[M II A II R II K]

Non-Conductive Tethers - Free Artificial Gravity In Orbit

http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=256

Tethers connecting satellites or space stations have some interesting effects even if they are not conductive. A non-conductive tether made of a very strong, light material like Kevlar can be used to connect two objects in orbit, one farther away from the Earth than the other.

Two forces act on any object in stable orbit; an outward-pulling centrifugal force balanced by a downward gravitational force. Connecting two satellites in different orbits will cause them to act as one system. The outer satellite will experience a weaker gravitational force and a stronger centrifugal force; a net force pushes the satellite outward. The opposite set of conditions prevails on the lower satellite. The lower satellite orbits faster, and tows the other along like a water skier. The system reaches equilibrium when the tether aligns in the radial direction towards Earth.

The effect is rather small; a fifty kilometer tether would produce about one percent of Earth's gravity. However, it may be that this very small acceleration could reduce the problems with constant free fall, which is a constant irritant on space missions. Liquids would tend to settle (slowly), and everyone would know where "up" was.



http://www.technovelgy.com/graphics/content/edt-gravity.jpg

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http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980204c.html

Gravity is the least understood of the four basic forces in Physics (Gravity, Electricity & Magnetism, and the Strong and Weak Nuclear Forces). We do know how to describe it, and understand it seems a property associated with mass. There is no known mechanism at this point for artificially creating gravity, other than having a suitably large mass at hand.

However, that's not to say you could not "fake it", so to speak. You could keep a rocket constantly accelerating at 9.81 meters per second per second, and then flip the rocket around halfway to your destination and constantly accelerated in the opposite direction the rest of the way. Anyone in the space vehicle would feel as if they were experiencing gravity on Earth, except for a few dizzy moments when the spaceship gets flipped around. However, there's a little problem of having to have fuel enough to keep a rocket firing at that high a rate the whole time. Even the largest rockets NASA and the Russian Space Agency have will only burn for a few minutes before running out of fuel: the rest of the journey for space vehicles is done "coasting" to their destination and then using much smaller rockets to adjust their speed to slow down or change their orbit.

Another "trick" would be to make the entire space vehicle spin. Imagine a ball on a string: you can twirl it around and feel the string tugging on your arm. If you have a bucket of water on a string, you can twirl it around and if you twirl it around fast enough, the water stays in the bucket even if you spin it so it goes upside down during part of the swing. The same thing could be done in space: take two space vehicles and connect them on a tether and make them swing around each other to generate a sense of gravity. Theoretically, this is a very attractive idea; early tests with Gemini XI and XII showed that, while it was possible to generate microgravity (too weak for the astronauts to feel), stationkeeping of two tethered spacecrafts was very difficult. NASA has also flown a couple of shuttle missions attempting to deploy a tethered satellite. There were several goals with the tether system, but at least one was to work out how to deploy tethered systems in space.

Jesse Allen

[M II A II R II K]

At 3:30 it really starts getting to the point.


b7mwIHCBrjo

[Krases]

Ringworld uses the same concept, but on a titanic scale.

[M II A II R II K]

Researchers create gravity in lab experiment

http://www.scienceblog.com/cms/scientists_find_evidence_for_artifical_gravity_10282.html

Scientists funded by the European Space Agency have measured the gravitational equivalent of a magnetic field for the first time in a laboratory. Under certain special conditions the effect is much larger than expected from general relativity and could help physicists to make a significant step towards the long-sought-after quantum theory of gravity.

Just as a moving electrical charge creates a magnetic field, so a moving mass generates a gravitomagnetic field. According to Einstein's Theory of General Relativity, the effect is virtually negligible. However, Martin Tajmar, ARC Seibersdorf Research GmbH, Austria; Clovis de Matos, ESA-HQ, Paris; and colleagues have measured the effect in a laboratory.

Their experiment involves a ring of superconducting material rotating up to 6 500 times a minute. Superconductors are special materials that lose all electrical resistance at a certain temperature. Spinning superconductors produce a weak magnetic field, the so-called London moment. The new experiment tests a conjecture by Tajmar and de Matos that explains the difference between high-precision mass measurements of Cooper-pairs (the current carriers in superconductors) and their prediction via quantum theory. They have discovered that this anomaly could be explained by the appearance of a gravitomagnetic field in the spinning superconductor (This effect has been named the Gravitomagnetic London Moment by analogy with its magnetic counterpart).

Small acceleration sensors placed at different locations close to the spinning superconductor, which has to be accelerated for the effect to be noticeable, recorded an acceleration field outside the superconductor that appears to be produced by gravitomagnetism. "This experiment is the gravitational analogue of Faraday's electromagnetic induction experiment in 1831.

It demonstrates that a superconductive gyroscope is capable of generating a powerful gravitomagnetic field, and is therefore the gravitational counterpart of the magnetic coil. Depending on further confirmation, this effect could form the basis for a new technological domain, which would have numerous applications in space and other high-tech sectors" says de Matos. Although just 100 millionths of the acceleration due to the Earth’s gravitational field, the measured field is a surprising one hundred million trillion times larger than Einstein’s General Relativity predicts. Initially, the researchers were reluctant to believe their own results.

"We ran more than 250 experiments, improved the facility over 3 years and discussed the validity of the results for 8 months before making this announcement. Now we are confident about the measurement," says Tajmar, who performed the experiments and hopes that other physicists will conduct their own versions of the experiment in order to verify the findings and rule out a facility induced effect.

In parallel to the experimental evaluation of their conjecture, Tajmar and de Matos also looked for a more refined theoretical model of the Gravitomagnetic London Moment. They took their inspiration from superconductivity. The electromagnetic properties of superconductors are explained in quantum theory by assuming that force-carrying particles, known as photons, gain mass. By allowing force-carrying gravitational particles, known as the gravitons, to become heavier, they found that the unexpectedly large gravitomagnetic force could be modelled.

"If confirmed, this would be a major breakthrough," says Tajmar, "it opens up a new means of investigating general relativity and it consequences in the quantum world."

The results were presented at a one-day conference at ESA's European Space and Technology Research Centre (ESTEC), in the Netherlands, 21 March 2006. Two papers detailing the work are now being considered for publication. The papers can be accessed on-line at the Los Alamos pre-print server using the references: gr-qc/0603033 and gr-qc/0603032.

From European Space Agency

[Krases]

I would imagine being able to generate gravity would be the first step towards being able to build anti-gravity. I am just thinking on an architectural scale, but if a building could levitate, imagine the architectural possibilities.

[Trantor]

from a quick google search, this Clóvis de Matos guy was born in France, but his name is clearly brazilian... probably his parents were brazilian?

full name is Clóvis Jacinto de Matos... totally portuguese origin name, but probably brazilian, since Clóvis and Jacinto are NOT common names in portugal.

[1ajs]

interesting.....

[Yankee]

That's fascinating. Shouldn't it be in the Space thread though?