Echoes: a new instrumental concept of Doppler Spectro-Imager for the ESA mission project JUICE

Fourier transform spectrometry allows us to detect small Doppler velocity shifts of spectral lines by measuring phase shifts of their associated interference patterns. In this paper, we present the project of space-borne Doppler Spectro Imager (DSI), Echoes, dedicated to Jovian seismology and aeronomy, which is proposed as payload to the JUICE mission project (ex-EJSM/Laplace), which competes in the Cosmic Vision program of the European Space Agency (ESA). The instrumental principle inherits from the ground based experiment SYMPA (Schmider et al, 2007, Gaulme et al, 2008): it is a Mach-Zehnder interferometer working in the visible domain that is sensitive to Doppler shifts of solar spectral lines reflected on the planetary atmosphere. It aims to detect small periodic movements of Jupiter's upper troposphere generated by internal acoustic modes, and to measure their temporal frequencies and spatial geometry. Such measurement would bring unprecedented knowledge on the internal structure of Jupiter, especially on the central region, and would provide unique constraints on giant planet formation models. We are currently realizing a prototype to measure the real instrumental performance in laboratory and to demonstrate the capacity to reach the Technology Readiness Level 5. We describe the experimental set-up and the expected results.