## 3 Results
### Mission Analysis
#### 3.1.2 Power Subsystem and Budget  
The power subsystem consists of three separated main elements: the Electric Power System (EPS), the batteries, and the solar panels. An overall 80% efficiency has been considered for the Maximum Power Point Tracking (MPPT) and charger. The scheduler defines the set of rules under which the EPS will provide power to every subsystem on demand. On their behalf, each subsystem will try to be powered up when the satellite passes over certain defined areas (TA, GS, or during all orbit). Table 5 lists each subsystem, the regions over which they need to be powered on, and the typical and maximum power consumption. The battery heater's schedule is controlled by the thermal budget, which monitors its temperature. The state of the battery heater responds to survival reasons, so it might need to be powered on over any area. Similarly, the ADCS needs to be powered on over TAs (for payload pointing accuracy) and GSs (for antenna pointing reasons), but the power peak when switching it on may indicate that it is preferable to keep the ADCS on during all orbit.  
* Solar Panels  
The Indium Gallium phosphide/Gallium arsenide/Germanium (GaInP/GaAs/Ge) triple-junction cells solar panels considered have 30% efficiency [31]. In order to account for the total energy collected by the satellite, both the direct Sun radiation and the radiation scattered on the surface of the Earth (albedo radiation, Figure 6) have been considered changing along the track. The platform has been modelled as a ~10 \(\times\) 20 \(\times\) 30 cm\({}^{3}\) parallelepiped so as to consider the incident angle between  
\begin{table}
\begin{tabular}{l c c} \hline \hline  & \multicolumn{2}{c}{**Consued Power**} & \multirow{2}{*}{**TA**} & \multirow{2}{*}{**GS**} & \multirow{2}{*}{**All Orbit**} \\ \cline{2-2} \cline{4-4}  & **Typical (W)** & & & \\ \hline Optical payload & - & 6 & \\ GNNS-R payload & 1.5 & 2 & \\ Battery heater & 0.5 & 2.5 & \\ ADCS & 0.5 & 2.5 & \\ S-band TX & 8 & 12 & \\ VHF TX & 2.9 & 3.1 & \\ Primary OBC & 2.3 & 2.3 & \\ Secondary OBC & 0.2 & 0.9 & \\ \hline \hline \end{tabular}
\end{table}
Table 5: The different subsystems will try to power on over different regions. The scheduler is in charge of checking the state of the satellite to allow or deny the activation of all non-survival subsystems. Green—attempt to power up; Yellow—powered up under survival conditions and power save mode; Red—no attempt to power up.  
subsystems that must be powered on all the time, but others may not be activated due to low battery charge values.  
* Power Budget  
The power budget provides instantaneous battery charge throughout the simulation period (Figure 8). It shows the state of the batteries' charge (A-h), already balancing the incoming/outgoing charge from the photovoltaic converter and to the subsystems. The eclipse periods, which account for approximately 30% of the orbit, are automatically treated by the scheduler, which denies all power demands from the subsystems that are not essential for survival. In the simulation, a maximum 20% usage of the total battery charge has been established in order to increase the lifespan of the satellite as much as possible.