ESA Voyage 2050 White Paper: Detecting life outside our solar system with a large high-contrast-imaging mission

In this white paper, we recommend the European Space Agency plays a proactive role in developing a global collaborative effort to construct a large high-contrast imaging space telescope, e.g. as currently under study by NASA. Such a mission will be needed to characterize a sizable sample of temperate Earth-like planets in the habitable zones of nearby Sun-like stars and to search for extraterrestrial biological activity. We provide an overview of relevant European expertise, and advocate ESA to start a technology development program towards detecting life outside the Solar system.Stars and planetary systemsInstrumentatio

Artificial Intelligence system and Optimized Modal control for the ADONIS adaptive optics instrument

ADONIS is an adaptive optics user friendly instrument for the ESO 3.6-m telescope. The modal control technique is presented as a tool for optimizing the control of ADONIS. The perturbed wavefront is spread over a base of modes treated by the system in terms of their behavior with respect to the observing conditions (turbulence characteristics, anisoplanatic angle and star magnitude). This optimization and the multiple parameters influencing the system performance are difficult to handle by the astronomer. Moreover, the wide range of situations the astronomical AO system has to deal with requires a flexible configuration which has to be optimized for each case. The ADONIS instrument also has to be easy to use by an astronomer who doesn't have a deep knowledge of AO techniques. Finally, it must make efficient use of the telescope time. Hence, a new human interface and an intelligent control system have been designed. 1 INTRODUCTION The ADONIS instrument 2,14 is based on the adaptive o..

High contrast imaging: a new frontier for exoplanets search and characterization

Although very successful (more than 350 planets discovered tip to now), indirect methods for extrasolar planet detection (Radial velocities, transits) are sensitive to planets quite close to their hosts. Moreover, accurate studies of the planet characteristics are feasible only for a subset of objects which are strongly irradiated by their parent stars.High contrast imaging will be the new frontier of exoplanets search and characterization. This technique will provide the opportunity to have at once a deep glance in the neighborhood of the target star in a yet unexplored region of star-planet separation.The possibility to couple integral field spectrograph to extreme adaptive optics module at the focus of 8m telescope class (SPHERE for VLT and GPI for South Gemini) and in future to ELTs (EPICS) gives also the possibility to have a first order characterization of the exoplanets themselves.Here we present the potentiality of the high contrast imaging with the detection and characterization capability of the new planet finder instruments comparing them with the RVs and transit methods

The come-on-plus adaptive optics system : results and performance

Communication to : ICO Conference on Active and Adaptive Optics, Garching (Germany), August 2-5, 1993Available at INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1993 n.123 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Compensation of high-order quasi-static aberrations on SPHERE with the coronagraphic phase diversity (COFFEE)

International audienceContext. The second-generation instrument SPHERE, dedicated to high-contrast imaging, will soon be in operation on the European Very Large Telescope. Such an instrument relies on an extreme adaptive optics system coupled with a coronagraph that suppresses most of the diffracted stellar light. However, the coronagraph performance is strongly limited by quasi-static aberrations that create long-lived speckles in the scientific image plane, which can easily be mistaken for planets. Aims. The wavefront analysis performed by SPHERE's adaptive optics system uses a dedicated wavefront sensor. The ultimate performance is thus limited by the unavoidable differential aberrations between the wavefront sensor and the scientific camera, which have to be estimated and compensated for. In this paper, we use the COFFEE approach to measure and compensate for SPHERE's quasi-static aberrations. Methods. COronagraphic Focal-plane waveFront Estimation for Exoplanet detection (COFFEE), which consists in an extension of phase diversity to coronagraphic imaging, estimates the quasi-static aberrations, including the differential ones, using only two focal plane images recorded by the scientific camera. In this paper, we use coronagraphic images recorded from SPHERE's infrared detector IRDIS to estimate the aberrations upstream of the coronagraph, which are then compensated for using SPHERE's extreme adaptive optics loop SAXO. Results. We first validate the ability of COFFEE to estimate high-order aberrations by estimating a calibrated influence function pattern introduced upstream of the coronagraph. We then use COFFEE in an original iterative compensation process to compensate for the estimated aberrations, leading to a contrast improvement by a factor that varies from 1.4 to 4.7 between 2 lambda/D and 15 lambda/D on IRDIS. The performance of the compensation process is also evaluated through simulations. An excellent match between experimental results and these simulations is found

SPHERE / ZIMPOL : Characterization of the ZIMPOL PSF

"We characterize the point spread function (PSF) and the coronagraphic images in the visual range (V-, R, and I-band) obtained with the SPHERE \"planet finder\" instrument. The PSF delivered by the extreme AO system depends on wavelength, atmospheric parameters, and the brightness of the object. Particularly at short wavelengths, in V, the performance depends strongly on the observing conditions.

Sphere extreme AO control scheme: final performance assessment and on sky validation of the first auto-tuned LQG based operational system (Orale)

International audienceThe SPHERE (Spectro-Polarimetry High-contrast Exoplanet Research) instrument is an ESO project aiming at the direct detection of extra-solar planets. SPHERE has been successfully integrated and tested in Europe end 2013 and has been re-integrated at Paranal in Chile early 2014 for a first light at the beginning of May. The heart of the SPHERE instrument is its eXtreme Adaptive Optics (XAO) SAXO (SPHERE AO for eXoplanet Observation) subsystem that provides extremely high correction of turbulence and very accurate stabilization of images for coronagraphic purpose. However, SAXO, as well as the overall instrument, must also provide constant operability overnights, ensuring robustness and autonomy. An original control scheme has been developed to satisfy this challenging dichotomy. It includes in particular both an Optimized Modal Gain Integrator (OMGI) to control the Deformable Mirror (DM) and a Linear Quadratic Gaussian (LQG) control law to manage the tip-tilt (TT) mirror. LQG allows optimal estimation and prediction of turbulent angle of arrival but also of possible vibrations. A specific and unprecedented control scheme has been developed to continuously adapt and optimize LQG control ensuring a constant match to turbulence and vibrations characteristics. SPHERE is thus the first operational system implementing LQG, with automatic adjustment of its models. SAXO has demonstrated performance beyond expectations during tests in Europe, in spite of internal limitations. Very first results have been obtained on sky last May. We thus come back to SAXO control scheme, focusing in particular on the LQG based TT control and the various upgrades that have been made to enhance further the performance ensuring constant operability and robustness. We finally propose performance assessment based on in lab performance and first on sky results and discuss further possible improvements