Experimental Validation of an Onboard Transient Luminous Events Observation System for VisionCube via Ground Simulation Environment

Seho Kim,Taehyung Nam,Dongwon Jung

doi:10.3390/aerospace5040100

Abstract

The VisionCube is a 2-unit CubeSat developed in house, of which the primary mission is detecting the occurrence of transient luminous events (TLEs) in the upper atmosphere and obtaining corresponding images from a low Earth orbit. An onboard TLE observation system of the VisionCube CubeSat is designed and developed by incorporating a photon-sensitive multi-anode photon-multiplier tube (MaPMT) and an image sensor. Also, a distinctive TLE observation software which enables detection of the TLEs and capture of images in a timely manner is devised. By taking into account the limited resources of a small CubeSat in size and power, the onboard observation system is developed employing a system-on-chip device by which both hardware and software can be integrated seamlessly. The purpose of this study is to investigate the functionality of the hardware and the validity of the software algorithm to show that the onboard system will function properly with no human intervention during the operations in space. To this end, a ground simulation facility is constructed to emulate TLEs occurring in space using a set of ultraviolet light-emitting diodes (UV LEDs) inside a darkbox. Based on the analysis of the spectral and temporal properties of the TLEs, the randomly generated UV LED pulses are chosen for verification scenarios for the TLE observation system. The validation results show that the hardware and the software algorithm of the onboard observation systems can effectively detect the TLEs and obtain the images during the in-orbit operation.

Highlights

Transient luminous events (TLEs) are a result of electrical discharge phenomena that occur in the upper atmosphere
With the major components of the hardware logic are verified for its functionality, the actual operation of the transient luminous events (TLEs) observation system was verified on the ground simulation facility
The onboard TLE observation system consists of dedicated hardware and software so as to detect occurrence of TLEs and obtain corresponding images from the low Earth orbit

Summary

Introduction

Transient luminous events (TLEs) are a result of electrical discharge phenomena that occur in the upper atmosphere. Sprites are large-scale TLEs that typically occur in the upper stratosphere and mesosphere regions (altitude of 40 to 90 km) and move rapidly downwards at speeds of up to 10,000 km/s [14] It resembles a reddish-orange colored carrot with tendrils below. The hardware should include low-level logic to process signals from the detector and CMOS image sensor on the order of a few microseconds, as well as high-level processing unit capable of handling large amounts of data in a few seconds Such a hardware will allow implementation of the TLE observation algorithm involving the detection of TLEs and the acquisition of digital images. The SoC consists of field programmable gate array (FPGA) and embedded

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Conclusion