# In-Orbit Results and Attitude Analysis of the SNUGLITE CubeSatellite
## 2 Materials and Methods  
### SNUGLITE CubeSat Project  
SNUGLITE's shape is described in Figure 1. The project was selected at the 2015 CubeSat competition by the Korea Aerospace Research Institute. After three years of development, SNUGLITE was launched on December 3, 2018. It settled successfully in the target orbit, which is sun-synchronous at an altitude of 575 km. SNUGLITE's designated satellite number given by the North American Aerospace Defense Command (NORAD) is 43,784.  
Figure 1: (**a**) SNUGLITE CubeSat before deployment; (**b**) SNUGLITE CubeSat after deployment.  
SNUGLITE is a 2-unit CubeSat whose specifications are described in Table 1. One of the scientific missions of the SNUGLITE CubeSat is to monitor the disturbance of the ionosphere and the magnetic field by seismic events, such as earthquakes, volcanoes, and tsunamis. SNUGLITE has two dual-frequency GPS receivers. The first receiver, which is for satellite positioning, has its antenna mounted at the top of the satellite in the \(-\)z direction of Figure 1 to the zenith direction. The second GPS antenna is mounted on the side of the CubeSat in the \(+\)y direction in order to measure the ionospheric delay on the path from other GPS satellites to the SNUGLITE.  
One of the technical missions of the SNUGLITE CubeSat is to verify the in-orbit operation of the on-board L1/L2C GPS receivers, which we developed in co-operation with TelAce Inc. (Seoul, Korea). The receivers are shown in Figure 2. Another technical objective is to develop an LQG-based attitude system.  
Since launch, the SNUGLITE CubeSat has continuously broadcast its status data in beacons. Ground stations in Asia, Europe, North America, and South America have been receiving the beacons. The ground facility for the SNUGLITE team was constructed in Seoul National University using a conventional amateur satellite transceiver, antenna modules, and amplifiers to communicate with the satellite.  
However, an uplink problem occurred, and the SNUGLITE CubeSat became unresponsive to tele-commands from the ground station. Given that commands from the ground station are required  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Item** & **Description** \\ \hline \multirow{7}{*}{satellite size} & main payloads & \multicolumn{2}{c}{dual-frequency L1/L2C Global Position System (GPS) receiver (2 units)} \\  & secondary payloads & \multicolumn{2}{c}{3-axis flux-gate magnetometer} \\  & before deployment & \(100\times 100\times 227\) mm (2U) \\  & after deployment & \(100\times 100\times 727\) mm (boom deployment) \\  & satellite weight & & 1.87 kg \\  & \multirow{2}{*}{frequency} & uplink & 437.275 MHz \({}^{1}\) (UHF \({}^{2}\)) \\  & & downlink & 437.275 MHz \({}^{1}\) (UHF \({}^{2}\)) \\  & & & 2405 MHz \({}^{1}\) (S-band) \\ satellite & \multirow{2}{*}{data rate} & uplink & 9600 bps (UHF \({}^{2}\)) \\ communication & & downlink & 9600 bps (UHF \({}^{2}\)) \\  & & modulation & 106,000 bps (S-band) \\  & \multirow{2}{*}{production} & GMSK (UHF \({}^{2}\)), DQPSK (S-band) \\  & & protocol & AX.25 (UHF \({}^{2}\)) \\  & orbit & & sun-synchronous 575 km \\ \hline \hline \end{tabular} \({}^{1}\) Amateur radio band; \({}^{2}\) Ultra High Frequency.  
\end{table}
Table 1: Specifications of SNUGLITE.  
Figure 2: L1/L2C dual-frequency Global Position System (GPS) receiver (2 units) for the CubeSat.  
to initiate the scientific mission, the SNUGLITE CubeSat has not proceeded to 'observation mode' for ionosphere and magnetic field monitoring, and it is currently in standby mode.  
Though a problem has occurred in performing the scientific mission, the analysis of the attitude system can be still be performed using the received status data, as they include the estimated attitude, the calculated position and velocity measured by GPS receivers, and other related information.