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The first 8.4-meter (28-foot) primary mirror in the telescope cell

(PLANETQUEST) -- The first of two huge primary mirrors for the Large Binocular Telescope have arrived on site in Arizona, marking an important milestone in the construction of a ground-based instrument that will be powerful enough to obtain some of the first images of planets around other stars.

The goal of the project is to construct a binocular telescope consisting of two 8.4-meter mirrors on a common mount. This telescope will be equivalent in light-gathering power to a single 11.8-meter instrument. Because of its binocular arrangement, the telescope will have a resolving power (ultimate image sharpness) corresponding to a 22.8-meter telescope.

A NASA-funded project will use the Large Binocular Telescope as a testbed to develop nulling and interferometry technologies. Nulling interferometry is a technique which cancels the overwhelming glare from a star by interference of light. This allows the detection of nearby planets or dust disks which would otherwise be obscured by the much brighter star. The technique is being studied in preparation for NASA's Terrestrial Planet Finder misson.

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Jason Smith, Jim Slagle and Doug Officer in front of the telescope's elevation structure in an April 2003 photo (University of Arizona).

Although more than 100 planets have been indirectly detected around nearby stars in recent years, the Large Binocular Telescope Interferometer (LBTI) will be among the first instruments capable of observing some of them directly. The planets that fall within the LBTI's detection range are called "Hot Jupiters" -- extremely hot, gas giant planets located in close proximity to their host stars.

The telescope itself and support structures were manufactured in Italy, then disassembled and shipped to Arizona in mid-2002. The parts are now being reassembled in a pre-constructed enclosure as part of the Mount Graham International Observatory in Arizona.

Surveys of nearby stars for extrasolar planetary systems using the Large Binocular Telescope Interferometer are scheduled to begin between 2006-2013.