Beginning in the mid-1970s, DARPA orchestrated extensive research into the semiconductor material gallium arsenide, which could host faster transistors operating at higher power than could silicon. The work would contribute to subsequent DARPA-spurred achievement in the 1980s to miniaturize receivers for GPS.

In a seminal moment in the development of the Internet, DARPA’s Robert Kahn (who joined the Information Processing Techniques Office as a program manager in 1972) asked Vinton Cerf of Stanford University to collaborate on a project to develop new communications protocols for sending packets of data across the ARPANET. That query resulted in the creation of the Transmission Control Protocol (TCP) and the Internet Protocol (IP), most often seen together as TCP/IP. These protocols remain a mainstay of the Internet’s underlying technical foundation.

ARPA began a program to demonstrate and encourage the use of brittle high-temperature materials in engineering design, with an eye on ceramic components for gas turbine applications. The approach included major efforts in ceramic design, materials development, fabrication process development, and test and evaluation methodology.

In the early 1970s, a DARPA study brought to light the extent of vulnerabilities of U.S. aircraft and their on-board equipment to detection and attack by adversaries, who were deploying new advanced air-defense missile systems. These systems integrated radar-guided surface-to-air missiles (SAMs) and air-launched radar-guided missiles, all networked with early-warning, acquisition, and targeting radars, and coordinated within sophisticated command and control frameworks.

Building on earlier joint efforts, the U.S. Navy and DARPA initiated a new joint program in 1978 with the objective of achieving a laser communications link between aircraft, space platforms or mirrors, and submerged submarines. The ground-based laser-space mirror part of this effort built largely on DARPA efforts toward high-powered, gas-phase excimer lasers (that could emit in the shorter, more water-penetrating region of the electromagnetic spectrum) that had led to the demonstration of a workable, moderate power, laser-optical receiver combination.

In 1978, DARPA integrated a number of technologiesincluding lasers, electro-optical sensors, microelectronics, data processors, and radarsimportant for precision guided munitions (PGMs) under its Assault Breaker program. Over a four-year period, Assault Breaker laid the technological foundation for several smart-weapon systems that were ultimately fielded with high success.

The National Aeronautics and Space Administrations (NASA) Hubble Telescope takes the clearest images of the universe and transmits these to Earth via its antennas. From 1978 to 1980, DARPA funded the design, fabrication, delivery and installation of two antenna booms for the Hubble Space Telescope to demonstrate the advantages of metal-matrix composites. Made of a graphite-fiber/aluminum matrix, these booms permit radio frequency conduction while simultaneously serving as structural supports.

DARPA established the Defense Sciences Office (DSO) in 1980, combining the Nuclear Monitoring Research Office, materials science research, and cybernetic technology efforts into a single office. Since its inception, DSO has spawned two additional technology offices at DARPA: the Microsystems Technology Office (MTO) in 1992 and the Biological Technologies Office (BTO) in 2014.

In the mid-1970s, high-energy lasers showed great promise for anti-air warfare and in particular anti-ballistic missile defense. DARPA supported many technology and early system concepts for tactical high-energy lasers. This support culminated in DARPA funding the development of the Baseline Demonstration Laser (BDL) and the Navy ARPA Chemical Laser (NACL), the latter with a joint funding arrangement with the Navy.

In the late 1970s, DARPA initiated a program with Lockheed Space Systems Division to develop the technology of welding aluminum-lithium alloys, which would combine high stiffness with low density and therefore lower weight. At the time, no one understood how to prepare these materials for welding and how to control impurities in the metals and welding process. Such control would be critical for producing materials repeatedly with predictable behavior and performance.