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6 March 2014 1:04 pm ,
Vol. 343 ,
Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
Antiretroviral drugs can protect people from becoming infected by HIV. But so-called pre-exposure prophylaxis, or PrEP...
Two studies show that eating a diet low in protein and high in carbohydrates is linked to a longer, healthier life, and...
Considered an icon of conservation science, researchers at World Wildlife Fund (WWF) headquarters in Washington, D.C.,...
The new atlas, which shows the distribution of important trace metals and other substances, is the first product of...
Early in April, the first of a fleet of environmental monitoring satellites will lift off from Europe's spaceport in...
Since 2000, U.S. government health research agencies have spent almost $1 billion on an effort to churn out thousands...
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ScienceShot: Asteroid Vesta As a Failed Planet
10 May 2012 2:00 pm
Since slipping into orbit around the solar system's second-most massive asteroid last July, NASA's Dawn spacecraft has confirmed Vesta's status as a body whose arrested growth denied it true planethood. In a series of papers published online today in Science, researchers report that according to Dawn observations, Vesta did indeed agglomerate enough rocky debris as it grew to heat itself by the decay of the rock's radioactive elements. That heat led to the separation of the primordial body into a rocky crust, an underlying rocky mantle, and a central metallic core, hallmarks of planet Earth and the other rocky planets. Dawn was the first to detect Vesta's now-solid core. The trick was to record its subtle gravitational signature during many orbits of the asteroid. Vesta also grew large enough to survive a massive battering about a billion years ago that formed the 500-kilometer-wide Rheasilvia impact crater and its 22-kilometer-high central mound (above). But at a diameter of only 530 kilometers, Vesta was not quite massive enough to pull itself back into a sphere after the Rheasilvia impact. And, like the rest of the asteroids, it stopped growing far short of the mass needed to gravitationally clear other bodies from the vicinity of its orbit. That was Pluto's downfall, as well.
See more ScienceShots.