Chinese Coast Guard vessel prowling near the Senkaku Islands
By The Sankei Shimbun
The Japanese government plans to develop and produce micro radar satellites in an attempt to step up monitoring activities at the the Senkaku Islands and its adjacent areas in the East China Sea, the Sankei Shimbun has learned.
The information obtained by Sankei Shimbun suggests Japan’s intention to accelerate its strategy to cope with China's recent ambitious maritime expansion.
The plan to use micro radar satellites should complement existing intelligence-gathering satellites at a low cost. The aim is to introduce the devices within a couple of years, working with private launch teams to ensure adequate capacity to carry the micro radar satellites into orbit.
According to the plan, private companies would launch a constellation of micro radar satellites. Intelligence-gathering satellites would be simultaneously deployed, enabling Japan to monitor Chinese Coast Guard and other vessels around the Senkaku Islands.
Micro radar satellites have the advantage of significantly curbing the development costs. The cost of intelligence-gathering satellites often reaches several hundred billion Japanese yen. In comparison, each micro radar satellite would cost only several hundred million Japanese yen per year — a fraction of the cost of the intelligence satellites.
Information-gathering satellites have the ability to highly discriminate and are easily capable of recognizing the equipment and payloads of seagoing vessels. The drawback, however, is that this requires a significant amount of energy, which means each satellites is capable of taking images only once a day.
They have more frequencies for filming images in accordance with the number deployed, however. For instance, if dozens of micro radar satellites are deployed, they are capable of keeping watch every several hours. They would also be capable of continuously tracking the moves of warships departing from China’s military ports.
The key to realizing the plan is to miniaturize the synthetic aperture radars (SAR) with day-and-night and weather-independent image filming capabilities. The Senkaku Islands and neighboring areas in the South China Sea are mostly covered with clouds. Downsizing the synthetic aperture radars is indispensable to ensuring their effective monitoring capability.
Micro radar satellites are also expected to be useful in responding to disasters and for business purposes. Private companies involved begin trials on their capabilities next year.
iQPS Inc (Institute for Q-shu Pioneers of Space, Inc.), for instance, is a venture firm specializing in space engineering in Fukuoka on the western Japan Island of Kyushu. The company sets out in October to assemble micro radar satellites capable of recognizing one-meter long objects, in order to be in time for the planned blast-off slated for summer of 2019.
Meanwhile, Keio University professor Seiko Ishizuka and other researchers plan to launch micro radar satellites by the end of 2019. The Japanese government is providing financial assistance for the project in the amount of about JPY2 billion (USD17.5 million).
If the private companies are able to demonstrate the credibility of the technology, it would become possible to build tens of micro radar satellite systems in a short period of time.
“Utilizing micro radar satellites is becoming more likely. We will start taking advantage of micro radar satellites after we see that their technology trends and transitions,” said officials of the Cabinet Satellite Intelligence Center (CSICE), the government body that is operating intelligence-gathering satellites.
The principle behind coordinating two radar satellites and two optical satellites is like operating a digital camera. The Japanese government plans to deploy four mission-critical satellites, four time-axis diversification satellites, and two data relay satellites after 2026.
However, prospects for realizing the project are still unclear. The frequency for taking images would be only once every half-day, even if it becomes a reality.
On the other hand, China has launched more than 20 spy satellites and these reportedly pass above Japan multiple times in a day.
A synthetic aperture radar (SAR) is a radar system mounted on a moving platform, such as an artificial satellite or spacecraft, that is used for ground-base observation. It transmits radio waves towards the ground and receives radio waves reflected from the ground. It then creates black-and-white images. Synthesizing the successive radio waves has the unusual effect of lengthening radar antennas (aperture plane). As the radar requires a large amount of electricity to beam up radio waves, it is difficult to downscale the satellite.
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