A few thousand microsatellites with deployable telescopes could provide constant image monitoring of the earth at 0.25 meter to 0.5 resolution. This would scale up persistent drone monitoring to a global scale. There would be issues of data transmission and storage.
The current larger commercial earth observation (EO) satellites provide images with approximately 0.5 meter GSD and fly at altitudes of approximately 600 km above the earth’s surface. These parameters drive the size of the primary mirror and put it at about one meter. Such mirror size pushes the satellite weight to between 1000kg to 2000kg.
Deployable telescopes provide several benefits like the ability to use the telescope at a much longer wavelength. Typically a wavelength which is 10 times longer requires a 10 time larger mirror diameter. Using a deployable telescope keeps the size and mass of the satellite the same as for a satellite with a sensor for a 10 times shorter wavelength. A satellite class on the order of 80-100 kg with deployable telescopes, flying at altitudes of 500-400 km above the earth’s surface, could providing images with resolution better than 0.5 meters.
Another concept study was performed to develop a deployable instrument that can reach a ground resolution of 25 cm from an orbital altitude of 500 km. Two classes of instruments were analyzed: the Fizeau synthetic aperture, a telescope that uses a segmented primary mirror, and a Michelson synthetic aperture, an instrument concept that combines the light of a distributed array of afocal telescopes into a final image. In a trade-off the Fizeau synthetic aperture was selected as the most promising concept for obtaining high resolution imagery from a Low Earth Orbit. In the stowed configuration, the design fills a hexagonal envelope with sides of 35 cm and a height of 1.1 meter. In 2014, the nominal mass of the designed instrument was estimated to be 75 kg.
The optical design of the Fizeau synthetic aperture is based on a full-field Korsch telescope that has been optimized for compactness and an excellent wavefront quality. It uses three aperture segments in a tri-arm configuration that can be folded alongside the instrument during launch. The secondary mirror is mounted on a deployable boom, further decreasing the launch volume.
Small aircraft already used for crime detection and monitoring and drone would work as well
In 2014, Persistent Surveillance Systems (PSS) flew a small Cessna aircraft 10,000 feet overhead. The surveillance planes were loaded up with specialized 192 megapixel cameras that could watch 25 square miles of territory, and it provided a Tivo-style time machine that could watch and record movements of every person and vehicle below.
After learning about the attempted robberies, PSS conducted frame-by-frame video analysis of the bookstore and sandwich shop and was able to show that exactly one car traveled between them. Further analysis showed that the suspect then moved on to a Family Dollar store in the northern part of the city, robbed it, stopped for gas—where his face was captured on video—and eventually returned home.
A person shows up as one single pixel and they can track movement of the person to a vehicle and then track the movement of vehicles.
PSS systems have witnessed 34 people being murdered within their imaged areas and been able to track people to and from those scenes. The people who confessed on being captured with assistance of their imagery confessed to a total of 75 murders. Many of the people confessed once captured to many more murders than PSS Systems tracked them to.
They work from reported crimes and start with the exact time and location of the crime. Then they track movement in and out of the crime scene.
About 900 drones in the air at the same time with 50 gigapixel cameras could monitor movement over every part of the United States.