Title
SPEX: the SPectropolarimeter for planetary EXploration
Author
Snik, F.
Rietjens, J.H.H.
van Harten, G.
Stam, D.M.
Keller, C.U.
Smit, J.M.
Laan, E.C.
Verlaan, A.L.
ter Horst, R.
Navarro, R.
Wielinga, K.
Moon, S.G.
Voors, R.
Publication year
2010
Abstract
SPEX (Spectropolarimeter for Planetary EXploration) is an innovative, compact instrument for spectropolarimetry, and in particular for detecting and characterizing aerosols in planetary atmospheres. With its ∼1-liter volume it is capable of full linear spectropolarimetry, without moving parts. The degree and angle of linear polarization of the incoming light is encoded in a sinusoidal modulation of the intensity spectrum by an achromatic quarter-wave retarder, an athermal multiple-order retarder and a polarizing beam-splitter in the entrance pupil. A single intensity spectrum thus provides the spectral dependence of the degree and angle of linear polarization. Polarimetry has proven to be an excellent tool to study microphysical properties (size, shape, composition) of atmospheric particles. Such information is essential to better understand the weather and climate of a planet. The current design of SPEX is tailored to study Martian dust and ice clouds from an orbiting platform: a compact module with 9 entrance pupils to simultaneously measure intensity spectra from 400 to 800 nm, in different directions along the flight direction (including two limb viewing directions). This way, both the intensity and polarization scattering phase functions of dust and cloud particles within a ground pixel are sampled while flying over it. We describe the optical and mechanical design of SPEX, and present performance simulations and initial breadboard measurements. Several flight opportunities exist for SPEX throughout the solar system: in orbit around Mars, Jupiter and its moons, Saturn and Titan, and the Earth.
Subject
Atmospheric particles
Cloud particles
Entrance pupil
Flight direction
Ground pixels
Ice clouds
In-orbit
Incoming light
Intensity spectrum
Limb-viewing
Linear polarization
Martian dust
Microphysical property
Multiple-order retarders
Optical and mechanical designs
Performance simulation
Planetary atmosphere
Planetary exploration
Polarization scattering
Polarizing beam splitters
Quarter waves
Single-intensity
Sinusoidal modulation
Spectral dependences
Spectropolarimeters
Spectropolarimetry
Atmospheric aerosols
Atmospheric composition
Interplanetary flight
Interplanetary spacecraft
Millimeter wave devices
Millimeter waves
Optical telescopes
Space telescopes
Vehicular tunnels
Industrial Innovation
Physics & Electronics
OPT - Optics
TS - Technical Sciences
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TNO identifier
425159
ISBN
9780819482211
ISSN
0277-786X
Source
Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave, 27 June - 2 July 2010, San Diego, CA, USA, 7731 (7731)
Series
Proceedings of SPIE - The International Society for Optical Engineering
Document type
conference paper