The Soviet launch of Sputnik 1 in October 1957 led President Eisenhower to authorize the Advanced Research Projects Agency in February 1958, with $520 million and a place inside the Office of the Secretary of Defense. Its first director, Roy Johnson, left a $160,000 job at General Electric to take the post for $18,000. When NASA formed later in 1958, ARPA lost its civilian space work and most of its funding, and Johnson resigned. The agency pivoted to high-risk basic research: Project Defender for missile defense, Project Vela for nuclear test detection, and the Navy’s Transit satellite system with Johns Hopkins, which used the Doppler effect and became a precursor to GPS.

Under director Jack Ruina, J.C.R. Licklider ran the Information Processing Techniques Office, funding time-sharing at MIT and leading to ARPANET, the first wide-area packet switching network. ARPA also backed Douglas Engelbart’s NLS hypertext system and the Aspen Movie Map. The 1973 Mansfield Amendment restricted defense research to direct military uses, pushing computer scientists toward Xerox PARC and startups while the agency turned to stealth and lasers, producing the F-117 Nighthawk. After 9/11 its Information Awareness Office pursued Total Information Awareness and the LifeLog project; Congress defunded the office in 2003, though Edward Snowden’s 2013 disclosures showed some of its concepts persisted under other names.

• Packet switching splits data into pieces that route around a destroyed node, a design aimed at surviving a nuclear strike.
• The Mansfield Amendment’s funding squeeze helped push DARPA-trained talent into the personal computer industry.
• In 2024 an AI flew a modified F-16 against a human pilot in the first human versus AI dogfight.
• The RACER program builds off-road autonomous vehicles, and Manta Ray develops underwater drones that can hibernate on the seafloor.
• The DRACO project with NASA and Lockheed Martin aims to build a nuclear thermal rocket.