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ATS-2
ATS-2 (Applications Technology Satellite) was a communications satellite launched by NASA on April 6, 1967, on an Atlas-Agena D rocket from Cape Canaveral. Objectives The ATS-2 had the following objectives: test new concepts in spacecraft design, propulsion and stabilization; capture high quality images of cloud cover; collect data measurements in an aerospace environment; and test improved communication systems. Features The satellite had a cylindrical shape with a diameter and a height of . After including the motor cover, the satellite was about tall. The surface of the satellite was covered by solar panels, and it utilized gravity-gradient stabilization for control. Experiments The following 12 experiments were conducted: * Radio astronomy * Magnetospheric electric fields * Electron magnetic spectrometer deflection * Particle telescope * Omnidirectional proton and electron detectors * Very low frequency (VLF) receiver * Earth's albedo ( DoD) * Microwave comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravity-gradient Stabilization
Gravity-gradient stabilization (a.k.a. "tidal stabilization") is a method of stabilizing artificial satellites or space tethers in a fixed orientation using only the orbited body's mass distribution and gravitational field. The main advantage over using active stabilization with propellants, gyroscopes or reaction wheels is the low use of power and resources. It can also reduce or prevent the risk of propellant contamination of sensitive components. The idea is to use the Earth's gravitational field and tidal forces to keep the spacecraft aligned in the desired orientation. The gravity of the Earth decreases according to the inverse-square law, and by extending the long axis perpendicular to the orbit, the "lower" part of the orbiting structure will be more attracted to the Earth. The effect is that the satellite will tend to align its axis of minimum moment of inertia vertically. The first experimental attempt to use the technique on a human spaceflight was performed on Sep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sierra (supercomputer)
Sierra or ATS-2 is a supercomputer built for the Lawrence Livermore National Laboratory for use by the National Nuclear Security Administration as the second Advanced Technology System. It is primarily used for predictive applications in stockpile stewardship, helping to assure the safety, reliability and effectiveness of the United States' nuclear weapons. Sierra is very similar in architecture to the Summit supercomputer built for the Oak Ridge National Laboratory. The Sierra system uses IBM POWER9 CPUs in conjunction with Nvidia Tesla V100 GPUs. The nodes in Sierra are Witherspoon IBM S922LC OpenPOWER servers with two GPUs per CPU and four GPUs per node. These nodes are connected with EDR InfiniBand. In 2019 Sierra was upgraded with IBM Power System AC922 nodes.Sierrahas consistently appeared on the Top500 list, peaking a#2 in November 2018 See also * Trinity (supercomputer) – ATS-1, the first Advanced Technology System * OpenBMC The OpenBMC project is a Linux ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Applications Technology Satellite
The Applications Technology Satellites (ATS) were a series of experimental satellites launched by NASA, under the supervision of, among others, Wernher von Braun. The program was launched in 1966 to test the feasibility of placing a satellite into geosynchronous orbit. The satellites were primarily designed to act as communication satellites, but also carried equipment related to meteorology and navigation. ATS-6 was the world's first educational satellite as well as world's first experimental Direct Broadcast Satellite (DBS) as part of the Satellite Instructional Television Experiment (SITE) between NASA and ISRO. Summary of Missions See also * Geostationary Operational Environmental Satellite * Synchronous Meteorological Satellite References External links ATSat NASA's Mission and Spacecraft Library Mission and Spacecraft Library (MSL) is a reference web site, maintained by NASA, containing information about satellites. It contains a catalog of several hundreds of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Panel
A solar cell panel, solar electric panel, photo-voltaic (PV) module, PV panel or solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame, and a neatly organised collection of PV panels is called a photovoltaic system or solar array. Solar panels capture sunlight as a source of radiant energy, which is converted into electric energy in the form of direct current (DC) electricity. Arrays of a photovoltaic system can be used to generate solar electricity that supplies electrical equipment directly, or grid-connected photovoltaic system, feeds power back into an alternate current (AC) electric grid, grid via an solar inverter, inverter system. History In 1839, the ability of some materials to create an electrical charge from light exposure was first observed by the French physicist Edmond Becquerel. Though these initial solar panels were too inefficient for even simple electric devices, they were used as an instrument to measure light. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1967 In Spaceflight
The year 1967 in spaceflight saw the most orbital launches of the 20th century and more than any other year until 2021, including that of the first Australian satellite, WRESAT, which was launched from the Woomera Test Range atop an American Sparta rocket. The United States National Space Science Data Center catalogued 172 spacecraft placed into orbit by launches which occurred in 1967. The year saw both setbacks and advances for the United States Apollo programme. Three astronauts; Virgil "Gus" Grissom, Ed White and Roger B. Chaffee, were killed in a fire aboard the AS-204 spacecraft at Cape Kennedy Launch Complex 34 on 27 January whilst rehearsing the launch. On 20 October the Saturn V rocket made its maiden flight The maiden flight, also known as first flight, of an aircraft is the first occasion on which it leaves the ground under its own power. The same term is also used for the first launch of rockets. The maiden flight of a new aircraft type is alw .... ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmosphere
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosphere is the outer region of a star, which includes the layers above the opaque photosphere; stars of low temperature might have outer atmospheres containing compound molecules. The atmosphere of Earth is composed of nitrogen (78%), oxygen (21%), argon (0.9%), carbon dioxide (0.04%) and trace gases. Most organisms use oxygen for respiration; lightning and bacteria perform nitrogen fixation to produce ammonia that is used to make nucleotides and amino acids; plants, algae, and cyanobacteria use carbon dioxide for photosynthesis. The layered composition of the atmosphere minimises the harmful effects of sunlight, ultraviolet radiation, the solar wind, and cosmic rays to protect organisms from genetic damage. The current comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microwave Transmission
Microwave transmission is the transmission of information by electromagnetic waves with wavelengths in the microwave frequency range of 300MHz to 300GHz(1 m - 1 mm wavelength) of the electromagnetic spectrum. Microwave signals are normally limited to the line of sight, so long-distance transmission using these signals requires a series of repeaters forming a microwave relay network. It is possible to use microwave signals in over-the-horizon communications using tropospheric scatter, but such systems are expensive and generally used only in specialist roles. Although an experimental microwave telecommunication link across the English Channel was demonstrated in 1931, the development of radar in World War II provided the technology for practical exploitation of microwave communication. During the war, the British Army introduced the Wireless Set No. 10, which used microwave relays to multiplex eight telephone channels over long distances. A link across the English Channel allowe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albedo
Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that reflects all incident radiation. Surface albedo is defined as the ratio of Radiosity (radiometry), radiosity ''J''e to the irradiance ''E''e (flux per unit area) received by a surface. The proportion reflected is not only determined by properties of the surface itself, but also by the spectral and angular distribution of solar radiation reaching the Earth's surface. These factors vary with atmospheric composition, geographic location, and time (see position of the Sun). While bi-hemispherical reflectance is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period. The temporal resolution may range from seconds (as ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Very Low Frequency
Very low frequency or VLF is the ITU designation for radio frequencies (RF) in the range of 3–30 kHz, corresponding to wavelengths from 100 to 10 km, respectively. The band is also known as the myriameter band or myriameter wave as the wavelengths range from one to ten myriameters (an obsolete metric unit equal to 10 kilometers). Due to its limited bandwidth, audio (voice) transmission is highly impractical in this band, and therefore only low data rate coded signals are used. The VLF band is used for a few radio navigation services, government time radio stations (broadcasting time signals to set radio clocks) and for secure military communication. Since VLF waves can penetrate at least 40 meters (131 ft) into saltwater, they are used for military communication with submarines. Propagation characteristics Because of their long wavelengths, VLF radio waves can diffract around large obstacles and so are not blocked by mountain ranges, and can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetospheric Electric Convection Field
The impact of the solar wind onto the magnetosphere generates an electric field within the inner magnetosphere (r θm) and within the inner magnetosphere (r ≤ 10 a) is the Volland-Stern model (see Fig. 1 a)). The use of an electrostatic field means that this model is valid only for slow temporal variations (of the order of one day or larger). The assumption of a coaxial magnetic dipole field implies that only global scale structures can be simulated. The electric field components are derived from as \begin & E_r = - \frac\Phi_\mathrm \\ & E_\theta = \frac \cot\theta~\Phi_c \\ & E_\lambda = - \frac \cot(\lambda - \lambda_\mathrm) \Phi_\mathrm \end In the presence of the geomagnetic field an electric field is generated in a rotating on frame of reference in order to compensate for the Lorentz force. This is the so-called electric co-rotation field measured by an observer rotating with the Earth. With the simplifying conditions given above its potential is with Φro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation coming from the Milky Way. Subsequent observations have identified a number of different sources of radio emission. These include stars and galaxies, as well as entirely new classes of objects, such as radio galaxies, quasars, pulsars, and masers. The discovery of the cosmic microwave background radiation, regarded as evidence for the Big Bang theory, was made through radio astronomy. Radio astronomy is conducted using large radio antennas referred to as radio telescopes, that are either used singularly, or with multiple linked telescopes utilizing the techniques of radio interferometry and aperture synthesis. The use of interferometry allows radio astronomy to achieve high angular resolution, as the resolving power of an interferometer is set ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rocket
A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely from propellant carried within the vehicle; therefore a rocket can fly in the vacuum of space. Rockets work more efficiently in a vacuum and incur a loss of thrust due to the opposing pressure of the atmosphere. Multistage rockets are capable of attaining escape velocity from Earth and therefore can achieve unlimited maximum altitude. Compared with airbreathing engines, rockets are lightweight and powerful and capable of generating large accelerations. To control their flight, rockets rely on momentum, airfoils, auxiliary reaction engines, gimballed thrust, momentum wheels, deflection of the exhaust stream, propellant flow, spin, or gravity. Rockets for military and recreational uses date back to at least 13th-century China. Signific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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