The excerpt looks back to the early Crisis Era, when Earth’s nations undertook vast engineering projects to defend the Solar System. Unlike projects such as the space elevator, nuclear tests on Mercury, and fusion breakthroughs, the Staircase Project was judged a reckless failure and was forgotten before the Great Ravine.

Centuries later, that failed project unexpectedly becomes important because the probe carrying Yun Tianming’s brain appears to have been intercepted by the Trisolarans. The text explains that the probe lost a sail cable near Jupiter, deviated from its planned course, and vanished from Earth’s tracking, making its later capture extremely difficult to explain.

The most plausible explanation is that sophons followed the probe during its acceleration phase and obtained its final flight parameters, though the interception still required luck because dust or later course changes could have ruined the estimate. The excerpt suggests that a high-velocity ship from the First Trisolaran Fleet, possibly the one that never decelerated and later turned away after dark forest deterrence began, may have encountered and captured the probe.

The likely interception is estimated to have occurred thirty to fifty years earlier, after the Deterrence Era began. The Trisolarans’ motive would have been clear: Yun Tianming was the only possible live human specimen they could directly study beyond their limited contact through droplets.

Yun Tianming is now believed to be aboard the First Trisolaran Fleet, most of which is heading toward Sirius, though his physical condition is unknown. His approved request to see Cheng Xin raises urgent questions about whether he still serves humanity, whether he has gained status in Trisolaran society, and whether he influenced the last century of events; nevertheless, the desperate people of Earth greet the news as a miraculous hope.