Item from deaths-end by
Humanity's first interstellar mission — a tiny probe driven by sequential nuclear detonations, carrying Yun Tianming's frozen brain toward the Trisolaran fleet.
The Staircase Program is Wade's project — born of Wade's grasp that to survive humanity must do morally indefensible things first. Stripped of normal payload limits, the only thing the capsule can carry is a single human brain, frozen and shielded. Yun Tianming, terminally ill, volunteers in secret. The launch succeeds; the capsule is later lost in midcourse and presumed destroyed. Decades later, the Trisolarans confirm that they intercepted, revived, and integrated him. The program is remembered with shame and gratitude in roughly equal measure.
A small radiation-shielded capsule the size of a beer bottle suspended at the focus of a vast, gossamer-thin solar sail. Behind it, a long cable threads through a series of stationary nuclear devices arranged along a 2-AU corridor. Each detonation accelerates the sail and capsule in sequence, ramping toward 1% of lightspeed.