Asteroid Vesta Not An Asteroid After All

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Since putting itself into orbit around Vesta in July, Dawn has found evidence that the object evolved more like a planet, with geologic processes that formed an inner core, most likely made of iron, and a mix of minerals on its surface. invisible soldier

Scientists don't know how Vesta survived the impacts that destroyed so many other objects in the Main Asteroid Belt, which lies between Mars and Jupiter. Vesta does bear the scars of brutal beatings, including a 290-mile diameter impact crater that left basin walls three times higher than Mount Everest.

"There were several large impacts that have tried to destruct Vesta," Reddy told Discovery News. "We don't know whether its general structure has something to do with the way it has been protected and still intact today. We're not sure if it has something to do with Vesta's location. We have a family of objects (meteorites) that actually are pieces of Vesta ... so we know that some pieces have been taken off. The question is why has it remained intact? I don't know." After a year of study at Vesta, Dawn is scheduled to move on to the largest object in the region, the dwarf planet Ceres.

Conversely I wonder what prevents Vesta from accumulating debris and growing into a full fledged planet? Why do we expect some things to be destroyed by collisions and assume others we created by the same forces?

Nice find I wonder if its made up of more structurally sound material.

reply to post by iforget

Conversely I wonder what prevents Vesta from accumulating debris and growing into a full fledged planet?

I would go with the presumption that the influence of Jupiter is to blame. This is mentioned often.

The great mass that Jupiter possesses served as a sort of "clearing house" in a sense early in the formation of the Solar System, and prevented the accretion of the dust, debris and other material that was accumulating at the orbital range that is the location of the "Asteroid Belt". Had Jupiter not been so massive, there very likely would have been another rocky planet, perhaps similar to Mars in size, at that location.

The "final result" of any planetary system as it forms is most likely going to be due to the distribution of the initial conditions, and how the dust and gases are arranged, and then the chaotic way that they will interact, as they coalesce. In addition, there can be outside influences during this process, that alter the arrangements. Without a time machine, we will always be making educated guesses on this, and will get more information as many observations can be made of other star systems being born, and seeing the various stages of development.

reply to post by ProudBird


Looks like Vesta gave it a go though. I guess it needed some of the smaller particles that Jupiter swept up. Must be something to learn about planet formation there in the asteroid belt. Thanks for the information.

Besides Jupiter early during accretion, Vesta is too tectonically inactive now to accumulate appreciable mass from collisions. Collisions now would be minor and if they are major Vesta already shows ancient scars of a larger collision by having a great deal of its mass removed thus creating its onion shape it could not reform as a sphere due to its low mostly inactive mass. Its more likely to get smaller than larger because collisions hit with such energy the debris would reach escape velocity and be lost to space. Forget about an atmosphere helping with friction.

I don't have the figures on hand for a Vesta escape velocity but consider the earth's at just over 25,000 mph, and the moon's around 5,300 mph and Vesta is but a fraction of the moon. Achieving orbit of an asteroid even the size of Vesta is a serious challenge, and would be a very serious challenge for a manned craft to land on it. Launching tethers were brought up in discussions to anchor a landing for possible/hypothetical manned crafts visiting some of the largest asteroids. Ceres is much larger than Vesta but has much lower mass/per volume, so its gravity wouldn't be magnitudes more than Vesta's.

I would venture to say that a bullet shot from a sniper rifle would reach Vesta escape velocity, and an impact could provide much more energy than that.

reply to post by iforget


very good question.

so many unanswered questions.... thankfully.

Very interesting. And to think there're so many other solar system bodies. How many mountains and valleys are just waiting to be loved by someone? I wonder if one day we'll actually live on these other places? Or will we see no purpose? Maybe we'll live on spacecraft or on computers or in other dimensions? All of this is juicy goodness when one ponders future potentials.

reply to post by Illustronic


I appreciate your valuable insight Illustronic.

More than anything to me it is surprising how fascinating Vesta can be when you start to get hard answers and good information about these seemingly simple objects in the asteroid belt. I can't wait to learn some of the actual good questions that are raised by Dawn and our other robotic spacecraft. I wish that we could stop killing ourselves long enough to get out there and look around some more.

reply to post by iforget


You don't have to be in the Main Asteroid belt to be susceptible to impact risks. You may have seen the Lunar Impact Monitoring site I have linked in the past a couple times, but I'll link again because I find this program to be damn interesting. Even more interesting is Marshall Space Flight Center offers amateur astronomers with data for some of the best times to view lunar impacts, and can actually be seen with assessable telescopes for the avid sky watchers out there.

The moon being such it is with its relatively large mass, impacts would add to the moons mass minutely, as its gravity is large enough to keep most all that hits it.

Marshall Space Flight Center-Lunar Impacts

Poke around on the site they have many images of impacts captured and even videos of some occurring caught live. They monitor impacts down to a pound in mass, and I find it fascinating the impacts can be viewed from here on earth.