## 5 Conclusions  
The Ten-Koh satellite, launched on 29 October 2018, was the second satellite developed in a series of two, similarly-sized, low-cost and rapidly-developed small satellites from the Okuyama laboratory of the Kyushu Institute of Technology. The satellite was used to collect data pertaining to degradation of materials in space and high-energy particle fluxes in low-Earth orbit during the solar minimum. Preliminary analysis of the data has shown that the main missions were able to acquire data within the expected ranges, except for the DLP that could not be operated due to the described power line failure. The CPD instrument has detected electrons, protons and galactic cosmic rays, which provides information about the radiation environment inside the spacecraft. In the case of the magnetometer, it has been shown that the selected design, where the instrument is attached directly on the top of the spacecraft without a boom, is able to produce measurements of the geofield that serve for attitude and science purposes. Above all, the in-orbit data have shown that the university-built satellite worked as intended, which is a success in its own right due to the limited resources that were available for its development. The joint observations with the ARASE satellite show that the high-energy electrons mission on-board Ten-Koh has contributed to the field of particle science. Moreover, this mission has shown that small-satellites can be used as a complement to other missions investigating space environment. Figure 18: Estimated planetary index during the time the Ten-Koh anomaly occurred on 19 March 2019 (showed with the red bars). A variety of failures, relating to both the satellite subsystems and the ground segment have been described. The most critical ones have been associated with triggering of over-current protection, degradation of EEPROM memory due to space radiation, and single-event upsets. These should be taken into account when developing future low-cost space missions, which will face similar challenges to those described in this paper. The best means of recovering from such failures has been found to be a power cycle of a unit, which should be implemented in future missions. The abundance of radiation-related failures, with consequences as severe as disabling the entire satellite, indicates that understanding of the space environment and its effects remains vital. This shows that the mission objectives of Ten-Koh served a valid scientific purpose, and should be pursued by more missions. Space environment effects are especially important in the era where small satellites are proliferating because such spacecraft do not use radiation-hardened parts and thus are likely to suffer similar issues as the satellite described herein. Thus, the lessons learned described in this paper should be taken into account when developing similar satellites. Lastly, the interplay between programmatic constraints and scientific return has been highlighted. One notable example of this is how discarding attitude control in order to meet the resources and schedule constraints has caused satellite rotation to be visible in CPD readings. Trading off cost, schedule, risk as well as return of the mission will be particularly important for small satellites, which cannot afford the luxury of postponing launches in order to meet their original scientific objectives. This is a large shortcoming of relying on piggyback launch opportunities, and space agencies worldwide should consider offering more flexible launch slots in order to maximize the return they get from small satellite missions. If the launch date cannot be postponed, spacecraft developers ought to consider reducing the scope of their mission by discarding certain objectives in order to satisfy the schedule constraint. Conceptualization, I.F., A.A.L., J.G.-L., R.R., R.M. and K.-i.O. ; methodology, I.F. A.A.L., J.G.-L., K.-i.O., P.S., D.H. and T.D. ; validation, I.F., A.A.L., S.A.B., J.G.-L., R.R., R.M., K.-i.O., D.F., M.M. ([PERSON]), N.U., R.K., M.M.