Speaker
Description
One of the most ambitious goals of modern astronomy is to uncover signs of extraterrestrial biological activity. This is, primarily achieved through spectroscopic analysis of light emitted by exoplanets to identify specific atmospheric molecules. Most exoplanets are indirectly identified through techniques like transit or Doppler shift of the host star's flux. Long-term surveys have yielded statistical insights into the occurrence rates of different planet types based on factors such as radius/mass, orbital period, and the spectral type of the host star. Initial estimations of terrestrial planets within the habitable zone have also emerged. However, the lack of detected light from these exoplanets leaves much unknown about their nature, formation, and evolution. Following the ”ESA-voyage 2050” call, the senior committee recommended the “characterisation of the temperate exoplanets” for a possible future Class L mission: “Answering the question of the existence and distribution of life elsewhere in the Universe has been an important driver for the exploration of other worlds, both in and outside of our Solar System.” As the number of detected rocky exoplanets around nearby stars rises, questions about their atmospheric composition, evolutionary trajectory, and habitability increase. Measuring the infrared spectrum of these planets poses significant challenges due to the star/planets contrast and very small angular separation from their host stars.
From previous research, it has been shown that space-based telescopes are mandatory, and unless large primary mirrors (>30m in diameter) can be sent into space, interferometric techniques become essential. These techniques, combining light from distant telescopes, allow access to information at minimal angular separation, operating within the diffraction limit of individual telescopes. Furthermore, nulling interferometry addresses the challenge of achieving a high contrast between the star and the planet, allowing for spectroscopic measurements of their atmospheres as well as reflected and thermal background light. This is done by the combination of the light coming from four telescopes with corresponding phase delays applied on each of the beams, resulting in the suppression of the incident light in the direction of the line of sight by destructive interference.
Despite successful demonstrations of nulling interferometry on the ground, a space-based mission has not been carried out yet but is vital to sidestep and tackle this scientific question. Even if technologically challenging, nulling interferometry has shown the highest potential in scientific return.
In this project, we explore different architectures and payload configurations for a four-telescope, single S/C interferometer (i.e using several apertures/telescopes with deployable structures, but avoiding a formation flying configuration).
At the core of a nulling interferometric mission is the beam combination. The choice of the four-beam combination scheme and phase shifting to supress the stellar light is manifold. In addition to theoretical studies on the effects of beam combination, chromaticity and polarization within a nulling interferometer, further experimental research is needed to complement the groundwork leading to future design choices. This challenge is being addressed at TUDelft, with a testbench dedicated to experimental studies on four beam, broadband (3-20μm) and polarization sensitive nulling interferometry. In addition to the experimental approach, our parametric study covers a range of 1-3 m for the diameter of the telescope and a 10-60 m baseline. The most promising concept working in the infrared range (3-20μm) will be highlighted. Launch constraints, tied to the use of an Ariane 6 launch vehicle, dictate the interferometer's size. This study is conducted by TUDelft in cooperation with KULeuven, CSL/ULiège, Amos and with the support of the European Space Agency. We will present the recent progress made to develop this mission concept and the related experimental activities.
| Talk category | Instrumentation (contact wijnen@strw.leidenuniv.nl) |
|---|---|
| Preference for a talk or poster | Talk |
| Talk preference for PhD students | 2nd year PhD |
