# Novel 3U Stand-Alone CubeSat Architecture for Autonomous Near Earth Asteroid Fly-By
## 6 Conclusions  
A review and applicability assessment of CubeSat technologies has been performed for the design of a 3U autonomous navigation CubeSat aimed to perform a NEA fly-by and provide added scientific information on the object. Despite the many challenges related to the large constraints of the mission (mass, volume, power, \(\Delta V\) budgets), the feasibility of a 3U architecture has been demonstrated, meeting all the MRs. The architecture is composed by all the necessary components to make the CubeSat fully autonomous, during all the operational phases. As it has been highlighted, the main challenges are related to the navigation and AOCS subsystems, because to ensure fully autonomous architecture, the uncertainties (especially related to asteroids ephemeris) need to be properly compensated by the coupling between navigation strategy/techniques and hardware support (star tracker performances and micro-propulsion system propellant budget for TCMs). Wheels de-saturation problem, can be addressed with the main propulsion engine in case of either orientable nozzles or multiple thrusters (as the case of MPS-130), as it has been assumed in the ADCS section.  
Off-the-shelf electric propulsion systems appear at this stage less performant than their chemical counterpart, however, thanks to more detailed trajectory optimization approaches, their performances may be comparable, and the set of reachable targets may be extended. However, using electric micro-propulsion systems introduce two large challenges for a small satellite: the increased power demand and the increased mission time.  
Communication based on X-band transmitter and antenna ensure an acceptable transmitable dataset, also compliant with the short-duration of the scientific phase. Clearly, if different scenarios will be considered, such as rendezvous with an extended scientific phase, the communication subsystem may become one of the driving component of the design, to allow the downlink of a larger dataset.  
To conclude, this works presented a low-cost and compact solution to explore a sufficient portion of the NEA region, which is expected to characterize the next decades of space exploration. CubeSats can be exploited to enrich the Solar System exploration and to enlarge the interest of the scientific community.  
Conceptualization, S.C. and I.F.; methodology, S.C., and I.F.; software, S.C.; validation, S.C., I.F. and A.C.; formal analysis, S.C., and I.F.; investigation, S.C.; resources, S.C.; data curation, S.C., I.F., and A.C.; writing--original draft preparation, S.C.; writing--review and editing, S.C., I.F., A.C., B.M., and E.G.; visualization, S.C.; supervision, B.M., A.C., and E.G.; project administration, A.C., and B.M.; funding acquisition, A.G., B.M., and E.G. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the EU H2020 MSCA ITN Stardust-R, grant agreement 813644.  
The authors wish to thank [PERSON] (Strathclyde University) for his support in the low-thrust trajectory analysis section, [PERSON] (University of Belgrade) for the interesting conversations over the Yarkowski effect, and [PERSON] (Polytechnic University of Milan) for the proficient discussions over autonomous relative navigation around asteroids.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
ADCS - Attitude Determination and Control System  
BOL - Beginning-of-Life  
CF - Clock Frequency  
COTS - Commercial-off-the-Shelf  
DOD - Depth-of-Discharge  
DSN - Deep-Space Network