[3B2-9] man2011030004.3d 27/7/011 16:26 Page 4 Why the Arpanet Was Built Stephen J. Lukasik Georgia Institute of Technology The who, what, when, and how of the Arpanet is usually told in heroic terms—Licklider’s vision, the fervor of his disciples, the dedication of computer scientists and engineers, the work of graduate students, and so forth. Told by one of the key actors in this salient part of US and Internet history, this article addresses why the Arpanet was built. The who, what, when, and how of the Arpa- agencies, as well as to international research net is usually told in heroic terms. J.C.R. and operations communities. Licklider’s vision, the fervor of his disciples, Numerous people made substantial contri- the dedication of computer scientists and butions to this endeavor. At the very begin- engineers, the work of graduate students, ning, networks of people (US friends and and the attraction of the Arpanet to early par- foreign adversaries) provided assistance and ticipants carries with it a sense of inevitabil- pressure to succeed. In the development ity. But why the Arpanet was built is less mid-phase, the number of people contribu- frequently addressed. Writing from the view- ting their expertise, covering a number of point of the person who signed most of the technical fields, grew rapidly. And as the checks for Arpanet’s development, in this ar- bounds of both the research and user net- ticle, I detail the rationale for investing US works expanded beyond the US, the people Department of Defense resources for research participating in networking continued to and development of the first operational grow exponentially. packet-switched network. The goal was to ex- The individuals identified in Figure 1 and ploit new computer technologies to meet the in the references provide chronological tie- needs of military command and control points in a network of events and people, against nuclear threats, achieve survivable some tightly coupled, some quite loosely control of US nuclear forces, and improve coupled, and some completely accidental. military tactical and management decision Events are tied to the textual discussion making. Although not central to the decision with letters corresponding to those bracketed to pursue networking, it was recognized that in the text. these capabilities were common to non- defense needs. The Cold War The relationships among the various events The first step on the journey to networking recounted here can be better understood in computers was taken on 29 August 1949 terms of their organization into six sequences when the Soviet Union detonated its first nu- of events. ARPA’s existence and sole purpose clear weapon, a major event in the postwar was to respond to new national security con- confrontation between the US and the Soviet cerns requiring high-level visibility. In this Union.1,[A] Because aircraft were the only way case, it was the command and control of mil- to deliver a nuclear weapon to a distant target itary forces, especially those deriving from the at that point, air defense became an immedi- existence of nuclear weapons and deterring ate US concern. their use. The translation of these needs to The US took two actions. In 1948, the Air programs and capabilities were the joint re- Force had already studied the need for an sponsibility of the technical community air defense early-warning network of radar and the agency’s managers. This included stations and had an 85-station network of both network theory and engineering the limited capability underway. In December critical experiments central to making practi- 1949, the Air Force Science Advisory Board cal progress. The next steps were dependent convened an Air Defense System Engineering on the transfer of the R&D results to users, Committee (ADSEC), chaired by Massachu- both in the DoD and related US government setts Institute of Technology professor 4 IEEE Annals of the History of Computing Published by the IEEE Computer Society 1058-6180/11/$26.00 c 2011 IEEE [3B2-9] man2011030004.3d 27/7/011 16:26 Page 5 1950 1960 1970 1980 USSR/RAND/Baran ARPA/C2/Licklider MIT/UCLA/Kleinrock ARPANET/Taylor/Roberts/Kahn TRANSFER/Foster/Rechtin/Lukasik UK/Davies/Kirstein Figure 1. Chronological development of the Arpanet. The points highlight when individuals, organizations, and random chance intervened. Events are tied to the textual discussion with letters corresponding to those bracketed in the text. George Valley, with the intention of recom- In early 1950, ADSEC recommended auto- mending a system that would overcome the mating this process. Radar data would be many deficiencies of the ad hoc radar net- digitized, transmitted over telephone lines, work hurriedly being assembled (tellingly and analyzed by the new digital computers called Lashup).2 The second was on 31 Janu- being developed. The MIT Whirlwind com- ary 1950 when President Truman decided to puter, funded by the Office of Naval Research, accelerate the development of fusion weap- was seen as pointing to the technology ons to deter Soviet use of their less powerful needed for such a system. Although the cal- fission weapons.3 culations involved in correlating and dis- MIT’s Radiation Laboratory had been a playing radar data were simple, slide-rule major center of radar development in WWII level, the mass of data and the need for and some of the participants in that work, real-time display for the command and con- in the now-renamed Research Laboratory trol of response forces dictated something for Electronics, naturally turned to the new more powerful. problem. Current air defense technology The urgency of US air defense increased was the same as in WWII. Data from radars when North Korea invaded South Korea on scanning air sectors was posted by people 25 June 1950 and when China intervened with grease pencils writing in reverse on on 26 November of that year, thus bringing transparent boards. From this display, tacti- the specter of nuclear war with the commu- cal air defense commanders determined nist world even closer. bomber routes, projected positions, avail- Discussions between the Air Force and able response time, and the targets to be MIT to establish an Air Defense Development attacked. Decisions included alerting anti- Center in the mode of the Radiation Labora- aircraft units, dispatching fighter aircraft tory proceeded. MIT convened a study group, and guiding them to intercept the incoming Project Charles, consisting of its faculty and a bomber streams, providing warning to civil- number of outside experts to vet the pro- ians to take shelter, and alerting civil defense posal. The result was to approve the idea for workers. an off-campus classified Project Lincoln, July–September 2011 5 [3B2-9] man2011030004.3d 27/7/011 16:26 Page 6 Why the Arpanet Was Built named for its proposed location near Lin- flexibility in management and contractual coln, Massachusetts.Asignificantdemon- arrangements, enforcement of the highest stration occurred on 20 April 1951 when a level of excellence from its contractors, and ‘‘bomber’’ was intercepted in real time by a openness to technical ideas from all direc- ‘‘fighter’’ using actual radar data transmitted tions.4 It sought results that redefined how over telephone lines and analyzed by Whirl- one looked at the problems it tackled— wind. The result of this effort was the Semi- game-changing solutions to what today are Automatic Ground Environment (SAGE) air called ‘‘DARPA-hard’’ problems. Modest evo- defense system. lutionary improvements were left to others. The launch of an earth satellite by the ARPA’s early years were characterized by Soviet Union on 4 October 1957 was another ‘‘Presidential Issues,’’ assignments coming major development in the Cold War con- to it directly as the result of White House frontation.[B] If the USSR could launch sat- concerns about its most critical technical ellites of that size, they could also deliver concerns. ARPA initiated programs in large missiles armed with nuclear warheads to boosters to close the missile gap highlighted the US. Besides initiating a space race to ac- in the 1960 Presidential election; reconnais- company the advancing arms race, the sance, communication, navigation, meteoro- event resulted in rethinking the US policy logical, and missile launch warning satellites; for science and technology and in substan- ballistic missile defense; a worldwide satellite tial increases in research support for univer- tracking system; establishing a scientific basis sities and the education of students in in seismology for negotiating and monitor- science and engineering. Business-as-usual ing nuclear test ban treaties; counterin- was put aside. The best minds in the coun- surgency and unconventional warfare; and try were enlisted in the equivalent of the creating an interdisciplinary science of mate- WWII Manhattan Project, and the national rials from the separate disciplines of physics, security establishment went into crisis chemistry, metallurgy, ceramics, and engi- mode. neering. Shorter-term efforts were in solid One US response, DoD Directive 5105.15 propellant chemistry, energy conversion, dated 7 February 1958, established the Presidential protection following the Ken- Advanced Research Projects Agency (ARPA, nedy assassination, and other matters that now DARPA.) The directive is marvelously drew on its contracting lexibility, speed, ex- general: ‘‘to be responsible for the direction pertise, and innovative approaches. or performance of such advanced projects in the field of research and development as The Command and Control the Secretary of Defense shall, from time to of Military Forces time designate by individual projects or ARPA’s history and character lies at the heart by that category.’’ Over the years, this has of networking. To appreciate why things are come to be interpreted as seeing that techno- as they are, a deeper look at their origin is logical surprise would never be repeated, a ra- needed.