Tesla Tunguska - Total Non Sequitur
Now there is only the basement:
Tunguska Event: 1908
|Coordinate||40° 56′ 51.35″ N, 72° 53′ 53.54″ W||Decimal||40.947597,-72.898207|
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Wardenclyffe Tower located in Shoreham, Long Island, New York. The 94 ft (29 m) by 94 ft (29 m) brick building was designed by architect Stanford White. The station, including the tower structure was not completed due to financial difficulties.
Wardenclyffe Tower (1901 -- 1917) also known as the Tesla Tower, was an early wireless telecommunications aerial tower designed by Nikola Tesla and intended for commercial trans-Atlantic wireless telephony, broadcasting, and to demonstrate the transmission of power without interconnecting wires. The core facility was never fully operational and was not completed due to economic problems.
The tower was named after James S. Warden, a western lawyer and banker who had purchased land in Shoreham, Long Island, about sixty miles from Manhattan. Here he built a resort community known as Wardenclyffe-On-Sound. Warden believed that with the implementation of Tesla's "world system", a "Radio City" would arise in the area, and he offered Tesla 200 acres (81 hectares) of land close to a railway line on which to build his wireless telecommunications tower and laboratory facility.
Tesla's Wardenclyffe plant on Long Island in partial stage of completion. Work on the 55-foot diameter cupola had not yet begun. Note what appears to be a coal car parked next to the building. From this facility, Tesla hoped to demonstrate wireless transmission of electrical energy to France. Circa 1902.
Nikola Tesla began planning the Wardenclyffe Tower facility ca. 1898, and in 1901, construction began on the land near Long Island Sound. Architect Stanford White designed the Wardenclyffe facility main building. The tower was designed by W.D. Crow, an associate of White. Funding for Tesla's project was provided by influential industrialists and other venture capitalists. The project was initially backed by the wealthy J. P. Morgan (he had a substantial investment in the facility, initially investing $150,000).
In June 1902, Tesla moved his laboratory operations from his Houston Street laboratory to Wardenclyffe. However, in 1903, when the tower structure was near completion, it was still not yet functional due to last-minute design changes. Tesla intended for the tower to demonstrate how the ionosphere could be used to provide free electricity to everyone without the need for power lines. Morgan, who could not foresee any financial gain from providing free electricity to everyone, balked. Construction costs eventually exceeded the money provided by Morgan, and additional financiers were reluctant to come forward. By July 1904, Morgan (and the other investors) finally decided they would not provide any additional financing. Morgan also encouraged other investors to avoid the project. In May 1905, Tesla's patents on alternating current motors and other methods of power transmission expired, halting royalty payments and causing a severe reduction of funding to the Wardenclyffe Tower. In an attempt to find alternative funding, Tesla advertised the services of the Wardenclyffe facility, but he met with little success. By this time, Tesla had also designed the Tesla turbine at Wardenclyffe and produced Tesla coils for sale to various businesses.
By 1905, since Tesla could not find any more backers, most of the site's activity had to be shut down. Employees were laid off in 1906, but parts of the building remained in use until 1907. In 1908, the property was foreclosed for the first time. Tesla procured a new mortgage from the proprietor of the Waldorf-Astoria Hotel, George C. Boldt. The facility was partially abandoned around 1911, the tower structure eventually becoming deteriorated. Between 1912 and 1915, Tesla's finances unraveled, and when the funders wanted to know how they were going to recapture their investments, Tesla was unable to give satisfactory answers. Newspaper headlines of the time labeled it "Tesla's million-dollar folly." The facility's main building was breached and vandalized around this time. Collapse of the Wardenclyffe project may have contributed to the mental breakdown Tesla experienced during this period. Coupled to the personal tragedy of Wardenclyffe was the 1895 fire at 35 South 5th Avenue in the building which housed Tesla's laboratory. In this fire, he lost much of his equipment, notes and documents. This produced a state of severe depression for Tesla.
In 1915, legal ownership of the Wardenclyffe property was transferred to George Boldt for a $20,000 debt. In September 1917 during World War I, the tower was blown up with dynamite on orders of the United States Government which feared German spies were using it and that it could be used as a landmark for German submarines. Tesla was not in New York during the tower's destruction.
George Boldt wished to make the property available for sale. On April 20, 1922 Tesla lost an appeal of judgment versus his backers in the second foreclosure. This effectively locked Tesla out of any future development of the facility. In 1925, the property ownership was transferred to Walter L. Johnson of Brooklyn. On March 6, 1939, Plantacres, Inc. purchased the facility's land and subsequently leased it to Peerless Photo Products, Inc. (which was subsequently bought out by AGFA Corporation, the current owner). The main building remains standing to this day.
On February 14, 1967, the nonprofit public benefit corporation Brookhaven Town Historical Trust was established. It selected the Wardenclyffe facility to be designated as a historic site and as the first site to be preserved by the Trust on March 3, 1967. In the month of July in 1976, a plaque from Tesla's birth country, Yugoslavia, was installed by the Brookhaven Town Historic trust near the entrance of the building. It reads:
IN THIS BUILDING DESIGNED BY STANFORD WHITE, ARCHITECT
BORN SMILJAN, YUGOSLAVIA 1856, DIED NEW YORK, U.S.A. 1943
CONSTRUCTED IN 1901-1905 WARDENCLYFFE, HUGE RADIO STATION WITH
ANTENNA TOWER 187 FT. HIGH (DESTROYED 1917), WHICH WAS TO SERVE
AS HIS FIRST WORLD COMMUNICATIONS SYSTEM.
IN MEMORY OF 120TH ANNIVERSARY OF TESLA'S BIRTH AND 200TH
ANNIVERSARY OF U.S.A. INDEPENDENCE — July 10, 1976
Attempts to landmark the structure have been thwarted by the lack of cooperation by its owners (landmarking requires owner cooperation).
In 1976, an application was filed to nominate the main building for listing listed on the National Register of Historic Places. It failed to get approval. In 1994, the campaign for placement of the Wardenclyffe facility on the National Register of Historic Places of New York was renewed. In October 1994 a second Application for formal nomination was filed. The New York State Office of Parks, Recreation and Historic Preservation conducted inspections and determined the facility meets New York State criteria for historic designation.
The present owner of the existing Wardenclyffe facility is AGFA-Gevaert. The site is undergoing a final cleanup of waste produced during its Photo Products era. The clean up is being conducted under the scrutiny of the New York State Department of Environmental Conservation, and is being paid for by AGFA. The tower base is one of the areas where the clean up is under way.
Artistic representation of the station completed, including the tower structure.
Wardenclyffe is located near the Shoreham Post Office and Shoreham Fire House on Route 25A in Shoreham, Long Island, New York. Wardenclyffe was divided into two main sections. The tower, which was located in the back, and the main building compose the entire facility grounds.
The tower was 187 feet (57 meters) tall and 68 feet (20.7 m) in diameter. It had a supporting structure that was built of wood. It had a 55-ton steel (some report it was a better conducting material, such as copper) hemispherical structure at the top (referred to as a cupola). The tower was designed by one of Stanford White's associates. The design of this structure was such as to allow each piece to be taken out if needed and replaced as necessary. Beneath the tower, a shaft sank 120 feet (36.6 m) into the ground. Sixteen iron pipes were placed one length after another 300 additional feet (94.4 m) in order for the machine, in Tesla's words, "to have a grip on the earth so the whole of this globe can quiver." At this depth, telluric currents of the Earth could be transceived.
The main building occupied the rest of the facility grounds. It included a laboratory area, instrument room, boiler room, generator room and machine shop. Inside the main building, there were electromechanical devices, electrical generators, electrical transformers, glass blowing equipment, X-ray devices, Tesla coils, a remote controlled boat, cases with bulbs and tubes, wires, cables, a library, and an office. It was constructed in the style of the Italian Renaissance.
Theories of operation
The transmission of radiant energy
In 1891 and 1892, Tesla had used an oscillatory transformer that bears his name in demonstration lectures delivered before meetings of the American Institute of Electrical Engineers (AIEE) in New York City" and the Institute of Electrical Engineers (IEE) in London. Of two striking results that Tesla demonstrated, one was that the wireless transmission of electrical energy was possible. A later presentation, titled "On Light and Other High Frequency Phenomena" (Philadelphia/St. Louis; Franklin Institute in 1893), was a key event in the invention of radio and could be said to have begun the development of Wardenclyffe.
In the early presentations, the first experiment to be demonstrated was the operation of light and motive devices connected by a single wire to only one terminal of a high frequency induction coil, presented during the 1891 New York City lecture at Columbia University. While a single terminal incandescent lamp connected to one of an induction coil’s secondary terminals does not form a closed circuit "in the ordinary acceptance of the term", the circuit is closed in the sense that a return path is established back to the secondary by what Tesla called "electrostatic induction" (or 'displacement currents'). This is due to the fact that the lamp’s filament or refractory button has capacitance relative to the coil’s free terminal and environment and the secondary’s free terminal also has capacitance relative to the lamp and environment. At high frequencies, the displacement current required to charge these capacitances becomes sufficient to light the lamp.
The Tesla effect. A "world system" for "the transmission of electrical energy without wires" that depends upon electrical conductivity was proposed by Tesla. Through longitudinal waves, an operator uses the Tesla effect in the wireless transfer of energy to a receiving device.
The second result demonstrated how energy could be made to go through space without any connecting wires. This was the first step towards a practical wireless system. The wireless energy transmission effect involved the creation of an electric field between two metal plates, each being connected to one terminal of an induction coil’s secondary winding. Once again, a light-producing device (in this case a gas discharge tube) was used as a means of detecting the presence of the transmitted energy. "The most striking result obtained" involved the lighting of two partially evacuated tubes in an alternating electrostatic field while held in the hand of the experimenter. In Tesla's words,
... I suspend a sheet of metal a distance from the ceiling on insulating cords and connect it to one terminal of the induction coil, the other terminal being preferably connected to the ground. Or else I suspend two sheets as illustrated in Fig. 29 / 125, each sheet being connected with one of the terminals of the coil, and their size being carefully determined. An exhausted tube may then be carried in the hand anywhere between the sheets or placed anywhere, even a certain distance beyond them; it remains always luminous.
Here Tesla describes two different types of wireless transmitters, both employing a high-tension induction coil. The first, referred to here as the type-one transmitter, had a sheet of metal suspended from the ceiling and connected to one of the induction coil’s terminals. The other terminal was connected to ground. The second, referred to here as the type-two transmitter, had two sheets of metal suspended from the ceiling, each being connected with one of the coil’s terminals.
Theory of wireless transmission
While working to develop an explanation for the two observed effects mentioned above, Tesla recognized that electrical energy could be projected outward into space and detected by a receiving instrument in the general vicinity of the source without the need for any interconnecting wires. He went on to develop two theories related to these observations, which are:
1. By using two type-one sources positioned at distant points on the Earth’s surface, it is possible to induce a flow of electrical current between them.
2. By incorporating a portion of the Earth as part of a powerful type-two oscillator the disturbance can be impressed upon the Earth and detected "at great distance, or even all over the surface of the globe."
Tesla also made the assumption that the Earth is a charged body floating in space.
A point of great importance would be first to know what is the capacity of the Earth? and what charge does it contain if electrified? Though we have no positive evidence of a charged body existing in space without other oppositely electrified bodies being near, there is a fair probability that the Earth is such a body, for by whatever process it was separated from other bodies—and this is the accepted view of its origin—it must have retained a charge, as occurs in all processes of mechanical separation.
Tesla was familiar with demonstrations that involved the charging of Leyden jar capacitors and isolated metal spheres with electrostatic influence machines. By bringing these elements into close proximity with each other, and also by making direct contact followed by their separation the charge can be manipulated. He surely had this in mind in the creation of his mental image, not being able to know that the model of Earth’s origin was inaccurate. The presently accepted model of planetary origin is one of accretion and collision.
If it be a charged body insulated in space its capacity should be extremely small, less than one-thousandth of a farad.
We now know that the Earth is, in fact, a charged body, made so by processes—at least in part—related to the interaction between the continuous stream of charged particles called the solar wind that flows outward from the center of our solar system and Earth’s magnetosphere. And we also know that Tesla's capacitance estimate was correct: Earth's self-capacitance is about 710 microfarads.
But the upper strata of the air are conducting, and so, perhaps, is the medium in free space beyond the atmosphere, and these may contain an opposite charge. Then the capacity might be incomparably greater.
We now also know that one of the upper strata of Earth's atmosphere, the ionosphere, is conducting.
In any case it is of the greatest importance to get an idea of what quantity of electricity the Earth contains.
An additional condition of which we are now aware is that the Earth possesses a naturally existing negative charge with respect to the conducting region of the atmosphere beginning at an elevation of about 50 km. The potential difference between the Earth and this region is on the order of 400,000 volts. Near the Earth's surface there is a ubiquitous downward directed E-field of about 100 V/m. Tesla referred to this charge as the "electric niveau" or electric level.
It is difficult to say whether we shall ever acquire this necessary knowledge, but there is hope that we may, and that is, by means of electrical resonance. If ever we can ascertain at what period the Earth's charge, when disturbed, oscillates with respect to an oppositely electrified system or known circuit, we shall know a fact possibly of the greatest importance to the welfare of the human race. I propose to seek for the period by means of an electrical oscillator, or a source of alternating electric currents...
Some maintain the 200 kW wireless facility would have functioned by the propagation of electromagnetic radiation, or radio waves, then called Hertzian radiation.
By Tesla's own account, his earth resonance system works by the creation of powerful disturbances in Earth's natural electric charge. The Wardenclyffe facility had a dual purpose. In addition to point-to-point telecommunications and broadcasting it was also intended to demonstrate the transmission of electrical power on a reduced scale. He stated,
It is intended to give practical demonstrations of these principles with the plant illustrated. As soon as completed, it will be possible for a business man in New York to dictate instructions, and have them instantly appear in type at his office in London or elsewhere. He will be able to call up, from his desk, and talk to any telephone subscriber on the globe, without any change whatever in the existing equipment. An inexpensive instrument, not bigger than a watch, will enable its bearer to hear anywhere, on sea or land, music or song, the speech of a political leader, the address of an eminent man of science, or the sermon of an eloquent clergyman, delivered in some other place, however distant. In the same manner any picture, character, drawing, or print can be transferred from one to another place. Millions of such instruments can be operated from but one plant of this kind. More important than all of this, however, will be the transmission of power, without wires, which will be shown on a scale large enough to carry conviction.
Wardenclyffe was the first of many installations to be constructed near major population centers around the world. If Tesla's plans had moved forward without interruption the Long Island prototype would have been followed by a second plant built somewhere along the southwest coast of England, perhaps in Cornwall. Each of these towers would have been a large magnifying transmitter of a design loosely based upon the apparatus which Tesla assembled at the Colorado Springs Experimental Station in 1899.
"... The plant in Colorado was merely designed in the same sense as a naval constructor designs first a small model to ascertain all the quantities before he embarks on the construction of a big vessel. I had already planned most of the details of the commercial plant, subsequently put up at Long Island, except that at that time the location was not settled upon. The Colorado plant I have used in determining the construction of the various parts, and the experiments which were carried on there were for the practical purpose of enabling me to design the transmitters and receivers which I was to employ in the large commercial plant subsequently erected..."
Using a global array of these magnifying transmitters, it was Tesla's plan to establish what he called the "World System," providing multi-channel global broadcasting, an array of secure wireless telecommunications services, and a long range aid to navigation, including means for the precise synchronization of clocks. In a more highly developed state he envisioned the World System would expand to include the wireless industrial transmission of electric power.
The installation was also used by Tesla as a laboratory for designing a power distribution system that would allow electricity to be transmitted over great distances without wires. This cannot be accomplished with what Tesla called "Hertz waves," which explains why Wardenclyffe was designed in a different manner than modern radio transmitters. Instead of distributing electricity through copper wire, remote users would be able to "receive" power through a buried ground connection, along with a spherical antenna terminal mounted just above their roof. At the time the power grid was quite limited in terms of who it reached and the Wardenclyffe prototype represented a way in which to significantly reduce the cost of "electrifying" the countryside. Tesla called his wireless technique the "disturbed charge of ground and air method".
The prototype facility was also meant to serve as a reduced-scale model for a national (and later global) system of towers to transmit electrical energy to users in the form of earth currents and magnetohydrodynamic waves. There is evidence that Wardenclyffe would have used extremely low frequency signals combined with higher frequency signals. In practice, the transmitter electrically influences both the Earth and the space above it. He made a point of describing the process as being essentially the same as transmitting electricity by conduction through a wire. Tesla stated that electrical energy can be efficiently transmitted back and forth between World System transmitter / receiver facilities via electrical conduction through the ground. To accommodate this plan each facility includes one or two elevated terminal connections and one or two ground terminal connections.
Tesla clearly specified the Earth as being one of the conducting media involved in ground and air system technology. The other specified medium is the atmosphere above 5 miles (8.0 km) elevation. While not an ohmic conductor, in this region of the troposphere and upwards, the density or pressure is sufficiently reduced to so that, according to Tesla’s theory, the atmosphere’s insulating properties can be easily impaired, allowing an electric current to flow. His theory further states that the conducting region is developed through the process of atmospheric ionization, in which the effected portions thereof are changed to plasma. The presence of the magnetic fields developed by each plant’s helical resonator suggests that an embedded magnetic field and flux linkage is also involved. Flux linkage with Earth’s natural magnetic field is also a possibility, especially in the case of an earth resonance transmission system.
The atmosphere below 5 miles (8.0 km) is also viewed as a propagating medium for a portion of the above-ground circuit, and, being an insulating medium, electrostatic induction would be involved rather than true electrical conduction. Tesla felt that with a sufficiently high electrical potential on the elevated terminal the practical limitation imposed upon its height could be overcome. He anticipated that a highly energetic transmitter, as was intended at Wardenclyffe, would charge the elevated terminal to the point where the atmosphere around and above the facility would break down and become ionized, leading to a flow of true conduction currents between the two terminals by a path up to and through the troposphere, and back down to the other facility. The ionization of the atmosphere directly above the elevated terminals would be facilitated by the use of an ionizing beam of ultraviolet radiation to form what might be called a high-voltage plasma transmission line. [ed. see maxwellian waves and waves in plasmas] Powered by an industrial alternator, a generator facility's tower was intended to inject large amounts of energy into a natural Earth circuit, using the Earth-Ionosphere network as the transmission circuit.
In various writings, Tesla explained that the Earth itself behaves as a resonant LC circuit when it is electrically excited at certain frequencies. At Wardenclyffe he operated at frequencies ranging from 1,000 Hz to 100 kHz. Tesla found the frequency range up to 30 -- 35 kHz "to be most economical." Excitation of earth resonance at or near a fundamental frequency (about 7.5 to 7.9 Hz), might suggest the utilization of what is now known as a Schumann resonance mode. The entire Earth can be electrically resonated with a single type-two source, so an earth-resonance based system would require, at a minimum, that only one generating facility be constructed. Alternatively, two distantly spaced type-one generating facilities could be constructed. Such a system would not be so dependent upon the excitation of an earth-resonance mode. In either case a surface or ground wave, similar to the Zenneck wave would be utilized. Artificially induced earth currents would be utilized. According to Tesla, the planet's large cross-sectional area provides a low resistance path for the flow of earth currents. The greatest losses are apt to occur at the points where the transmitting / receiving plants and dedicated receiving stations are connected with the ground. This is why Tesla stated,
You see the underground work is one of the most expensive parts of the tower. In this system that I have invented it is necessary for the machine to get a grip of the Earth, otherwise it cannot shake the Earth. It has to have a grip on the Earth so that the whole of this globe can quiver, and to do that it is necessary to carry out a very expensive construction.
To close the circuit a second path would be established between the two type-one plants' elevated high-voltage terminals through the rarefied atmospheric strata above five miles (8 km). The connection would be made by some combination of electrostatic induction and electrical conduction through plasma. While a number of his wireless patents, including "Apparatus for transmitting electrical energy", U.S. Patent No. 1,119,732, December 1, 1914, describe a system which uses the plasma-conduction scheme, his "Art of transmitting electrical energy through the natural mediums", U.S. Patent No. 787,412, April 18, 1905 and some of his Wardenclyffe design notes from 1901 show that he also had a plan to electrostatically induce oscillations in the potential associated with Earth's self-capacitance by rapidly transferring large amounts of electrical charge between the large topload capacitance and the self-capacitance of the whole Earth. The type-two transmitter is especially designed for this purpose. Tesla wrote,
The specific plan of producing the stationary waves, here-in described, might be departed from. For example, the circuit which impresses the powerful oscillations upon the earth might be connected to the latter at two points.
Tesla firmly believed that a fully developed system with generating stations based upon the Wardenclyffe prototype would permit wireless transmission and reception across large distances with negligible losses.
Variants were suggested by Tesla for receiving power from electromagnetic radiation, or alternating electric near fields, of practicable frequency, and for exploiting the vertical voltage gradient in the Earth's atmosphere. Tesla performed experiments of the former type with some success, particularly in the area of receiving what was probably the near electric field of a large transmitting Tesla coil some distance away. He felt that several of his experiments were operating on a basis of Hertzian waves, electromagnetic waves propagated in space without artificial guide.
Tesla stated that one of the seven features of this world wireless system was the construction of a "resonant receiver". The secondary of a Tesla Coil and its capacitor can be used in receive mode. Tesla himself demonstrated wireless transmission of electric power from his transmitter to his receiver. These concepts and methods are part of his wireless transmission of electric power distribution system (US1119732 — Apparatus for Transmitting Electrical Energy — 1902 January 18). Tesla made a proposal that there needed to be "thirty" such antennas worldwide. The receiving circuit of these towers are connected each with a condenser and a device adapted to open and close the receiving circuit at predetermined intervals of time. The Tesla Coil receiver has means for commutating, directing, or selecting the current impulses in the charging circuit so as to render them suitable for charging the storage device, a device for closing the receiving-circuit, and means for causing the receiver to be operated by the energy accumulated.
Tesla coil in one experiment of many conducted in Colorado Springs. This is a grounded tuned coil in resonance with a distant transmitter; Light is glowing near the bottom.
A Tesla Antenna as a receiver acts as a step-down transformer with high current output. The parameters of a Tesla Coil transmitter are identically applicable to it being a receiver (e.g., an antenna circuit), due to reciprocity. Impedance, generally though, is not applied in an obvious way; for electrical impedance, the impedance at the load (e.g., where the power is consumed) is most critical and, for a Tesla Coil receiver, this is at the point of utilization (such as at an induction motor) rather than at the receiving node. Complex impedance of an antenna is related to the electrical length of the antenna at the wavelength in use. Commonly, impedance is adjusted at the load with a tuner or a matching networks composed of inductors and capacitors.
A Tesla Coil can receive electromagnetic impulses from atmospheric electricity and radiant energy, besides normal wireless transmissions. Radiant energy throws off with great velocity minute particles which are strongly electrified and other rays falling on the insulated-conductor connected to a condenser (i.e., a capacitor) can cause the condenser to indefinitely charge electrically. The helical resonator can be "shock excited" due to radiant energy disturbances not only at the fundamental wave at one-quarter wave-length but also is excited at its harmonics. Hertzian methods can be used to excite the Tesla Antenna with limitations that result in great disadvantages for utilization, though. The methods of ground conduction and the various induction methods can also be used to excite the Tesla Antenna, but are again at a disadvantages for utilization. The charging-circuit can be adapted to be energized by the action of various other disturbances and effects at a distance. Arbitrary and intermittent oscillations that are propagated via conduction to the receiving resonator will charge the receiver's capacitor and utilize the potential energy to greater effect. Various radiations can be used to charge and discharge conductors, with the radiations considered electromagnetic vibrations of various wavelengths and ionizing potential. The Tesla Antenna utilizes the effects or disturbances to charge a storage device with energy from an external source (natural or man-made) and controls the charging of said device by the actions of the effects or disturbances (during succeeding intervals of time determined by means of such effects and disturbances corresponding in succession and duration of the effects and disturbances). The stored energy can also be used to operate the receiving device. The accumulated energy can, for example, operate a transformer by discharging through a primary circuit at predetermined times which, from the secondary currents, operate the receiving device.
While Tesla Coils can be used for these purposes, much of the public and media attention is toward the transmitting applications of the Tesla Coil since the plasma discharges are fascinating to most people. Regardless of this fact, Tesla did suggest that this variation of the Tesla coil could utilize the phantom loop effect to form a circuit to induct energy from the Earth's magnetic field and other radiant energy sources (including, but not limited to, electrostatics). With regard to Tesla's statements on the harnessing of natural phenomena to obtain electric power, he stated:
Ere many generations pass, our machinery will be driven by a power obtainable at any point of the universe. — "Experiments with Alternate Currents of High Potential and High Frequency" (February 1892)
Tesla stated that the output power from these devices, attained from Hertzian methods of charging, was low, but alternative charging means are available. Tesla receivers operated correctly act as a step-down transformer with high current output. There are, to date, no commercial power generation entities or businesses that have utilized this technology to full effect. The power levels achieved by Tesla Coil receivers have, thus far, been a fraction of the output power of the transmitters.
Ignoring earth currents and other natural electromagnetic phenomena the Tesla antenna can receive, atmospheric electricity's total power of only all the sky-to-ground lightning everywhere on Earth from moment to moment has been stated at 700 megawatts. By comparison, a typical fossil fuel power plant (such as oil or gas) feeding the utility grid may have two gas turbines and a single steam turbine utilizing the heat from the discharged flue gas of the gas turbines, with each of the three turbines rated at 100 megawatts. On the load side, 700 MW is seen to correspond to two million parsimonious households averaging 350 watts of power use, contrasted with a world population of over six billion people. As regards methods, atmospheric electricity includes static electricity and other phenomena. Modern HVDC technology inverts DC at such voltages to AC well enough to be very popular for use in the power grid; a Tesla coil variant is not the only way to do this, nor necessarily the best way, either for atmospheric electricity or telluric power. Earth's surface has a negative charge and the atmosphere has a positive charge.
The amount of electromagnetic radiation present on the surface of the Earth is known to those whose technical work on radio communication or regulatory compliance involves reception and measurement. Radiation is monitored from ten-thousands of hertz (cycles per second) up to thirty billion hertz (wavelength one centimeter) or more, in many cases. Authorized radio transmissions and minor but unwanted emissions from equipment being designed are not greatly overshadowed by naturally occurring radio frequency energy. This natural and unnatural 'noise' is abundant in the environment and can be received via wideband reception, although this article does not cite any demonstration providing power on the scale needed for household, commercial or industrial purposes at the present time.
-- Tesla's ray
Related to the operation and utilization of Wardenclyffe Tower was Nikola Tesla's work on a macroscopic particle beam weapon called Teleforce in the 1930s. A Wardenclyffe styled facility which included the weapon was contemplated by Tesla. He offered it to Westinghouse Electric & Manufacturing Company in early 1934. It was also offered to the US War Department, Great Britain, and Yugoslavia. A descriptive 17-page type-written document on Tesla's office letterhead titled, "New Art of Projecting Concentrated Non-Dispersive Energy Through Natural Media," which presently exists in the Nikola Tesla Museum archive in Belgrade, shows that his macroscopic particle beam, also dubbed the "Peace Ray" or the "death ray" by contemprary media, was a narrow stream of charged clusters of mercury or tungsten accelerated by high voltage, produced by either a huge Van de Graaff generator or Tesla Coil. Immediately after his death, a component of the particle beam projector that may have been found among Tesla's possessions is said to have disappeared. Russian spies reportedly raided the room and the safe containing the schematics of the "death ray". The FBI never found any of the important parts of the schematics nor the trunk with the prototype, as far as existing public records show.
Please help improve this section by expanding it. Further information might be found on the talk page or at requests for expansion. (May 2008)
After Wardenclyffe, Tesla built the Telefunken Wireless on the South Shore of Long Island. Some of what he wanted to achieve at Wardenclyffe was achieved with the Telefunken Wireless. In West Sayville, Long Island, New York, Tesla assisted in the building of three 600-foot (180 m) radio towers, creating the western wireless communication station in a North America and Europe network.
* "As soon as [the Wardenclyffe facility is] completed, it will be possible for a business man in New York to dictate instructions, and have them instantly appear in type at his office in London or elsewhere. He will be able to call up, from his desk, and talk to any telephone subscriber on the globe, without any change whatever in the existing equipment. An inexpensive instrument, not bigger than a watch, will enable its bearer to hear anywhere, on sea or land, music or song, the speech of a political leader, the address of an eminent man of science, or the sermon of an eloquent clergyman, delivered in some other place, however distant. In the same manner any picture, character, drawing, or print can be transferred from one to another place ..." - Nikola Tesla, "The Future of the Wireless Art", Wireless Telegraphy and Telephony, 1908, pg. 67-71.
* "It is not a dream, it is a simple feat of scientific electrical engineering, only expensive — blind, faint-hearted, doubting world! [...] Humanity is not yet sufficiently advanced to be willingly led by the discoverer's keen searching sense. But who knows? Perhaps it is better in this present world of ours that a revolutionary idea or invention instead of being helped and patted, be hampered and ill-treated in its adolescence — by want of means, by selfish interest, pedantry, stupidity and ignorance; that it be attacked and stifled; that it pass through bitter trials and tribulations, through the strife of commercial existence. So do we get our light. So all that was great in the past was ridiculed, condemned, combatted, suppressed — only to emerge all the more powerfully, all the more triumphantly from the struggle." -- Nikola Tesla (at the end of his dream for Wardenclyffe) [Wardenclyffe — A Forfeited Dream]
Nikola Tesla's patents
* "Means for Generating Electric Currents," U.S. Patent 514,168 , February 6, 1894
* "Electrical Transformer," U.S. Patent 593,138 , November 2, 1897
* "Method Of Utilizing Radiant Energy," U.S. Patent 685,958 November 5, 1901
* "Method of Signaling," U.S. Patent 723,188 , March 17, 1903
* "System of Signaling," U.S. Patent 725,605 , April 14, 1903
* "Art of Transmitting Electrical Energy Through the Natural Mediums," U.S. Patent 787,412 , April 18, 1905
* "Apparatus for Transmitting Electrical Energy," January 18, 1902, U.S. Patent 1,119,732 , December 1, 1914
See also: List of Tesla patents
* Hansell, U.S. Patent 2,389,432 , Communication system by pulses through the Earth.
* Leydorf, G. F., U.S. Patent 3,278,937 , "Antenna near field coupling system". 1966.
* Transceiver: transmitter and receiver
* Devices: Tesla coil and Magnifying Transmitter
1. ^ Anderson, Leland I., Nikola Tesla On His Work with Alternating Currents and Their Application to wireless Telegraphy, Telephony, and Transmission of Power, Twenty First Century Books, 2002, pp. 106, 153, 170.; Councel, "This Wardenclyffe station was that -- experimental?" Tesla, "No, it was a commercial undertaking. . . ."
2. ^ "The Future of the Wireless Art," Wireless Telegraphy & Telephony, Van Nostrand, 1908
3. ^ Cheney, Margaret(1999), Tesla Master of Lightning, New York: Barnes & Noble Books, ISBN 0-7607-1005-8, pp. 107.; "Unable to overcome his financial burdens, he was forced to close the laboratory in 1905."
4. ^ When Morgan wanted to know "Where can I put the meter?", Tesla had no answer. Tesla's vision of free power did not agree with Morgan's worldview; nor would it pay for the maintenance of the transmission system.
5. ^ See http://earlyradiohistory.us/1917tes.htm (citing page 293 of the September, 1917 issue of The Electrical Experimenter): "SUSPECTING that German spies were using the big wireless tower erected at Shoreham, L. I., about twenty years ago by Nikola Tesla, the Federal Government ordered the tower destroyed and it was recently demolished with dynamite."
6. ^ This plaque is located near the entrance to the building, not the entrance to the site, and as such is not accessible by the public in any way.
7. ^ Tesla, a Little-Recognized Genius, Left Mark in Shoreham - New York Times - November 10, 2002
8. ^ Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony, and Transmission of Power, ISBN 1-893817-01-6, p. 203
9. ^ "Experiments With Alternating Currents of Very High Frequency, and Their Application to Methods of Artificial Illumination," AIEE, Columbia College, N.Y., May 20, 1891
10. ^ "Experiments With Alternate Currents of High Potential and High Frequency," IEE Address, London, February 3, 1892" (Inventions, Researches and Writings of Nikola Tesla).
11. ^ "On Light and Other High Frequency Phenomena," February 24, 1893, before the Franklin Institute, Philadelphia, March 1893, before the National Electric Light Association, St. Louis.
12. ^ Norrie, H. S., "Induction Coils: How to make, use, and repair them". Norman H. Schneider, 1907, New York. 4th edition.
13. ^ Electrical experimenter, January 1919. pg. 615
14. ^ Tesla: Man Out of Time By Margaret Cheney. Page 174
15. ^ "The Transmission of Electrical Energy Without Wires," Electrical World, March 5, 1904
16. ^ a b c d e f "Experiments With Alternating Currents of Very High Frequency, and Their Application to Methods of Artificial Illumination," AIEE, Columbia College, N.Y., May 20, 1891
17. ^ "Episode 126: Capacitance and the equation C =Q/V", Institute of Physics website > Schools and Colleges > Projects > Teaching Advanced Physics > Electricity > Capacitors, accessed 2008-09-25
18. ^ As noted by James Corum, et al in the paper "Concerning Cavity Q", Proceedings of the 1988 International Tesla Symposium. (ed. along with other sources)
19. ^ "On Light and Other High Frequency Phenomena," February 24, 1893, before the Franklin Institute, Philadelphia, March 1893, before the National Electric Light Association, St. Louis.
20. ^ "The Future of the Wireless Art," Wireless Telegraphy and Telephony, Walter W. Massie & Charles R. Underhill, 1908, pp. 67-71
21. ^ Anderson, Leland, "Nikola Tesla On His Work with Alternating Currents and Their Application to wireless Telegraphy, Telephony, and Transmission of Power," Twenty First Century Books, 2002, pp. 170.
22. ^ "U.S. Blows Up Tesla Radio Tower," Electrical Experimenter, September 1917, p. 293.
23. ^ Peterson, Gary, "Rediscovering the Zenneck Surface Wave," Feed Line No. 4.
24. ^ Anderson, Leland, Nikola Tesla On His Work With Alternating Currents and Their Application to Wireless Telegraphy, Telephony and Transmission of Power, p. 203
25. ^ U.S. Patent No. 787,412, April 18, 1905 and some of his Wardenclyffe design notes
26. ^ Peterson, Gary, "Nikola Tesla's Wireless Work: The development of a ground-based system for wireless transmission"
27. ^ Peterson, Gary, "Comparative Study of the Hertz, Marconi and Tesla Low-Frequency Wireless Systems"
28. ^ Peterson, Gary, "Tesla Coils & the World System: Nikola Tesla's Engineering Legacy"
29. ^ Peterson, Gary, "A Museum at Wardenclyffe: The Creation of a Monument to Nikola Tesla".
30. ^ Definition of "Hertzian"
31. ^ Marc J. Seifer, Wizard: The Life and Times of Nikola Tesla. Page 228.
32. ^ Tesla, Nikola, "The True Wireless". Electrical Experimenter, May 1919. (Available at pbs.org)
33. ^ U.S. Patent 645,576
34. ^ U.S. Patent 725,605
35. ^ U.S. Patent 685,957 , Apparatus for the utilization of radiant energy, N. Tesla
36. ^ U.S. Patent 685,958 , Method of utilizing of radiant energy, N. Tesla
37. ^ "Apparatus for Transmitting Electrical Energy", Jan. 18, 1902, U.S. Patent 1,119,732, December 1, 1914 (available at U.S. Patent 1,119,732 and tfcbooks' Apparatus for Transmitting Electrical Energy)
38. ^ Marc J. Seifer, Wizard: The Life and Times of Nikola Tesla. Page 472. (cf. "Each tower could act as a sender or a receiver. In a letter to Katherine Johnson, Tesla explains the need for well over thirty such towers".)
39. ^ U.S. Patent 0685956
40. ^ U.S. Patent 0685955 Apparatus for Utilizing Effects Transmitted From A Distance To A Receiving Device Through Natural Media
41. ^ G. L. Peterson, Rediscovering the Zenneck Surface Wave.
42. ^ 'Energy-sucking' Radio Antennas, N. Tesla's Power Receiver.
43. ^ William Beaty, "Tesla invented radio?". 1992.
44. ^ Nikola Tesla's Contributions to Radio Developments. www.tesla-symp06.org.
45. ^ A. H. Taylor, "Resonance in Aërial Systems". American Physical Society. Physical review. New York, N.Y.: Published for the American Physical Society by the American Institute of Physics. (cf. The Tesla coil in the receiver acts as a step-down transformer, and hence the current is greater than in the aerial itself.)
46. ^ This would include being able to be "shock excited" by all electrical phenomena of transverse waves (those with vibrations perpendicular to the direction of the propagation) and longitudinal waves (those with vibrations parallel to the direction of the propagation). Further information can be found in U.S. Patent 685,953 , U.S. Patent 685,954 , U.S. Patent 685,955 , U.S. Patent 685,956 , U.S. Patent 685,957 and U.S. Patent 685,958 .
47. ^ Marc J. Seifer, Wizard: The Life and Times of Nikola Tesla. Page 221 (cf. "The inventor had tuned his equipment so carefully that "in one instance the devices recorded effects of lightning discharges fully 500 miles away […]"
48. ^ Hermann Plauson, U.S. Patent 1,540,998 , "Conversion of atmospheric electric energy". Jun. 1925.
49. ^ Nikola Tesla, "Tuned Lightning", English Mechanic and World of Science, March 8, 1907.
50. ^ U.S. Patent 685,957 , Apparatus for the utilization of radiant energy, N. Tesla
51. ^ U.S. Patent 685,958 , Method of utilizing of radiant energy, N. Tesla
52. ^ US685957 Utilization of Radiant Energy
53. ^ U.S. Patent 0685953 Apparatus for Utilizing Effects Transmitted from a Distance to a Receiving Device through Natural Media
54. ^ U.S. Patent 0685953 Apparatus for Utilizing Effects Transmitted from a Distance to a Receiving Device through Natural Media
55. ^ U.S. Patent 0685953 Apparatus for Utilizing Effects Transmitted from a Distance to a Receiving Device through Natural Media
56. ^ US685957 Utilization of Radiant Energy
57. ^ U.S. Patent 0685954 Method of Utilizing Effects Transmitted through Natural Media
58. ^ U.S. Patent 0685954 Method of Utilizing Effects Transmitted through Natural Media
59. ^ Bell, Louis (1901). Electric Power Transmission; a Practical Treatise for Practical Men, p. 10. Retrieved on 2007-02-15. "Both kinds of strains exist in radiant energy, […] The stresses in electro-magnetic energy are at right angles both to the electrostatic stresses and to the direction of their motion or flow."
60. ^ U.S. Patent 0685953 "Apparatus for Utilizing Effects Transmitted from a Distance to a Receiving Device through Natural Media"
61. ^ A. H. Taylor, "Resonance in Aërial Systems". American Physical Society. Physical review. New York, N.Y.: Published for the American Physical Society by the American Institute of Physics. (cf. The Tesla coil in the receiver act as a step-down transformer, and hence the current is greater than in the aerial itself.)
62. ^ Lightning: The Most Common Source of Overvoltage (Hubbell Power Systems Inc.)
63. ^ A treatment of natural electricity is provided in The Earth's Electrical Environment, CPSMA, USA National Academies Press
64. ^ USA Federal Communications Commission Rules Part 15 (47CFR15) See signals to be detected
* Anderson, Leland, "Rare Notes from Tesla on Wardenclyffe", in Electric Spacecraft - A journal of Interactive Research, Issue 26, September 14, 1998. Contains copies of rare documents from the Tesla Museum in Belgrade including Tesla's notes and sketches from 1901
* Bass, Robert W., "Self-Sustained Non-Hertzian Longitudal Wave Oscillations as a Rigorous Solution of Maxwell's Equations for Electromagnetic Radiation". Inventek Enterprises, Inc., Las Vegas, Nevada.
* "Boundless Space: A Bus Bar". The Electrical World, Vol 32, No. 19.
* Massie, Walter Wentworth, "Wireless telegraphy and telephony popularly explained ". New York, Van Nostrand. 1908.
* Rather, John, "Tesla, a Little-Recognized Genius, Left Mark in Shoreham". The New York Times. Long Island Weekly Desk.
* Tesla, Nikola, "On the Transmission of Electricity Without Wires". Electrical World and Engineer, March 5, 1904.
Of course TESLA was a crazy man, fantasizing about technology:
The lighting of the ocean ... is only one of the less important results to be achieved by the use of this invention [the transmitter]. I have planned many of the details of a plant which might be erected at the Azores and which would be amply sufficient to illuminate the entire ocean so that such a disaster as that of the Titanic would not be repeated. The light would be soft and of very small intensity, but quite adequate to the purpose.
Nikola Tesla, 1914 from the New York American of December 7th, 1914
Magnifying Transmitter’s Test Path
Trees knocked over by the Tunguska blast. Photograph from Kulik's 1927 expedition
Although the cause is the subject of some debate, the explosion was most likely caused by the air burst of a large meteoroid or comet fragment at an altitude of 5–10 kilometres (3–6 miles) above Earth's surface. Different studies have yielded varying estimates for the object's size, with general agreement that it was a few tens of metres across.
Although the meteor or comet burst in the air rather than directly hitting the surface, this event is still referred to as an impact. Estimates of the energy of the blast range from 5 megatons to as high as 30 megatons of TNT, with 10–15 megatons the most likely - roughly equal to the United States' Castle Bravo thermonuclear explosion set off in late February 1954, about 1,000 times as powerful as the bomb dropped on Hiroshima, Japan and about one third the power of the Tsar Bomba, the largest nuclear weapon ever detonated. The explosion knocked over an estimated 80 million trees over 2,150 square kilometres (830 square miles). It is estimated that the earthquake from the blast would have measured 5.0 on the Richter scale, which was not yet developed at the time. An explosion of this magnitude is capable of destroying a large metropolitan area. This possibility has helped to spark discussion of asteroid deflection strategies.
Although the Tunguska event is believed to be the largest impact event on land in Earth's recent history, impacts of similar size in remote ocean areas would have gone unnoticed before the advent of global satellite monitoring in the 1960s and 1970s.
Approximate location of the Tunguska event in Siberia.
At around 7:17 a.m. local time, Tungus natives and Russian settlers in the hills northwest of Lake Baikal observed a column of bluish light, nearly as bright as the Sun, moving across the sky. About 10 minutes later, there was a flash and a sound similar to artillery fire. Eyewitnesses closer to the explosion reported the sound source moving east to north. The sounds were accompanied by a shock wave that knocked people off their feet and broke windows hundreds of miles away. The majority of eyewitnesses reported only the sounds and the tremors, and not the sighting of the explosion. Eyewitness accounts differ as to the sequence of events and their overall duration.
The explosion registered on seismic stations across Eurasia. Although the Richter scale was not developed until 1935, in some places the shock wave would have been equivalent to an earthquake of 5.0 on the Richter scale. It also produced fluctuations in atmospheric pressure strong enough to be detected in Great Britain. Over the next few weeks, night skies were aglow such that one could read in their light, caused by dust suspended in the stratosphere by the explosion. In the United States, the Smithsonian Astrophysical Observatory and the Mount Wilson Observatory observed a decrease in atmospheric transparency that lasted for several months, also from the suspended dust.
The Guinness Book of World Records (1966 edition) states that because of the rotation of Earth, if the collision had occurred 4 hours 47 minutes later, it would have completely destroyed the Imperial Russian capital, Saint Petersburg.
Selected eyewitness reports
* Testimony of S. Semenov, as recorded by Leonid Kulik's expedition in 1930.
"At breakfast time I was sitting by the house at Vanavara trading post (65 kilometres/40 miles south of the explosion), facing North. [...] I suddenly saw that directly to the North, over Onkoul's Tunguska road, the sky split in two and fire appeared high and wide over the forest (as Semenov showed, about 50 degrees up - expedition note). The split in the sky grew larger, and the entire Northern side was covered with fire. At that moment I became so hot that I couldn't bear it, as if my shirt was on fire; from the northern side, where the fire was, came strong heat. I wanted to tear off my shirt and throw it down, but then the sky shut closed, and a strong thump sounded, and I was thrown a few yards. I lost my senses for a moment, but then my wife ran out and led me to the house. After that such noise came, as if rocks were falling or cannons were firing, the earth shook, and when I was on the ground, I pressed my head down, fearing rocks would smash it. When the sky opened up, hot wind raced between the houses, like from cannons, which left traces in the ground like pathways, and it damaged some crops. Later we saw that many windows were shattered, and in the barn a part of the iron lock snapped."
* Testimony of Chuchan of Shanyagir tribe, as recorded by I.M.Suslov in 1926.
"We had a hut by the river with my brother Chekaren. We were sleeping. Suddenly we both woke up at the same time. Somebody shoved us. We heard whistling and felt strong wind. Chekaren said, 'Can you hear all those birds flying overhead?' We were both in the hut, couldn't see what was going on outside. Suddenly, I got shoved again, this time so hard I fell into the fire. I got scared. Chekaren got scared too. We started crying out for father, mother, brother, but no one answered. There was noise beyond the hut, we could hear trees falling down. Chekaren and I got out of our sleeping bags and wanted to run out, but then the thunder struck. This was the first thunder. The Earth began to move and rock, wind hit our hut and knocked it over. My body was pushed down by sticks, but my head was in the clear. Then I saw a wonder: trees were falling, the branches were on fire, it became mighty bright, how can I say this, as if there was a second sun, my eyes were hurting, I even closed them. It was like what the Russians call lightning. And immediately there was a loud thunderclap. This was the second thunder. The morning was sunny, there were no clouds, our Sun was shining brightly as usual, and suddenly there came a second one! "Chekaren and I had some difficulty getting out from under the remains of our hut. Then we saw that above, but in a different place, there was another flash, and loud thunder came. This was the third thunder strike. Wind came again, knocked us off our feet, struck against the fallen trees. "We looked at the fallen trees, watched the tree tops get snapped off, watched the fires. Suddenly Chekaren yelled 'Look up' and pointed with his hand. I looked there and saw another flash, and it made another thunder. But the noise was less than before. This was the fourth strike, like normal thunder. "Now I remember well there was also one more thunder strike, but it was small, and somewhere far away, where the Sun goes to sleep."
* Sibir newspaper, July 2, 1908
"On the 17th of June, around 9 in the AM, we observed an unusual natural occurrence. In the N Karelinski village (200 verst N of Kirensk) the peasants saw to the North-West, rather high above the horizon, some strangely bright (impossible to look at) bluish-white heavenly body, which for 10 minutes moved downwards. The body appeared as a "pipe", i.e. a cylinder. The sky was cloudless, only a small dark cloud was observed in the general direction of the bright body. It was hot and dry. As the body neared the ground (forest), the bright body seemed to smudge, and then turned into a giant billow of black smoke, and a loud knocking (not thunder) was heard, as if large stones were falling, or artillery was fired. All buildings shook. At the same time the cloud began emitting flames of uncertain shapes. All villagers were stricken with panic and took to the streets, women cried, thinking it was the end of the world. "The author of these lines was meantime in the forest about 6 verst N of Kirensk, and heard to the NE some kind of artillery barrage, that repeated in intervals of 15 minutes at least 10 times. In Kirensk in a few buildings in the walls facing north-east window glass shook."
* Siberian Life newspaper, July 27, 1908
"When the meteorite fell, strong tremors in the ground were observed, and near the Lovat village of the Kansk uezd two strong explosions were heard, as if from large-caliber artillery."
* Krasnoyaretz newspaper, July 13, 1908
"Kezhemskoe village. On the 17th an unusual atmospheric event was observed. At 7:43 the noise akin to a strong wind was heard. Immediately afterwards a horrific thump sounded, followed by an earthquake which literally shook the buildings, as if they were hit by a large log or a heavy rock. The first thump was followed by a second, and then a third. Then - the interval between the first and the third thumps were accompanied by an unusual underground rattle, similar to a railway upon which dozens of trains are traveling at the same time. Afterwards for 5 to 6 minutes an exact likeness of artillery fire was heard: 50 to 60 salvoes in short, equal intervals, which got progressively weaker. After 1.5 - 2 minutes after one of the "barrages" six more thumps were heard, like cannon firing, but individual, loud, and accompanied by tremors. "The sky, at the first sight, appeared to be clear. There was no wind and no clouds. However upon closer inspection to the North, i.e. where most of the thumps were heard, a kind of an ashen cloud was seen near the horizon which kept getting smaller and more transparent, and possibly by around 2-3 p.m. completely disappeared."
There was little scientific curiosity about the impact at the time, possibly due to the isolation of the Tunguska region. If there were any early expeditions to the site, the records were likely to have been lost during the subsequent chaotic years — World War I, the Russian Revolution of 1917, and the Russian Civil War.
The first recorded expedition arrived at the scene more than a decade after the event. In 1921, the Russian mineralogist Leonid Kulik, visiting the Podkamennaya Tunguska River basin as part of a survey for the Soviet Academy of Sciences, deduced from local accounts that the explosion had been caused by a giant meteorite impact. He persuaded the Soviet government to fund an expedition to the Tunguska region, based on the prospect of meteoric iron that could be salvaged to aid Soviet industry.
Photograph from the Soviet Academy of Science 1927 expedition led by Leonid Kulik.
Kulik's party reached the site in 1927. To their surprise, no crater was to be found. There was instead a region of scorched trees about 50 kilometres (30 miles) across. A few near ground zero were still strangely standing upright, their branches and bark stripped off. Those farther away had been knocked down in a direction away from the center.
During the next ten years there were three more expeditions to the area. Kulik found a little "pothole" bog that he thought might be the crater, but after a laborious exercise in draining the bog, he found there were old stumps on the bottom, ruling out the possibility that it was a crater. In 1938, Kulik arranged for an aerial photographic survey of the area, which revealed that the event had knocked over trees in a huge butterfly-shaped pattern. Despite the large amount of devastation, there was no crater to be seen.
Expeditions sent to the area in the 1950s and 1960s found microscopic silicate and magnetite spheres in siftings of the soil. Similar spheres were predicted to exist in the felled trees, although they could not be detected by contemporary means. Later expeditions did identify such spheres in the resin of the trees, however. Chemical analysis showed that the spheres contained high proportions of nickel relative to iron, which is also found in meteorites, leading to the conclusion they were of extraterrestrial origin. The concentration of the spheres in different regions of the soil was also found to be consistent with the expected distribution of debris from a meteorite airburst. Later studies of the spheres found unusual ratios of numerous other metals relative to the surrounding environment, which was taken as further evidence of their extraterrestrial origin.
Chemical analysis of peat bogs from the area also revealed numerous anomalies considered consistent with an impact event. The isotopic signatures of stable carbon, hydrogen, and nitrogen isotopes at the layer of the bogs corresponding to 1908 were found to be inconsistent with the isotopic ratios measured in the adjacent layers, and this abnormality was not found in bogs located outside the area. The region of the bogs showing these anomalous signatures also contains an unusually high proportion of iridium, similar to the iridium layer found in the K–T boundary. These unusual proportions are believed to result from debris from the impacting body that deposited in the bogs. The nitrogen is believed to have been deposited as acid rain, a suspected fallout from the explosion.
In scientific circles, the leading explanation for the explosion is the airburst of a meteoroid 6–10 kilometres (4–6 miles) above Earth's surface.
Meteoroids enter Earth's atmosphere from outer space every day, usually travelling at a speed of more than 10 kilometres per second (6 miles/sec or 21,600 mph). Most are small but occasionally a larger one enters. The heat generated by compression of air in front of the body (ram pressure) as it travels through the atmosphere is immense and most meteoroids burn up or explode before they reach the ground. Since the second half of the 20th century, close monitoring of Earth's atmosphere has led to the discovery that such meteoroid airbursts occur rather frequently. A stony meteoroid of about 10 metres (30 ft) in diameter can produce an explosion of around 20 kilotons, similar to that of the Fat Man bomb dropped on Nagasaki, and data released by the U.S. Air Force's Defense Support Program indicate that such explosions occur high in the upper atmosphere more than once a year. Tunguska-like megaton-range events are much rarer. Eugene Shoemaker estimated that such events occur about once every 300 years.
The explosion's effects on the trees near ground zero was replicated during atmospheric nuclear tests in the 1950s and 1960s. These effects are caused by the shock wave produced by large explosions. The trees directly below the explosion are stripped as the blast wave moves vertically downward, while trees further away are knocked over because the blast wave is travelling closer to the horizontal when it reaches them.
Soviet experiments performed in the mid-1960s, with model forests (made of matches) and small explosive charges slid downward on wires, produced butterfly-shaped blast patterns strikingly similar to the pattern found at the Tunguska site. The experiments suggested that the object had approached at an angle of roughly 30 degrees from the ground and 115 degrees from north and had exploded in mid-air.
Asteroid or comet?
The composition of the Tunguska body remains a matter of controversy. In 1930, the British astronomer F.J.W. Whipple suggested that the Tunguska body was a small comet. A cometary meteorite, being composed primarily of ice and dust, could have been completely vaporized by the impact with the Earth's atmosphere, leaving no obvious traces. The comet hypothesis was further supported by the glowing skies (or "skyglows" or "bright nights") observed across Europe for several evenings after the impact, possibly explained by dust and ice that had been dispersed from the comet's tail across the upper atmosphere. The cometary hypothesis gained a general acceptance amongst Soviet Tunguska investigators by the 1960s.
In 1978, Slovak astronomer L(ubor Kresák suggested that the body was a fragment of the short-period Comet Encke, which is responsible for the Beta Taurid meteor shower; the Tunguska event coincided with a peak in that shower, and the approximate trajectory of the Tunguska impactor is consistent with what would be expected from such a fragment. It is now known that bodies of this kind explode at frequent intervals tens to hundreds of kilometres above the ground. Military satellites have been observing these explosions for decades.
In 1983, astronomer Zdene(k Sekanina published a paper criticizing the comet hypothesis. He pointed out that a body composed of cometary material, travelling through the atmosphere along such a shallow trajectory, ought to have disintegrated, whereas the Tunguska body apparently remained intact into the lower atmosphere. Sekanina argued that the evidence pointed to a dense, rocky object, probably of asteroidal origin. This hypothesis was further boosted in 2001, when Farinella, Foschini, et al. released a study suggesting that the object had arrived from the direction of the asteroid belt.
Proponents of the comet hypothesis have suggested that the object was an extinct comet with a stony mantle that allowed it to penetrate the atmosphere.
The chief difficulty in the asteroid hypothesis is that a stony object should have produced a large crater where it struck the ground, but no such crater has been found. It has been hypothesized that the passage of the asteroid through the atmosphere caused pressures and temperatures to build up to a point where the asteroid abruptly disintegrated in a huge explosion. The destruction would have to have been so complete that no remnants of substantial size survived, and the material scattered into the upper atmosphere during the explosion would have caused the skyglows. Models published in 1993 suggested that the stony body would have been about 60 metres across, with physical properties somewhere between an ordinary chondrite and a carbonaceous chondrite.
Christopher Chyba and others have proposed a process whereby a stony meteorite could have exhibited the behavior of the Tunguska impactor. Their models show that when the forces opposing a body's descent become greater than the cohesive force holding it together, it blows apart, releasing nearly all its energy at once. The result is no crater, and damage distributed over a fairly wide radius, all of the damage being blast and thermal.
During the 1990s, Italian researchers extracted resin from the core of the trees in the area of impact, to examine trapped particles that were present during the 1908 event. They found high levels of material commonly found in rocky asteroids and rarely found in comets.
See also: Lake Cheko
In June 2007 it was announced that scientists from the University of Bologna had identified a lake in the Tunguska region as a possible impact crater from the event. They do not dispute that the Tunguska body exploded mid-air, but believe that a one meter fragment survived the explosion and impacted the ground. Lake Cheko is a small bowl shaped lake approximately 8 kilometres north-north-west of the hypocenter. The hypothesis has been disputed by other impact crater specialists. A 1961 investigation had dismissed a modern origin of Lake Cheko, saying that the presence of metres thick silt deposits at the lake's bed suggests an age of at least 5,000 years, however more recent research suggests that only a meter or so of the sediment layer on the lake bed is "normal lacustrine sedimentation", a depth indicating a much younger lake, about 100 years. Acoustic-echo soundings of the lake floor provide support for the hypothesis that the lake was formed by the Tunguska event. The soundings revealed a conical shape for the lake bed, which is consistent with an impact crater. Magnetic readings indicate a possible meter-sized chunk of rock below the lake's deepest point, which may be a fragment of the colliding body. Finally, the lake's long axis points to the hypocenter of the Tunguska explosion, about 7.0 km away. Work is still being done at Lake Cheko to determine its origins.
Scientific understanding of the behaviour of meteorites in the Earth's atmosphere was much sparser during the early decades of the 20th century. Due to this lack of knowledge, as well as a lack of scientific data about Tunguska due to Soviet secrecy during the Cold War, a great many other hypotheses for the Tunguska event have sprung up, none of which are accepted by the scientific community.
End of the World?
“ Perhaps the earliest widely-held theory for the Tunguska explosion was that the world was about to end. As the minutes passed, this theory was dropped in favour of other, less final theories, until today one is hard-pressed to find anyone who truly believes the world ended on the morning of 30 June 1908... ”
According to G. K. Kulesh, head of the Kirensk Meteorological Station
“ The peasants of the village [of Korelina] were so stunned by the crashes that they sent a deputation to town to the local archpriest to ask if the end of the world was beginning, [and] how they were preparing for it in Kirensk. ”
In 1989, D'Alessio and Harms suggested that some of the deuterium in a comet entering the Earth's atmosphere may have undergone a nuclear fusion reaction, leaving a distinctive signature in the form of carbon-14. They concluded that any release of nuclear energy would have been almost negligible. Independently, in 1990, César Sirvent proposed that a deuterium comet, i.e., a comet with an anomalous high concentration of deuterium in its composition, could have exploded as a natural hydrogen bomb, generating most of the energy released. The sequence would be first a mechanical or kinetic explosion, triggering a thermonuclear reaction. These proposals are inconsistent with knowledge both of the composition of comets and of the temperature and pressure conditions necessary for initiating a nuclear fusion reaction. Studies have found the concentration of radioactive isotopes in the blast region to be inconsistent with those expected following a nuclear explosion, fusion or otherwise.
In 1973, Albert A. Jackson and Michael P. Ryan, physicists at the University of Texas, proposed that the Tunguska event was caused by a "small" (around 1017 kg to 1019 kg) black hole passing through the Earth. This hypothesis fails, as there was no so-called "exit event" — a second explosion occurring as the black hole, having tunnelled through the Earth, shot out the other side on its way back into space, which would have happened in the Southern Ocean, about 10 degrees west of the Drake Passage — nor were there the continuous seismic disturbances that would occur along the hole's path through the mantle.
The hypothesis was used by Larry Niven in his science fiction story The Borderland of Sol, and by David Brin, in his novel Earth, as well as by Bill DeSmedt in his novel Singularity. It also figures in Dan Simmons's Hyperion Cantos novels.
In 1965, Cowan, Atluri, and Libby suggested that the Tunguska event was caused by the annihilation of a chunk of antimatter falling from space. However, as with the other hypotheses described in this section, this does not account for the mineral debris left in the area of the explosion. Furthermore, there is no astronomical evidence for the existence of such chunks of antimatter in our region of the universe. If such objects existed, they should be constantly producing energetic gamma rays due to annihilation against the interstellar medium, but such gamma rays have not been observed.
Various UFO aficionados have claimed that the Tunguska event was the result of an exploding alien spaceship or even an alien weapon going off to "save the Earth from an imminent threat". These claims appear to originate from a science fiction story penned by Soviet engineer Alexander Kazantsev in 1946, in which a nuclear-powered Martian spaceship, seeking fresh water from Lake Baikal, blew up in mid-air. This story was inspired by Kazantsev's visit to Hiroshima in late 1945.
Many events in Kazantsev's tale were subsequently confused with the actual occurrences at Tunguska. The nuclear-powered UFO hypothesis was adopted by TV drama critics Thomas Atkins and John Baxter in their book The Fire Came By (1976). The 1998 television series The Secret KGB UFO Files (Phenomenon: The Lost Archives), broadcast on Turner Network Television, referred to the Tunguska event as "the Russian Roswell" and claimed that crashed UFO debris had been recovered from the site. In 2004, a group from the Tunguska Space Phenomenon Public State Fund claimed to have found the wreckage of an alien spacecraft at the site.
The proponents of the UFO hypothesis have never been able to provide any significant evidence for their claims. It should be noted that the Tunguska site is downrange from the Baikonur Cosmodrome and has been contaminated repeatedly by Russian space debris, most notably by the failed launch of the fifth Vostok test flight on December 22, 1960. The payload landed close to the Tunguska impact site, and a team of engineers was dispatched there to recover the capsule and its two Soviet space dogs (who survived).
Astrophysicist Wolfgang Kundt has suggested the Tunguska event was caused by the sudden release and subsequent explosion of 10 million tonnes of natural gas from within the Earth's crust. The similar Verneshot hypothesis has also been suggested as a possible cause of the Tunguska event.
The Tunguska event is the strongest, but not the only, significant meteorite airburst in recent history. A selection of similar events follows. This list is quite biased, since recording of meteorite explosive yields is relatively recent:
Date Place Yield of explosion (TNT equivalent) Height of explosion Remarks
June 30, 1908 60 kilometres (37 mi) westnorthwest of Vanavara, at 60°53' 09"N, 101°53' 40"E in Krasnoyarsk Krai, Imperial Russia 10–15 Mt 8.5 km (5.3 mi) Tunguska event
August 13, 1930 Curuçá River Area, Amazonas, Brazil 0.1-1.0 Mt
May 31, 1965 Southeast Canada 600 t 13 km (8 mi) 1 g (0.035 oz) material from meteorite found
September 17, 1966 Lake Huron, Michigan, United States 600 t 13 km (8 mi) No material from meteorite found
February 5, 1967 Vilna Alberta, Canada 600 t 13 km (8 mi) Two very small fragments found - 48 milligrams (0.0017 oz) and 94 milligrams (0.0033 oz).
Stored at University of Alberta, in Edmonton. 
September 22, 1979 Southern Indian Ocean 2 kt
January 19, 1993 Lugo, Northern Italy > 10 kt > -20a
January 18, 1994 Cando, Spain
June 6, 2002 Mediterranean Sea between Libya and Greece 26 kt
September 25, 2002 Bodaybo, Russia 0.5 – 5 kt
Tunguska event in fiction
Main article: Tunguska event in fiction
* Asteroid deflection strategies
* Cando event
* Cretaceous–Tertiary extinction event
* Doomsday event
* Eastern Mediterranean Event
* Lonar crater
* Vela Incident
* Vitim event
* Sikhote-Alin meteorite
* Baxter, John and Thomas Atkins, The Fire Came By: The Riddle of the Great Siberian Explosion, Macdonald and Jane's, London 1975. ISBN 044689396X.
* Brown, J.C, and Hughes, D.W. Nature 268, 512–514 (1977)
* Furneaux, Rupert. The Tungus Event, Nordon Publications, New York, 1977. ISBN 058604423X.
* Gallant, Roy A. The Day the Sky Split Apart: Investigating a Cosmic Mystery, Atheneum Books for Children, New York, 1995. ISBN 0689803230.
* Gasperini, Luca, Bonatti, Enrico and Longo, Giuseppe. The Tunguska Mystery 100 Years Later, Scientific American, June, 2008
* Krinov, E. L. Giant Meteorites, trans. J.S. Romankiewicz (Part III: The Tunguska Meteorite), Pergamon Press, Oxford, 1966
* Morgan, J. Phipps, Ranero, C.R., Reston, T.J. Contemporaneous mass extinctions, continental flood basalts, and ‘impact signals’: are mantle plume-induced lithospheric gas explosions the causal link?, Earth and Planetary Science Letters. 217. 263-284 (2004)
* Lerman, J. C., Mook, W. G. & Vogel, J. C. Nature, Effect of the Tunguska Meteor and Sunspots on Radiocarbon in Tree Rings, (9 December 1967) | doi:10.1038/216990a0; 216, 990–1 (1967)
* Ol'khovatov, A.Yu. Earth, Moon and Planets, v.93, pp.163–173 (2003)
* Stoneley, Jack. Cauldron of Hell: Tunguska, Simon and Schuster, New York, 1977. ISBN 0671229435.
* Verma, Surendra. The Tunguska Fireball: Solving One of the Great Mysteries of the 20th century, Icon Books, Cambridge, 2005. ISBN 1840466200.
* Verma, Surendra. The Mystery of the Tunguska Fireball, Icon Books, Cambridge, 2006. ISBN 1840467282.
1. ^ P. Farinella, L. Foschini, Ch. Froeschlé, R. Gonczi, T. J. Jopek, G. Longo, P. Michel Probable asteroidal origin of the Tunguska Cosmic Body
2. ^ a b Trayner, C. Perplexities of the Tunguska meteorite
3. ^ Lyne, J.E., Tauber, M. The Tunguska Event
4. ^ "Sandia supercomputers offer new explanation of Tunguska disaster". Sandia National Laboratories (2007-12-17). Retrieved on 2007-12-22.
5. ^ a b c d e Shoemaker, Eugene (1983), "Asteroid and Comet Bombardment of the Earth", Annual Review of Earth and Planetary Sciences (US Geological Survey, Flagstaff, Arizona: Annual Review of Earth and Planetary Sciences) 11: 461, doi:10.1146/annurev.ea.11.050183.002333, http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.ea.11.050183.002333?prevSearch=Tunguska
6. ^ Verma (2005), p1.
7. ^ Longo, Giuseppe (2007), "18", in Bobrowsky, Peter T.; Rickman, Hans, Comet/Asteroid Impacts and Human Society, An Interdisciplinary Approach, Berlin Heidelberg New York: Springer-Verlag, pp. 303–330, ISBN 3-540-32709-6
8. ^ APOD: 2007 November 14 - Tunguska: The Largest Recent Impact Event
9. ^ a b Traynor, Chris, The Tunguska Event, Journal of the British Astronomical Association, 107, 3, 1997
10. ^ N. V. Vasiliev, A. F. Kovalevsky, S. A. Razin, L. E. Epiktetova (1981). Eyewitness accounts of Tunguska (Crash)., Section 6, Item 4
11. ^ Vasiliev, Section 5
12. ^ Vasiliev, Section 1, Item 2
13. ^ Vasiliev, Section 1, Item 3
14. ^ Vasiliev, Section 1, Item 5
15. ^ Longo G.. "The 1938 aerophotosurvey". Retrieved on 2008-01-03.
16. ^ a b Florenskiy, K P (1963). "Preliminary results from the 1961 combined Tunguska meteorite expedition". Meteoritica 13. Retrieved on 2007-06-26.
17. ^ a b c Kolesnikov et al. Finding of probable Tunguska Cosmic Body material: isotopic anomalies of carbon and hydrogen in peat, Planetary and Space Science, Volume 47, Issues 6-7, June 1, 1999, Pages 905-916
18. ^ Hou et al. Discovery of iridium and other element anomalies near the 1908 Tunguska explosion site, Planetary and Space Science, Volume 46, Issues 2-3, February-March 1998, Pages 179-188
19. ^ Kolesnikov et al. Isotopic anomaly in peat nitrogen is a probable trace of acid rains caused by 1908 Tunguska bolide, Planetary and Space Science, Volume 46, Issues 2-3, February-March 1998, Pages 163-167
20. ^ "The Tunguska object - A fragment of Comet Encke". Astronomical Institutes of Czechoslovakia. Retrieved on 2007-02-15.
21. ^ Nemtchinov, I.V.; C. Jacobs and E. Tagliaferri (1997). "Analysis of Satellite Observations of Large Meteoroid Impacts". Annals of the New York Academy of Sciences 822: 303–317.
22. ^ Longo, G.; Serra R., Cecchini S. and Galli M., (1994). "Search for microremnants of the Tunguska Cosmic Body". Planetary and Space Science 42 (2): 163–177. UK: Elsevier Science Ltd.
23. ^ Serra, R.; Cecchini S. and Galli M, and Longo G. (1994). "Experimental hints on the fragmentation of the Tunguska cosmic body". Planetary and Space Science 42 (9): 777–783. UK: Elsevier Science Ltd.
24. ^ "A possible impact crater for the 1908 Tunguska Event", Department of Physics, University of Bolongna
25. ^ Rincon Paul (2007) "Team makes Tunguska crater claim", BBC (2007-06-27)
26. ^ Gasperini, L. et al (April 2008). "Reply - Lake Cheko and the Tunguska Event: impact or non-impact?". Terra Nova 20 (2): 169–172. doi:10.1111/j.1365-3121.2008.00792.x. Retrieved on 2008-05-27.
27. ^ a b c Gasperini, L. et al (June 2008). "The Tunguska Mystery". Scientific American: 80–86. Retrieved on 2008-06-08.
28. ^ Crater From 1908 Russian Space Impact Found, Team Says
29. ^ K. Zahnle, Nature 383, 674-75 (1996)
30. ^ :Quoted in N. V. Vasilyev et al., Pokazaniya Ochevidtsev Tungusskogo Padeniya (Testimony of Eyewitnesses to the Tunguska Impact), VINITI (1981), available on line at http://olkhov.narod.ru/tungwitn1.htm or at http://tunguska.tsc.ru/ru/science/1/0. This document is in Russian, but a translation of Kulesh's full report may be found at http://www.vurdalak.com/tunguska/witness/kulesh_gk.htm.
31. ^ The nuclear and aerial dynamics of the Tunguska Event
32. ^ Universiteit Leiden - "Making a comet nucleus" - By Greenberg, J.M. 1998
33. ^ “Was the Tungus Event due to a Black Hole?” Nature, vol. 245, September 14, 1973, pp. 88-89.
34. ^ Cowan, C., Atluri, C. R. & Libby, Possible Anti-Matter Content of the Tunguska Meteor of 1908. Nature 206, 861 - 865 (29 May 1965); doi:10.1038/206861a0
35. ^ SPACE.com - "Russian Alien Spaceship Claims Raise Eyebrows, Skepticism "
36. ^ Choi, Charles Q., Massive Tunguska Blast Still Unsolved 100 Years Later, Fox News, July 1, 2008
37. ^ 100 years on, mystery shrouds massive 'cosmic impact' in Russia, Agence France-Presse, June 28, 2008
38. ^ Morgan et al, "Contemporaneous mass extinctions, continental flood basalts, and ‘impact signals’: are mantle plume-induced lithospheric gas explosions the causal link?", Earth and Planetary Science Letters 217, January 15, 2004
39. ^ Vilna
Wikimedia Commons has media related to:
* Article about the events, special attention to Leonid Kulik on MysteryDatabase.com
* Quasi Three-Dimensional Modeling of Tunguska Comet Impact (1908) Dr. Andrei E. Zlobin, Paper of 2007 Planetary Defense Conference.
* Tunguska Comet Impact 1908
* The Tunguska Event in 1908: Evidence from Tree-Ring Anatomy - Evgenii A. Vaganov, Malkolm K. Hughes, Pavel P. Silkin and Valery D. Nesvetailo, Astrobiology, Volume 4, Number 3, 2004, pp.391-399
* Tunguska.ru Russian site with a tiny English section. Includes some gorgeous Tunguska photos.
* Tunguska A research group at University of Bologna that has conducted several recent expeditions to the site.
* Tunguska pictures Many Tunguska-related pictures with comments in English.
* Preliminary results from the 1961 combined Tunguska meteorite expedition
* Probable asteroidal origin of the Tunguska Cosmic Body A 2001 paper arguing for the asteroidal hypothesis.
* "Russian Alien Spaceship Claims Raise Eyebrows, Skepticism" article, arguing the event was caused by meteor explosion
* "The Vurdalak Conjecture" website explores the science behind the black-hole impact hypothesis.
* 1908 Siberia Explosion. Reconstruction by William K. Hartmann.
* Simulation of such an event & origin of King Tut's glass
* Team makes Tunguska crater claim (BBC News)
* Astronomy Picture of the Day on Tunguska
* Mystery space blast 'solved' (BBC News)
* Sound of the Tunguska event (reconstruction)
* The Tunguska Event 100 Years later NASA
* There Was a Hot Time in Tunguska That Night