# Novel 3U Stand-Alone CubeSat Architecture for Autonomous Near Earth Asteroid Fly-By
## 5 Results--Instantiated Architecture  
Two reference 3U CubeSat architectures are introduced for comparison with the proposed architecture: Delfi-n3 xt and INSPIRE. Delfi-n3 Xt is a 3U CubeSat, launched on 21 November 2013. Its goals were pre-qualification of \(T^{3}\mu PS\) micropropulsion system, pre-qualification of multifunctional particle spectrometer, scientific radiation experiment of Si solar cells, qualification of a high efficiency modular communication platform, and proof-of-concept for a radiation risk-free implementation of commercial solid-state data storage devices. The original launch configuration was characterized by a modular subsystem approach and it includes--Attitude Determination and Control System (ADCS), propulsion system, On-Board Computer (OBC), communication (primary and secondary radio transceiver, deployable antenna board, S-band radio interface board, and S-band radio transmitter), and power (Electrical Power System (EPS), batteries, and batteries management). This configuration leaves 90 mm \(\times\) 90 mm \(\times\) 27 mm volume for the payload. To increase the available volume for the payload, two variant configurations were proposed. The lean configuration variant was based on removing all redundant system, S-band transceiver dedicated board, and secondary transceiver. Moreover, the spacing between the systems was removed using the stackable CS14 connector, which allows also OBC and EPS boards height reduction. This configuration leaves a larger volume for the payload, with a stack height of 165 mm). A further improvement in payload available volume was given by the advanced configuration, whose integrated core units combines EPS control and distribution, the OBC, and the ADCS microcontroller. The payload available volume stack height was then increase up to 260 mm. The launch configuration of Delfi-n3 xt is taken as a reference for LEO CubeSats, for the comparison with the newly proposed architecture [25]. Another interesting 3U architecture is the one exploited by NASA/JPL INSPIRE project [87], which is currently under development. The project is characterized by two identical CubeSats aimed to demonstrate nanosatellites capabilities in deep-space, especially in terms of communication, navigation, functionality, and payload-hosting technologies. The architecture is also based on a modular subsystems approach, including: ADCS (cold-gas thrusters and star tracker), power (EPS and batteries), communication (Iris X-band transponder for ground, Ultra High Frequency (UHF) radio and deployable antennas for crosslink capability between spacecrafts), and command and data handling (which integrates also the UHF radio). The main differences between the two architectures are related to their objectives. The first clear difference concerns the communication subsystem (S-band for Delfi-n3 Xt, X-band and UHF for INSPIRE). Then, the ADCS, which is based on reaction wheels, Sun sensors and magnetometers for the former, while it is based on star tracker and cold-gas propulsion system for the latter. Moreover, both architectures exploit deployable solar panels, but with different deployment mechanism. Delfi-n3 Xt solar panel arrays consist in four 1U \(\times\) 3U solar arrays, deployable across the short side. INSPIRE solar panel arrays are based on a 1-fixed 1-deployable (across the long side). Based on the concepts and systems highlighted in the previous sections, an instantiated 3U architecture is designed. Table 7 reports the list of the components, with mass and volume budgets. To fit the 3U volume, a modular subsystems approach has been exploited, and, as the volume budget sketch in Figure 9 shows, limiting the space between the components is necessary (in an approach similar to the lean and advanced Delfi-n3 Xt architectures). A classical approach, placing the propulsion system and the payload at the extremities, has been exploited. However, the actual location of the subsystems will depend especially on the attitude control strategy in the various phases.