Robert S. Langer
Robert Samuel Langer, Jr. FREng is an American chemical engineer, entrepreneur and one of the 10 Institute Professors at the Massachusetts Institute of Technology, he was the Germeshausen Professor of Chemical and Biomedical Engineering and maintains activity in the Department of Chemical Engineering and the Department of Biological Engineering at MIT. He is a faculty member of the Harvard-MIT Division of Health Sciences and Technology and the David H. Koch Institute for Integrative Cancer Research, he is a recognized and cited researcher in biotechnology in the fields of drug delivery systems and tissue engineering. His publications have been cited over 273,000 times and his h-index is 261. According to Google Scholar, Langer is one of 7 most cited individuals in history, he is the most cited engineer in history. Langer's research laboratory at MIT is the largest biomedical engineering lab in the world. In 2015, Langer was awarded the Queen Elizabeth Prize for Engineering. Langer was born August 29, 1948 in Albany, New York, USA.
He is an alumnus of The Milne School and received his bachelor's degree from Cornell University in chemical engineering. He earned his Sc. D. in chemical engineering from MIT in 1974. His dissertation was entitled "Enzymatic regeneration of ATP" and completed under the direction of Clark K. Colton. From 1974–1977 he worked as a postdoctoral fellow for cancer researcher Judah Folkman at the Children's Hospital Boston and at Harvard Medical School. Langer credits Folkman as a fantastic role model. Langer and his wife, a fellow MIT graduate, have three children. Langer is regarded for his contributions to medicine and biotechnology, he is considered a pioneer of many new technologies, including controlled release systems and transdermal delivery systems, which allow the administration of drugs or extraction of analytes from the body through the skin without needles or other invasive methods. Langer worked with Judah Folkman at Boston Children's Hospital to isolate the first angiogenesis inhibitor, a macromolecule to block the spread of blood vessels in tumors.
Macromolecules tend to be broken down by digestion and blocked by body tissues if they are injected or inhaled, so finding a delivery system for them is difficult. Langer's idea was to encapsulate the angiogenesis inhibitor in a noninflammatory synthetic polymer system that could be implanted in the tumor and control the release of the inhibitor, he invented polymer systems that would work. This discovery is considered to lay the foundation for much of today's drug delivery technology, he worked with Henry Brem of the Johns Hopkins University Medical School on a drug-delivery system for the treatment of brain cancer, to deliver chemotherapy directly to a tumor site. The wafers or chips that he and his teams have designed have become more sophisticated, can now deliver multiple drugs, respond to stimuli. Langer is regarded as the founder of tissue engineering in regenerative medicine, he and the researchers in his lab have made advances in tissue engineering, such as the creation of engineered blood vessels and vascularized engineered muscle tissue.
Bioengineered synthetic polymers provide a scaffolding on which new skin, muscle and entire organs can be grown. With such a substrate in place, victims of serious accidents or birth defects could more grow missing tissue; such polymers can be biodegradable. Langer is involved in several projects related to diabetes. Alongside Daniel G. Anderson, he has contributed bioengineering work to a project involving teams from MIT, Harvard University and other institutions, to produce an implantable device to treat type 1 diabetes by shielding insulin-producing beta cells from immune system attacks, he is part of a team at MIT that have developed a drug capsule that could be used to deliver oral doses of insulin to people with type 1 diabetes. Langer holds over pending patents, he is one of the world's most cited researchers, having authored over 1,400 scientific papers, has participated in the founding of multiple technology companies. Langer is the youngest person in history to be elected to all three American science academies: the National Academy of Sciences, the National Academy of Engineering and the Institute of Medicine.
He was elected as a charter member of National Academy of Inventors. He was appointed an International Fellow of the Royal Academy of Engineering in 2010. Langer has received more than 220 major awards, he is one of four living individuals to have received both the U. S. National Medal of Science and the National Medal of Technology and Innovation. 2018: Inducted into Advanced Materials Hall of Fame 2018: Leadership Award for Historic Scientific Advancement, American Chemical Society 2018: Named 1# Translational Researcher in the World by Nature Biotechnology. 2017: Named 1# Translational Researcher in the World by Nature Biotechnology. 2017: Kabiller Prize, World's Largest Prize in Nanomedicine. 2016: Benjamin Franklin Medal in Life Science 2015: Hoover Medal 2015: Kazemi Prize 2015: Scheele Award 2015: Named Cornell University's 2015 Entrepreneur of the Year. 2015: Queen Elizabeth Prize for Engineering, the most influential prize in the world for engineering. 2014: Kyoto Prize 2014: Awarded the $3 million Breakthrough Prize in Life Sciences for his work.
2014: The Biotechnology Industry Organization and the Chemical Heritage Foundation selected Robert Langer as the winner of the 2014 Biotechnology Heritage Award for significant contribution to the growth of biotechnology. 2013: IEEE Medal for Innovations in Healthcare Technology 2013
Sir Timothy John Berners-Lee known as TimBL, is an English engineer and computer scientist, best known as the inventor of the World Wide Web. He is a professor of computer science at the University of Oxford and the Massachusetts Institute of Technology, he made a proposal for an information management system on March 12, 1989, he implemented the first successful communication between a Hypertext Transfer Protocol client and server via the internet in mid-November the same year. Berners-Lee is the director of the World Wide Web Consortium, which oversees the continued development of the Web, he is the founder of the World Wide Web Foundation and is a senior researcher and holder of the 3Com founders chair at the MIT Computer Science and Artificial Intelligence Laboratory. He is a director of the Web Science Research Initiative, a member of the advisory board of the MIT Center for Collective Intelligence. In 2011, he was named as a member of the board of trustees of the Ford Foundation, he is a founder and president of the Open Data Institute, is an advisor at social network MeWe.
In 2004, Berners-Lee was knighted by Queen Elizabeth II for his pioneering work. In April 2009, he was elected a foreign associate of the United States National Academy of Sciences. Named in Time magazine's list of the 100 Most Important People of the 20th century, Berners-Lee has received a number of other accolades for his invention, he was honoured as the "Inventor of the World Wide Web" during the 2012 Summer Olympics opening ceremony, in which he appeared in person, working with a vintage NeXT Computer at the London Olympic Stadium. He tweeted "This is for everyone", spelled out in LCD lights attached to the chairs of the 80,000 people in the audience. Berners-Lee received the 2016 Turing Award "for inventing the World Wide Web, the first web browser, the fundamental protocols and algorithms allowing the Web to scale". Berners-Lee was born in London, United Kingdom, one of four children born to Mary Lee Woods and Conway Berners-Lee, his parents worked on the first commercially built computer, the Ferranti Mark 1.
He attended Sheen Mount Primary School, went on to attend south west London's Emanuel School from 1969 to 1973, at the time a direct grant grammar school, which became an independent school in 1975. A keen trainspotter as a child, he learnt about electronics from tinkering with a model railway, he studied at The Queen's College, from 1973 to 1976, where he received a first-class bachelor of arts degree in physics. While he was at university, Berners-Lee made a computer out of an old television set, which he bought from a repair shop. After graduation, Berners-Lee worked as an engineer at the telecommunications company Plessey in Poole, Dorset. In 1978, he joined D. G. Nash in Ferndown, where he helped create type-setting software for printers. Berners-Lee worked as an independent contractor at CERN from June to December 1980. While in Geneva, he proposed a project based on the concept of hypertext, to facilitate sharing and updating information among researchers. To demonstrate it, he built a prototype system named ENQUIRE.
After leaving CERN in late 1980, he went to work at John Poole's Image Computer Systems, Ltd, in Bournemouth, Dorset. He ran the company's technical side for three years; the project he worked on was a "real-time remote procedure call" which gave him experience in computer networking. In 1984, he returned to CERN as a fellow. In 1989, CERN was the largest internet node in Europe, Berners-Lee saw an opportunity to join hypertext with the internet: I just had to take the hypertext idea and connect it to the Transmission Control Protocol and domain name system ideas and—ta-da!—the World Wide Web... Creating the web was an act of desperation, because the situation without it was difficult when I was working at CERN later. Most of the technology involved in the web, like the hypertext, like the internet, multifont text objects, had all been designed already. I just had to put them together, it was a step of generalising, going to a higher level of abstraction, thinking about all the documentation systems out there as being part of a larger imaginary documentation system.
Berners-Lee wrote his proposal in March 1989 and, in 1990, redistributed it. It was accepted by his manager, Mike Sendall, who called his proposals'vague, but exciting', he used similar ideas to those underlying the ENQUIRE system to create the World Wide Web, for which he designed and built the first Web browser. His software functioned as an editor, the first Web server, CERN HTTPd. Mike Sendall buys a NeXT cube for evaluation, gives it to Tim. Tim's prototype implementation on NeXTStep is made in the space of a few months, thanks to the qualities of the NeXTStep software development system; this prototype offers WYSIWYG browsing/authoring! Current Web browsers used in'surfing the internet' are mere passive windows, depriving the user of the possibility to contribute. During some sessions in the CERN cafeteria, Tim and I try to find a catching name for the system. I was determined that the name should not yet again be taken from Greek mythology..... Tim proposes'World-Wide Web'. I like this much, except that it is difficult to pronounce in French... by Robert Cailliau, 2 November 1995.
The first website was built at CERN. Despite this being an international organisation hosted by Switzerland, the office that Berners-Lee used was just across the border in France; the website was put online on 6 August 1991 for the first time: info.cern.ch was th
Charles K. Kao
Sir Charles Kuen Kao was a physicist and electrical engineer who pioneered the development and use of fibre optics in telecommunications. In the 1960s, Kao created various methods to combine glass fibres with lasers in order to transmit digital data, which laid the groundwork for the evolution of the Internet. Known as the "Godfather of Broadband", the "Father of Fiber Optics", the "Father of Fiber Optic Communications", Kao was awarded the 2009 Nobel Prize in Physics for "groundbreaking achievements concerning the transmission of light in fibers for optical communication". Born in Shanghai, Kao was a permanent resident of Hong Kong and held citizenships in the United Kingdom and the United States. Charles Kao was born in Shanghai, China in 1933, his ancestral home is in nearby Jinshan, at that time a separate administrative area, he studied Chinese classics at home under a tutor. He studied English and French at an international school in Shanghai French Concession, founded by a number of progressive Chinese educators including Cai Yuanpei.
Kao's family moved to Taiwan and British Hong Kong in 1948 where he completed his secondary education at St. Joseph's College in 1952, he did his undergraduate studies in electrical engineering at Woolwich Polytechnic, obtaining his Bachelor of Engineering degree. He pursued research and received his PhD in electrical engineering in 1965 from University of London, under Professor Harold Barlow of University College London as an external student while working at Standard Telecommunication Laboratories in Harlow, the research centre of Standard Telephones and Cables, it is there that Kao did his first groundbreaking work as an engineer and researcher working alongside George Hockham under the supervision of Alec Reeves. Kao's father Kao Chun-Hsiang was a lawyer who obtained his J. D. from the University of Michigan Law School in 1925. He was a professor at Soochow University Comparative Law School of China, his grandfather was Gao Xie, a famous scholar, literator, a leading figure of the South Society during the late Qing Dynasty.
Some influential writers including Gao Xu, Yao Guang, Gao Zeng were Gao's close relatives. His father's cousin was astronomer Kao Ping-tse. Kao has a younger brother named Timothy Wu Kao, a civil engineer and Professor Emeritus at the Catholic University of America in Washington, D. C, his research is in hydrodynamics. Kao met his future wife Gwen May-Wan Kao in London after graduation, when they worked together as engineers at Standard Telephones and Cables, she is British Chinese. They were married in 1959 in London, had two children, a son and a daughter, both of whom reside and work in Silicon Valley, California. According to Kao's autobiography, Kao was a Catholic who attended Catholic Church while his wife attended Anglican Communion. In the 1960s at Standard Telecommunication Laboratories based in Harlow, Essex and his co-workers did their pioneering work in the realisation of fibre optics as a telecommunications medium, by demonstrating that the high-loss of existing fibre optics arose from impurities in the glass, rather than from an underlying problem with the technology itself.
In 1963, when Kao first joined the optical communications research team he made notes summarising the background situation and available technology at the time, identifying the key individuals involved. Kao worked in the team of Antoni E. Karbowiak, working under Alec Reeves to study optical waveguides for communications. Kao's task was to investigate fibre attenuation, for which he collected samples from different fibre manufacturers and investigated the properties of bulk glasses carefully. Kao's study convinced himself that the impurities in material caused the high light losses of those fibres; that year, Kao was appointed head of the electro-optics research group at STL. He took over the optical communication program of STL in December 1964, because his supervisor, left to take the Chair in Communications in the School of Electrical Engineering at the University of New South Wales, Australia. Although Kao succeeded Karbowiak as manager of optical communications research, he decided to abandon Karbowiak's plan and overall change research direction with his colleague George Hockham.
They not only considered optical physics but the material properties. The results were first presented by Kao to the IEE in January 1966 in London, further published in July with George Hockham; this study first theorized and proposed to use glass fibres to implement optical communication, the ideas described are the basis of today's optical fibre communications. In 1965, Kao with Hockham concluded that the fundamental limitation for glass light attenuation is below 20 dB/km, a key threshold value for optical communications. However, at the time of this determination, optical fibres exhibited light loss as high as 1,000 dB/km and more; this conclusion opened the intense race to find low-loss materials and suitable fibres for reaching such criteria. Kao, together with his new team, pursued this goal by testing various materials, they measured the attenuation of light with different wavelengths in glasses
An optical fiber is a flexible, transparent fiber made by drawing glass or plastic to a diameter thicker than that of a human hair. Optical fibers are used most as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths than electrical cables. Fibers are used instead of metal wires. Fibers are used for illumination and imaging, are wrapped in bundles so they may be used to carry light into, or images out of confined spaces, as in the case of a fiberscope. Specially designed fibers are used for a variety of other applications, some of them being fiber optic sensors and fiber lasers. Optical fibers include a core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers, while those that support a single mode are called single-mode fibers.
Multi-mode fibers have a wider core diameter and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 1,000 meters. Being able to join optical fibers with low loss is important in fiber optic communication; this is more complex than joining electrical wire or cable and involves careful cleaving of the fibers, precise alignment of the fiber cores, the coupling of these aligned cores. For applications that demand a permanent connection a fusion splice is common. In this technique, an electric arc is used to melt the ends of the fibers together. Another common technique is a mechanical splice, where the ends of the fibers are held in contact by mechanical force. Temporary or semi-permanent connections are made by means of specialized optical fiber connectors; the field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics.
The term was coined by Indian physicist Narinder Singh Kapany, acknowledged as the father of fiber optics. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London, 12 years later. Tyndall wrote about the property of total internal reflection in an introductory book about the nature of light in 1870:When the light passes from air into water, the refracted ray is bent towards the perpendicular... When the ray passes from water to air it is bent from the perpendicular... If the angle which the ray in water encloses with the perpendicular to the surface be greater than 48 degrees, the ray will not quit the water at all: it will be reflected at the surface.... The angle which marks the limit where total reflection begins is called the limiting angle of the medium. For water this angle is 48°27′, for flint glass it is 38°41′, while for diamond it is 23°42′.
In the late 19th and early 20th centuries, light was guided through bent glass rods to illuminate body cavities. Practical applications such as close internal illumination during dentistry appeared early in the twentieth century. Image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. In the 1930s, Heinrich Lamm showed that one could transmit images through a bundle of unclad optical fibers and used it for internal medical examinations, but his work was forgotten. In 1953, Dutch scientist Bram van Heel first demonstrated image transmission through bundles of optical fibers with a transparent cladding; that same year, Harold Hopkins and Narinder Singh Kapany at Imperial College in London succeeded in making image-transmitting bundles with over 10,000 fibers, subsequently achieved image transmission through a 75 cm long bundle which combined several thousand fibers. Their article titled "A flexible fibrescope, using static scanning" was published in the journal Nature in 1954.
The first practical fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C. Wilbur Peters, Lawrence E. Curtiss, researchers at the University of Michigan, in 1956. In the process of developing the gastroscope, Curtiss produced the first glass-clad fibers. A variety of other image transmission applications soon followed. Kapany coined the term fiber optics, wrote a 1960 article in Scientific American that introduced the topic to a wide audience, wrote the first book about the new field; the first working fiber-optical data transmission system was demonstrated by German physicist Manfred Börner at Telefunken Research Labs in Ulm in 1965, followed by the first patent application for this technology in 1966. NASA used fiber optics in the television cameras. At the time, the use in the cameras was classified confidential, employees handling the cameras had to be supervised by someone with an appropriate security clearance. Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables were the first, in 1965, to promote the idea that the attenuation in optical fibers could be reduced below 20 decibels per kilometer, making fibers a practical communication medium.
They proposed th
Draper Laboratory is an American not-for-profit research and development organization, headquartered in Cambridge, Massachusetts. The laboratory specializes in the design and deployment of advanced technology solutions to problems in national security, space exploration, health care and energy; the laboratory was founded in 1932 by Charles Stark Draper at the Massachusetts Institute of Technology to develop aeronautical instrumentation, came to be called the "MIT Instrumentation Laboratory". It was renamed for its founder in 1970 and separated from MIT in 1973 to become an independent, non-profit organization; the expertise of the laboratory staff includes the areas of guidance and control technologies and systems. In 1932 Charles Stark Draper, an MIT aeronautics professor, created a teaching laboratory to develop the instrumentation needed for tracking and navigating aircraft. During World War II, Draper’s lab was known as the “Confidential Instrument Development Laboratory”; the name was changed to the MIT Instrumentation Laboratory.
The laboratory was renamed for its founder in 1970 and remained a part of MIT until 1973 when it became an independent, not-for-profit research and development corporation. The transition to an independent corporation arose out of pressures for divestment of MIT laboratories doing military research at the time of the Vietnam War, despite the absence of a role of the laboratory in that war. A primary focus of the laboratory's programs throughout its history has been the development and early application of advanced guidance and control technologies to meet the U. S. Department of Defense’s and NASA’s needs; the laboratory’s achievements includes the design and development of accurate and reliable guidance systems for undersea-launched ballistic missiles as well as the Apollo Guidance Computer that guided the Apollo astronauts to the Moon and back safely to Earth, every time. The laboratory contributed to the development of inertial sensors and other systems for the GN&C of commercial and military aircraft, submarines and tactical missiles and unmanned vehicles.
Inertial-based GN&C systems were central for navigating ballistic missile submarines for long periods of time undersea to avoid detection and guiding their submarine-launched ballistic missiles to their targets, starting with the UGM-27 Polaris missile program. Draper has locations in several U. S. cities: Cambridge, MA Houston, TX at NASA Johnson Space Center Reston, VA Huntsville, ALFormer locations include Tampa, FL at University of South Florida, St. Petersburg, FL. According to its website, the laboratory staff applies its expertise to autonomous air, land and space systems; when appropriate, Draper works with partners to transition their technology to commercial production. The laboratory encompasses seven areas of technical expertise: Strategic Systems—Application of guidance and control expertise to hybrid GPS-aided technologies and to submarine navigation and strategic weapons security. Space Systems—As "NASA’s technology development partner and transition agent for planetary exploration", development of GN&C and high-performance science instruments.
Expertise addresses the national security space sector. Tactical Systems—Development of: maritime intelligence and reconnaissance platforms, miniaturized munitions guidance, guided aerial delivery systems for materiel, soldier-centered physical and decision support systems, secure electronics and communications, early intercept guidance for missile defense engagement. Special Programs—Concept development, low-rate production, field support for first-of-a-kind systems, connected with the other technical areas. Biomedical Systems—Microelectromechanical systems, microfluidic applications of medical technology, miniaturized smart medical devices. Air Warfare and ISR—Intelligence technology for targeting and target planning applications. Energy Solutions—Managing the reliability and performance of equipment throughout complex energy generation and consumption systems, including coal-fired power plants or the International Space Station. Project areas that have surfaced in the news referred to Draper Laboratory's core expertise in inertial navigation, as as 2003.
More emphasis has shifted to research in innovative space navigation topics, intelligent systems that rely on sensors and computers to make autonomous decisions, nano-scale medical devices. The laboratory staff has studied ways to integrate input from Global Positioning Systems into Inertial navigation system-based navigation in order to lower costs and improve reliability. Military inertial navigation systems cannot rely on GPS satellite availability for course correction—required by error growth—owing to blocking or jamming of signal. A less accurate inertial system means a less costly system, but one that requires more frequent checking of position from another source, like GPS. Systems that integrate GPS with INS are classified as “loosely coupled”, “tightly coupled”, or "deeply integrated", depending on the degree of integration of the hardware; as of 2006, it was envisioned that many military and civilian uses would integrate
Global Positioning System
The Global Positioning System Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Air Force. It is a global navigation satellite system that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. Obstacles such as mountains and buildings block the weak GPS signals; the GPS does not require the user to transmit any data, it operates independently of any telephonic or internet reception, though these technologies can enhance the usefulness of the GPS positioning information. The GPS provides critical positioning capabilities to military and commercial users around the world; the United States government created the system, maintains it, makes it accessible to anyone with a GPS receiver. The GPS project was launched by the U. S. Department of Defense in 1973 for use by the United States military and became operational in 1995.
It was allowed for civilian use in the 1980s. Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS and implement the next generation of GPS Block IIIA satellites and Next Generation Operational Control System. Announcements from Vice President Al Gore and the White House in 1998 initiated these changes. In 2000, the U. S. Congress authorized the modernization effort, GPS III. During the 1990s, GPS quality was degraded by the United States government in a program called "Selective Availability"; the GPS system is provided by the United States government, which can selectively deny access to the system, as happened to the Indian military in 1999 during the Kargil War, or degrade the service at any time. As a result, several countries have developed or are in the process of setting up other global or regional satellite navigation systems; the Russian Global Navigation Satellite System was developed contemporaneously with GPS, but suffered from incomplete coverage of the globe until the mid-2000s.
GLONASS can be added to GPS devices, making more satellites available and enabling positions to be fixed more and to within two meters. China's BeiDou Navigation Satellite System is due to achieve global reach in 2020. There are the European Union Galileo positioning system, India's NAVIC. Japan's Quasi-Zenith Satellite System is a GPS satellite-based augmentation system to enhance GPS's accuracy; when selective availability was lifted in 2000, GPS had about a five-meter accuracy. The latest stage of accuracy enhancement uses the L5 band and is now deployed. GPS receivers released in 2018 that use the L5 band can have much higher accuracy, pinpointing to within 30 centimetres or 11.8 inches. The GPS project was launched in the United States in 1973 to overcome the limitations of previous navigation systems, integrating ideas from several predecessors, including classified engineering design studies from the 1960s; the U. S. Department of Defense developed the system, which used 24 satellites, it was developed for use by the United States military and became operational in 1995.
Civilian use was allowed from the 1980s. Roger L. Easton of the Naval Research Laboratory, Ivan A. Getting of The Aerospace Corporation, Bradford Parkinson of the Applied Physics Laboratory are credited with inventing it; the work of Gladys West is credited as instrumental in the development of computational techniques for detecting satellite positions with the precision needed for GPS. The design of GPS is based on similar ground-based radio-navigation systems, such as LORAN and the Decca Navigator, developed in the early 1940s. Friedwardt Winterberg proposed a test of general relativity – detecting time slowing in a strong gravitational field using accurate atomic clocks placed in orbit inside artificial satellites. Special and general relativity predict that the clocks on the GPS satellites would be seen by the Earth's observers to run 38 microseconds faster per day than the clocks on the Earth; the GPS calculated positions would drift into error, accumulating to 10 kilometers per day. This was corrected for in the design of GPS.
Winterberg, Friedwardt. “Relativistische Zeitdilatation eines künstlichen Satelliten ” When the Soviet Union launched the first artificial satellite in 1957, two American physicists, William Guier and George Weiffenbach, at Johns Hopkins University's Applied Physics Laboratory decided to monitor its radio transmissions. Within hours they realized that, because of the Doppler effect, they could pinpoint where the satellite was along its orbit; the Director of the APL gave them access to their UNIVAC to do the heavy calculations required. Early the next year, Frank McClure, the deputy director of the APL, asked Guier and Weiffenbach to investigate the inverse problem—pinpointing the user's location, given that of the satellite; this led them and APL to develop the TRANSIT system. In 1959, ARPA played a role in TRANSIT. TRANSIT was first tested in 1960, it used a constellation of five satellites and could provide a navigational fix once per hour. In 1967, the U. S. Navy developed the Timation satellite, which proved the feasibility of placing accurate clocks in space, a technology required for GPS.
In the 1970s, the ground-based OMEGA navigation system, based on phase comparison of signal transmission from pairs of stations