# Novel 3U Stand-Alone CubeSat Architecture for Autonomous Near Earth Asteroid Fly-By
## 4 Subsystems Analysis
### Power  
Power budget for the whole mission can be analyzed phase by phase involving all the subsystems having an active role. Table 6 summarizes the power demand in each phase. From mostly all products datasheets both nominal and peak power consumptions are available. The phases involving the propulsion system require large power consumption, especially during the Earth escape phase, when the propulsion system will be turned on for a longer period of time, while TCM maneuvers will be faster. The maneuvers planning (apogee raising) will therefore depend on limiting the power consumption, since 39 W are required only for the propulsion system to be turned on. So considering an average consumption of the other subsystems during thrusting maneuvers, the requirement for solar panels can be set around 40 W at 1 AU. The ADCS power demand is present in all the phases because it is important to point thrusters, cameras, sensors, antennas. In the first two phases the navigation power demand is computed with GNSS receiver datasheet, while in the other phases it is less straightforward because it involves either star tracker and Sun sensors, or payload camera. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Producer** & **Product** & **CF [Mhz]** & **Vol. [U]** & **Mass [g]** & **PC [mW]** & **MS [Gb]** \\ \hline Endurosat & OBC [77] & 216 & 0.23 & 58 & 340 & 0.256 \\ AAC Clyde Space & KRYTEN-M3 [78] & 50 & 0.23 & 61.9 & 400 & 0.008 \\ AAC Clyde Space & S. OBC LEON3 FT [79] & 50 & 0.17 & 130 & 1300 & 2 \\ AAC Clyde Space & S. TCM LEON3 FT [80] & 50 & 0.17 & 134 & 1300 & 32 \\ InnoFlight & CFC-300 [81] & 767 & 0.14 & 120 & 1000 & 16–384 \\ Hyperion Technologies & CP400.85 [82] & 500 & 0.01 & 7 & 550 & 7.5–64 \\ GomSpace & NanoMind A3200 [83] & 64 & 0.02 & 24 & 170 & 0.160 \\ SatRevolution & Advanced OBC [84] & 216 & 0.08 & 52 & 1000 & 0.008 \\ ISIS & iOBC [85] & 400 & 0.12 & 100 & 400 & 4–32 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Commercial-off-the-shelf (COTS) On-Board Computer (OBC) Characteristics. The primary power is usually made available by solar panels. Many companies produce solar cells (AzurSpace, Emcore Corporation, Spectrolab, Solaero Technologies), which are assembled to form solar panels (AAC Clyde Space, DHV, Endurosat, GomSpace, ISIS, MMA Design LLC, NanoAvionics, Spectrolab). Solar cells efficiency is usually around 30%. There are many options feasible for 3U CubeSats, ranging from fixed panels to various configuration of deployable arrays. In order to increase the available on-board power, deep-space applications require deployable solar panels, such as used on MaRCO [86], Juventas [7], NEAScout [10], and INSPIRE [87]. Endurosat produces a 1-fixed 1-deployable solar panel configuration for a 3U CubeSat. Each panel contains up to 7 Triple Junction Solar Cells InGaP/GaAs/Ge. The total mass, below 300 g, of a single panel does not fit with this application [88]. ISIS offers a similar configuration made of GaAs solar cells, each 3U panel characterized by around 150 g of mass and 6.9 W of delivered power. NanoAvionics produces deployable solar panels configuration characterized by 36.95 mW/cm\({}^{2}\) power-generation capacity in LEO [89]. Another type of deployable configuration is offered by GomSpace, characterized by double deployable solar arrays (135\({}^{\circ}\) version). The configuration of two near faces is characterized by a total of 2 fixed panels and 4 deployable ones. GomSpace configuration has a total of 36 GaInP/GaAs/Ge solar cells, 30.18 cm\({}^{2}\) effective area each, giving up to 1.15 W per cell in LEO. DHV configuration is characterized instead by 42 triple junction GaAs solar cells giving around 29.6W at 1 AU for a total mass of 410 g [90]. The problems related to this configuration are the limited power generation of the fixed solar cells and the limited orientability of the panels. MMA design LLC configurations overcome these problems by means of totally deployable solar panels.