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Finally we can see the real face of Vesta, asteroid number 4, discovered on 29th March 1807 by Olbers. It was photographed on 9th July by the Dawn probe, after a journey of almost four years that began in September 2007.
This image was taken from a distance of 41,000 km and shows a great deal of surface detail, even though the resolution is only 3.8 km/pixel. At first glance, Vesta resembles many of the other minor bodies in the solar system, particularly some of the satellites of the giant planets with similar diameters of around 500 km.
After taking this image Dawn continued to approach Vesta, and at about 1am tomorrow morning (EDT) will be captured into a stable orbit about the asteroid. This will be possible only after a long process of trajectory refinements made to Dawn's path by flight technicians, that will allow the probe to gently enter orbit without heavy use of its directional rockets.
The probe is expected to enter asteroid orbit at a distance of 16,000 km from Vesta, but the exact distance and time will only be known in a few days, after the mass has been calculated through observations of the behaviour of the asteroid's new "satellite". The rendez-vous will take place at a distance of 188 million km from Earth.
Dawn will stay in orbit around Vesta for a year, after which it will leave for it's second target, the dwarf planet Ceres (ex asteroid number 1), where it will perform a similar manoeuvre to that at Vesta. This will actually be the first time that a probe has entered into orbit around more than one solar system body.
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