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JCSAT-1
JCSAT-1 was a geostationary communications satellite designed and manufactured by Hughes (now Boeing) on the HS-393 satellite bus. It was originally ordered by Japan Communications Satellite Company (JCSAT), which later merged into the JSAT Corporation. It had a Ku-band payload and operated on the 150° East longitude until it was replaced by JCSAT-1B. Satellite description The spacecraft was designed and manufactured by Hughes on the HS-393 satellite bus. It had a launch mass of , a mass of after reaching geostationary orbit and an 8-year design life. When stowed for launch, its dimensions were long and in diameter. With its solar panels fully extended it spanned . Its power system generated approximately 2350 watts of power thanks to two cylindrical solar panels. It also had a two 38 Ah NiH2 batteries. It would serve as the main satellite on the 150° East longitude position of the JSAT fleet. Its propulsion system was composed of two R-4D-12 liquid apogee engine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JSAT Corporation
JSAT Corporation (JSAT) was the first private Japanese satellite operator, which owned the JSAT satellites, as well as operated and partially owned the N-Star with NTT DoCoMo. Its origins can be traced to the funding of Japan Communications Satellite Company (JCSAT) and Satellite Japan Corporation in 1985. Both companies merged into Japan Satellite Systems Inc. in 1993. In 2000 the company was renamed as JSAT Corporation and was listed in the First Section of the Tokyo Stock Exchange. On September 1, 2008, the company was merged into the SKY Perfect JSAT Group. History With the opening of the Japanese satellite communications market to private investment, Japan Communications Satellite Company (JCSAT) and Satellite Japan Corporation were founded in 1985. In June of the same year, JCSAT awarded an order to Hughes Space and Communications for two identical satellites, JCSAT-1 and JCSAT-2, based on the spin-stabilized HS-393 satellite bus. JCSAT-1, the first commercial Japane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JCSAT-1B
JCSAT-1B, known as JCSAT-5 before launch, is a geostationary communications satellite operated by SKY Perfect JSAT Group (JSAT) which was designed and manufactured by Hughes (now Boeing) on the HS-601 satellite bus. It has a pure Ku-band payload and was used to replace JCSAT-1 at the 150° East longitude. It covers Japan, Korea, most of China, Thailand, Vietnam, Laos, part of Indonesia, part of Malaysia and Hawaii. Satellite description The spacecraft was designed and manufactured by Boeing Satellite Development Center on the HS-601 satellite bus. It had a launch mass of and a 12-year design life. Its solar panels span when fully deployed and generated approximately 5 kW of power, with its antennas in fully extended configuration it is wide. It would provide communications services throughout Japan, East Asia, South Asia, Australia and Hawaii. Its payload is composed of sixteen 36 MHz plus another sixteen 27 MHz Ku-band transponders, for a total bandwidth of 1008 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HS-393
The Hughes 393 (sometimes referred to as the HS-393) is a communications satellite bus introduced in 1985 by Hughes Space and Communications Company. It was a spin-stabilized bus that had twice as much power as the HS-376 platform. Design The satellite bus was designed and manufactured by Hughes. It had a launch mass of , a mass of after reaching geostationary orbit, and an 8-year design life. When stowed for launch, its dimensions were in height and in diameter. With its solar panels fully extended its height was . Its power system generated approximately 2,350 watts of power at beginning of life and 2,200 at end of life, thanks to two cylindrical solar panels. These panels used K7 and K4-3/4 solar cells, with more than twice the number of cells than on the HS-376. The bottom panel was retracted around the body and top panel for launch, and extended downwards for operation. It also had two 38 Ah NiH2 batteries. Its propulsion system was composed of two R-4D liquid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Communications Satellite
A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Many communications satellites are in geostationary orbit above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form satellite constellations in low Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently. The high frequency radio waves used for telecommunications links travel by line of sight and so are obstructed by the curve of the Earth. The purpose of communications sate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrusters (spacecraft)
A thruster is a spacecraft propulsion device used for orbital station-keeping, attitude control, or long-duration, low-thrust acceleration, often as part of a reaction control system. A vernier thruster or gimbaled engine are particular cases used on launch vehicles where a secondary rocket engine or other high thrust device is used to control the attitude of the rocket, while the primary thrust engine (generally also a rocket engine) is fixed to the rocket and supplies the principal amount of thrust. Some devices that are used or proposed for use as thrusters are: *Cold gas thruster * Electrohydrodynamic thruster, using ionized air (only for use in an atmosphere) *Electrodeless plasma thruster, electric propulsion using ponderomotive force * Electrostatic ion thruster, using high-voltage electrodes *Hall effect thruster, a type of ion thruster *Ion thruster, using beams of ions accelerated electrically *Magnetoplasmadynamic thruster, electric propulsion using the Lorentz force * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipropellant Rocket
A liquid-propellant rocket or liquid rocket utilizes a rocket engine that uses liquid propellants. Liquids are desirable because they have a reasonably high density and high specific impulse (''I''sp). This allows the volume of the propellant tanks to be relatively low. It is also possible to use lightweight centrifugal turbopumps to pump the rocket propellant from the tanks into the combustion chamber, which means that the propellants can be kept under low pressure. This permits the use of low-mass propellant tanks that do not need to resist the high pressures needed to store significant amounts of gasses, resulting in a low mass ratio for the rocket. An inert gas stored in a tank at a high pressure is sometimes used instead of pumps in simpler small engines to force the propellants into the combustion chamber. These engines may have a higher mass ratio, but are usually more reliable, and are therefore used widely in satellites for orbit maintenance. Liquid rockets can be mono ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R-4D
The R-4D is a small hypergolic rocket engine, originally designed by Marquardt Corporation for use as a reaction control system thruster on vehicles of the Apollo crewed Moon landing program. Today, Aerojet Rocketdyne manufactures and markets modern versions of the R-4D. History Developed as an attitude control thruster for the Apollo Command/Service Module and Lunar Module in the 1960s, each unit for the modules employed four quadruple clusters (pods). It was first flown on AS-201 in February 1966. Approximately 800 were produced during the Apollo program. Post-Apollo, modernized versions of the R-4D have been used in a variety of spacecraft, including the U.S. Navy's Leasat, Insat 1, Intelsat 6, Italsat, and BulgariaSat-1. It has also been used on Japan's H-II Transfer Vehicle and the European Automated Transfer Vehicle, both of which deliver cargo to the International Space Station. It is also used on the Orion spacecraft Design The R-4D is a fuel-film cooled engine. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Longitude
Longitude (, ) is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians are semicircular lines running from pole to pole that connect points with the same longitude. The prime meridian defines 0° longitude; by convention the International Reference Meridian for the Earth passes near the Royal Observatory in Greenwich, England on the island of Great Britain. Positive longitudes are east of the prime meridian, and negative ones are west. Because of the Earth's rotation, there is a close connection between longitude and time measurement. Scientifically precise local time varies with longitude: a difference of 15° longitude corresponds to a one-hour difference in local time, due to the differing position in relation to the Sun. Comparing local time to an absolute measure of time allows ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nickel–hydrogen Battery
A nickel–hydrogen battery (NiH2 or Ni–H2) is a rechargeable electrochemical power source based on nickel and hydrogen. It differs from a nickel–metal hydride (NiMH) battery by the use of hydrogen in gaseous form, stored in a pressurized cell at up to 1200 psi (82.7 bar) pressure. The nickel–hydrogen battery was patented on February 25, 1971 by Alexandr Ilich Kloss and Boris Ioselevich Tsenter in the United States. NiH2 cells using 26% potassium hydroxide (KOH) as an electrolyte have shown a service life of 15 years or more at 80% depth of discharge (DOD) The energy density is 75 Wh/ kg, 60 Wh/dm3 specific power 220 W/kg. 15 years) in satellite applications. The cells can tolerate overcharging and accidental polarity reversal, and the hydrogen pressure in the cell provides a good indication of the state of charge. However, the gaseous nature of hydrogen means that the volume efficiency is relatively low (60-100 Wh/L for an IPV (individual pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ampere Hour
An ampere hour or amp hour (symbol: A⋅h or A h; often simplified as Ah) is a unit of electric charge, having dimensions of electric current multiplied by time, equal to the charge transferred by a steady current of one ampere flowing for one hour, or 3,600 coulombs. The commonly seen milliampere hour (symbol: mA⋅h, mA h, simplified as mAh) is one-thousandth of an ampere hour (3.6 coulombs). Use The ampere hour is frequently used in measurements of electrochemical systems such as electroplating and for battery capacity where the commonly known nominal voltage is dropped. A ''milliampere second'' (mA⋅s) is a unit of measurement used in X-ray imaging, diagnostic imaging, and radiation therapy. It is equivalent to a ''millicoulomb''. This quantity is proportional to the total X-ray energy produced by a given X-ray tube operated at a particular voltage. The same total dose can be delivered in different time periods depending on the X-ray tube current. To help e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watt
The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Watt (1736–1819), an 18th-century Scottish inventor, mechanical engineer, and chemist who improved the Newcomen engine with his own steam engine in 1776. Watt's invention was fundamental for the Industrial Revolution. Overview When an object's velocity is held constant at one metre per second against a constant opposing force of one newton, the rate at which work is done is one watt. : \mathrm In terms of electromagnetism, one watt is the rate at which electrical work is performed when a current of one ampere (A) flows across an electrical potential difference of one volt (V), meaning the watt is equivalent to the volt-ampere (the latter unit, however, is used for a different quantity from the real power of an electrical circuit). : ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
