A new class of extremely large telescope is on the drawing board. The
European Southern Observatory (ESO) is funding a feasibility study for a
ground-based, fully steerable, 100 m optical telescope christened OWL
(Over-Whelmingly Large) for its keen night vision.
The project, the
brainchild of ESO astronomer Roberto Gilmozzi, uses segmented primary and
secondary mirrors and integrated active optics. “OWL owes much of its design
characteristics to features of existing telescopes,” said ESO engineer Philippe
Dierickx.
Indeed, recent breakthroughs in cost-effective optics and
mechanical support structures, together with the knowledge gained of active
optical control (e.g. at the VLT, Gemini and Subaru), have encouraged
astronomers to dream of bigger things.
A 100 m telescope would mean
major advances. Imagine measuring the Hubble constant unencumbered by
local effects. OWL could measure “standard candles”, such as Cepheid
variables, as far away as the Virgo cluster; supernovae could be seen up to a
redshift of 10 and beyond; and with a large light-collecting area, observations
of rapidly varying sources become possible and faint objects, such as planets,
can be imaged directly. There is even talk of looking for planetary
biospheres.
However, the OWL study is still in an early phase. ESO’s
activities are currently focused on the completion of the Very Large Telescope
and the ALMA project – an array of submillimetre antennae to be installed on
Chajnantor in the Chilean Altiplano. “OWL could materialize at the horizon
beyond ALMA,” said Dierickx. “There is indeed very strong interest in the
scientific community to pursue efforts towards such extremely large
ground-based telescopes.” Current estimates suggest that OWL would cost
around a thousand million Euros with a construction time of 11-12 years.
