May 20, 2019

03.05.11: The Mysteries of Vesta.

A projected model of Vesta. (Credit: NASA/JPL/CALTech/UCLA/PSI).

In a string of recent firsts, scientists are about to get a good look at an enigmatic solar system body for the first time this summer. Launched in 2007, NASA’s Dawn spacecraft is due to orbit the asteroid Vesta in August of this year, giving us the first non-blurry close up images of the 530 kilometer diameter world. Discovered in 1807 by Heinrich Wilhelm Olbers, Vesta is one of the very few bodies identified that we actually have meteorite samples from (other include our Moon and Mars). But what is Vesta? Like the controversial worlds Pluto and Eris, Vesta exhibits some very un-asteroid-like characteristics. For example, scientists have known since 1972 that Vesta is dense enough to experience layering, or differentiation, in stark contrast to being a simple “rubble pile”. We know this from spectroscopic analysis of its relatively dark basaltic surface. Also, Vesta is very close to that all important tipping point when bodies obtain hydrostatic equilibrium and become basically round. Terms such as “planetoid,” “planetesimal”, “dwarf planet” and even “Vestoid” are all tossed about by researchers, but clearly, this is a unique world onto itself. Why go to Vesta? Well, such remnants may just give us the key to the beginnings of bodies in the very early solar system, and provide us with a snapshot of how terrestrial planets like our own Earth formed. One key mystery, for example, is how growing worldlets went from low speed “clumping” to acquiring more and more material via building gravitation. Vesta also shows some color variation in the blurry images acquired by Hubble, and may prove to be more that just another “cratered rock…” As reported earlier in this space, Dawn will also break orbit from Vesta after a 12 month stay, using its ion propulsion drive to head for the largest of the asteroids, Ceres in February, 2015. Expect the Dawn mission to be the highlight for planetary science in the summer of 2011! (And just think, us science bloggers will finally have more than just blurry images and artist’s conceptions to post on Vesta!)   

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