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Random Positioning Machine
A random positioning machine, or RPM, rotates biological samples along two independent axes to change their orientation in space in complex ways and so eliminate the effect of gravity.Jack J.W.A. van Loon (2007). Some history and use of the random positioning machine, RPM, in gravity related research. Advances in Space Research 39: 1161-1165 RPMs are often used as an alternative to sub-orbital flights or drop towers in research studying the effects of weightlessness or microgravity on biological systems. Description The RPM is a more sophisticated development of the single-axis clinostat. RPMs usually consist of two independently rotating frames. One frame is positioned inside the other giving a very complex net change of orientation to a biological sample mounted in the middle. The RPM is sometimes wrongly referred to as the "3-D clinostat" (which rotates both axis in the same direction, i.e. both clockwise). It is a microweight ('micro-gravity') simulator that is based on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Clinostat
A clinostat is a device which uses rotation to negate the effects of gravitational pull on plant growth (gravitropism) and development (gravimorphism). It has also been used to study the effects of microgravity on cell cultures, animal embryos and spider webs. Description A single-axis (or horizontal) clinostat consists of a disc attached to a motor. They were originally clockwork but nowadays an electric motor is used. The disc is held vertically and the motor rotates it slowly at rates in the order of one revolution per minute. A plant is attached to the disc so that it is held horizontally. The slow rotation means that the plant experiences a gravitational pull that is averaged over 360 degrees, thus approximating a weightlessness, weightless environment. Clinostats have also been used to cancel out effects of sunlight and other stimuli besides gravity. This type of clinostat must be exactly horizontal to simulate absence of gravity. If the clinostat is at an angle from horizont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Free Fall Machine
The free fall machine (FFM) is designed to permit the development of small biological sample such as cell cultures with a simulated effect of micro-gravity, under free fall conditions.Schwarzenberg M, Pippia P, Meloni MA, Cossu G, Cogoli-Greuter M, Cogoli A. (1999). Signal transduction in T lymphocytes--a comparison of the data from space, the free fall machine and the random positioning machine. Adv Space Res. 24(6): 793-800 Description The free fall machine (FFM) addresses some of the problems of the simple horizontal clinostat or random positioning machines (RPM). In a typical machine samples are allowed to cycle between free fall for about a metre down a column (micro-gravity simulation, near "0 g") and a "bounce" back to the top of the column that is intended to be so fast (c. 20 g for 20 ms) that it is undetected by the biological sample. Long duration of hyper-gravity is often simulated by machines such as the large diameter centrifuge (LDC) at ESA. To simulate partial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Gravity
In physics, gravity (), also known as gravitation or a gravitational interaction, is a fundamental interaction, a mutual attraction between all massive particles. On Earth, gravity takes a slightly different meaning: the observed force between objects and the Earth. This force is dominated by the combined gravitational interactions of particles but also includes effect of the Earth's rotation. Gravity gives weight to physical objects and is essential to understanding the mechanisms responsible for surface water waves and lunar tides. Gravity also has many important biological functions, helping to guide the growth of plants through the process of gravitropism and influencing the circulation of fluids in multicellular organisms. The gravitational attraction between primordial hydrogen and clumps of dark matter in the early universe caused the hydrogen gas to coalesce, eventually condensing and fusing to form stars. At larger scales this results in galaxies and clust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Sub-orbital Spaceflight
A sub-orbital spaceflight is a spaceflight in which the spacecraft reaches outer space, but its trajectory intersects the surface of the primary (astronomy), gravitating body from which it was launched. Hence, it will not complete one orbital revolution, will not become an artificial satellite nor will it reach escape velocity. For example, the path of an object launched from Earth that reaches the Kármán line (about – above sea level), and then falls back to Earth, is considered a sub-orbital spaceflight. Some sub-orbital flights have been undertaken to test spacecraft and launch vehicles later intended for orbital spaceflight. Other vehicles are specifically designed only for sub-orbital flight; examples include crewed vehicles, such as the North American X-15, X-15 and SpaceShipTwo, and uncrewed ones, such as intercontinental ballistic missile, ICBMs and sounding rockets. Flights which attain sufficient velocity to go into low Earth orbit, and then de-orbit before com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Drop Tube
In physics and materials science, a drop tower or drop tube is a structure used to produce a controlled period of weightlessness for an object under study. Air bags, polystyrene pellets, and magnetic or mechanical brakes are sometimes used to arrest the fall of the experimental payload. In other cases, high-speed impact with a substrate at the bottom of the tower is an intentional part of the experimental protocol. Not all such facilities are towers: NASA Glenn's Zero Gravity Research Facility is based on a vertical shaft, extending to below ground level. Typical operation For a typical materials science experiment, a sample of the material under study is loaded into the top of the drop tube, which is filled with inert gas or evacuated to create a low-pressure environment. Following any desired preprocessing (e.g. induction heating to melt a metal alloy), the sample is released to fall to the bottom of the tube. During its flight or upon impact the sample can be charact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Weightlessness
Weightlessness is the complete or near-complete absence of the sensation of weight, i.e., zero apparent weight. It is also termed zero g-force, or zero-g (named after the g-force) or, incorrectly, zero gravity. Weight is a measurement of the force on an object at rest in a relatively strong gravitational field (such as on the surface of the Earth). These weight-sensations originate from contact with supporting floors, seats, beds, scales, and the like. A sensation of weight is also produced, even when the gravitational field is zero, when contact forces act upon and overcome a body's inertia by mechanical, non- gravitational forces- such as in a centrifuge, a rotating space station, or within an accelerating vehicle. When the gravitational field is non-uniform, a body in free fall experiences tidal forces and is not stress-free. Near a black hole, such tidal effects can be very strong, leading to ''spaghettification''. In the case of the Earth, the effects are minor, especiall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Hypergravity
Hypergravity is defined as the condition where the force of gravity (real or perceived) exceeds that on the surface of the Earth. This is expressed as being greater than 1 '' g''. Hypergravity conditions are created on Earth for research on human physiology in aerial combat and space flight, as well as testing of materials and equipment for space missions. Manufacturing of titanium aluminide turbine blades in 20 ''g'' is being explored by researchers at the European Space Agency (ESA) via an 8-meter wide Large Diameter Centrifuge (LDC). Bacteria NASA scientists looking at meteorite impacts discovered that most strains of bacteria were able to reproduce under acceleration exceeding 7,500 ''g''. Recent research carried out on extremophiles in Japan involved a variety of bacteria including ''Escherichia coli'' and ''Paracoccus denitrificans'' being subject to conditions of extreme gravity. The bacteria were cultivated while being rotated in an ultracentrifuge at hig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Large Diameter Centrifuge
The large diameter centrifuge, or LDC, is any centrifuge extending several meters, which can rotate samples to change their acceleration in space to enhance the effect of gravity. Large diameter centrifuges are used to understand the effect of hyper-gravity (gravitational strengths stronger than that of the Earth) on biological samples, including and not limiting to plants, organs, bacteria, and astronauts (Such as NASA's Human Performance Centrifuge) or non-biological samples to undertake experiments in the field of fluid dynamics, geology, biochemistry and more. Description Frequently, "LDC" is used to refer to the centrifuge at the European Space Agency (ESA)'s campus known as ESTEC (European Space research and TEChnology center). This is an 8-m diameter, four-arm centrifuge covered by a dome, which is available for research. A total of six gondolas, each being able to carry an 80 kg payload, can spin at a maximum of 20 times Earth's gravity, equaling 67 revolutions p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Gravitropism
Gravitropism (also known as geotropism) is a coordinated process of differential growth by a plant in response to gravity pulling on it. It also occurs in fungi. Gravity can be either "artificial gravity" or natural gravity. It is a general feature of all higher and many lower plants as well as other organisms. Charles Darwin was one of the first to scientifically document that roots show ''positive gravitropism'' and stems show ''negative gravitropism''. That is, roots grow in the direction of gravitational pull (i.e., downward) and stems grow in the opposite direction (i.e., upwards). This behavior can be easily demonstrated with any potted plant. When laid onto its side, the growing parts of the stem begin to display negative gravitropism, growing (biologists say, turning; see tropism) upwards. Herbaceous (non-woody) stems are capable of a degree of actual bending, but most of the redirected movement occurs as a consequence of root or stem growth outside. The mechanism is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Weightlessness
Weightlessness is the complete or near-complete absence of the sensation of weight, i.e., zero apparent weight. It is also termed zero g-force, or zero-g (named after the g-force) or, incorrectly, zero gravity. Weight is a measurement of the force on an object at rest in a relatively strong gravitational field (such as on the surface of the Earth). These weight-sensations originate from contact with supporting floors, seats, beds, scales, and the like. A sensation of weight is also produced, even when the gravitational field is zero, when contact forces act upon and overcome a body's inertia by mechanical, non- gravitational forces- such as in a centrifuge, a rotating space station, or within an accelerating vehicle. When the gravitational field is non-uniform, a body in free fall experiences tidal forces and is not stress-free. Near a black hole, such tidal effects can be very strong, leading to ''spaghettification''. In the case of the Earth, the effects are minor, especiall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Laboratory Equipment
A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratories are found in a variety of settings such as schools, universities, privately owned research institutions, corporate research and testing facilities, government regulatory and forensic investigation centers, physicians' offices, clinics, hospitals, regional and national referral centers, and even occasionally personal residences. Overview The organisation and contents of laboratories are determined by the differing requirements of the specialists working within. A physics laboratory might contain a particle accelerator or vacuum chamber, while a metallurgy laboratory could have apparatus for casting or refining metals or for testing their strength. A chemist or biologist might use a wet laboratory, while a psychologist's laboratory might be a room with one-way mirrors and hidden cameras in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |