Beta angle in the Earth's shadow, and results in extremely reduced absorption of solar energy. At a LEO of 280 kilometers, the object is in sunlight through 59% of its orbit (approximately 53 minutes in Sunlight, and 37 minutes in shadow.) On the other extreme, an object launched into an orbit parallel to the terminator results in a beta angle of 90 degrees (formula_2 = 90°), and the object is in sunlight 100% of the time. An example would be a polar orbit initiated at local dawn or dusk on an equinox. Beta angle can be controlled to keep a satellite as
Type 90 Kyū-maru procurement plan was established in the 1980s while Japan was experiencing asset price bubble. After the asset price bubble burst in 1991 and the collapse of Soviet Union in 1992, Japan started to cut its defence budget. In order to save budget for Kongo Class missile destroyers and other new weapons, Japan made a plan to reduce the size of its tank force. The production of Type 90 therefore slowed down and part of its budget was shifted to the research and development of the new Type 10 main battle tank. Being 12 tonnes heavier than its predecessor Type 74