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Aug 11

Dawn's smooth orbital insertion at Vesta

Source: NASA Science News


Dawn's image of Vesta on July 24, 2011.
Image credits: NASA/Dawn.

When a NASA spacecraft goes into orbit around a new world for the first time, the control room is usually packed to capacity with scientists, engineers, and dignitaries ready to leap and shout when the retro-rockets fire. It's a big, noisy event.

July 15, 2011, was one of those days. NASA's Dawn spacecraft approached Vesta and became the first probe from Earth to orbit a main belt asteroid. Dawn's cameras revealed a desolate world of transcendent beauty, thrilling everyone who worked on the project.

Needless to say, the control room was .... silent?

This was because with Dawn all could be fuel controlled previously. (read more)

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1
Aug 11

Segue 1 - The heart of darkness

Source: W.M. Keck Observatory


Segue 1 galaxy. We are not joking!
Image credit: Keck/Marla Geha

Astronomers using the 10-meter Keck II telescope in Hawaii have confirmed in a new paper that a troupe of about 1000 small, dim stars just outside the Milky Way comprise the darkest known galaxy, as well as something else: a treasure trove of ancient stars.

By “dark” astronomers are not referring to how much light the galaxy, called Segue 1, puts out, but the fact that the dwarf galaxy appears to have 3,400 times more mass than can be accounted for by its visible stars. In other words, Segue 1 is mostly an enormous cloud of dark matter decorated with a sprinkling of stars. (read more)

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