Chronogram of Solar Observations for the EXOMARS16 Solar Irradiance Sensor

Abstract

ExoMars16 is the first mission of the ESA ExoMars programme. Its launch is planned for the Mars 2016 window and the arrival to Mars in October 2016. The mission consists of the Trace Gas Orbiter and an entry, descent and landing demonstrator module known as Schiaparelli. The latter is equipped with new testing technologies; including a Solar Irradiation Sensor (SIS) developed by the Instituto Nacional de Técnica Aeroespacial. SIS belongs to the DREAMS experiment to characterize the atmospheric environment of the Mars surface. SIS main goal is to measure the solar spectrum in Mars, the transparency of the atmosphere and the atmospheric dust content. Combined with the measurement of the electric fields from MicroAres, these measurements will allow to study the role of electric forces on dust lifting, the mechanism that initiates dust storms. The objective of this work is to characterize the visibility of the Sun from the Schiaparelli module and to establish a chronogram of solar observations for SIS. For this establishment the Sun position as seen from SIS has been calculated, determining the sunrises and sunsets times in UT. To obtain local coordinates, azimuth and elevation, a Montecarlo simulation of 1000 random positions within the ESA forecasted landing ellipse for Schiaparelli. Then, the most probable Sun visibility chronogram is determined, as well as the chronogram for the ellipse characteristic points that limit the error margins of this determination. This allows planning adequately the solar irradiation observations for SIS. The Sun will be visible for approximately 12 hours and 26 minutes each sol.