Gravity Assist

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At a great lost to the world,  unfortunately Dr. Michael A Minovitch now resides in heaven.  He passed away on September 16th, 2022

For information pertaining to Dr. Minovitch's inventions, discoveries, patents, historial papers, etc., please contact:

Bill Cress, CEO & CFO 

AccessAerospace, LLC

Tel 973-489-5701 or email Bill@AccessAerospace.com 

28 Worcester Dr, Wayne NJ 07470 US

 

Background Information and Purpose of this Web Site

The Classical Theory of Space Travel and the Impossibility of Exploring Most of the Solar System

The Creation of a new Theory of Space Travel -- Gravity Propelled Space Travel

How Did Minovitch Discover (Create) His New Theory Of Space Travel?

A Technical Explanation of Minovitch’s Theory of Gravity Propelled Interplanetary Space Travel.

The Missions That Minovitch’s New Theory of Space Travel Made Possible

The IAF Project

Design of the Web Site

How The Web Site Can Be Used To Obtain The Most Technically and Historically Correct Description of the Invention

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Background Information and Purpose of this Web Site

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The history behind the exploration and determination of the structure of atomic and subatomic particles is well known and described in countless science books.  The fact that it required the invention of various particle accelerators such as linear accelerators and cyclotrons in order to generate the high kinetic energies is taught in every high school and college physics class.  However, the history behind the exploration and determination of the structure of the Solar System using instrumented spacecraft is very hard to find and virtually unknown.  Although the accumulated scientific information obtained from these spacecraft is filling row after row of professional journals in astrophysics, and space science in every large science library, an accurate description of the history behind the technical breakthrough that made it possible to circumvent the classical high-energy barriers of reaction propulsion cannot be found in a single book.  The purpose of this Web Site is intended to correct this problem by identifying the key technical papers and references describing this breakthrough.

 

The Classical Theory of Space Travel and the Impossibility of Exploring Most of the Solar System

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The Classical Theory of space travel was based on Newton’s Third Law of Motion  -- For Every Action There is An Equal And Opposite Reaction.  Thus, by burning a combustible fuel (propellant) using an oxidizer and expelling the combustion products in one direction at high velocity, an equal and opposite reaction thrust is generated in the opposite direction.  This thrust generating principle is independent of any surrounding medium, and works best when there is no surrounding medium such as the vacuum of space.  This concept was so elementary it became the basic principle for achieving vehicle propulsion above the Earth’s atmosphere, and hence the theoretical possibilities of achieving interplanetary space travel.  It became known as “reaction propulsion,”

 

When this classical theory of space travel became an engineering research and development effort in the 1930s, it became apparent that only a small fraction of the Solar System could ever be reached with space vehicles.  The propulsive energy required to send a vehicle to distant targets in the Solar System was enormous.  The problem was that this energy had to be generated off the Earth’s surface by the combustible fuel that had to be carried by the vehicle itself along with the oxidizer.  The relatively low energy densities of chemical propellants required huge amounts of propellant to generate any significant amount of propulsive energy.  Unfortunately, this increased the vehicle’s inertial mass which required even more energy to overcome.  Thus, the exploration of the entire Solar System was believed to be a technical impossibility by all of the early pioneers.  A casual investigation of the early history of interplanetary space travel reveals that one of the most famous pioneers who contributed in formulating the basic theory, Professor Hermann Oberth, actually proved mathematically that the exploration of most of the Solar System would not be possible.

 


 

With the advent of nuclear power generation after World War II the theoretical possibility of breaking the high-energy barriers of classical space travel based on reaction propulsion and exploring the entire Solar System changed.   If certain technical problems could be solved, it would indeed be possible to explore the entire Solar System.  Although the United States spent about two billion dollars over a period of many years beginning in the 1950s in an effort to solve these technical problems, they were simply too difficult to surmount.  (The Soviet Union and other countries also tried to solve the problems, but were also unsuccessful.)  The required advanced nuclear propulsion systems were simply beyond engineering feasibility.  When this information became an undeniable fact in the mid-1960s, it appeared that most of the Solar System would indeed remain unknown.  However, in a relatively short period of time beginning in the 1970s, most of the major bodies and regions of the Solar System were explored, and it was achieved with relatively small launch vehicles and conventional chemical rocket propulsion.  And this included regions close to the sun, regions far above and below the ecliptic plane over the sun’s polar regions, and deep space far beyond the orbit of Pluto.  The entire three-dimensional particle and field structure of the Solar System was essentially completely determined.

 

How was this achieved?  How was it possible to penetrate one of the most fundamental energy barriers of space science?  What was the technical breakthrough that made it possible?  The answer to these questions is very simple but virtually unknown.  It was achieved by a fundamentally new theory of space travel invented by Dr. Michael A. Minovitch in 1961 which he calls “Gravity Propelled Interplanetary Space Travel.”

 

The Creation of a new Theory of Space Travel -- Gravity Propelled Space Travel 

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The Invention of Minovitch’s theory of Gravity Propelled Interplanetary Space Travel was so radical it did not require any rocket fuel or any on-board energy generating system, but was capable of generating vehicle velocities far greater than the most advanced nuclear propulsion system, and was independent of the vehicle’s mass.  Moreover, it was not even based on Newton’s Third Law of Motion.  When Minovitch presented it to JPL in the form of 47 page technical paper dated August 23, 1961, it was dismissed by the head of JPL’s Trajectory Group as impossible.  How could a young graduate student in mathematics and physics who never studied the problem of space propulsion, space travel or astrodynamics before the summer of 1961 ever invent a completely new theory of space travel that could not only be fundamentally different from the classical theory based on reaction propulsion which all of the professionals took for granted as the “only possible theory” but far surpass it in terms of what it could achieve?  The answer to this question is because Minovitch invented his theory by using his fields of expertise which were advanced mathematics and advanced physics and not using anything from the classical theory of reaction propulsion.  It was such a radical departure from the classical theory of space travel that it didn’t even use any of the most basic operating principles in the classical theory. 

How Did Minovitch Discover (Create) His New Theory Of Space Travel?

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JPL did not hire Minovitch in June 1961 to create a new theory of space travel.  He was assigned to work on a specific problem in JPL’s Trajectory Group.  It involved formulating an alternative method for solving a relatively straight-forward problem that any graduate student in mathematics or physics could have solved at that time.  The problem was to determine the parameters of a conic trajectory (semi-major axis and eccentricity) of a free-fall vehicle passing between two given points with a given flight time moving under the gravitational field of the sun.  Minovitch solved the problem and presented his solution in the form of his first JPL paper dated July 21, 1961.  His supervisor liked the paper and instructed him to prepare the paper as a formal external laboratory publication known as a JPL Technical Report.

 

During this process, Minovitch became interested in a much more difficult trajectory problem that was still unsolved at that time.  It was the problem of determining the exact three-dimensional approach trajectory of a free-fall space vehicle approaching some target planet (Mars) such that the effect of its gravitational field, acting simultaneously and continuously with the gravitational field of the sun, will deflect the vehicle’s trajectory without rocket propulsion onto a new trajectory such that the vehicle will return to the launch planet at some unknown future time.  The problem was difficult because it required solving one of the most difficult and famous problems of celestial mechanics known as the “Restricted Three-Body Problem” for motion through the solar system.  (The Restricted Three-Body Problem of celestial mechanics involved determining the trajectory of a body having negligible mass moving under the simultaneous gravitational influence of two other bodies having much larger mass moving under the influence of their mutual gravitational fields.)  Minovitch believed that he could solve this round-trip trajectory problem by developing a different method for defining a conic orbit in three-dimensional space and using a technique for numerically solving complicated differential equations known as “differential corrections.”  He began working 12 to 16 hours a day both at JPL and at home in July 1961.

 

While working on this problem, he discovered something while converting from a planet centered reference frame to a sun centered reference frame that he immediately recognized could be used as the basis for creating an entirely new theory for achieving unlimited interplanetary space travel throughout the entire solar system without using any rocket propulsion whatsoever -- his theory of gravity propelled interplanetary space travel.  What he discovered is that relative to the sun centered reference frame, the vehicle’s orbital energy after the planetary flyby will always be different from the vehicle’s pre-encounter orbital energy which can be very large depending on the distance of closest approach, and the mass of the flyby planet.  Mathematically, he still did not know if his new analytical techniques represented the first numerical solution of the unsolved Restricted Three-Body Problem.  But he knew that if he did solve this problem, he could apply his solution serially and hence his new theory for achieving unlimited interplanetary space travel throughout the entire solar system would become a reality. 

A Technical Explanation of Minovitch’s Theory of Gravity Propelled Interplanetary Space Travel.

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With the ability to determine the precise approach trajectory that a free-fall space vehicle needed to have while approaching a target planet such that the effect of its gravitational field, together with the gravitational field of the sun acting continuously and simultaneously brings the vehicle back to Earth, Minovitch recognized that the energy change generated by the planetary flyby itself could be used as a propulsive source to catapult the vehicle to a more distant planet instead of returning it back to Earth (which could always be achieved without any change in orbital energy).  This change in orbital energy provided a means for reaching a distant planet using only an initial amount of launch energy that was a small fraction of what would ordinarily be required using the traditional “minimum-energy” Hohmann direct-transfer trajectory which all the professionals believed represented the minimum-energy trajectory required for reaching any planet in the Solar System.  What Minovitch recognized was that a distant, hard-to-reach planet, could be reached by launching a free-fall vehicle to an easy-to-reach near-by planet and using the gravitational field of that planet to catapult the vehicle to the distant target planet without using any additional rocket propulsion beyond the relatively little amount needed for reaching the intermediate planet.  It was a significant discovery because it represented a means for reaching a distant target planet using an amount of launch energy way below that of the famous Hohmann “minimum-energy” co-tangential trajectory which was one of the most important and oldest principles of the classical theory of space travel.   But Minovitch recognized much more than this.

 

Minovitch also recognized that the more distant planet could be utilized in the same manner to change the trajectory without rocket propulsion and catapult it to another more distant planet in a process that could be continued indefinitely.  Once the vehicle is launched from Earth, it became possible to achieve unlimited interplanetary space travel to explore the entire Solar System without using any rocket propulsion beyond that needed for the initial escape from Earth.  Thus, the new theory of space travel that Minovitch invented during the summer of 1961 could be represented by a non-stop multiplanetary trajectory having the form P1 – P2 – P3 ··· – PN where P1 represents the launch planet, P2, P3, ... ,PN-1 represents N-2 intermediate “gravity propulsion planets” and PN represents the final planet or target body in the trajectory.  It is achieved by applying the mathematical solution of the Restricted Three-Body Problem serially to determine the precise approach trajectory to each successive flyby planet Pi (i = 2, 3, ... N-1) such that its gravitational field will catapult the vehicle to the next planet Pi+1 in the series.  It is a problem much more difficult than the classical Restricted Three-Body Problem because there are N-1 flybys instead of only one, and each flyby had to have a distance of closest approach to the center to each planet greater than the planet’s radius to avoid crashing into the planet’s surface.  The theory represented one of the most elegant and sophisticated applications of analytical mechanics ever conceived, and one of the most mathematically difficult to solve.  At that time, (1961) the much easier Restricted Three-Body Problem for motion through the Solar System was unsolved and regarded as one of the most difficult of all the unsolved problems of celestial mechanics.  Minovitch received confirmation that he solved the much more difficult problem of determining gravity propelled interplanetary trajectories necessary to implement his new theory of space travel near the end of April 1962. 

The Missions That Minovitch’s New Theory of Space Travel Made Possible

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One of the most important facts in the history of space travel is that the advanced nuclear propulsion systems were never developed.  (And they have still not been developed.)  By the mid 1960s, after spending over two billion dollars in the effort (and huge amounts by other countries), it became evident that the advanced systems were beyond engineering feasibility.  The exploration of most of the Solar System appeared to be beyond technical possibility.  One of the most ironic and little known facts in the history of space travel is the fact that the exploration of most the Solar System could not be achieved within the classical theory laid down by the founding pioneers.  But most of the Solar System was explored, and it was carried out with ordinary chemical rocket propulsion and relatively small launch vehicles in a short period of about 35 years.   This is what Minovitch’s invention of gravity propelled interplanetary space travel accomplished -- it made it possible to explore the entire Solar System with instrumented space vehicles.  It achieved what was believed to be impossible within the classical theory set forth by Tsiolkovsky, Goddard and Oberth.

 

The gravity propelled trajectories and their names that were made possible by this new theory of space travel were: Earth-Venus-Mercury (Mariner 10); Earth-Jupiter-Interstellar (Pioneer 10); Earth-Jupiter-Saturn-Interstellar (Pioneer 11); Earth-Jupiter-Saturn-Interstellar (Voyager 1); Earth-Jupiter-Saturn-Uranus-Neptune-Interstellar (Voyager 2); Earth-Jupiter-Out-Of-Ecliptic (Ulysses); and the low launch-energy mission, Earth-Venus-Earth-Earth-Jupiter (Galileo).  The combined scientific information obtained from these missions filled many books on astrophysics, space science, and geology, and essentially represented the first detailed information on the structure of the Solar System.  There are also new gravity propelled missions such as the Earth-Venus-Venus-Earth-Jupiter-Saturn (Cassini) mission that enabled a spacecraft to be placed into orbit around Saturn using a relatively small launch vehicle, and the exploration of Pluto using an Earth-Jupiter-Pluto trajectory. And there are other gravity-assist missions to small bodies such as comets and asteroids in various stages of planning.

 The invention, therefore, was one of the most important in the history of space travel because it literally made it possible to explore most of the Solar System.  It was the invention that broke the minimum-energy requirements set by Hohmann’s direct-transfer trajectory that were previously believed to be unbreakable.  It is therefore critically important for the history of space travel to thoroughly document the invention.  Minovitch believes that he has a responsibility to accurately explain the historical and technical aspects of the invention and provide this information, along with the all-important documentation, to the entire world via the Internet so that it can be accurately preserved as part of our common space heritage. 

The IAF Project 

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It is believed that the advancement of science and technology has two important components.  First, the benefits that the inventions bring to society as a whole and secondly; the human story behind the invention that represents the human advancement of Civilization.  The invention of gravity propelled space travel was fundamentally important in the advancement of science because it made it possible to explore the entire Solar System with instrumented spacecraft.  Most of the physical and field structure of Solar System was made possible by this invention.  However, the invention could never have taken place if it were not for achieving the technical means that made it possible -- discovering the first analytical solution of the Restricted Three Body Problem of celestial mechanics for motion through the solar system.  Thus, the invention represented a significant technical achievement in its own rite and a significant achievement in terms of what it accomplished in the technical ability to discover new scientific information previously believed to be unattainable for a very long time.  The detailed story behind this invention has been presented and documented in three very detailed professional papers published by the IAF (International Astronautical Federation based in Paris France) in a project that spanned almost 10 years.

 

In 1989, while the Voyager 2 spacecraft was approaching Neptune, JPL and NASA published a book entitled The Voyager Neptune Travel Guide, which explained the technical and historical details of this particular gravity propelled mission that was one example of Minovitch’s invention.  It was 267 pages long with an entire chapter explaining the fact that the mission was made possible by Minovitch’s invention.  Minovitch was invited to participate in the August 26, 1989 celebrations at JPL as an honored guest during the Voyager 2 flyby of Neptune.  During that time Minovitch met three individuals who expressed great interest in the history behind the invention.  Two were technical support engineers on the Voyager 2 mission named William Kosmann and Rex Ridenhoure.  The third was a space historian and member of the IAF named Richard Dowling.  These three individuals suggested that the technical and historical details of invention should be made known by publishing a series of papers on the invention by the International Astronautical Federation.  Dr. Frederick Ordway III who was friend of Mr. Dowling and an important member of this international space society concurred and encouraged the project.  These papers were entitled:

 

1.  Dowling, R.L. et al, “The Origin of Gravity-Propelled Interplanetary Space Travel,” 41stCongress of The International Astronautical Federation, October 6-12, 1990, Dresden, Germany, IAA Paper No. 90-630. (Published in, History of Rocketry and Astronautics, (ed.   J.D. Huntly), AAS History Series, Volume 19, (Donald C. Elder, Series Editor), American Astronautical Society, 1997, Ch. 2, pp. 63-102.)

Click Here for Download Information and References: The Origin of Gravity-Propelled Interplanetary Space Travel 

2.  Dowling, R.L. et al, "Gravity Propulsion Research at UCLA and JPL 1962-1964," 42nd  Congress of The International Astronautical Federation, October 5-11, 1991, Montreal,  Canada, IAA Paper No. 91-677. (Published in, History of Rocketry and Astronautics, (ed. J.D.  Huntly), AAS History Series, Volume 20, (Donald C. Elder, Series Editor), American Astronautical Society, 1997, Ch. 2, pp. 27-106.) 

Click Here for Download Information and References: Gravity Propulsion Research at USCL and JPL

3.  Dowling, R.L. et al, "The Effect of Gravity-Propelled Interplanetary Space Travel on the Exploration of the Solar System -- Historical Survey, 1961 to 2000,” 50th International Astronautical Congress, 4-8 Oct 1999/Amsterdam, The Netherlands, IAA Paper No. IAA-99-IAA.2.1.08.

Click Here for Download Information and References: The Effect of Gravity-Propelled Interplanetary Space Travel on the Exploration of the Solar System.

Design of the Web Site 

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Since these papers were intended to document the invention by citing numerous professional papers from the archival literature, and many unpublished documents from JPL and UCLA, the IAF papers represented one of the most thoroughly documented and accurate accounts of the invention ever published.  Unfortunately, the papers were academically oriented and hard to find.  Therefore, since the invention was still relatively unknown and technically misunderstood, even after the third paper was published in 1999, it was recognized that one way to correct the situation was to make the papers easily accessible to the entire world by presenting them on the Internet with the domain name “www.gravityassist.org.”  However, this project became very large because not only were the three IAF papers presented, but the hundreds of source documents (i.e. all the references for each paper) were also presented.  This represented an unprecedented source of the most accurate technical and historical information describing the invention.  Thus, all of Minovitch’s JPL papers that he wrote during the summer of 1961 were presented.  In fact, all the papers he wrote at JPL and UCLA during the time period 1961-64 were presented.  Therefore, when reading any one of the IAF papers, each reference can be examined on an individual basis by simply selecting it from the corresponding list of references.  The Web Sight is set up as a “non-profit” educational Web Sight.  Therefore, by using the provisions of the “fair use provision” of the 1977 copyright law, most of the references in all the Reports can be individually downloaded for detailed personal use and examination.  (Care is suggested to avoid any commercial use of any downloaded copyrighted material.)  All government Reports that have been copyrighted by the US Government can be downloaded.  All non-copyrighted documents such as letters, JPL technical papers, and various JPL Interoffice memorandums (IOM’s) can be downloaded provided that they will not be used for commercial use.

 Thus, the Web Site is designed and presented as an academic Web Site for the specific purpose of describing the invention of gravity propelled interplanetary space travel and its historical and technical significance by presenting essentially all of the published and unpublished documents relating to it.  

How The Web Site Can Be Used To Obtain The Most Technically and Historically Correct Description of the Invention:

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It should be pointed out and emphasized that the most accurate information describing the facts behind and surrounding any invention can only be obtained by examining the original source documents (or reproductions of them).  For example, several professional astrodynamicists from JPL have, for over 30 years, tried to describe the invention as an old idea invented by Walter Hohmann during the 1920's by citing his famous book “Die Erreichbarkeit der Himmelskorper,” R. Oldenbourg, Munich - Berlin, 1925.  However, there is an English translation of this book that is rarely cited.  It is NASA Technical Translation F-44, “The Attainability Of Heavenly Bodies,” Nov. 1960.  On pages 79-89 of this NASA document one finds how Hohmann actually designed his multiplanetary trajectories and, in particular, how he regarded the effects of planetary gravitational perturbations generated during the planetary flybys. 

 Hohmann’s own descriptions reveal that he regarded them as annoying disturbances that had to be canceled out by using on-board rocket propulsion.  This NASA English translation is only one of hundreds of documents presented on this Web Site.  When it is examined one will be able so see that all the previous publications describing Minovitch’s invention as an old idea invented by Hohmann are completely false.  This is only one example of many.  Others have tried to give the credit to the Russian astrodynamicist A. F. Tsander also working during the 1920's by citing his papers written in Russian.  Problema poleta pri pomoshchi reaktivnykh apparatova: Mezhplanetnve poletv 1925.  But this book of collected papers of Tsander has also been translated into English by NASA entitled Problems of Flight by Jet Propulsion: Interplanetary Flights --NASA Technical Translation F-147, 1964. 

An examination of this book reveals the fact that Tsander never wrote a single paper describing the possibility of multiplanetary trajectories and hence, could not have invented or anticipated Minovitch’s theory of gravity propelled interplanetary space travel.  (A close reading of the English translation of Tsander’s papers reveal that he regarded the effects of planetary perturbations as dangerous disturbances that should be avoided as much as possible.)  These facts from the NASA English translation are also part of the cited reference collection of the IAF papers given in this Web Site and prove that all the papers that have been published over the past several decades giving the credit to Tsander are also erroneous.  Still other papers have tried to give the credit to Crocco by citing his 1956 multiplanetary Earth – Mars – Venus – Earth trajectory presented at the VII International Astronautical Congress.  However, by examining a copy of that paper, which is also made available on the present Web Site, one finds that Crocco’s multiplanetary trajectory was designed by canceling out the effects of planetary perturbations to obtain an “ideal” trajectory close to a trajectory where there are no effects of planetary perturbations. 

Hence, Crocco’s multiplanetary trajectory was not an example of a gravity-assist trajectory and all the papers published in the “professional literature” (by professional astrodynamicists) over the past several decades giving the credit to Crocco are also erroneous.  One will discover that an extraordinary effort has been made by a few professional astrodynamicists to cover up Minovitch’s invention for over 40 years by claiming that it was an old idea invented by others.  And these professionals had important positions at JPL and in various professional aerospace societies such as the AIAA (American Institute of Astronautics and Aeronautics).

 Thus, the user of this Web Site will have the documented evidence to correct many completely erroneous accounts of the invention that were published decades ago that are still being published in the professional literature by professional astrodynamicists. 

Chapter 7 entitled  “Slingshot Magic,” published in, The Voyager Neptune Travel Guide, JPL/NASA Publication 89-24, June 1, 1989, pp. 103-109 is also presented to show that JPL/NASA does understand the revolutionary significance of the invention and the fact that Minovitch was the inventor.  However, for some reason, JPL Management has denied Minovitch the “official credit” for his invention that JPL routinely grants their previous employees for making important scientific discoveries.  This may be due to the fact that JPL began publishing erroneous accounts of the invention attempting to give the credit to other JPL employees many years ago.  Although Minovitch has presented JPL upper management with overwhelming documentation hoping that JPL will officially grant him “official credit” before he dies, JPL has never granted Minovitch the official credit for his revolutionary invention -- and this was the invention that JPL has been using since 1973 to explore the entire Solar System.  Minovitch therefore believes that there may be a small group at JPL that may attempt to claim the credit for his invention after he dies. This is another reason why this Web Site was created.  Minovitch is hoping that the documentation presented in the Web Site will induce some other scientific organization to grant him the honor and credit for his invention before he dies.

 To assist anyone or any organization in helping Minovitch obtain this recognition, the Web Site is also presenting the actual paper that Minovitch personally delivered to JPL’s entire upper management in 1997 containing the documentation proving that he was the person who invented gravity propelled interplanetary space travel (gravity-assist trajectories) and that JPL has a moral obligation to formally grant him this recognition and the honor that goes with it.  The paper is entitled “The Invention of Gravity Propelled Interplanetary Space Travel: A Technical And Historical Presentation To The Jet Propulsion Laboratory,” October 30, 1997.  It contains 170 references (a reproduction of each reference is included with this paper as in the case of all the IAF papers).

 In 1991, the U.S. National Academy of Sciences (together with NHK Japan) produced a 6-Part documentary series on the history of space travel entitled Space Age WQED/Pittsburgh narrated by Patrick Stewart.  Minovitch’s invention was explained in Episode 3: The Unexpected Universe.  The segment included an interview with Dr. Minovitch showing some of his original research material and trajectory computations from the 1961-1964 time period.   The segment also included some excellent footage of an IBM 7090 computer in operation during the early 1960's.  This 3rd Part can be obtained from Public Media Video by calling (800) 262-8600. 

 

Thank you for visiting this Web Site.  Please inform others interested in the history of space travel about this Web Site .

Several photographs of Minovitch are presented on the Web Site that can also be downloaded free of charge.   Home

 

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  This informational website is for you, the researcher, and is completely funded by the original author.     

 

 
All Information Copyright © 2003 Dr.  Michael A.  Minovitch