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STSAT-2B
STSat-2B, or Science and Technology Satellite-2B, was a South Korean satellite which was lost in the failure of the second flight of the Naro-1 launch vehicle. It was to have been operated by the Korea Aerospace Research Institute (KARI), and was intended to demonstrate technology for future spacecraft. The satellite had a mass of , and was expected to operate for at least two years. STSat-2B was originally intended to operate alongside a second spacecraft, STSat-2A; however STSat-2A was lost in 2009 after the payload fairing of its carrier rocket failed to separate, leaving the rocket unable to achieve orbit. Instruments The primary instrument aboard STSat-2B was the Dual-channel Radiometer for Earth and Atmosphere Monitoring, or DREAM, which would have measured the brightness temperature of the Earth at 23.8 GHz and 37 GHz. The secondary payload, the Laser Retroreflector Array (LRA) was to have been used for the Satellite laser ranging experiment, which was intended ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naro-1
Naro-1 ( ko, 나로호), previously designated the Korea Space Launch Vehicle or KSLV (also KSLV-1), was South Korea's first carrier rocket, and the first South Korean launch vehicle to achieve Earth orbit. On January 30, 2013, the third Naro-1 vehicle built successfully placed STSAT-2C into low Earth orbit. The first stage was a modified Russian Angara URM. The solid-fuel second stage was built by KARI, the national space agency of South Korea, and Korean Air. Neither the maiden flight on August 25, 2009, nor the second flight on June 10, 2010, reached orbit. The third flight on January 30, 2013, successfully reached orbit. The launches took place from the Naro Space Center. The official name of the first KSLV rocket, KSLV-I, is Naro, which is the name of the region in which Naro Space Center is located. Since Naro's retirement, the South Korean government has announced the rocket Nuri as its replacement and successor. History In 1992, Republic of Korea developed and la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technology
Technology is the application of knowledge to reach practical goals in a specifiable and reproducible way. The word ''technology'' may also mean the product of such an endeavor. The use of technology is widely prevalent in medicine, science, industry, communication, transportation, and daily life. Technologies include physical objects like utensils or machines and intangible tools such as software. Many technological advancements have led to societal changes. The earliest known technology is the stone tool, used in the prehistoric era, followed by fire use, which contributed to the growth of the human brain and the development of language in the Ice Age. The invention of the wheel in the Bronze Age enabled wider travel and the creation of more complex machines. Recent technological developments, including the printing press, the telephone, and the Internet have lowered communication barriers and ushered in the knowledge economy. While technology contributes to econom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brightness Temperature
Brightness temperature or radiance temperature is the temperature at which a black body in thermal equilibrium with its surroundings would have to be in order to duplicate the observed intensity of a grey body object at a frequency \nu. This concept is used in radio astronomy, planetary science and materials science. The brightness temperature of a surface is typically determined by an optical measurement, for example using a pyrometer, with the intention of determining the real temperature. As detailed below, the real temperature of a surface can in some cases be calculated by dividing the brightness temperature by the emissivity of the surface. Since the emissivity is a value between 0 and 1, the real temperature will be greater than or equal to the brightness temperature. At high frequencies (short wavelengths) and low temperatures, the conversion must proceed through Planck's law. The brightness temperature is not a temperature as ordinarily understood. It characterizes radi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ahn Byung-man
Ahn or AHN may refer to: People * Ahn (Korean surname), a Korean family name occasionally Romanized as ''An'' * Ahn Byeong-keun (born 1962, ), South Korean judoka * Ahn Eak-tai (1906–1965, ), Korean composer and conductor * Ahn Jung-hwan (born 1976, ), South Korean footballer * Ahn Cheol-soo (born 1962, ), founder of AhnLab Inc, an antivirus software company * Kristie Ahn (born 1992), American tennis player * Natalie Ahn (born 1957), American chemist and biochemist * Philip Ahn (1905-1978), American actor * Ralph Ahn (1926-2022), American actor * Viktor An, (born 1985 as Ahn Hyun-soo, ) South Korean short track speed skater * Luis von Ahn, (born 1978) Guatemalan creator of CAPTCHA and co-founder of Duolingo Other uses * Ahn, Luxembourg, a town * All Headline News, a US news agency * Allegheny Health Network, a non-profit hospital and healthcare group in Pennsylvania * Ashton-under-Lyne railway station, UK (National Rail code) * Athens–Ben Epps Airport Athens–Ben Epps Airpo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Launch Window
In the context of spaceflight, launch period is the collection of days and launch window is the time period on a given day during which a particular rocket must be launched in order to reach its intended target. If the rocket is not launched within a given window, it has to wait for the window on the next day of the period. Launch periods and launch windows are very dependent on both the rocket's capability and the orbit to which it is going. A launch period refers to the days that the rocket can launch to reach its intended orbit. A mission could have a period of 365 days in a year, a few weeks each month, a few weeks every 26 months (e.g. Mars launch periods), or a short period time that won't be repeated. A launch window indicates the time frame on a given day in the launch period that the rocket can launch to reach its intended orbit. This can be as short as a second (referred to as an instantaneous window) or even the entire day. For operational reasons, the window almost ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solid-fuel Rocket
A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses solid propellants ( fuel/oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder; they were used in warfare by the Arabs, Chinese, Persians, Mongols, and Indians as early as the 13th century. All rockets used some form of solid or powdered propellant up until the 20th century, when liquid-propellant rockets offered more efficient and controllable alternatives. Solid rockets are still used today in military armaments worldwide, model rockets, solid rocket boosters and on larger applications for their simplicity and reliability. Since solid-fuel rockets can remain in storage for an extended period without much propellant degradation and because they almost always launch reliably, they have been frequently used in military applications such as missiles. The lower performance of solid propellants (as compared to liquids) does not favor their use as primary propulsion in mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angara (rocket Family)
The Angara rocket family (Russian: Ангара) is a family of launch vehicles being developed by the Moscow-based Khrunichev State Research and Production Space Center. The launch vehicles are to put between and into low Earth orbit and are intended, along with Soyuz-2 variants, to replace several existing launch vehicles. History After the dissolution of the Soviet Union, many formerly Soviet launch vehicles were built in or required components from companies now located in Ukraine, such as Yuzhnoye Design Bureau, which produced Zenit-2, and Yuzhmash, which produced Dnepr and Tsyklon. Additionally, the Soviet Union's main spaceport, Baikonur Cosmodrome, was located in Kazakhstan, and Russia encountered difficulties negotiating for its use. This led to the decision in 1992 to develop a new entirely Russian launch vehicle, named Angara, to replace the launch vehicles now built outside of the country, and ensure Russian access to space without Baikonur. It was decided that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megabits Per Second
In telecommunications, data-transfer rate is the average number of bits (bitrate), characters or symbols (baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are multiples of bits per second (bit/s) and bytes per second (B/s). For example, the data rates of modern residential high-speed Internet connections are commonly expressed in megabits per second (Mbit/s). Standards for unit symbols and prefixes Unit symbol The ISQ symbols for the bit and byte are ''bit'' and ''B'', respectively. In the context of data-rate units, one byte consists of 8 bits, and is synonymous with the unit octet. The abbreviation bps is often used to mean bit/s, so that when a ''1 Mbps'' connection is advertised, it usually means that the maximum achievable bandwidth is 1 Mbit/s (one million bits per second), which is 0.125 MB/s (megabyte per second), or about 0.1192 MiB/s (mebibyte per second). The Institu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sun Sensor
A sun sensor is a navigational instrument used by spacecraft to detect the position of the sun. Sun sensors are used for attitude control, solar array pointing, gyro updating, and fail-safe recovery. In addition to spacecraft, sun sensors find use in ground-based weather stations and sun-tracking systems, and aerial vehicles including balloons and UAVs. Mechanism There are various types of sun sensors, which differ in their technology and performance characteristics. Sun presence sensors provide a binary output, indicating when the sun is within the sensor's field of view. Analog and digital sun sensors, in contrast, indicate the angle of the sun by continuous and discrete signal outputs, respectively. In typical sun sensors, a thin slit at the top of a rectangular chamber allows a line of light to fall on an array of photodetector cells at the bottom of the chamber. A voltage is induced in these cells, which is registered electronically. By orienting two sensors perpendicular to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Tracker
A star tracker is an optical device that measures the positions of stars using photocells or a camera. As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may be used to determine the orientation (or attitude) of the spacecraft with respect to the stars. In order to do this, the star tracker must obtain an image of the stars, measure their apparent position in the reference frame of the spacecraft, and identify the stars so their position can be compared with their known absolute position from a star catalog. A star tracker may include a processor to identify stars by comparing the pattern of observed stars with the known pattern of stars in the sky. History In the 1950s and early 1960s, star trackers were an important part of early long-range ballistic missiles and cruise missiles, in the era when inertial navigation systems (INS) were not sufficiently accurate for intercontinental ranges. C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulsed Plasma Thruster
A pulsed plasma thruster (PPT), also known as a plasma jet engine, is a form of electric spacecraft propulsion. PPTs are generally considered the simplest form of electric spacecraft propulsion and were the first form of electric propulsion to be flown in space, having flown on two Soviet probes ( Zond 2 and Zond 3) starting in 1964. PPTs are generally flown on spacecraft with a surplus of electricity from abundantly available solar energy. Operation Most PPTs use a solid material (normally PTFE, more commonly known as Teflon) for propellant, although very few use liquid or gaseous propellants. The first stage in PPT operation involves an arc of electricity passing through the fuel, causing ablation and sublimation of the fuel. The heat generated by this arc causes the resultant gas to turn into plasma, thereby creating a charged gas cloud. Due to the force of the ablation, the plasma is propelled at low speed between two charged plates (an anode and cathode). Since the plas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spacecraft Attitude Control
Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle/satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle attitude requires sensors to measure vehicle orientation, actuators to apply the torques needed to orient the vehicle to a desired attitude, and algorithms to command the actuators based on (1) sensor measurements of the current attitude and (2) specification of a desired attitude. The integrated field that studies the combination of sensors, actuators and algorithms is called guidance, navigation and control (GNC). Overview A spacecraft's attitude must typically be stabilized and controlled for a variety of reasons. It is often needed so that the spacecraft high-gain antenna may be accurately pointed to Earth for communications, so that onboard experiments may accomplish precise pointing for accurate collectio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
