A 4.1-meter
primary mirror arrived at its new mountaintop home of Cerro Paranal, Chile. The disc makes up part of the VISTA (the Visible and Infrared Survey Telescope for
Astronomy), part of ESO's Very Large Telescope facility. The delicate object
was flown in a special cradle using tennis balls for cushioning, then survived
a road trek to the observatory which stands at an altitude of 8260 feet (2518 meters),
in Chile's Atacama Desert.
The VISTA primary mirror is the most strongly curved large mirror ever polished to such a
precise and exacting surface accuracy — deviations of
less than 1/3000th of the thickness of a human hair. On arrival, it was washed
and coated with a thin layer of protected silver. Silver is optimum for the
purpose since it reflects over 98% of near-infrared light, better than the more
commonly used aluminium. To date, the reflectivity produced by the silver
coating exceeds all other telescopes.
VISTA will survey the southern sky at
near infrared wavelengths to study objects not easily seen in optical light. VISTA's surveys will help our understanding of the nature and distribution and origin of
known types of stars and galaxies, and help determine the relation between the
3-dimensional structure of the universe and dark energy and dark matter.
Full
scientific operations are expected to start early next year.
— ESO and SPACE.com Staff
Credit: ESO/M. Cullum
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