# A Reliability Engineering Approach for Managing Risks in CubeSats
## 4 Results
### Step 5: Mitigating Strategies  
After acquiring the knowledge of the riskiest areas, the method provides the chance to design mitigation actions in order to reduce, avoid or decrease the impact of the probable failures on the system. This methodology led to draw up mitigation actions that could even be seen as:  
* procedures to adopt during the MAIT (Manufacturing Assembly Integration and Test) phase, i.e.,: 1. cables of data lines and power lines shall allow tolerances and they shall be free, in order not to be stressed and strained by vibrations;
* sources of external electromagnetic fields (mobiles, electronic devices, smartwatches, laboratory instruments, etc.) shall be far from subsystems during ground processing and integration;
* the cables and wirings well-functioning shall be thoroughly tested in order to avoid signal or power loss;
* SD integration shall be tested against vibration, fixed and blocked during MAIT;
* the on-board instrumentation shall be calibrated prior to satellite delivery and launch;
* the spacecraft components or assembly storage and transport shall be managed in order to avoid oxidation, condense or dust deposit. Moreover, inspections shall confirm, before and after each transport or storage period, the absence of scratches on optical components (such as lenses);
* sources of charged particles must be avoided while building, integrating and testing all units or subsystems (either the mechanical ones). Anti-static devices shall be used during each integration or ground processing phase to protect the spacecraft micro-electronics;
* procedures to adopt during the design phase, i.e.,: 8. the payload extension mechanism must not be influenced by maneuvers of the spacecraft;
* the spacecraft orbit shall allow the payload operations, while permitting acceptable performances of the EPS;
* the identified orbit shall take into account critical environmental factors, such as radiations;
* SW must consider corrupted signal;  
Figure 7: Distribution of RPN scores for each subsystem. 12. OPS must be designed to minimize the batteries depth of discharge and to maximize the operative lifetime of the EPS;
13. coherent conventions must be considered in design phase (International System of Units);
14. IMU and ADC sensors might be used to detect vibrations level during each mission phase in order to prevent the system overcoming structural limits, to reveal ADCS or extendable mechanisms OPS malfunctions, or debris impacts;
15. dampers might be taken into account;
16. the system sensors shall be in-depth tested. The verification of their saturation level shall be provided and taken into account in SW design;
17. EPS solar panels extensions (or partial extensions in case of failure) shall be taken into account for orbit asset computation;
* new requirements, i.e.,: 18. thermal coatings shall be attached to the extendible mechanism of payload;
19. the identified orbit shall take into account the up-to-date space debris mitigation guidelines. In particular, it must be remarked that a risk analysis performed during the design phase offers the opportunity to implement corrections and suggestions at little to no cost. The new requirement cited (point 18) is an example on how different sub-system design teams specialized in different fields (payload and thermal in this case) may omit common items, when focusing only on their own area of interest. The risk analysis during the definition of all the possible failures of each subsystem has been able to enlighten this critical aspect. Point 19 considers debris mitigation regulations that implied a change in terms of mission analysis, leading to a limitation set to 650 km of orbit height. This implies an additional effort in terms of preliminary design, because more possible orbits--including some possible orbital planes above the fixed limit height--needed to be analyzed, in order not to stop the design process of all the subsystems.