Hauchecorne, M. Meftah, P. Keckhut, SERB on Stratéole 2 and nano-satellite to study the Earth radiation budget and the Sun-Earth relations Hauchecorne, M. Meftah, P. Keckhut, LATMOS

1 – Scientific objectives of the mission (1/4) SERB nano-satellite and SERB on Stratéole 2, a joint venture to study the Sun and the Earth. Scientific goals: Nanosat to contribute to the series of Total Solar Irradiance (TSI) observations to observe the Earth radiative budget at global scale to study the relation between solar UV variability and stratospheric ozone Strateole 2 to measure the reflected solar and the upward IR thermal flux along balloon trajectories to correlate with other variables (temperature, wind, gravity waves, …) for the study of atmospheric processes and balloon in flight behavior

1 – Scientific objectives of the mission (2/4) • First objective: to extend Total Solar Irradiance variability measurement It’s very important to continue to measure this essential climate variable. The TSI is measured to vary by approximately +/-0.05 % (over the last three 11-year sunspot cycles). Composite TSI time series (ACRIM and PMOD) or TSI space instruments highlighting differences for some solar minima.

1 – Scientific objectives of the mission (3/4) The total solar irradiance is the main external heat input into the Earth’s climate system. The annual mean global energy balance for the Earth-atmosphere system is also very important to understand. Importance of the radiation balance of the Earth: Radiation at "visible" and "NIR" wavelengths warms the lower atmosphere and the surface of the Earth. The TSI is a good criterion of variability. Importance of the UV solar variability: UV radiation dissociates atmospheric molecules (initiating chains of chemical reactions, including those producing stratospheric ozone). It thus provides the main source of heating of the stratosphere. Interaction with ozone, and dependence with the solar activity Irbah, Meftah, 2012 (SPIE)

1 – Scientific objectives of the mission (4/4) Determination of the Outgoing Longwave Radiation (OLR) Determination of the Reflected Solar Radiation or albedo flux Evolution of the IR flux of the Earth during the year (« Outgoing Longwave Radiation » or OLR)

2 – The nano-satellite and SERB on Stratéole 2 (1/4) The nano-satellite « to study the Sun and the Earth » is a three-unit CubeSat. A preliminary configuration of the nano-satellite system can be seen below. The key element of the mission is the space segment, containing the nano-satellite (10×10×30 cm3, 3.6 kg maximum and 3.0 W nominal consumption) that includes the payload and the avionics. SERB X-CubeSat II is proposed by LATMOS for the nano-satellite program of Polytechnic School and CNES for a flight in 2019-2020. Inizan et al., 2012

2 – The nano-satellite and SERB on Stratéole 2 (2/4) The balloon instrument consists in a double radiometer looking at nadir to observe the solar reflected flux and the thermal IR flux. Black radiometer: 0 – 100 mm Solar + thermal IR flux White radiometer: 4-100 mm Solar flux only 1

2 – The nano-satellite and SERB on Stratéole 2 (3/4) Typical balloon instrumentation: Balloon flights present a rare opportunity for scientists to make long duration measurements. However, there is a direct link with the nano-satellite program. General block diagram A Bolometer to measure the IR flux.

2 – The nano-satellite and SERB on Stratéole 2 (4/4) Temperature sensor T2 T4 With different temperature sensors, we are able to determine the IR flux. T3 Temperature sensor T1

Conclusion SERB -balloon The SERB-Balloon radiometer will measure the upward solar reflected flux and thermal IR flux along the balloon trajectory SERB data in combination of other variables (temperature, wind, gravity waves, …) for the study of atmospheric processes and balloon in flight behavior It is derived from the SERB nanosat instrument developed in the frame of the Polytechnique student space center dedicated to the te study of Sun-Earth relations