Starship Asterisk*

Asteroid Vesta Full Frame

Explanation: Why is the northern half of asteroid Vesta more heavily cratered than the south? No one is yet sure. This unexpected mystery has come to light only in the past few weeks since the robotic Dawn mission became the first spacecraft to orbit the second largest object in the asteroid belt between Mars and Jupiter. The northern half of Vesta, seen on the upper left of the above image, appears to show some of the densest cratering in the Solar System, while the southern half is unexpectedly smooth. Also unknown is the origin of grooves that circle the asteroid nears its equator, particularly visible on this Vesta rotation movie, and the nature of dark streaks that delineate some of Vesta's craters, for example the crater just above the the image center. As Dawn spirals in toward Vesta over the coming months, some answers may emerge, as well as higher resolution and color images. Studying 500-km diameter Vesta is yielding clues about its history and the early years of our Solar System.

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This APOD is a repeat, so I will repeat myself==Vesta is a dwarf planet IMHO. I am not objecting to APOD repeats, I like dwarf planets.Thanx. .

This APOD is NOT a repeat. this is a new image of Vesta just released 2011 Aug 01. See previous post.

Hey, about time we see something new. vespa has lots of features. That dark impact crater looks as if it was a fireball rather than just a crater-interesting for once.

Is the appearance of heavier cratering toward the north not just the lighting (angle the sunlight was hitting it)? (you get the same effect when taking photos of the moon) Guess i'll have to check out more of the Vesta pics...

The grooves surely indicate that Vesta was once part of a much larger and/or geologically active body. Great stuff this.

Regarding the heavier cratering on the north side, I wonder if it doesn't just mean some bunch of stuff once came from that way. I presume the axis is pointing out of the plane of the solar system so that might mean some stuff was passing through the plane of the solar system. This is supposed to date a long way back.

named after princess vespa. huh?
but really, i wonder if the grooves that circle this object are a result of smaller orbiting bodies whose orbits gradually decay to the point that they end up rolling along the surface.

bto wrote:... vespa has lots of features ...

liebencrantz wrote:named after princess vespa. huh? ...

It's Vesta, not Vespa!

wikipedia: Vesta wrote:Vesta was the virgin goddess of the hearth, home, and family in Roman religion. Vesta's presence was symbolized by the sacred fire that burned at her hearth and temples. Her closest Greek equivalent is Hestia

HOORAY!!!! for bystander, for keeping everybody straight!

I was going to say what you did, which is: this is NOT a repeated image. A little link-following will show that.
And I was just going to ask: who is 'princess vespa', and what does she have to do with asteroid Vesta?

Great - and interesting - image and links!

Asteroids are often thought to be the shattered remnants of planetesimals that never grew large enough to become planets because they were torn apart by giant baobab trees. Vesta is, in fact, the ancient core of one of those baobab trees.

• Now there were some terrible seeds on the planet that was the home of the little prince; and these were the seeds of the baobab. The soil of that planet was infested with them. A baobab is something you will never, never be able to get rid of if you attend to it too late. It spreads over the entire planet. It bores clear through it with its roots. And if the planet is too small, and the baobabs are too many, they split it in pieces . . .

The first thing I noticed on today's picture was the crater with the black streaks; (what owlice calls a belly button. ) I wonder what the black substance is! I also noticed that on the rotation movie; that near the equator; there is a wide grove that seems to go all the way around the asteroid! I don't know if Vesta is round enough to be considered a planet!

Amazing pictures.

Maybe Vesta was part of a larger protoplanet which might explain the differnt hemispheres. Maybe the composition and density differs due to the position in the body of the hypothetical former protoplanet.

Or maybe Vesta was baked together from two different bodies in the young solar system.

Or maybe Vesta was once a moon of one of the greater planets with a fixed rotation so one side was more bombarded by space debris than the other.

Will Dawn be able to analyze the composition of Vesta's surface? Pretty-much all of the meteorites we have found are composed of nickel and iron, but that's after the outer bits burn off in the upper atmosphere. I wonder Vesta's surface is similar to the Moon samples that our Heroes brought back. [Anyone who makes a round-trip to the Moon and brings back souvenirs is a Hero in my book.]

(Aside: It occurs to me that not everyone has enjoyed, if 'enjoyed' is the word for which I'm searching, the movie by Mel Brooks, "Spaceballs," a spoof on "Star Wars V," with Princess Vespa as Princess Lea. http://www.imdb.com/title/tt0094012/ )

bystander wrote:

better than Obama wrote:... vespa has lots of features ...

liebencrantz wrote:named after princess vespa. huh? ...

It's Vesta, not Vespa!

wikipedia: Vesta wrote:
Vesta was the virgin goddess of the hearth, home, and family in Roman religion. Vesta's presence was symbolized by the sacred fire that burned at her hearth and temples. Her closest Greek equivalent is Hestia

Indigo_Sunrise wrote:... And I was just going to ask: who is 'princess vespa', and what does she have to do with asteroid Vesta? ...

• ----------------------------------------------------------------------
  [list]Memorable quotes for Spaceballs:

Princess Vespa:
I am Princess Vespa, daughter of Roland, King of the Druids.

Lone Starr: Oh great. That's all we needed. A Druish princess.
----------------------------------------------------------------------

• Memorable quotes for Private Benjamin:

Private Judy Benjamin:
To be truthful with you, I can't sleep in a room with 20 strangers.

Capt. Lewis: Oh dear.

Private Judy Benjamin:
And I mean look at this place. The army couldn't afford drapes?
I'll be up at the crack of Dawn here!
----------------------------------------------------------------------[/size][/list]

The upper left area is not the northern hemisphere, it is the equator.

If you look at the rotation movie, you will see that Vesta has grooves all around its equator. These look to me like impact grooves rather than, e.g. rift valleys.

Vesta is so oblate that most objects in low orbit around it (e.g. debris from collisions that didn't immediately fall back nor escape) will be tend to be dragged into a prograde equatorial orbit that eventually decays. (Based on my intuition of orbital mechanics of non-spherical dissipative bodies.)

Ground speed of a prograde equatorial circular orbit at touchdown height is about 150 m/s ~ 330 mph. This is much slower than most cratering impacts you are used to (in particular it is MUCH slower than sound speed in rock) so you don't get a point deposition of blast energy like you do with the more familiar case asteroid hitting the Earth or Moon with a much more vertical impact. Instead you are going to get a rock that comes in horizontally and slowly enough to gouge out a furrow as it touches down and starts rolling.

It wouldn't surprise me to see rubble piles at the ends of some of those furrows where the debris stopped rolling and then collapsed.

It looks like some of the impacts occurred on hard spots so that lower-velocity impactors would splatter rather than digging craters in softer material.

The Planetary Society Blog contains some thoughtful observations and conjectures about what we're seeing and a different version of the rotation movie.

Dmpalmer wrote:Based on my intuition of orbital mechanics of non-spherical dissipative bodies.

Wow, that's impressive all by itself! I have a lot of intuition, but I don't think I have even one brain cell involved in that particular aspect of it.

Amazing how much thought is spurred on just by having a good picture of something!

-Noel

Looking at the picture of Vesta and the cratered North comment, there seem to be some obviousities:

1. If I were to slam a large rock into the bottom of an otherwise uniformly cratered object, of the size that made a crater large enough to flatten a third of an otherwise "spherical" object, I would think the craters nearest to the said collision would be flattenned by just the pressure of the impact. Analogous to hitting the underside of a dent in the metal of your car will flatten the dent.

2. Likewise the same impact would create wrinkles where the acceleration for the impact material runs up against the inertia of the mass of the planetoid. wrinkling will occur, and depending on the material will show up vividly. Mimas and Phobos I believe have the same such wrinkles. Miranda is at the extreme end it came apart and it too has collision wrinkles.

So add a little observational logic to your mysteries, and an answer may spring forth

Thanks
Thongar

The video seems to betray a low data rate; it could take time to capture enough images for smooth animation.
http://www.youtube.com/watch?v=FaUaoy33gHE

why does the fact that there are more craters on the north side of Vesta remind me of the ice plasma plumes & subsequent comet-like tails streaming in what appeared to be a southerly polar flow?

Enceladus in this NASA photo: http://www.nasa.gov/centers/goddard/new ... ponge.html Anyone for enchiladas?

That being as it may, I understand that has nothing to do with Vesta directly. I wonder if they will find much trace sulfur from io, & would they find most of it on either (not both) hemispheres.
This leads to the question of whether what streams up through these large magnetic fields (whatever gas giant) would draw on nearby debris, propel it, and hurl any stray NiFe, or other magnetically-influenced object/field northward to hit home.(collector)

Were it to be an object already en route in the general direction of a magnetic episode during heavy solar winds (such as the previous decade) could it not be influenced by the magnetic flux and in-effect steered away from a large mass, aligned with the lines of magnetic force. Even if this predicted effect was unsuccessful at navigating the full loop of the lines of force, it would enable a re-capture event as the object(s) travel directly through the loop, instead of through the loop along the lines of force. Even a small acceleration could act like a 'natural' ion propulsion. If the object had company, say from a rubble-field, the effect could be pronounced like a 'stellar shotgun'.

If so, NASA has a new orbital class of asteroid to start looking for, as we might not be entirely immune.

The mysterious lines running along the surface are reminiscent of a good-sized encounter with that very effect. An object in motion will tend to find the path of least resistance to continue said motion.

If this was a natural feature of this solar system to be able to preferentially separating exo-solar meteorites and depositing them on a single pole, waiting for an explorer (robotic or otherwise) to discover exactly what was deposited. What if there was heavy, or even rare-earth metals propelled to their ultimate fate? Of course this could make such an exploration much riskier.

Perfectly pertinent is to find out how the solar flux effects, affects &/or how the magnetosphere of Jupiter can influence events in or around the asteroid belt. What would be the attenuation of the solar flux.

can anyone find cool pictures of io (or any other moons) emitting plumes of sulfur (or other gas) for me. I've been unsuccessful at that venture thus far.

Yep, just another boring hunk of dwarf planet.

Sorry, my friends, but I see the form of a white cross, even with the shadows inside the larger crater on the right??

Buzatti wrote:Sorry, my friends, but I see the form of a white cross, even with the shadows inside the larger crater on the right??

Given an essentially random arrangement of rocks, dust, craters, and other features, it's very possible to see such things as crosses, faces, roads, or anything else your imagination can conjure up. No need to apologize for it; it's a natural human tendancy.

Rob