Shape - A Spectro-Polarimeter Onboard Propulsion Module of Chandrayaan-3 Mission

SHAPE (Spectro-polarimetry of HAbitable Planet Earth) is an experiment onboard Chandrayaan-3 Mission for the study of spectro-polarimetric signatures of the habitable planet Earth in the near-infrared (NIR) wavelength range (1.0 - 1.7 µm). The spectro-polarimeter is the only scientific payload (experimental in nature) on the Propulsion Module (PM) of Chandrayaan-3 mission. The instrument is a compact and light-weight spectro-polarimeter with an Acousto-Optic Tunable Filter (AOTF) at its heart. The AOTF operates in the frequency range of 80 MHz to 135 MHz with a power of 0.5 - 2.0 Watts. The two output beams (e-beam and o-beam) from the AOTF are focused onto two InGaAs detectors (pixelated, 1D linear array) with the help of focusing optics. The primary (aperture) optics of ~ 2 mm diameter collects the NIR-light for input to the AOTF, defining the FOV of 2.6°. The payload is realized with a mass of 4.8 kg and a power of 25 Watts. In this manuscript, we highlight some of the ground-based results including the post-launch initial performance of the payload while orbiting around the Moon to observe Earth.