A New Kind of Spy How China obtains American technological secrets.

Greg Chung was eager to help China. “He has a big heart,” his wife said. Family Photograph Courtesy FBI

Greg Chung was at home on February 1, 2003, when the space shuttle Columbia fell from the sky. His son Jeffrey called to tell him the news: the ship had broken apart while returning to Earth, and all seven astronauts on board had died. “That’s not a good joke to make,” Chung said. An American citizen who was born in China, Chung lived with his wife, Ling, on a cul-de-sac in Orange, California. Until his retirement, a few months earlier, he had worked on NASA’s space-shuttle program. Among other things, he had helped to design the Columbia’s crew cabin. When he realized that Jeffrey was telling the truth, he hung up the phone and wept.

In 1972, NASA outsourced the design and development of its space shuttles to the Rockwell Corporation, which was later acquired by Boeing. For three decades, Chung was a structural engineer in the stress-analysis group. The work was repetitive, but he was well suited to it. He rarely left his office, even for coffee; instead, he sat at his desk, running computer models that predicted how the fuselage would hold up under various intensities of heat and pressure.

After the Columbia accident, NASA asked Boeing to improve the design of the next shuttle. Chung had been one of the best analysts in his group, and his former supervisor called to hire him back as a subcontractor. Though he was seventy, he was glad to postpone retirement. He returned to his former habits, coming home late for dinner and then working until midnight. He was driven not by the prospect of a promotion or a raise but by the pleasure of the work. “He’d tell me how much money he had saved for Boeing,” Ling told me later. “I always teased him: ‘your Boeing, your Boeing.’ “

In April, 2006, two F.B.I. agents visited Chung at home. He had designed the house in Orange, and it included a deck that he and Ling had built themselves. In the large front yard, Chung had planted lemon trees and a tomato patch, which he sprinkled with water recycled from the shower. Their two sons—Jeffrey and his older brother, Shane—lived nearby with their families.

Chung, a tall man with a lean, impassive face, invited the agents inside. They asked him about Chi Mak, an acquaintance of Chung’s, who had been arrested several months earlier. Mak had moved to California from Hong Kong in the seventies, and had worked as an engineer at Power Paragon, a company that builds power-distribution systems for the Navy. For years, China had been trying to modernize its naval fleet, and the F.B.I. suspected that Mak had been trained by Chinese intelligence services and sent to the United States as a spy.