The Carbonite-2 optical reconnaissance satellite launched last March into low earth orbit brings capability to track vehicles, aircraft and ships in still images and colour video, can undertake rapid tasking of satellites and provide fast data download within minutes of acquisition, using COTS telescope and high-definition video, one metre resolution images and 60 sec video clips with a swath of 5 kilometers. Limitations limited time over object of interest until constellation in orbit.
Built by Surrey Satellite Technology, Airbus company, launched on an Indian rocket from the Satish Dhawan Space Centre in Sriharikota, India. Funded by Earth-i, a commercial imagery provider, who are in turn partially funded by MOD/RAF to the tune of £4.5M. Constellation of five satellites ordered.
Complementary to the S-band (3.2 gigahertz) radar satellite NovaSAR launched last September, with a best resolution of 6m with a swath width of 15-20km, future variants will go to the higher-frequency X-band for higher resolution of one metre and less.
Wikipedia- A low Earth orbit requires the lowest amount of energy for satellite placement. It provides high bandwidth and low communication latency, used by spy satellites, earth observation, Hubble, Int Space Station etc. It requires less energy to place a satellite into a LEO, and a satellite there needs less powerful amplifiers for successful transmission, LEO is used for many communication applications.
Disadvantages, Satellites in LEO have a small momentary field of view, only able to observe and communicate with a fraction of the Earth at a time, meaning a network /constellation of satellites is required to in order to provide continuous coverage. Satellites in lower regions of LEO also suffer from fast orbital decay, requiring either periodic re-boosting to maintain a stable orbit, or launching replacement satellites when old ones re-enter.