Bits of knowledge about satellites                 知っておきたい人工衛星豆知識



Today, approximately 3,500 artificial satellites orbit the Earth. They are diverse in type and size. This article tries to look into some of them with a focus on their purposes.






 Atop the list is the earth observation satellite “Daichi-2”which Japan launched in May. It is the successor to “Daichi-1” orbited in 2006. Using infrared rays, it observes how things move on the earth in an earthquake and sends back data on the magnitude of the quake or the location of drift ice that may hits ships in navigation. In other words, it is tasked to collect information on everything discernible on the earth’s surface.






 Next are scientific satellites. Daichi may be broadly classified into this category. Primarily designed to observe outer space, they consist of various kinds such as solar and lunar probes. Widely known among those Japan has orbited are the middle atmosphere observation satellite “Ozora” and the asteroid explorer "Hayabusa".





 There are also navigation satellites. Sometimes called GPS (global positioning system) satellites, their primary mission is to support the navigation functions embedded in mobile phones and cars. They help us know exactly where we are. One of their characteristic features is the high altitude of their orbits. While Daichi-2 is in an orbit 628 kilometers high, most navigation satellites fly as high as about 20,000 kilometers, a key factor in accurate positioning.






 In addition to those, there are many other kinds of manmade satellites designed for purposes ranging from military to biological. Indeed we live our life, immeasurably depending on those satellites.






(Writen by: Takuya Shintate)




⇐Back   Next⇒