True remote sensing persistence requires a constellation of high-resolution X-Band space-based radar imaging satellites. Radar illumination is daylight independent and penetrates clouds, haze, dust and smoke.
With a planned launch in 2024, the XpressSAR constellation will guarantee collection in the cloud-persistent regions of the globe between 48° North and South. XpressSAR collects and delivers high resolution remote sensing data and data products within hours, guaranteed.
XpressSAR’s constellation of four X-band radar satellites has an average revisit rate of just a few hours. The XpressSAR system is highly tactical and designed to be a change detection machine. As such, XpressSAR can act as a watchful eye in space over any location in its coverage area. It can monitor harbors, airfields, active volcanoes, spreading floods, oil spills, ship traffic, and other sites and activities, with a periodicity of days or even hours.
And because radar illumination is consistent, XpressSAR collections of pairs, triplets or large stacks of images can be used for automated change detection, subsidence monitoring or quick digital elevation or terrain models. XpressSAR can persistently monitor the location you care about and alert you when something significant has occurred.
XpressSAR uses the most advanced commercial radar imaging technology available and is based on space proven TRL9 radar imaging technology used on satellites that have been taking high-quality, excellent signal-to-noise radar images for several years.
XpressSAR has quad-polarization with a wide range of collection modes ranging from small-area Spotlights with sub-meter resolution to large-area StripMaps with resolutions from 1-to-3 meters.
Radar measurements are naturally precise. When radar data are combined with commodity GPS orbit-determination processes, they are used to form images that are in line with the geolocation revolution. XpressSAR data has state-of-the-art geo-locational accuracy matching the scale of the pixel. No post-processing manipulation needed - you get precision with the image.
In addition to its core advantages of cloud penetration and day or night collection, radar imaging has other interesting capabilities. Radar sensors illuminate the ground using pulses of microwave radiation. The sensors emit thousands of pluses each second and record the resulting echoes. They measure the time it takes each pulse to travel from the sensor to the ground and back, as well as other characteristics of the return wave. From these raw measurements, the SAR technique is used to form images. SAR was a breakthrough in radar imaging because it synthesizes a large virtual antenna from a small physical antenna, allowing imaging from a small platform that can be put into orbit.
In addition, radar’s microwave pulses are coherent. They are controlled and consistent in structure from pulse to pulse. This contrasts to the random illumination of sunlight. The coherent nature of SAR enables high resolution from great distances. In fact, the resolution of a SAR sensor has the remarkable characteristic that it is not dependent on the distance between the sensor and the ground. Coherence also enables special image processing techniques like the precise measurement of surface structure changes over time. Commercial SAR systems have been used, for example, to measure ground subsidence in oil fields at a level of a few millimeters per year.
SAR imaging is not constrained by a fixed focal length like optical telescopes. Therefore imaging can be done in various modes with differing resolution and coverage. Another benefit of SAR is that the images have a natural geometric fidelity and accuracy. Multiple radar images taken over the same location can be managed so that they are all alike with consistent illumination and geometric characteristics. This makes change detection very reliable and one of SAR’s principal applications.
XpressSAR leverages all these technologies to provide the world's best commercial SAR data.