.php?id=17&L=1&tx_ttnews%5Btt_news%5D=48&cHash=87b2bf3be6e011932de9d31da5358ace
False color map of Vesta - very nice! It's not the full range of longitudes, only about 240 degrees long, and it doesn't register exactly with the recent base map (different projection), but it is interesting. This barely gets into the south polar depression at its southern edge.
Phil
Love it! Sooo cool! How about that massive chasma across the middle? (Blue material in false color)
It's clearly a basin. The trick is, what caused it? That wonderful south polar impact threw up a huge amount of ejecta, a fair portion of which would have fallen back to the surface in all sorts of interesting ways. Shaking from the impact doubtless created some interesting structures. Based on what we know so far, Vesta's going to be a tough (and tasty!) nut to crack.
I had an interesting and very pleasant communication with Dr. Marc Rayman; he explained me that, until few hours ago, Vesta distance reported in the Simulator was based on extrapolated values of distance from asteroid centre, not height. I corrected my database and now is clear that Dawn is very close to HAMO final orbit, both in terms of height and speed (685 km and 135 m/s):
Yes! It's very interesting to overlay the Hubble compositional maps (in Li et al., Icarus 208 (2010) 238–251, for instance) over the new maps. Even quite small crater ejecta deposits line up very well. The two 'red' patches (false color) were clearly seen, but mapped as different things (Eucrite and weathered materials). No doubt we'll be getting team publications on this in due course.
Phil
In Universe Today is an interview with Prof. Chris Russell and Carol Raymond.
South pole impact feature has been officially named Rhea Silvia after the mother of Romulus and Remus, mthyical mother of the Vestal virgins.
Prof. Chris Russell
“We have set ourselves a target to gather everything we know about the south pole impact feature and expect to have a press release from what ever we conclude at the GSA (Geological Society of America) meeting on October 12. “We will tell the public what the options are.
“We do not have a good analog to Vesta anywhere else in the Solar System and we’ll be studying it very intently.”
Sorry for the long url...
http://www.universetoday.com/89093/rhea-silvia-super-mysterious-south-pole-basin-at-vesta-is-named-after-romulus-and-remus-roman-mother/#more-89093
Craig
GSA meeting 10/12/11... DAWN session
Dawn at Vesta: Initial Results from the Survey Orbit
http://gsa.confex.com/gsa/2011AM/finalprogram/session_28729.htm
12 presentations!
Craig
And along a similar vein (!):
It makes some sense. The reason you think everything outside of Rheasilvia is older is because of the plethora of little impact craters that saturate much of the rest of Vesta (except around the snowmen) that you just don't see in it. The age estimate from lower res images like uses craters larger than these little guys and for those you could make the argument that there really aren't that many more outside the big crater than outside.
Perhaps the saturated crater population are secondaries from the big giant impact which basically reset the cratering age of Vesta. Only those secondaries that fell outside the crater which shall not be named survived. The larger craters, like the snowmen, formed after it.
When you say Rheasilvia, do you mean Rheasilvia or just Rheasilvia?
Phil
(just kidding!)
Hey, I am just trying to get used to the name...
Well, you're getting lots of experience!
Phil
I wouldn't mind if you called it Rheasliva.
It's got to be an impact crater, right? Not really? "Endogenic?" Would that be like the runaway radioactive-earth-birthing-the-moon hypothesis? Vesta just one day exploded like rotting fruit?
A little thing I've been playing with... the recently released map extended only to about 40 degrees north. I took the northern hemisphere and converted it to a pole-centred view. Many of the image releases including today's extend coverage into the north polar region, which I call 'Philstookia'. Here's the map so far.
Phil
In the last 5 days, Dawn didn't use his engine and remained in a slightly eccentric orbit (665x700 km height):
Just looking at Phil's picture.
What if a rapidly spinning Vesta was hit by a huge body early in the asteroid belt formation?
Would you get spiral grooves and terrain jumbled at odd angles?
Brian
Indeed, Vesta's midsection does look as if it has been worked on a lathe. But the rotational axis on an actual lathe is maintained by a mechanically rigid piece of machinery. For a pair of free-spinning celestial bodies, it is hard to see how they could maintain just the right distance for several revolutions so to gouge out the grooves without bouncing off, melting, breaking up, merging, etc. The sort of light, plowing, contact that monty is considering is a pretty unstable situation. That said, I don't have a better idea to explain how the grooves got there. I assume some common cause must operate on vesta, phobos, lutezia, maybe even iapetus, but most of the contending stories have holes in them. Let's keep working on it.
Latest journal entry shows that Rheasilvia is indeed the official name of the south pole crater!
My total ignorance of geology is showing, but I could imagine a scenario in which the southern basin impact partially melted the entire surface of Vesta, with the asteroid "ringing" seismically for a while afterward. The concentric grooves in Phil's polar projection remind me of waves that froze as the surface cools.
Again, I am not a geologist...just relaying the impression that I get from that projection.
Yes, here's the latest Dawn journal:
http://dawn.jpl.nasa.gov/mission/journal_09_27_11.asp
Two new stereoscopic images from my blog:
South polar mountain - http://4.bp.blogspot.com/-RSR4n8u4ToI/ToW1Px0wiLI/AAAAAAAAAA0/3ax2V9Ai0v8/s1600/spmce_s.png, http://3.bp.blogspot.com/-YnvbEcnz7C8/ToW1aPJv6hI/AAAAAAAAAA4/b1NrRBqhGMw/s1600/spm3d9z20gsi.png and http://my-favourite-universe.blogspot.com/2011/09/vesta-ve-3d-podruhe.html.
Wow, what an extraordinary structure that has turned out to be!
P
Is http://dawn.jpl.nasa.gov/multimedia/imageoftheday/image.asp?date=20111001 the first image from HAMO?
Looks splendid either way!
This image was released yesterday:
http://dawn.jpl.nasa.gov/multimedia/dawn_vesta_mapping_orbit.asp
It has a slightly lower pixel scale at 65 meters per pixel.
Indeed, while yesterday's published image was snapped on Sept,17 from 750km height (based on resolution and according to simulator data), the Volcanopele highlighted one was probably taken the following day, when Dawn reached nominal HAMO height, slightly below 700 km.
One question: do someone knows updated Vesta size after Dawn exploration?
I guess even preliminary estimates are a lot better than Hubble-based figures but, strangely, I cannot find anything else! (obviously, I am referring to average ellipsoidal 3 axes value)
From the EPSC-DPS Joint Meeting 2011 ..
Media release
Dawn at Vesta: Massive mountains, rough surface, and old-young dichotomy in hemispheres
http://www.europlanet-eu.org/outreach/index.php?option=com_content&task=view&id=352&Itemid=41
"NASA’s Dawn mission, which has been orbiting Vesta since mid-July, has revealed that the asteroid’s southern hemisphere boasts one of the largest mountains in the Solar System. Other results show that Vesta’s surface, viewed at different wavelengths, has striking diversity in its composition particularly around craters. The surface appears to be much rougher than most asteroids in the main asteroid belt. Preliminary results from crater age dates indicate that areas in the southern hemisphere are as young as 1-2 billion years old, much younger than areas in the north. The findings are being presented today at the EPSC-DPS Joint Meeting 2011 in Nantes, France"
This brieifing was webcast live at 6:15am Eastern U.S. and I missed the first 30 minutes.
Good stuff!
Craig
As mentioned in the press release, several names have been approved by the IAU for features that provide the names for mapping quadrants on Vesta. Here is a map identifying those craters (and one hill) :
... or part of the answer. She doesn't give the three axes.
Phil
Thanks for highlight, ElkGroveDan! And perfect timing, Emily!
Obviously, in the report volume exponent is missed (should be 7,532E+7 cubic km); average radius uncertain should be 850 m.
The big thing to me was Dr. Russell's mention of an appreciable iron core, detected though the denity and j2 measurements. So we have a differentiated body.
What a shame they lost the magnetometer to budget. Dr. Russell even mentioned that when a questioner asked what other instruments he would have liked included.
Craig
Update with zoomed scale on last 3 weeks:
Full inline quote - with image - removed - ADMIN
Looking at that orbital data, I would have to wonder if that is pretty much the closest to a constant-speed, constant-radius, circular orbit Dawn can manage, with Vesta so flattened and asymmetric.
I'm sure the little variations are yielding a picture of the source mass distribution. I can't devolve the gravity figure from the orbit data, doing the math in my head, unless I've had at least 2 beers, and it IS a weeknight. Maybe someone else can help...
Today's image of the day is pretty fun to look at:
http://dawn.jpl.nasa.gov/multimedia/imageoftheday/image.asp?date=20111009
A lot going on there.
Also-- does anyone know of a good RSS feed to get the image of the day into their reader?
Yea. It looks like there is a darker (older) layer of material the crater punched into. Is the darker material more loosely consolidated, as it looks to me that the north and south sides of the crater with more dark material slumped, and the pits in the crater bottom are in dark material.
I can't get over how the rays left grooves in the surface. I'm trying to picture in my mind how the impact happened and could do that.
Low gravity small body dynamics? The debris flying out gives a trajectory effectively parallel to the ground perhaps and just plows the surface for a really long way?
This paper written a few months before Dawn reached Vesta claims the impact near Vesta's south pole would have caused Vesta's axis to reorient and made some predictions based on this. Are we seeing any of the features they predicted?
http://www.es.ucsc.edu/~fnimmo/website/Isamu_Vesta.pdf
3-D perspective view of the south:
http://dawn.jpl.nasa.gov/multimedia/vesta_south_polar_region.asp
What a mess. Scientific disinformation in a place you wouldn't expect it. Thanks, members, for pointing it out. (So, can we pruduce the correct version here???)
I would hazard a guess that projecting onto an plane allows for better comparisons to other craters. Except that if you're doing that, you might want to de-exaggerate the height of things, because you're probably comparing to craters on worlds with higher gravity.
Once you have a DEM you can project it any way you like. A DEM of North America might be represented without planetary curvature, in fact it probably would be most often. This one is shown with a plane datum, the next might be done with curvature added. No problem either way. Anyone may prefer one over the other, but don't represent the other as wrong. In time we'll have everything.
Phil
Slew of new stuff:
http://dawn.jpl.nasa.gov/feature_stories/science_team_early_results.asp
http://dawn.jpl.nasa.gov/multimedia/vesta_dawn_gallery.asp
http://dawn.jpl.nasa.gov/multimedia/imageoftheday/image.asp?date=20111012
Some pretty cool slides:
http://dawn.jpl.nasa.gov/multimedia/images/slide5_image.jpg
etc.
Replay of conference here:
http://www.ustream.tv/recorded/17833902
Interesting comments about the troughs.
The latest image releases at the Dawn site are much higher resolution - very nice indeed. And it will get even better!
Phil
http://dawn.jpl.nasa.gov/multimedia/imageoftheday/archives.asp?month=2011-October
Any opinions on the strange half-craters on the recent http://dawn.jpl.nasa.gov/multimedia/imageoftheday/image.asp?date=20111021?
Sure looks like a trough between the two.
Railway embankment between the two craters?
(Broad gauge, obviously.)
It's strange isn't it. I see areas on vesta that look like hummocky flow features -like land slide debris - covering the surface. But the half craters look younger than this debris. Could it be that this debris is varying in thickness and distribution so that the the cratering events here punched into only parts of this less consolidated stuff which partially slumped into these craters?
The differing depth of loose ejecta may come into it, the boundary of the slump in the lower crater certainly climbs the slope of the smooth wall to the south. But I think that the angle of incidence of the impact may also have an effect. The floor of the crater is not in the center.
.
Vesta in almost natural colors (filters centered at 440, 650 and 750 nm).
Two basic images:
http://3.bp.blogspot.com/--9ixB2fzKVM/Tp2JYkpfDFI/AAAAAAAAABM/zqMX67v0R3s/s1600/rc2_b-g-r.png
http://2.bp.blogspot.com/-vjDACRxWBHs/Tp2MnxpgC7I/AAAAAAAAABc/AUlZKFP3n-Y/s1600/rc3_b-g-r_cor-f.png
English captions and 5 other versions are http://my-favourite-universe.blogspot.com/2011/10/vesta-nyni-vysilame-barevne.html.
Original "raw" images are available http://www.sendspace.com/file/5sctxp.
... and the full disk one fills in a bit more of the northern hemisphere. Here's my current coverage map of the north pole. Locations may not be very accurate at the terminator but the general appearance is clear.
Phil
Impressive, Phil!
Is grooves spiral structure real? Which is explaination?
I have impression that North pole is hiding something important but I suspect we have to wait looong time before seeing it!
The spiral pattern is mostly a map projection effect. One of our team has located them and they fit great circles.
On Iapetus, that process is called on to create a ridge... can it do both?
Phil
Impact debris here would form radial or spiral from the center. These are extension cracks formed from several possible sources. Examples include shape change and reorientation. Among others. It's proving difficult to get the exact ages however and we have some numerical models yet to test. Should be interesting!
I haven't much informations about this, I know only, that it's from anonymous source in the Dawn team and it was one-time thing, so we must
wait now for another (raw) data until official release (~ end of year 2012).
As probably you noticed in the simulator, starting from yesterday Dawn ignited engines and started spiraling toward LAMO:
Hi Stefan
Engines cut-off few hours ago, around 530 km height... probably thrust will resume soon:
What is the target altitude for LAMO? Edit found it:180 km. That low to get gravity field. See Marc Rayman's December 10, 2010 post on the http://dawn.jpl.nasa.gov/mission/journal_12_30_10.asp
Further update, showing in grey periods with engines off (with very indicative start/end times):
As anticipated, engine stops are more and more frequent (grey areas in the following updated plot):
Some interesting "simulated true color" images added at the end of October.
http://dawn.jpl.nasa.gov/multimedia/imageoftheday/image.asp?date=20111028
Crazy contrast, really. So I guess that begs the question of whether it's simulated but stretched.
Cranking up the saturation on the last image to help reveal the extent of different color units...
Nice work, Adam! Phil, based on your experience with cranking up the saturation on photos of odd-shaped bodies, do you think that the change in color from north to south is real or does it have more to do with photometric effects?
"Phil, based on your experience with cranking up the saturation on photos of odd-shaped bodies, do you think that the change in color from north to south is real or does it have more to do with photometric effects?
Hmmm... on any normal world I'd say I was worried about photometric effects, but we know the south polar terrain is different in this case, so I expect it's some combination of both things.
I think tree ornaments made to look like solar system objects would be a winner. I would buy them...
Phil
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)