Simon Ramo

Simon Ramo, an engineer and entrepreneur who helped develop the rocket technology that changed the nature of the Cold War’s nuclear face-off and powered the first Americans into space, died on Monday in Santa Monica, Calif. He was 103.

His son James confirmed his death.

Dr. Ramo, who advised a string of presidents, legislators and cabinet officials on science and technology, was a pioneering force in the aerospace and electronics industries throughout the postwar period.

Starting as an electrical engineer at General Electric, where he logged 25 patents before he was 30, Dr. Ramo later founded an aerospace company, the Ramo-Wooldridge Corporation, with Dean E. Wooldridge, a colleague he met while a doctoral student at the California Institute of Technology. The corporation merged with Thompson Products to become TRW.

Their enterprise grew into an industry giant, at one point employing tens of thousands of workers and 2 percent of the nation’s physicists. TRW was sold to the military contractor Northrop Grumman in 2002 for $7.8 billion, a deal that Dr. Ramo brokered.

But he was still working out of a former barbershop when President Dwight D. Eisenhower called to ask if he could build an intercontinental ballistic missile, capable of striking the Soviet Union in less than an hour, and if he could do it before the Russians built the same. “This is now our No. 1 project,” he recalled Mr. Eisenhower saying. “Let’s get it done.”

They did, ushering in a terrifying era when both superpowers were able to launch devastating nuclear attacks that could bypass each other’s defense systems.

Dr. Ramo applied a systems approach to problem-solving — using it to build rockets, to co-found two Fortune 500 companies and to develop a tennis strategy that he expanded into a successful book, “Extraordinary Tennis for the Ordinary Player,” one of dozens he published.

The son of Eastern European immigrants, Simon Ramo was born in Salt Lake City on May 7, 1913. His mother, Clara, was a homemaker. His father, Benjamin, a skilled bridge player, owned a men’s clothing store where Simon put in long hours helping out after school while developing his mathematical abilities.

Initially, he planned on becoming a concert violinist, but he said he decided to focus on science and engineering after hearing the virtuoso Jascha Heifetz perform with the Mormon Tabernacle Choir. “There’s no way that I could learn to play like that,” he once recalled.

Dr. Ramo was only 23 when he graduated magna cum laude from Caltech with his Ph.D.

He fulfilled the school’s language requirements by taking the French and German exams the same day — without ever studying either language. “I found I was a natural code breaker,” he explained, managing to decipher enough words to translate passages into English even though he “hadn’t the slightest idea what they were talking about.”

More interested in national security and defense than in commercial ventures like television, he left General Electric to join Hughes Aircraft in California, founded by Howard Hughes, turning what was then a fringe company into a formidable electronics and missile powerhouse. While there he worked on radar, computers, navigation systems and guided missiles that became standard on every American interceptor airplane.

He developed a close relationship with Defense Department officials who were becoming increasingly wary of Mr. Hughes’s growing emotional instability. He and Dr. Wooldridge had left Hughes to form their own company when they were drafted into spearheading the intercontinental ballistic missile race.

“Ramo was really the intellectual impetus behind the rocket programs,” said Gary Schmitt, a national security analyst at the American Enterprise Institute. He noted, though, that such a cozy relationship, without any oversight, between defense officials and military contractors could never exist today.

In an oral history, Dr. Ramo later listed other reasons such a project could not be repeated. “Keep it a secret,” he remembered Eisenhower saying. “Let’s not tell Congress about it.”

The successful Atlas rocket that the effort produced eventually served as the launch vehicle for the Project Mercury program, which sent John Glenn orbiting the Earth. A subsidiary that Dr. Ramo established on a 100-acre campus in Redondo Beach, Space Park, later won the first spacecraft contract issued by NASA. Noting that Southern California’s weather was perfect for flying airplanes, he helped turn the region into the center of the aerospace and weapons industry.

“He was among America’s greatest scientists and business and defense innovators,” Wes Bush, the chairman of Northrop Grumman, said in a statement. “He was a true aerospace visionary.”

He was also a nonstop talker, a creative party host and a fast wit. Asked about his politics once, he responded, “I’m a registered opportunist.”

He won a roomful of awards, including the National Medal of Science and the Presidential Medal of Freedom. His textbook “Fields and Waves in Communication Electronics” has sold more than one million copies and is used in more than 100 colleges and universities.

In addition to his son James, Dr. Ramo is survived by another son, Alan; four granddaughters; and three great-grandchildren. His wife, Virginia, died in 2009.

At the forefront of so many scientific advances himself, Dr. Ramo was able to foresee with astonishing clarity many technological breakthroughs.

He predicted the advent of a pervasive “electronic information network,” push-button factories, driverless cars and living-room consoles where people could instantaneously order and pay for every conceivable product. He warned, though, that “technology is moving faster than our ability to assimilate it” and pushed for a closer linkage between scientific developments and social betterment.

Ever the innovator, Dr. Ramo received his last patent — for a computer-based learning invention — in 2013, when he was 100.