## 3 On Orbit Operations and Anomaly Analysis
### Apparent Single Event Effect  
The spacecraft maintained a stable safe mode from launch till February 15. During this time, a few anomalies were detected in the received flight data that were not critical, but were nonetheless unexpected. Following deployment, the spacecraft began beaconing every 30 s using the late packet format previously defined in Table 3. FSW was designed such that the beacon packet format could only be changed upon received command. The satellite beacon format autonomously changed from late to normal on February 2, a situation that persisted, even following the 1.5 month COMM blackout, and was not corrected until reception of a ground station command resetting the packet format on 2 April.  
It is likely that this anomaly was caused by a single event effect (SEE) caused by high-energy particles. There are many ways in which high-energy particles can affect spacecraft electronics [33]. In this case, it is likely that the culprit was a single event upset (SEU), which caused corruption of the OBC SRAM memory address where the FSW variable controlling  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Date** & **Satellite Operation** & **Ground Station Operation** \\ \hline
2021-01-25 & Safe mode. & Flight data downlink from SatNOGS. \\  & & Anomaly: NCU ground station unable to receive beacon. \\ \hline
2021-01-26 & Safe mode. & Flight data downlink from SatNOGS. \\  & & NCU ground station servicing start. \\ \hline
2021-02-01 & Safe mode. & Flight data downlink from NCU ground station and \\  & & SatNOGS. \\ \hline
2021-02-02 &
\begin{tabular}{c} Safe mode. \\ Anomaly: Autonomous beacon format \\ change into Normal mode. \\ \end{tabular} & Flight data downlink from NCU ground station and \\  & & SatNOGS. \\ \hline
2021-02-15 & Anomaly: COMM blackout. & No signal received at NCU ground station and SatNOGS. \\ \hline
2021-02-25 & Anomaly: COMM blackout. &
\begin{tabular}{c} UHF SDR power output found to be insufficient to drive \\ primary UHF amplifier at NCU ground station. \\ Preamplifier added. \\ \end{tabular} \\ \hline
2021-03-03 & Anomaly: COMM blackout. & Ground station Tx power verified to be nominal following \\  & & preamplifier installation. \\ \hline
2021-04-02 &
\begin{tabular}{c} Safe mode. \\ beacon Tx resumes. \\ beacon is changed into Lite mode after \\ receiving command. \\ \end{tabular} & Command IDEASSat to change beacon format to Lite. \\  & & Flight data downlink from NCU ground station and \\  & & SatNOGS. \\ \hline
2021-04-04 & Anomaly: COMM blackout. & No signal received at NCU ground station and SatNOGS. \\ \hline
2021-09-02 & Decommissioning Review \\ \hline \hline \end{tabular}
\end{table}
Table 11: IDEASSat on-orbit event log.  
the beacon packet format was mapped. Although single error correction and double error detection (SECDED) was implemented on the OBC SmartFusion2 SRAM [15; 18; 19], an SEU affecting more than one bit would not be correctable. Additionally, the corrupted variable would be logged to the SD cards every six hours in safe mode, causing the error to persist following a power cycle. In such an event where the beacon format variable was corrupted, FSW would default to broadcasting the normal packet format. An important lesson learned is related to SEU precautions. For future OBCs designed using a similar hardware architecture with periodic logging of FSW variables to the SD-cards, we will prefer to use a higher-level SmartFusion2 model, such as the M2S090, with built-in error correction code (ECC) memory or implement error correction algorithms such as BCH code or Reed-Solomon code. Considering the use of SD cards for non-volatile data logging, the SEU rate in SD cards is very low, according to NASA/TP--2020-5008734, State-of-the-Art, Small Spacecraft Technology [12]. If the SD card is to be replaced by an even more robust option with respect to SEUs, magnetoresistive random-access memory (MRAM) or ferroelectric random-access memory (FRAM) can be considered [12].