Abstract
Nanosatellites are increasingly being used in space-related applications to demonstrate and test scientific capability and engineering ingenuity of space-borne instruments and for educational purposes due to their favourable low manufacturing costs, cheaper launch costs, and short development time. The use of CubeSat to demonstrate earth imaging capability has also grown in the last two decades. In 2017, a South African company known as Space Commercial Services launched a low-orbit nanosatellite named nSight-1. The demonstration nanosatellite has three payloads that include a modular designed SCS Gecko imaging payload, FIPEX atmospheric science instrument developed by the University of Dresden and a Radiation mitigation VHDL coding experiment supplied by Nelson Mandela University. The Gecko imager has a swath width of 64 km and captures 30 m spatial resolution images using the red, green, and blue (RGB) spectral bands. The objective of this study was to assess the interpretability of nSight-1 in the spatial dimension using Landsat 8 as a reference and to recommend potential earth observation applications for the mission. A blind image spatial quality evaluator known as Blind/Referenceless Image Spatial Quality Evaluator (BRISQUE) was used to compute the image quality for nSight-1 and Landsat 8 imagery in the spatial domain and the National Imagery Interpretability Rating Scale (NIIRS) method to quantify the interpretability of the images. A visual interpretation was used to propose some potential applications for the nSight1 images. The results indicate that Landsat 8 OLI images had significantly higher image quality scores and NIIRS results compared to nSight-1. Landsat 8 has a mean of 19.299 for the image quality score while nSight-1 achieved a mean of 25.873. Landsat 8 had NIIRS mean of 2.345 while nSight-1 had a mean of 1.622. The superior image quality and image interpretability of Landsat could be attributed for the mature optical design on the Landsat 8 satellite that is aimed for operational purposes. Landsat 8 has a GDS of 30-m compared to 32-m on nSight-1. The image degradation resulting from the lossy compression implemented on nSight-1 from 12-bit to 8-bit also has a negative impact on image visual quality and interpretability. Whereas it is evident that Landsat 8 has the better visual quality and NIIRS scores, the results also showed that nSight-1 are still very good if one considers that the categorical ratings consider that images to be of good to excellent quality and a NIIRS mean of 1.6 indicates that the images are interpretable. Our interpretation of the imagery shows that the data has considerable potential for use in geo-visualization and cartographic land use and land cover mapping applications. The image analysis also showed the capability of the nSight-1 sensor to capture features related to structural geology, geomorphology and topography quite prominently.
Highlights
The use of miniaturized satellite platforms such as microsatellite and nanosatellites for earth imaging has been gaining momentum globally over the last decade [1,2,3,4,5,6]
The Shapiro–Wilk test results confirmed a normal distribution for the image quality score and National Imagery Interpretability Rating Scale (NIIRS) variables for both nSight-1 and Landsat
The two-tailed t-test results indicate that Landsat 8 Optical Land Imager (OLI) images yielded significantly higher visual quality scores and NIIRS results compared to Landsat 8 OLI, indicative of Landsat 8’s superior image quality and better image interpretation compared to nSight-1
Summary
The use of miniaturized satellite platforms such as microsatellite and nanosatellites for earth imaging has been gaining momentum globally over the last decade [1,2,3,4,5,6]. Trends in miniaturization of low earth orbit earth observation satellites witnessed over the last few decades have been driven by universities, commercial satellite operators and space agencies that aim to reduce development cost, reduce launch overheads and scale down development time associated with large satellites such as Landsat, ENVISAT, and Sentinel missions. Small satellite missions are shifting the paradigm in earth observation because of their low development cost and short development time makes the development of imaging constellation feasible and mitigates the risk of single-point failures. The concept of small satellites has proven to be attractive due to the opportunities it provides for human capital development in the field of space science and technology and the partnerships forged between high-tech manufacturing small and medium enterprises, universities, and space agencies
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.