Array Configurations for a Space Infrared Nulling Interferometer Dedicated to the Search for Earthlike Extrasolar Planets

Mennesson, Bertrand; Mariotti, J. M.

doi:10.1006/icar.1997.5731

Cited by 102 publications

(52 citation statements)

References 7 publications

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“…However, a rapid rotation of the array would be difficult to implement and the detection is highly vulnerable to low frequency drifts in the stray light, thermal emission, and detector gain. A number of interferometer configurations with more than two collectors have then been proposed to perform faster modulation and overcome this problem by using phase chopping (Angel & Woolf 1997;Mennesson & Mariotti 1997;Absil 2001). The principle of phase chopping is to synthetize two different transmission maps with the same telescope array, by applying different phase shifts in the beam combination process.…”

Section: Introductionmentioning

confidence: 99%

Nulling interferometry: impact of exozodiacal clouds on the performance of future life-finding space missions

Defrère¹,

Absil²,

Hartog

et al. 2010

A&A

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Context. Earth-sized planets around nearby stars are being detected for the first time by ground-based radial velocity and space-based transit surveys. This milestone is opening the path toward the definition of instruments able to directly detect the light from these planets, with the identification of bio-signatures as one of the main objectives. In that respect, both the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) have identified nulling interferometry as one of the most promising techniques. The ability to study distant planets will however depend on the amount of exozodiacal dust in the habitable zone of the target stars. Aims. We assess the impact of exozodiacal clouds on the performance of an infrared nulling interferometer in the Emma X-array configuration. The first part of the study is dedicated to the effect of the disc brightness on the number of targets that can be surveyed and studied by spectroscopy during the mission lifetime. In the second part, we address the impact of asymmetric structures in the discs such as clumps and offset which can potentially mimic the planetary signal. Methods. We use the DarwinSIM software which was designed and validated to study the performance of space-based nulling interferometers. The software has been adapted to handle images of exozodiacal discs and to compute the corresponding demodulated signal. Results. For the nominal mission architecture with 2-m aperture telescopes, centrally symmetric exozodiacal dust discs about 100 times denser than the solar zodiacal cloud can be tolerated in order to survey at least 150 targets during the mission lifetime. Considering modeled resonant structures created by an Earth-like planet orbiting at 1 AU around a Sun-like star, we show that this tolerable dust density goes down to about 15 times the solar zodiacal density for face-on systems and decreases with the disc inclination. Conclusions. Whereas the disc brightness only affects the integration time, the presence of clumps or offset is more problematic and can hamper the planet detection. Based on the worst-case scenario for debris disc structures, the upper limit on the tolerable exozodiacal dust density is approximately 15 times the density of the solar zodiacal cloud. This gives the typical sensitivity that we will need to reach on exozodiacal discs in order to prepare the scientific programme of future Earth-like planet characterisation missions.

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Section: Introductionmentioning

confidence: 99%

Nulling interferometry: impact of exozodiacal clouds on the performance of future life-finding space missions

Defrère¹,

Absil²,

Hartog

et al. 2010

A&A

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“…They can be roughly classified in three groups of methods, one referring to Nulling interferometry (Bracewell 1978;Mennesson & Mariotti 1997;Angel & Woolf 1997), the second to direct imaging using coronagraphy and the last to apodization (Nisenson & Papaliolios 2001). Nulling interferometry has lead to the Darwin project (Leger 1993;Leger et al 1996), while coronagraphic techniques are presently under study for TPF (TPF Science Working Group 1999; Guyon & Roddier 2000;Boccaletti et al 2000;Pedretti et al 2000;Aime et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Interferometric apodization of rectangular apertures

Aime¹,

Soummer²,

Ferrari³

2001

A&A

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Abstract. We describe the principle of an apodization technique for rectangular apertures that can be implemented using a Michelson or a Mach-Zender interferometer. Using several interferometers, any integer power of cosine functions can be obtained. The technique is considered for application to the Apodized Square Aperture (ASA) concept recently proposed by Nisenson & Papaliolios (2001). Simple analytic expressions for the Point Spread Functions of such apodized apertures are given. For a cosine to the power N apodization, the resulting focal plane amplitude is simply the sum of N + 1 weighted and shifted sine cardinal functions. The interest of such apodized apertures for coronagraphy is investigated. It appears that these apodization functions are very efficient provided that only a central part of the cosine-arch is used. Analytic expressions are derived for the residual amplitude left in an image of the aperture after the coronagraphic experiment. Best results are obtained with a cosine squared apodization.

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“…We create the templates, as discussed by Mennesson & Mariotti (1997), for a 6:1 X-array formation of telescope apertures. For a recorded testbed signal S , truncated to an integer number of array rotations, and templates T (Ω, θ) where Ω is the angular separation from the star and θ is the rotation angle, we calculate the cross-correlation:…”

Section: Detection and Measurement Of The Planet Signalmentioning

confidence: 99%

Demonstration of exoplanet detection using an infrared telescope array

Martin¹,

Booth

2010

A&A

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Context. Technology is being developed for the characterization and detection of small, Earth-size exoplanets by nulling interferometry in the mid-infrared waveband. While high-performance nulling experiments have shown the possibility of using the technique, to achieve these goals, nulling has to be done on multiple beams, with high stability over periods of hours. To address the issues of the perceived complexity and difficulty of the method, a testbed was developed for the Terrestrial Planet Finder Interferometer (TPF-I) project which would demonstrate four beam nulling and faint exoplanet signal extraction at levels traceable to flight requirements. Containing star and planet sources, the testbed would demonstrate the principal functional processes of the TPF-I beam-combiner by generating four input beams of star and planet light, and recovering the planet signature at the output. Aims. Here we report on experiments designed with traceability to a flight system, showing faint exoplanet signal detection in the presence of strong starlight. The experiments were designed to show nulling at the flight level of ≈10 −5 , starlight suppression of 10 −7 or better, and detection of an exoplanet at a contrast of 10 −6 compared to the star. This performance level meets the flight requirements for the parts of the detection process that can be demonstrated using a monochromatic source. To achieve these results, the testbed would have to operate stably for several hours, showing control of disturbances at levels equivalent to the flight requirements. Methods. A test process was designed which would show that the necessary performance could be achieved. To show reproducibility, the tests were run on three separate occasions, separated by several days. The tests were divided into three main parts which would show first, starlight suppression, second, a realistic faint exoplanet signal production, and finally, exoplanet signal detection in the presence of the starlight. Results. A number of data sets were acquired showing the achievement of the required performance. The data reported here show nulling at levels between about 5.5 and 8.5 × 10 −6 , starlight suppression between 8.4 × 10 −9 and 1.4 × 10 −8 , and detection of planet signals with contrast to the star between 3.8 × 10 −7 and 4.4 × 10 −7 . The signal to noise ratios for the detections were between 14.0 and 26.9. These data met all the criteria of the demonstration, showing reproducible stable performance over several hours of operation. Conclusions. These data show the successful execution, at flight-like performance levels, of almost the whole exoplanet detection process using a four beam, nulling beam-combiner.

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Array Configurations for a Space Infrared Nulling Interferometer Dedicated to the Search for Earthlike Extrasolar Planets

Cited by 102 publications

References 7 publications

Nulling interferometry: impact of exozodiacal clouds on the performance of future life-finding space missions

Nulling interferometry: impact of exozodiacal clouds on the performance of future life-finding space missions

Interferometric apodization of rectangular apertures

Demonstration of exoplanet detection using an infrared telescope array

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