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A simple analog multiplier for the estimation of the power yield of a solar panel may be realized with a pulse width modulator working as analog multiplier circuit of the current yield and the duty cycle of the converter used to condition the panel. Though the output of the pulse width modulator multiplication is not exactly proportional to the output power of the solar panel, its maximum follows the maximum of the power curve of the panel. This multiplier allows a complete analog implementation of the maximum power point tracker of the panel keeping, at the same time, the simplicity needed in robust electronic systems. This paper presents the working principle of the maximum power point estimator for three different power conditioners of the solar panel: a step-down, a step-up and a SEPIC.

<p>In the frame work of HERA mission, the gravimeter for small solar system objects (GRASS) has been developed to measure the local acceleration vector on the surface of the moonlet of the binary asteroid, Dimorphos. GRASS will be onboard Juventas CubeSat which is one of the two daughtercraft of ESA’s Hera spacecraft. Launched in 2024 it will arrive in the binary system in 2026. Following the soft-landing of the Juventas CubeSat, GRASS will record the temporal variation of the surface gravity vector.</p><p>The average gravitational force expected on the Dimorphos surface is around 5 x 10<sup>-5</sup> m s<sup>-2</sup> (or 5 mGal). Apart from the self-gravitation of the body, centrifugal forces and the acceleration due to the main body of the system contribute to the surface acceleration. The temporal variations of local gravity vector at the landing site will be used to constrain the geological substructure (mass anomalies, local depth and lateral variations of regolith) as well as the surface geophysical environment (tides, dynamic sloped and centrifugal forces).</p><p>We will present the GRASS science objectives in the Hera mission the operational concept that is foreseen to reach these objectives, its current status of development including first test results and the by simulation estimated performances of the instrument.</p><p> </p>

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