PCS

Planetary Camera and Spectrograph for the ELT

Prospective contrast boundaries of PCS". Longer Caption:"Angular separation and I-band contrast for Earth-like (wrt size and insolation) exoplanets around stars within 10pc. The symbol size indicates the planet's apparent  brightness, the color indicates the stellar spectral type (red: M, yellow: solar). The shaded area is accessible to PCS.

The Planetary Camera and Spectrograph will be the ELT's equivalent to the  SPHERE instrument.  Equipped with its own eXtreme Adaptive Optics (XAO) system, sophisticated coronagraphs, differential imaging systems and high-resolution spectroscopic facilities it is foreseen to enable the detection and characterization of exoplanets down to Earth-size in the solar neighbourhood.  Achieving contrast levels of 10⁻⁹ at separations of a tenth of an arc second, PCS will be able to look for biosignatures in the atmospheres of nearby (<10pc) exoplanets.

Project Status

PCS is currently in a roadmap study phase. The goal of the study is to produce a white book detailing the science case, the instrument concept, and presenting technological demonstrator solutions for 2-stage AO control in the form of  SAXO+, and a high actuator count deformable mirror. The study and the fabrication and verification of the demonstrators are foreseen to be concluded by 2028 with the publication of a whitebook. Based on this, an actual instrument consortium can then be formed and an actual project can begin with a proper phase A study.

Instrument Concept

PCS instrument concept". Longer caption: "Block representation of a possible PCS instrument concept. The first two boxes on the left represent the ELT and its conventional Single-Conjugate Adaptive optics (SCAO) system, essentially a copy of the one in METIS (-&gt; link https://www.mpia.de/en/PSF/instrumentation/metis). The next two boxes from the left represent a second correction stage by an eXtreme AO system with its own WaveFront Sensor (WFS), Deformable Mirror (DM), and Tip-Tilt mirror (TTM). The following two boxes represent a third stage of wavefront control for the correction of Non-Common Path Aberrations (NCPA), and the creation of dark areas within the stellar point spread function. After that, a suite of coronagraphs feeds the science instruments

As the instrument concept has not actually been fixed yet, only symbolic blocks can be shown representing subsystems. The ELTs internal AO system will be augmented by an additional stage, operating with more actuators (>13.000 instead of 5352), and at higher loop frequencies (>2kHz instead of 1kHz). This will provide a higher wavefront quality than for any other ELT instrument existing at the time. In addition, sophisticated additional wavefront control will be applied to correct instrument-internal aberrations, and to support the coronagraphic units  in the creation of dedicated dark areas in the stellar point spread function. Imaging, possibly polarimetric, and high-resolution spectroscopic instruments in the science focal planes will complete the suite of exoplanet characterization tools.

Consortium

The current roadmap study is led by ESO, and contributed to by CNRS-LIRA, Paris, France; CNRS-LAM, Marseille, France; CNRS-CRAL, Lyon, France; CNRS-IPAG, Grenoble, France; CNRS-LAGRANGE, Nice, France; CNRS-INSU; LCF, Paris, France; INAF-OAS, Bologna, Italy, Geneva Observatory, Switzerland; Durham University, UK; MPIA, Heidelberg, Germany; IACE, Porto, Portugal; Leiden University, NOVA, Netherlands; and the ATC Edinburgh, UK.

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