atmospheric drag

Falling is movement due to gravity. By analogy, falling has other uses not directly related to gravity. Falling - Sensation. A sensation of falling occurs when the labyrinth or vestibular apparatus, a system of fluid-filled passages in the inner ear, detects motion. The same system also detects rotary motion. A similar sensation of falling can be induced when the eyes detect rapid apparent motion with respect to the environment. This system enables us to keep our balance by signalling w ...

Including:

• Falling - Sensation
• Falling - Accidents
• Falling - Classical physics
• Falling - Mathematics
• Falling - EXTERNAL LINKS

Read more here: » Falling: Encyclopedia - Falling

Weightlessness is the experience (by people and objects) during freefall, of having no apparent weight. This condition is also known as microgravity (see below). Weightlessness in common spacecraft is not due to an increased distance to the earth; the acceleration due to gravity at an altitude of 100 km is only 3% less than at the surface of the earth. Weightlessness means a zero g-force or zero apparent weight; acceleration is only due to gravity, as opposed to the cases where other forces are acting, including: s ...

Including:

• Weightlessness - Overview
• Weightlessness - Microgravity
• Weightlessness - NASA's KC-135 Reduced Gravity Aircraft
• Weightlessness - Zero Gravity Corporation
• Weightlessness - NASA's Zero-G Research Facility
• Weightlessness - Weightlessness in a spaceship
• Weightlessness - Weightlessness in the centre of a planet
• Weightlessness - Health effects

Read more here: » Weightlessness: Encyclopedia - Weightlessness

For an elliptical orbit specific orbital energy equation simplifies to: where: is the standard gravitational parameter is semi-major axis of the orbiting body For a parabolic orbit this equation simplifies to: For a hyperbolic trajectory this specific orbital energy equation takes form: In this case the specific orbital energy is also referred to as characteristic energy (or ) and is equal to the ...

See also:

Specific orbital energy, Specific orbital energy - Equation forms for different orbits, Specific orbital energy - Rate of change, Specific orbital energy - Additional energy, Specific orbital energy - Examples, Specific orbital energy - Applying thrust

Read more here: » Specific orbital energy: Encyclopedia II - Specific orbital energy - Equation forms for different orbits

To perform an orbital spaceflight, a spacecraft must go higher and faster than for a sub-orbital spaceflight. A spacecraft has not made orbit until it is circling the Earth at a sufficiently great speed such that the weight of the spacecraft is exactly equal to the centripetal acceleration required to keep it in a circular orbit (see circular motion). It must not only rise above the atmosphere, but must also achieve a sufficient orbital speed (angular velocity). For a low Earth orbit, this is about 7.9 km/s (18,000 mph). Robert God ...

See also:

Outer space, Outer space - Milestones on the way to space, Outer space - Regions of outer space, Outer space - Space does not equal orbit

Read more here: » Outer space: Encyclopedia II - Outer space - Space does not equal orbit

Shenzhou 6 - Launch. The astronauts arrived at the spacecraft about 2 hours and 45 minutes before the launch and the hatch closed 30 minutes after their arrival. At 01:00:03.583 UTC on October 12 Shenzhou 6 lifted off from the launch pad at Jiuquan Satellite Launch Center. The launch phase was reported to be normal with the escape rocket separating 120 seconds after launch when the rocket was travelling 1,300 m/s (4300 ft/s). Sixteen seconds later the four booster rockets separating at an altitude of 52 km ...

See also:

Shenzhou 6, Shenzhou 6 - Crew, Shenzhou 6 - Backup crew, Shenzhou 6 - Mission highlights, Shenzhou 6 - Launch, Shenzhou 6 - Five days in orbit, Shenzhou 6 - Re-entry and landing, Shenzhou 6 - Upgrades, Shenzhou 6 - Experiments, Shenzhou 6 - Tracking, Shenzhou 6 - International reaction, Shenzhou 6 - Parties within Greater China area, Shenzhou 6 - Foreign countries and international organizations

Read more here: » Shenzhou 6: Encyclopedia II - Shenzhou 6 - Mission highlights

The earliest rockets were created hundreds of years ago by the Chinese, and were used primarily for fireworks displays and as weapons. They were fueled with black powder, a type of gunpowder consisting of a mixture of charcoal, sulfur and potassium nitrate (saltpeter). Rocket propellant technology did not advance until the end of the 19th century, by which time smokeless powder had been developed, ori ...

See also:

Rocket fuel, Rocket fuel - Overview, Rocket fuel - Solid propellants, Rocket fuel - Liquid propellants, Rocket fuel - Hybrid propellants, Rocket fuel - Mixture ratio, Rocket fuel - Propellent density

Read more here: » Rocket fuel: Encyclopedia II - Rocket fuel - Solid propellants

What humans experience as weight is not actually the force due to gravity (even though that is the technical definition of weight). What we feel as weight is actually the normal reaction force of the ground (or whatever surface we are in contact with) pushing upwards against us to counteract the force due to gravity, that is the apparent weight. For example, a wood block in a container in free-fall experiences weightlessness. This is because there is no reaction to the wood block's weight from the container, as it is being pulled down ...

See also:

Weightlessness, Weightlessness - Overview, Weightlessness - Microgravity, Weightlessness - NASA's KC-135 Reduced Gravity Aircraft, Weightlessness - Zero Gravity Corporation, Weightlessness - NASA's Zero-G Research Facility, Weightlessness - Weightlessness in a spaceship, Weightlessness - Weightlessness in the centre of a planet, Weightlessness - Health effects

Read more here: » Weightlessness: Encyclopedia II - Weightlessness - Overview

The name "International Space Station" (abbreviated MKS in Russian) represents a neutral compromise ending a disagreement about a proper name for the station. The initially proposed name "Space Station Alpha" was rejected by Russia, since it would have implied that the station was something fundamentally new, whereas the Soviet Union already had operated eight orbital stations long before the ISS launch (see Space station). The Russian proposal to name the space station "Atlant" was in turn rejected by the US, which was worried about that na ...

See also:

International Space Station, International Space Station - Name, International Space Station - Radio call sign, International Space Station - History, International Space Station - Building the ISS, International Space Station - Criticism of the ISS, International Space Station - Space Tourism weddings and the ISS, International Space Station - Present status of the ISS, International Space Station - ISS Expeditions, International Space Station - ISS-related articles, International Space Station - Other

Read more here: » International Space Station: Encyclopedia II - International Space Station - Name

Due to luni-solar perturbations and the ellipticity of the Earth equator, an object placed in a GEO without any stationkeeping would not stay there. It would start building up inclination at an initial rate of about 0.85 degrees per year. After 26.5 years the object would have an inclination of 15 degrees, decreasing back to zero after another 26.5 years. Therefore, a lot of energy has to be devoted to maneuvers that compensate this tendency. This part of the GEO stationkeeping is called North-South control. The ellipticity of the Earth equa ...

See also:

Orbital stationkeeping, Orbital stationkeeping - Stationkeeping in LEO, Orbital stationkeeping - Stationkeeping in GEO

Read more here: » Orbital stationkeeping: Encyclopedia II - Orbital stationkeeping - Stationkeeping in GEO

At least three airmen have survived free falls of around 20,000 ft (6,000 m) without a parachute in the Second World War; Lt. I.M. Chisov was a Russian bomber, Sgt. Alan Magee an American gunner on a B-17, and Sgt. Nicholas Alkemade a British gunner on a Lancaster bomber. It is estimated that a person free falling horizontally, reaches a terminal velocity of around 120 mph (200 km/h) after a fall of just 2,000 ft (600 m), so the additional 18,000 ft (5,500 m) doesn't make these falls that much more dangerous, apart from the lack of oxygen at ...

See also:

Free-fall, Free-fall - People surviving free fall, Free-fall - Record free fall

Read more here: » Free-fall: Encyclopedia II - Free-fall - People surviving free fall

It is important to note that acceleration is a vector quantity, and the direction of the acceleration has a large impact on the overall efficiency. For instance, gravity drag would reduce a 2.6 G thrust directed upward to an acceleration of 1.6 G, for an efficiency of less than 62%. However, the same 2.6 G thrust could be directed at such an angle that it had a 1 G upward component, completely cancelled by gravity drag, and a horizontal component of 2.4 G, unaffected by gravity drag. Achieving 2.4 G accelerat ...

See also:

Gravity drag, Gravity drag - Vector considerations

Read more here: » Gravity drag: Encyclopedia II - Gravity drag - Vector considerations

That said, typical sub-orbital craft need go only just past the accepted edge of space at 100 km (62.5 miles) for the flight to be a spaceflight. At this arbitrary boundary there is still too much atmosphere present for a long term stable low Earth orbit (LEO). In order to be stable for more than just a few weeks or months the satellite or spacecraft is placed in orbit at an altitude where drag from the atmosphere truly is negligible. A stable LEO is usually at least 350 km up. But again, the difference in height should not be overemphasized: Whether the altitude is ...

See also:

Difference between sub-orbital and orbital spaceflights, Difference between sub-orbital and orbital spaceflights - Angular velocity, Difference between sub-orbital and orbital spaceflights - Difference in the real world, Difference between sub-orbital and orbital spaceflights - Atmospheric reentry a much bigger challenge with orbital flights, Difference between sub-orbital and orbital spaceflights - Energy calculations, Difference between sub-orbital and orbital spaceflights - Summary

Read more here: » Difference between sub-orbital and orbital spaceflights: Encyclopedia II - Difference between sub-orbital and orbital spaceflights - Difference in the real world

Falling is descent under gravity. All objects have mass and in the presence of sufficiently massive objects such as planets or moons they experience a strong attraction due to gravity. This is known as weight. If the force of gravity is not equalized by an opposite force directed away from the planet, the object will start to fall towards the center of mass of the system--in effect, towards the center of the planet. The acceleration of gravity is directly proportional to the mass of the planet. The planet will also fall towards the center of the system but, if the object is much less massive t ...

See also:

Falling, Falling - Sensation, Falling - Accidents, Falling - Classical physics, Falling - Mathematics

Read more here: » Falling: Encyclopedia II - Falling - Classical physics

There are 20 land-based tracking stations in the Chinese space telemetry network. These are supplemented by four Yuanwang-series tracking ships. The Beijing Aerospace Command global map showed their positions to be:[27] Yuanwang 1 in the Yellow Sea Yuanwang 2 about 1500 km (about 900 statute miles) southwest of French Polynesia Yuanwang 3 another off the Namibian coast Yuanwang 4 another off the coast of Western Australia in the Indian Ocean Only one other land-based tracking station is outs ...

See also:

Shenzhou 6, Shenzhou 6 - Crew, Shenzhou 6 - Backup crew, Shenzhou 6 - Mission highlights, Shenzhou 6 - Launch, Shenzhou 6 - Five days in orbit, Shenzhou 6 - Re-entry and landing, Shenzhou 6 - Upgrades, Shenzhou 6 - Experiments, Shenzhou 6 - Tracking, Shenzhou 6 - International reaction, Shenzhou 6 - Parties within Greater China area, Shenzhou 6 - Foreign countries and international organizations

Read more here: » Shenzhou 6: Encyclopedia II - Shenzhou 6 - Tracking

The Chinese space officials have said that the Long March 2F rocket featured a "fire security system" on the escape tower. Speculation on what this means ranges from better fail-safes to stop accidental firings, to the addition of a fire extinguisher. The Wen Wei Po newspaper have reported that the rocket appeared the same as that used for Shenzhou 5 except that a "transition segment" was visible at the top of the Shenzhou 6 stack, att ...

See also:

Shenzhou 6, Shenzhou 6 - Crew, Shenzhou 6 - Backup crew, Shenzhou 6 - Mission highlights, Shenzhou 6 - Launch, Shenzhou 6 - Five days in orbit, Shenzhou 6 - Re-entry and landing, Shenzhou 6 - Upgrades, Shenzhou 6 - Experiments, Shenzhou 6 - Tracking, Shenzhou 6 - International reaction, Shenzhou 6 - Parties within Greater China area, Shenzhou 6 - Foreign countries and international organizations

Read more here: » Shenzhou 6: Encyclopedia II - Shenzhou 6 - Upgrades

It was announced in July 2005 that Shenzhou 6 would carry one experiment involving the sperm of pigs from Rongchang County, Chongqing.[25] But on October 11 it was revealed by Liu Luxiang, director of the Centre for Space Breeding at the Chinese Academy of Agricultural Sciences, that there were no plans for animal or plant seeds on the flight. He said the focus of Shenzhou 6 was the physical reactions of the cre ...

See also:

Shenzhou 6, Shenzhou 6 - Crew, Shenzhou 6 - Backup crew, Shenzhou 6 - Mission highlights, Shenzhou 6 - Launch, Shenzhou 6 - Five days in orbit, Shenzhou 6 - Re-entry and landing, Shenzhou 6 - Upgrades, Shenzhou 6 - Experiments, Shenzhou 6 - Tracking, Shenzhou 6 - International reaction, Shenzhou 6 - Parties within Greater China area, Shenzhou 6 - Foreign countries and international organizations

Read more here: » Shenzhou 6: Encyclopedia II - Shenzhou 6 - Experiments

A hybrid rocket usually has a solid fuel and a liquid or gas oxidizer. The fluid oxidizer can make it possible to throttle and restart the motor just like a liquid fuelled rocket. Hybrid rockets are also cleaner than solid rockets because practical high-performance solid-phase oxidizers all contain chlorine, versus the more benign liquid oxygen or nitrous oxide used in hybrids. Because just one propellant is ...

See also:

Rocket fuel, Rocket fuel - Overview, Rocket fuel - Solid propellants, Rocket fuel - Liquid propellants, Rocket fuel - Hybrid propellants, Rocket fuel - Mixture ratio, Rocket fuel - Propellent density

Read more here: » Rocket fuel: Encyclopedia II - Rocket fuel - Hybrid propellants

Although liquid hydrogen gives a high Isp, its low density is a significant disadvantage: hydrogen occupies about 7x more volume per kilogram than dense fuels such as kerosene. This not only penalises the tankage, but also the pipes and fuel pumps leading from the tank, which need to be 7x bigger and heavier. (The oxidiser side of the engine and tankage is of course unaffected.) This makes the vehicle's dry mass very much higher, so the use of liquid hydrogen is not such a big win as might be expected. Indeed, some dense hydrocarbon/LOX propellant combinations have higher per ...

See also:

Rocket fuel, Rocket fuel - Overview, Rocket fuel - Solid propellants, Rocket fuel - Liquid propellants, Rocket fuel - Hybrid propellants, Rocket fuel - Mixture ratio, Rocket fuel - Propellent density

Read more here: » Rocket fuel: Encyclopedia II - Rocket fuel - Propellent density

A sensation of falling occurs when the labyrinth or vestibular apparatus, a system of fluid-filled passages in the inner ear, detects motion. The same system also detects rotary motion. A similar sensation of falling can be induced when the eyes detect rapid apparent motion with respect to the environment. This system enables us to keep our balance by signalling when a physical correction is necessary. When a human [Alyson Innes] is in free fall in an orbiting spacecraft, or in an aircraft in a steep dive, the sensation ...

See also:

Falling, Falling - Sensation, Falling - Accidents, Falling - Classical physics, Falling - Mathematics

Read more here: » Falling: Encyclopedia II - Falling - Sensation

The theoretical exhaust velocity of a given propellant chemistry is a function of the energy released per unit of propellant mass (specific energy). Unburned fuel or oxidizer drags down the specific energy. Surprisingly, most rockets run fuel-rich. The usual explanation for fuel-rich mixtures is that fuel-rich mixtures have lower molecular weight exhaust, which by reducing M increases the ratio , which is approximately equal to the theoretical exhaust velocity. This explanation, though found in some ...

See also:

Rocket fuel, Rocket fuel - Overview, Rocket fuel - Solid propellants, Rocket fuel - Liquid propellants, Rocket fuel - Hybrid propellants, Rocket fuel - Mixture ratio, Rocket fuel - Propellent density

Read more here: » Rocket fuel: Encyclopedia II - Rocket fuel - Mixture ratio