# Robust and Reconfigurable On-Board Processing for a Hyperspectral Imaging Small Satellite
## 4 Testing and In-Orbit Results
### In-Orbit Results  
HYPSO-1 was launched on 13 January 2022 aboard a Falcon 9 rocket flying the SpaceX Transporter-3 Mission. Since then, as of January 2023, more than 1000 hyperspectral data cubes have been recorded and downlinked [36], which is more than 188 GB of hyperspectral data. With the average compressed datacube file size being about 70 MB, this corresponds to about 8 days of downlink time over the 1 Mbit/s link of the S-Band radio. Only the ground station at NTNU was used initially. Later on, the KSat ground stations on Svalbard via the KSATlite service were used for data downlink as well. However, because the passes over KSATlite on Svalbard and over NTNU overlap, this did not result in a big improvement in downlink capacity. During operations, it was found that over the course of a day, a single ground station is able to downlink about 5-6 images with nominal dimensions. Operations are ongoing and targets are imaged daily. Corresponding to the 1000+ captures, the OPU performed more than 1000 boot sequences with at least 300 additional boot sequences for delayed buffering and manual operation. The second SD card slot shown in Figure 1b was intended to store another boot image for triple redundancy. This could not be implemented due to a technical design error. However, the OPU is yet to boot the golden image on the eMMC, indicating that the degree to which integrity and redundancy was included in the system was adequate. Considering the 80 most recent captures before 19 April 2023, the average delay until the whole data cube was downloaded was about 432 min, which is 7.2 h. Frame rate performance, binning timing, software and FPGA compression timing are consistent with on-ground testing. The nominal cube dimensions were used most. However, for some captures other cube dimensions were configured, including, for example, for the purpose  
Figure 10: Length of time taken by long compression in software and on FPGA on the OPU. (**a**) Software compression. (**b**) Compression on FPGA. of wider spatial coverage or calibration purposes. See Table 8 for a distribution out of a selection of 1043 captures. A software update of the main application was performed by uploading a newer version of the program to the SD card and running this version from a PC script after the OPU has booted. This was a successful test, although the newer version did not add substantial new functionality. Energy Usage  
The energy use of the first HYPerspectral Smallsat for Ocean observation (HYPSO-1) payload measured by the EPS is plotted in Figure 11. The energy use of the payload is shown during recording, processing and buffering of an image. This operation consists of four phases. These are:  
1. Preparations for image recording (seconds 45 to 165). 2. Image recording (seconds 165 to 210). 3. Post actions, including software compression (seconds 210 to 730). 4. Buffering the data to the PC (seconds 1990 to 4408). The HSI camera is turned on only for phase 1 and 2. The EPS telemetry logging rate was increased during phases 1 to 3, but not during phase 4. The telemetry logging rates were 10 s and 5 min, respectively. This image was recorded using a wider spatial imaging mode, for which compression on FPGA is not implemented and software compression is used. Software compression makes phase 3 take about 520 s. The OPU is directly connected to the EPS battery which has a voltage of around 8 V. The HSI camera is connected to a 12 V output of the EPS. Power draw of the payload peaks at just above 6 W during imaging. Figure 11: Plot of energy-use-related telemetry of the OPU and HSI from the EPS. Top to bottom: Current draw of the OPU and the HSI, Battery voltage to the OPU, 12V to the HSI, power use of the OPU and the HSI.