Loros: laboratory simulations of the Optical RadiOmeter Composed of CHromatic Imagers (OROCHI) experiment of the Martian Moons eXploration (MMX) mission

Abstract The Laboratory OROCHI Simulator (LOROS) is an emulator of the Optical RadiOmeter composed of CHromatic Imagers (OROCHI), a multispectral and multiview imaging system for the Japan Aerospace Exploration Agency (JAXA) Martian Moons eXploration (MMX) spacecraft, that will study Phobos and Deimos with the objective of determining their origin. OROCHI consists of 8 visible/near-infrared (390–950 nm) spectral channels, hosted on 8 separate camera systems, arranged in a 3 $$\times $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>×</mml:mo> </mml:math> 3 grid (with an empty central site) with 0.10 m spacing. Prior to completion of the OROCHI Flight Model it is important to demonstrate the ability of the cameras to resolve the subtle spectral features expected at Phobos and Deimos, and to investigate the implications of the multiview configuration when performing near-field imaging on the Phobos surface. LOROS provides a robust and portable emulator of the OROCHI Flight Model, composed of commercial off-the-shelf components and materials compliant with the ISO-6 restrictions of the JAXA Extraterrestrial Sample Curation Centre. Here we describe the configurations of the components and control software that we have developed and present the results of a series of calibration experiments, demonstrating the comparable performance of the two systems. We achieve agreement between LOROS and the expected performance of OROCHI to within 3% across metrics of system sensitivity, effective full-well capacity and maximum achievable signal-to-noise ratio, and demonstrate the measurement of the reflectance of a dark diffuse reflector reference standard with a mean temporal signal-to-noise ratio of 120.