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SkySat-1: very high-resolution imagery from a small satellite
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2014
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The paper describes the SkySat‑1 microsatellite mission, a low‑cost commercial earth‑observation system that delivers sub‑meter panchromatic and pan‑sharpened imagery and enables a large constellation with high temporal and spatial resolution. SkySat‑1 achieves high‑resolution imagery by simplifying the spacecraft design, using a custom optical telescope and high‑frame‑rate CMOS sensors, and applying ground‑based digital TDI image‑processing algorithms that combine multiple frames to boost SNR and reduce GSD. The mission was launched at an order‑of‑magnitude lower cost than comparable systems, produced the first commercial high‑definition full‑frame panchromatic video from space (~1 m GSD), and demonstrated that processed imagery matches pre‑launch simulations.
This paper presents details of the SkySat-1 mission, which is the first microsatellite-class commercial earth- observation system to generate sub-meter resolution panchromatic imagery, in addition to sub-meter resolution 4-band pan-sharpened imagery. SkySat-1 was built and launched for an order of magnitude lower cost than similarly performing missions. The low-cost design enables the deployment of a large imaging constellation that can provide imagery with both high temporal resolution and high spatial resolution. One key enabler of the SkySat-1 mission was simplifying the spacecraft design and instead relying on ground- based image processing to achieve high-performance at the system level. The imaging instrument consists of a custom-designed high-quality optical telescope and commercially-available high frame rate CMOS image sen- sors. While each individually captured raw image frame shows moderate quality, ground-based image processing algorithms improve the raw data by combining data from multiple frames to boost image signal-to-noise ratio (SNR) and decrease the ground sample distance (GSD) in a process Skybox calls digital TDI". Careful qual-ity assessment and tuning of the spacecraft, payload, and algorithms was necessary to generate high-quality panchromatic, multispectral, and pan-sharpened imagery. Furthermore, the framing sensor configuration en- abled the first commercial High-Definition full-frame rate panchromatic video to be captured from space, with approximately 1 meter ground sample distance. Details of the SkySat-1 imaging instrument and ground-based image processing system are presented, as well as an overview of the work involved with calibrating and validating the system. Examples of raw and processed imagery are shown, and the raw imagery is compared to pre-launch simulated imagery used to tune the image processing algorithms.