Britain has undertaken an effort to develop a cluster of three half-ton satellites that can more accurately detect what is on the ground using SAR (synthetic aperture radar) as well as passive devices to collect electronic activity down there. This project, called Project Oberon, is now possible because Britain left the European Union (EU) and is now free to undertake projects like Oberon. While a member of the EU, a member nation needed EU permission for things like Project Oberon.
Remote sensing satellites have long been used to track all matter of activity on the planetary surface. This often-involved economic activity like agriculture, mining, forestry and fishing. There were also military and intelligence uses,
China has come up with some novel applications. A decade ago China put a cluster of three remote sensing satellites in orbit, moving in formation at an altitude of 600 kilometers across the Pacific. Equipped with either SAR radar or digital cameras, these three birds can scan the ocean for ships, even though the Chinese say their purpose is purely scientific. A typical SAR can produce photo quality images at different resolutions. At medium resolution (3 meters) the radar covers an area 40x40 kilometers. Low resolution (20 meters) covers 100x100 kilometers. This three satellite Chinese posse looks suspiciously like a military ocean surveillance system. This is the missing link for the Chinese ballistic missile system designed to attack American aircraft carriers. Since then, China has launched three more of these Yaogan satellite clusters. Each new cluster launched had been an improvement on earlier ones. All these Yaogan satellites were indeed in support of ground-based DF-21D ballistic missiles’ ability to hit warships at sea and over a thousand kilometers distant. The basic DF-21 is a 15 ton, two stage, solid fuel missile that is 10.7 meters (35 feet) long and 140cm (4.6 feet) in diameter. Range varies (from 1,700-3,000 kilometers) depending on model. The DF-21D is believed to have a range of 1,500-2,000 kilometers. While the 500-2,000 kg (.5-2 ton) warhead usually contains a nuclear weapon, there are also several types of conventional warheads, including one designed for use against warships. China has been developing the DF-21D since about 2002 and needed the Yaogan clusters to find and track targets.