Technology is allowing for miniaturizing instruments to enable smaller satellite platforms greater measurement capabilities. Cosine, the Prime of the ESA GSTP project HyperCube, has created a miniaturized hyperspectral imager called HyperScout. It has a wide Field Of View (FOV) giving a swath width (@300km) of 164 km with a 40m Ground Sampling Distance (GSD). HyperScout images in 45 spectral bands, each with a spectral resolution <10nm, and within the spectral range of 450 – 1000 nm. The radiometric resolution is 12 mega pixels. The entire instrument weighs only 1.1 kg and fits into a 1 cubesat unit form factor.
However, the measurement data stream from HyperScout remains almost the same as for larger instruments, particularly because it is a hyperspectral camera. And smaller platforms, such as cubesats, do not carry downlink and storage capacities equivalent of the larger platforms. Thus, there is a need for compressing the instrument data, pre-processing it and selectively downlinking only the useful or relevant measurements. Furthermore, the HyperScout instrument is envisioned to be a scouting instrument, forward mounted on larger platforms to look for interesting features in the scenery ahead of a higher resolution, narrow FOV camera. This requires onboard data processing of the HyperScout measurement stream in real-time to allow for an onboard evaluation of where the interesting features are located in the upcoming scenery, to enable an efficient pointing of the higher resolution camera to the relevant location.
We use commercial off the shelf processing boards, following the Qseven 2.0 form factor standard. The boards typically have two or four processing cores, runs a simplified Linux operating system and communicates across the standard satellite communication interfaces (PCIe, I2C bus, SPI, SATA, USB, Gigabit Ethernet, LPC bus, SDIO).
The processing board is connected with the instrument through a shared data storage unit. It can be fully controlled by an external microcontroller, shut on and off, and paused (it will resume exactly where it left off). The processing board is designed for low power consumption, and optimized for the available mission power duty cycles. For instance, when the board is paused it uses very little power in standby mode (0.39 W). For processing itself, the board will maximize usage of the available processing resources within an efficient time frame, to lower the power consumption as much as possible.