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Pyrotechnic Valves
A pyrotechnic valve, also explosive actuated valve, short pyro valve or pyrovalve is a one time use propulsion component often used to control propellant or pressurant systems aboard spacecraft or space probes. The device is activated by an electric signal, upon which one or several small explosive charges are ignited. These in turn produce high-pressure gas which either push a small, perforated piston which initially blocked the flow path of the working fluid forward until the hole aligns with the tubing, allowing the working fluid to flow, or force a sharpened piston through a weakened part of the attached tube to block the flow path of the working fluid. These two versions of pyrotechnic valves are referred to as normally-closed (NC) or normally-open (NO) valves respectively, depending on their initial state before initiation of the pyrotechnic charge. Modern pyrotechnic valves feature two redundant explosive charges in order to maximize reliability of the valve. There are s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single Use
A disposable (also called disposable product) is a product designed for a single use after which it is recycled or is disposed as solid waste. The term is also sometimes used for products that may last several months (e.g. disposable air filters) to distinguish from similar products that last indefinitely (e.g. washable air filters). The word "disposables" is not to be confused with the word "consumables", which is widely used in the mechanical world. For example, welders consider welding rods, tips, nozzles, gas, etc. to be "consumables", as they last only a certain amount of time before needing to be replaced. Consumables are needed for a process to take place, such as inks for printing and welding rods for welding, while disposable products are products that can be thrown away after it becomes damaged or otherwise unuseful. Etymology "Disposable" is an ''adjective'' meaning something not reusable but is disposed of after use. Many people now use the term as a noun or substant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milliseconds
A millisecond (from ''milli-'' and second; symbol: ms) is a unit of time in the International System of Units (SI) equal to one thousandth (0.001 or 10−3 or 1/1000) of a second and to 1000 microseconds. A unit of 10 milliseconds may be called a centisecond, and one of 100 milliseconds a decisecond, but these names are rarely used. To help compare orders of magnitude of different times, this page lists times between 10−3 seconds and 100 seconds (1 millisecond and one second). ''See also'' times of other orders of magnitude. Examples The Apollo Guidance Computer used metric units internally, with centiseconds used for time calculation and measurement. *1 millisecond (1 ms) – cycle time for frequency 1 kHz; duration of light for typical photo flash strobe; time taken for sound wave to travel about 34 cm; repetition interval of GPS C/A PN code *1 millisecond - time taken for light to travel 204.19 km in a single mode fiber optic cable for a wavelength of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrotechnics
Pyrotechnics is the science and craft of creating such things as fireworks, safety matches, oxygen candles, explosive bolts and other fasteners, parts of automotive airbags, as well as gas-pressure blasting in mining, quarrying, and demolition. This trade relies upon self-contained and self-sustained exothermic chemical reactions to make heat, light, gas, smoke and/or sound. The name comes from the Greek words ''pyr'' ("fire") and ''tekhnikos'' ("made by art"). People responsible for the safe storage, handling, and functioning of pyrotechnic devices are known as pyrotechnicians. Proximate pyrotechnics Explosions, flashes, smoke, flames, fireworks and other pyrotechnic-driven effects used in the entertainment industry are referred to as proximate pyrotechnics. Proximate refers to the pyrotechnic device's location relative to an audience. In the majority of jurisdictions, special training and licensing must be obtained from local authorities to legally prepare and use proximate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mars Rover
A Mars rover is a motor vehicle designed to travel on the surface of Mars. Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place themselves in sunny positions to weather winter months, and they can advance the knowledge of how to perform very remote robotic vehicle control. They serve a different purpose than orbital spacecraft like ''Mars Reconnaissance Orbiter''. A more recent development is the Mars helicopter. , there have been six successful robotically operated Mars rovers; the first five, managed by the American NASA Jet Propulsion Laboratory, were (by date of Mars landing): ''Sojourner'' (1997), ''Spirit'' (2004–2010), ''Opportunity'' (2004–2018), ''Curiosity'' (2012–), and ''Perseverance'' (2021–). The sixth, managed by the China National Space Administration, is ''Zhurong'' (2021–). On January 24, 2016, NASA reported that then current studies on Mars by ''Opportunit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perseverance (rover)
''Perseverance'', nicknamed ''Percy'', is a car-sized Mars rover designed to explore the Jezero crater on Mars as part of NASA's Mars 2020 mission. It was manufactured by the Jet Propulsion Laboratory and launched on July 30, 2020, at 11:50 UTC. Confirmation that the rover successfully landed on Mars was received on February 18, 2021, at 20:55 UTC. As of , ''Perseverance'' has been active on Mars for sols ( Earth days, or ) since its landing. Following the rover's arrival, NASA named the landing site Octavia E. Butler Landing. ''Perseverance'' has a similar design to its predecessor rover, ''Curiosity'', although it was moderately upgraded. It carries seven primary payload instruments, nineteen cameras, and two microphones. The rover also carried the mini-helicopter '' Ingenuity'' to Mars, an experimental aircraft and technology testbed that made the first powered flight on another planet on April 19, 2021. As of December 22, 2022, it has made 37 successful flights. '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decade
A decade () is a period of ten years. Decades may describe any ten-year period, such as those of a person's life, or refer to specific groupings of calendar years. Usage Any period of ten years is a "decade". For example, the statement that "during his last decade, Mozart explored chromatic harmony to a degree rare at the time" merely refers to the last ten years of Wolfgang Amadeus Mozart's life without regard to which calendar years are encompassed. Also, 'the first decade' of a person's life begins on the day of their birth and ends at the end of their 10th year of life when they have their 10th birthday; the second decade of life starts with their 11th year of life (during which one is typically still referred to as being "10") and ends at the end of their 20th year of life, on their 20th birthday; similarly, the third decade of life, when one is in one's twenties or 20s, starts with the 21st year of life, and so on, with subsequent decades of life similarly described by ref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Years
A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars. For the Gregorian calendar, the average length of the calendar year (the mean yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space
Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework. Debates concerning the nature, essence and the mode of existence of space date back to antiquity; namely, to treatises like the ''Timaeus'' of Plato, or Socrates in his reflections on what the Greeks called ''khôra'' (i.e. "space"), or in the ''Physics'' of Aristotle (Book IV, Delta) in the definition of ''topos'' (i.e. place), or in the later "geometrical conception of place" as "spac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evaporation
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidity affects rate of evaporation of water. When the molecules of the liquid collide, they transfer energy to each other based on how they collide. When a molecule near the surface absorbs enough energy to overcome the vapor pressure, it will escape and enter the surrounding air as a gas. When evaporation occurs, the energy removed from the vaporized liquid will reduce the temperature of the liquid, resulting in evaporative cooling. On average, only a fraction of the molecules in a liquid have enough heat energy to escape from the liquid. The evaporation will continue until an equilibrium is reached when the evaporation of the liquid is equal to its condensation. In an enclosed environment, a liquid will evaporate until the surrounding air is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valve Leakage
Valve leakage refers to flow through a valve which is set in the 'off' state. The importance of valve leakage depends on what the valve is controlling. For example, a dripping tap is less significant than a leak from a six-inch pipe carrying high-pressure radioactive steam. In the United States, the American National Standards Institute specifies six different leakage classes, with "leakage" defined in terms of the full open valve capacity: * Class I, or 'dust-tight' valves, are intended to work but have not been tested * Class II valves have no more than 0.5% leakage with (or less if operating pressure is less) of air pressure at the operating temperature * Class III valves have no more than 0.1% leakage under those conditions; this may require soft valve seats, or lapped metal surfaces * Class IV valves have no more than 0.01% leakage under those conditions; this tends to require multiple graphite piston rings or a single Teflon Polytetrafluoroethylene (PTFE) is a synthet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Response Time (technology)
In technology, response time is the time a system or functional unit takes to react to a given input. Computing Response time is the total amount of time it takes to respond to a request for service. That service can be anything from a memory fetch, to a disk IO, to a complex database query, or loading a full web page. Ignoring transmission time for a moment, the response time is the sum of the service time and wait time. The service time is the time it takes to do the work you requested. For a given request the service time varies little as the workload increases – to do X amount of work it always takes X amount of time. The wait time is how long the request had to wait in a queue before being serviced and it varies from zero, when no waiting is required, to a large multiple of the service time, as many requests are already in the queue and have to be serviced first. With basic queueing theory math you can calculate how the average wait time increases as the device providing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spacecraft Propulsion
Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric entry. Several methods of pragmatic spacecraft propulsion have been developed each having its own drawbacks and advantages. Most satellites have simple reliable chemical thrusters (often monopropellant rockets) or resistojet rockets for orbital station-keeping and some use momentum wheels for attitude control. Soviet bloc satellites have used electric propulsion for decades, and newer Western geo-orbiting spacecraft are starting to use them for north–south station-keeping and orbit raising. Interplanetary vehicles mostly use chemical rockets as well, although a few have used ion thrusters and Hall-effect thrusters (two different types of electric propulsion) to great success. Hypothetical in-space propulsion technologies describe the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
