Realtime adaptive optics will enable exoplanet search and characterization by 30 meter and 40 meter ground based telescopes

The new camera and adaptive optics of the Giant Magellan Telescope are enabling the sharpest images of the night sky ever. This is just the start for the next generation of ground based telescopes. The Giant Magellan telescope still must be completed for its combined lens for 27 meter collecting area.

Two other big ground based telescopes are the Thirty meter telescope and the European Extremely Large Telescope. They will have up to one hundred times the resolution of the Hubble Telescope and 20 times the collecting area.

The European Extremely Large Telescope (E-ELT) is a planned ground-based extremely large telescope for the optical/near-infrared range, to be built by the European Southern Observatory (ESO) on a mountain top in Cerro Armazones, Chile. The design comprises a reflecting telescope with a 39.3 metre diameter segmented primary mirror, a 4.2 metre diameter secondary mirror, and will be supported by adaptive optics and multiple instruments

European Extremely Large Telescope (E-ELT)

The primary mirror for the 39.3 metre design will be composed of 798 hexagonal segments, each 1.45 meters across but only 50 mm thick. A special correcting mirror in the telescope will be supported by more than 6,000 actuators that can distort its shape a thousand times per second. The telescope main structure will weigh about 2,800 tons

The E-ELT will search for extrasolar planets — planets orbiting other stars. This will include not only the discovery of planets down to Earth-like masses through indirect measurements of the wobbling motion of stars perturbed by the planets that orbit them, but also the direct imaging of larger planets and possibly even the characterisation of their atmospheres. The telescope will attempt to image Earthlike exoplanets, which may be possible.

Furthermore, the E-ELT’s suite of instruments will allow astronomers to probe the earliest stages of the formation of planetary systems and to detect water and organic molecules in protoplanetary discs around stars in the making.

The GMT recently took 0.02 arcsecond resolution images. The previously designed angular resolution of the GMT was 0.21–0.3 arcsecond resolution at 500 nm.
The E_ELT should have 0.001 to 0.65 arcseconds of angular resolution depending on instrument.

The Thirty Meter Telescope (TMT) is a planned ground-based large segmented mirror reflecting telescope, proposed to be built on Mauna Kea in Hawaii. The telescope is much larger than existing telescopes (though the planned European Extremely Large Telescope’s mirror is 30% larger), and designed for observations from the near-ultraviolet to the mid-infrared (0.31 to 28 μm wavelengths). In addition, its adaptive optics system would help correct for image blur caused by the atmosphere of the Earth, helping it to reach the potential of such a large mirror.

Thirty Meter Telescope

Integral to the TMT observatory is a Multi-Conjugate Adaptive Optics (MCAO) system. This MCAO system will measure atmospheric turbulence by observing a combination of natural (real) stars and artificial laser guide stars. Based on these measurements, a pair of deformable mirrors will be adjusted many times per second to correct optical wavefront distortions caused by the intervening turbulence.

This system will produce diffraction-limited images over a 30 arcsecond diameter field-of-view. For example, the core of the point spread function will have a size of 0.015 arcsecond at a wavelength of 2.2 micrometers, almost 10 times better than the Hubble Space Telescope.

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