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Reaction Wheel
A reaction wheel (RW) is used primarily by spacecraft for three-axis attitude control, and does not require rockets or external applicators of torque. They provide a high pointing accuracy, and are particularly useful when the spacecraft must be rotated by very small amounts, such as keeping a telescope pointed at a star. A reaction wheel is sometimes operated as (and referred to as) a momentum wheel, by operating it at a constant (or near-constant) rotation speed, to provide a satellite with a large amount of stored angular momentum. Doing so alters the spacecraft's rotational dynamics so that disturbance torques perpendicular to one axis of the satellite (the axis parallel to the wheel's spin axis) do not result directly in spacecraft angular motion about the same axis as the disturbance torque; instead, they result in (generally smaller) angular motion (precession) of that spacecraft axis about a perpendicular axis. This has the effect of tending to stabilize that spacecraft ax ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reaction Wheel00
Reaction may refer to a process or to a response to an action, event, or exposure: Physics and chemistry *Chemical reaction *Nuclear reaction *Reaction (physics), as defined by Newton's third law *Chain reaction (other). Biology and medicine *Adverse drug reaction *Allergic reaction *Reflex, neural reaction *Hypersensitivity, immune reaction *Intolerance (other) * Light reaction (other). Psychology *Emotional, reaction *Reactivity (behaviour) *Proactivity, opposite of reactive behaviour *Reactive attachment disorder. Politics and culture *Reactionary, a political tendency *Reaction video *Commentary (other). Proper names and titles * ''Reaction'' (album), a 1986 album by American R&B singer Rebbie Jackson ** "Reaction" (song), the title song from the Rebbie Jackson album *"Reaction", a single by Dead Letter Circus *ReAction GUI, a GUI toolkit used on AmigaOS *Reaction.life, a political news and commentary website edited by Iain Martin *Re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetorquer
A magnetorquer or magnetic torquer (also known as a torque rod) is a satellite system for attitude control, detumbling, and stabilization built from electromagnetic coils. The magnetorquer creates a magnetic dipole that interfaces with an ambient magnetic field, usually Earth's, so that the counter-forces produced provide useful torque. Functional principle Magnetorquers are essentially sets of electromagnets laid out to yield a rotationally asymmetric (anisotropic) magnetic field over an extended area. That field is controlled by switching current flow through the coils on or off, usually under computerized feedback control. The magnets themselves are mechanically anchored to the craft, so that any magnetic force they exert on the surrounding magnetic field will lead to a magnetic reverse force and result in mechanical torque about the vessel's center of gravity. This makes it possible to freely pivot the craft around in a known local gradient of the magnetic field by only using ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Weather
Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the time varying conditions within the Solar System, including the solar wind, emphasizing the space surrounding the Earth, including conditions in the magnetosphere, ionosphere, thermosphere, and exosphere. Space weather is distinct from, but conceptually related to, the terrestrial weather of the atmosphere of Earth (troposphere and stratosphere). The term "space weather" was first used in the 1950s and came into common usage in the 1990s. Later, it was generalized to a " space climate" research discipline, which focuses on general behaviors of longer and larger-scale variabilities and effects. History For many centuries, the effects of space weather were noticed, but not understood. Displays of auroral light have long been observed at high latitudes. Genesis In 1724, George Graham reported that the needle of a magnetic compass was regularly deflected from magnetic north over the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light
Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). In physics, the term "light" may refer more broadly to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. The primary properties of light are intensity, propagation direction, frequency or wavelength spectrum and polarization. Its speed in a vacuum, 299 792 458 metres a second (m/s), is one of the fundamental constants of nature. Like all types of electromagnetic radiation, visible light propagates by massless elementary particles called photons that represents the quanta of electromagnetic field, and can be analyzed as both waves and par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Momentum
In Newtonian mechanics, momentum (more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass and is its velocity (also a vector quantity), then the object's momentum is : \mathbf = m \mathbf. In the International System of Units (SI), the unit of measurement of momentum is the kilogram metre per second (kg⋅m/s), which is equivalent to the newton-second. Newton's second law of motion states that the rate of change of a body's momentum is equal to the net force acting on it. Momentum depends on the frame of reference, but in any inertial frame it is a ''conserved'' quantity, meaning that if a closed system is not affected by external forces, its total linear momentum does not change. Momentum is also conserved in special relativity (with a modified formula) and, in a modified form, in electrodynamics, quantum mechanics, quan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LightSail
LightSail is a project to demonstrate controlled solar sailing within low Earth orbit using a CubeSat. The project was developed by The Planetary Society, a global non-profit organization devoted to space exploration. It consists of two spacecraft — LightSail 1 and LightSail 2. LightSail 1 was an engineering demonstration mission designed to test its new sail deployment method in space, it did not perform solar sailing. LightSail 2 was a fully functional spacecraft intended to demonstrate true solar sailing and incorporated the lessons learned from LightSail 1. LightSail is a follow-on project to ''Cosmos 1'' — a solar-sail spacecraft designed by The Planetary Society in the early 2000s, which was destroyed during a launch failure in 2005. Both LightSail spacecraft measured (3U CubeSat) in their stowed configuration. After sail deployment, the total area of each spacecraft was . History In 2005, The Planetary Society attempted to send a solar sail satellite named ''Cosmo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Webb Space Telescope
The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Space Telescope. This will enable investigations across many fields of astronomy and cosmology, such as observation of the first stars, the formation of the first galaxies, and detailed atmospheric characterization of potentially habitable exoplanets. The U.S. National Aeronautics and Space Administration (NASA) led JWST's design and development and partnered with two main agencies: the European Space Agency (ESA) and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center (GSFC) in Maryland managed telescope development, the Space Telescope Science Institute in Baltimore on the Homewood Campus of Johns Hopkins University operates JWST, and the prime contractor was Northrop Grumman. The telescope is named after James E. Webb, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-energy Transfer
A low-energy transfer, or low-energy trajectory, is a route in space that allows spacecraft to change orbits using significantly less fuel than traditional transfers. These routes work in the Earth–Moon system and also in other systems, such as between the moons of Jupiter. The drawback of such trajectories is that they take longer to complete than higher-energy (more-fuel) transfers, such as Hohmann transfer orbits. Low-energy transfers are also known as Weak Stability Boundary trajectories, and include ballistic capture trajectories. Low-energy transfers follow special pathways in space, sometimes referred to as the Interplanetary Transport Network. Following these pathways allows for long distances to be traversed for little change in velocity, or . Example missions Missions that have used low-energy transfers include: * ''Hiten'', from JAXA * '' SMART-1'', from ESA * ''Genesis'', from NASA. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of Australia). The Moon is a planetary-mass object with a differentiated rocky body, making it a satellite planet under the geophysical definitions of the term and larger than all known dwarf planets of the Solar System. It lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's at , with Jupiter's moon Io being the only satellite in the Solar System known to have a higher surface gravity and density. The Moon orbits Earth at an average distance of , or about 30 times Earth's diameter. Its gravitational influence is the main driver of Earth's tides and very slowly lengthens Earth's day. The Moon's orbit around Earth has a sidereal period of 27.3 days. During each synodic period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Falcon 9
Falcon 9 is a partially reusable medium lift launch vehicle that can carry cargo and crew into Earth orbit, produced by American aerospace company SpaceX. The rocket has two stages. The first (booster) stage carries the second stage and payload to a certain altitude, after which the second stage lifts the payload to its ultimate destination. The rocket evolved through several versions. V1.0 flew from 2010–2013, V1.1 flew from 2013–2016, while V1.2 Full Thrust first launched in 2015, encompassing the Block 5 variant, flying since May 2018. The booster is capable of landing vertically to facilitate reuse. This feat was first achieved on flight 20 in December 2015. Since then, SpaceX has successfully landed boosters over 100 times. Individual boosters have flown as many as 15 flights. Both stages are powered by SpaceX Merlin engines, using cryogenic liquid oxygen and rocket-grade kerosene (RP-1) as propellants. The heaviest payloads flown to geostationary transfer or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beresheet
''Beresheet'' ( he, בְּרֵאשִׁית, ''Bərēšīṯ'', "In the beginning"; Book of Genesis) was a demonstrator of a small robotic lunar lander and lunar probe operated by SpaceIL and Israel Aerospace Industries. Its aims included inspiring youth and promoting careers in science, technology, engineering, and mathematics (STEM), and landing its magnetometer, time capsule, and laser retroreflector on the Moon. The lander's gyroscopes failed on 11 April 2019 causing the main engine to shut off, which resulted in the lander crashing on the Moon. Its final resting position is 32.5956°N, 19.3496°E. The lander was previously known as ''Sparrow'' and was officially renamed to ''Beresheet'' in December 2018. Its net mass was ; when fueled at launch, its mass was . It had been compared to a washing machine, as it stood at about the height of one at and was similar in width to large household appliances. It used seven ground stations for Earth–lander communication. Its missi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apollo Telescope Mount
The Apollo Telescope Mount, or ATM, was a crewed solar observatory that was a part of Skylab, the first American space station. It could observe the Sun in wavelengths ranging from soft X-rays, ultra-violet, and visible light. The ATM was manually operated by the astronauts aboard Skylab from 1973–74, yielding data principally as exposed photographic film that was returned to Earth with the crew. The film magazines had to be changed out by the crew during spacewalks, although some instruments had a live video feed that could be observed from inside the space station. Some of the first Polaroid photos (an instant film-to-hard copy camera) in space were taken of a Skylab CRT video screen displaying the Sun as recorded by an ATM instrument. Although the ATM was integrated with the Skylab station, it started as a separate project related to use of the Apollo spacecraft, which is why it has the name Apollo in it rather than Skylab; the Skylab station was visited by astronauts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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