The spectroscopy table and the use of open-source electronics for outreach demonstrators.
Authors: Roger Thibaut 
Published: July 2024

The spectroscopy table is an &#8220;all-in-one&#8221; outreach demonstrator that enable you to engage in an interactive and playful way with students or the general public, to demonstrate several concepts of spectroscopy, focusing on its use for planetary sciences. Its modular and open-source design allows you to quickly reconfigure it to explore a vast array of science concepts more in line with the science topics explored by your own institute.With bright LEDs modeling the visible spectrum, it attracts spectators from far away in crowded events. This device is aimed to be used both as a 5-minute entry point into the wonderful world of spectroscopy for the general public, or to be expended for lectures or for the more curious publics into a full 45-minute experience serving as an effective crash-course exploring the many subtle way to use spectroscopy.Currently in its second prototype iteration &#8211; and already used in events which enable to improve design based on feedbacks &#8211; the end goal of this project is to be fully available in open-source once completed (summer 2024). This will allow other institutes and scientists to replicate it and adapt it to their own needs. The table can be easily assembled with off-the-shelves components and its electronics is based around the equally open-source Arduino boards. In its default mode, individually addressable RGB LEDs strips have been calibrated to accurately represent the visible spectrum, while a series of switches enable to select chemical elements (atoms or molecules) and see their effects on the spectrum (the current 8 elements have been carefully selected for their relevance to the science cases explored by my institute, but can be adapted as wishes). More buttons and rotary elements allow to change the parameters of what you are representing such as the mass and period of a planet around a star, and to visualise thanks to the LEDs, their (exaggerated) effect on a spectrum (i.e., radial velocity).By demonstrating them or by triggering discussions for further explanations, the current model tackles several key concepts related to spectroscopy and astrophysics, focusing on exoplanets as it is developed in a planetary science institute. This includes: emission and absorption spectroscopy by atoms or molecules, electrons orbits, stellar characterisation, Doppler-Fizeau effect, radial velocity of both exoplanets or binary stars, stellar typing, transit method for exoplanets detection and transit spectroscopy for atmospheric characterisation, eclipsing binaries, stellar rotation speed and the Rossiter-McLaughlin effect. The commands being built symmetrically, you can even turn the table in a playful &#8220;mastermind&#8221;-like spectroscopy game where participants have to figure out the chemical components hidden in a spectrum and test their understanding of the demonstrated scientific concepts.Design in a similar-fashion, my already-completed project nicknamed the Trappist-1 lightshow has all building instructions, including the Arduino-code to run it, available on my personal website (see http://thibaut-roger.com/Wordpress/trappist-1-lightshow/). This device again enables a 5-minute surface scratch or a 45-minute deep-dive on several astrophysical topics. With it, you can explore the concepts of exoplanets, transit method, habitable zone, resonances, tidal locking, M-dwarf and their properties, stellar eruption and space weather, as well as astrobiology.Beyond the specific example of the spectroscopy table (and of the Trappist-1 lightshow), I will also discuss the pros and cons of open-source/off the shelves electronic components, and tell the story how proprietary technology on the contrary proved a problem to maintain another demonstrator developed at my institute.&#160;&#160;This project has received support from the Swiss Society for Astrophysics and Astronomy and from the National Centre of Competence in Research (NCCR) PlanetS. The National Centres of Competence in Research are a funding instrument of the Swiss National Science Foundation.&#160;