SkySat-1: very high-resolution imagery from a small satellite

Abstract

This paper presents details of the SkySat-1 mission, which is the first microsatellite-class commercial earthobservation 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 groundbased 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 sensors. 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 quality 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 enabled 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.

The future of Earth observation in hydrology

“…Indeed, it is the private sector that is leading the charge in realizing and utilizing the technology, with Google's TerraBella (recently acquired by Planet) providing high spatial (approx. 1 m) and temporal (30 fps -frames per second) full-motion video imagery (Murthy et al, 2014). UrtheCast (https://www.urthecast.com/) is another company exploring this potential, with similar spatial (1 m) but lower temporal (3 fps) specifications (see Fig.…”

Simulation of Multiangular Remote Sensing Products Using Small Satellite Formations

“…DSMs have only recently been proposed for or implemented in large scales in government [13] (e.g., NASA's Earth Science Technology Office 2030 Science Vision envisions "distributed observations" and formation flight), academia (e.g., Europe's QB50 mission [14]) and industry (e.g., Planet Labs, [15] and Skybox, [16]) to address the need for repeated, global measurements for Earth observations, monitoring and quick response. NASA's decadal surveys or their mid-term assessments have called for the consideration of DSMs in areas of Earth science, Astrophysics, Heliophysics, and Planetary science.…”

A High-Dynamic-Range Optical Remote Sensing Imaging Method for Digital TDI CMOS

“…Therefore, for the pushbroom imaging cameras in a low Earth orbit, the CMOS cannot complete multi-stage signal superposition in the charge domain as with time delay integration charge coupled device (TDI CCD). In recent years, the Skysat series [4] and Jilin-1 [5] satellites have used digital TDI technology to achieve pushbroom imaging with array CMOSs, which significantly reduced manufacturing costs and shortened the development cycle. With special design and compensation algorithms, digital TDI CMOSs approximate TDI CCDs in terms of sensitivity, ground sampling distance, and other measures of performance.…”