## 1 Introduction  
In recent years, micro- and low-cost satellite development has increased in the private sector, including small- and medium-sized companies, venture companies, and universities [1]. In particular, nanosatellites of 100 kg or less have been developed by private-sector groups because of their lower cost and development time compared to conventional satellites. Nanosatellites can be more readily applied to space-based research and industry, and can serve as a platform for demonstrating newly developped technology [2, 3]. Figure 1 shows the CubeSat nanosatellite, which weighs several kilograms and can be developed within a short period at a low cost. Thus, CubeSat can potentially facilitate new space development by functioning as a platform for the rapid demonstration of new technologies in space and for space business. CubeSat can also be the subject of university-level space education and research [4]. Research and development of highly reliable space components and materials that can withstand long periods for usage in extreme space environments has been conducted throughout the history of satellite development [5]. In accordance with current technological developments, the use of electronic components (i.e., digital cameras, microprocessors, communication transceivers, and DC/DC converters) designed for consumer applications, such as laptop computers, smartphones, and automobiles, is now expected [6]. This is because consumer electronic components do not require space environment tests, such as severe radiation tests, and newer technologies can be rapidly implemented in such products; therefore, they are smaller and have a higher performance, lower power consumption, and lower cost than space components, which are developed for use in space environments. Although consumer components are not developed for use in space environments, sufficient reliability may be ensured by thorough reliability evaluation tests involving simulated space environments, such as vibration, thermal vacuum, and radiation tolerance evaluation tests. In Japan, nanosatellite-class communication systems have not changed significantly over the past decade [7]. At present, only one company produces communication devices for space applications that combine consumer integrated circuits (ICs) with discrete components for the 144 and 430 MHz amateur frequency bands used by many universities [8]. This communication equipment is highly reliable and has been used by several universities in Japan; however, currently, Japanese research on communication equipment and antennas is lagging behind the experimental and pioneering work being conducted in other countries [9; 10]. Although detailed experimental research on Doppler shift tolerance in the 434 MHz band using the CubeSat LoRa module has been reported [11], few studies have evaluated the radiation tolerance of consumer electronic components for potential use in CubeSat; such evaluations are important to determine component feasibility for space application. The objective of this study is to demonstrate the process of applying consumer products to satellite space missions after subjecting them to appropriate space environmental testing. This approach can reduce the time and cost if the required component for the space research mission is not available in the market. In our mission, as a suitable communication system in terms of the cost and design flexibility was unavailable, we developed and verified a communication system for a CubeSat-class nanosatellite that actively utilizes current consumer communication devices. We fabricated a small software-controllable communication system using a current consumer communication IC and single-chip mi  
Figure 1: University of Tsukuba CubeSat ITF-2 (YUI-2). crocomputer. The prototype was then evaluated through radiation testing. In previous studies, we conducted radiation tolerance evaluation on microcomputers using heavy-ion irradiation [12; 13]. In this study, we evaluate the radiation tolerance of the transceiver IC using the same method.