Shocked by recovered memories, Ryland Grace realizes Stratt coerced him onto the mission and calls himself a coward. Despite the emotional blow, he resolves to keep working. Rocky arrives to encourage focus, and Grace proposes controlled-environment tests to pinpoint why Taumoeba failed on Venus and Threeworld.

Rocky fabricates a precise xenonite test chamber. Grace insists on earlier lab gravity, so they dangerously spin up using beetles; he manages centrifuge operations and gains seven days of productive science before they later spin down.

Experiments show Taumoeba thrive in Adrian conditions, tolerate extreme temperatures, need some carbon dioxide, and can endure near vacuum. Crucially, when nitrogen is added to Venus or Threeworld mixes, Taumoeba die within seconds. After comparing Earth and Eridian biology, Grace draws on antibiotic resistance: he and Rocky will breed Taumoeba for nitrogen tolerance by exposing successive generations to gradually higher N2.

Rocky builds ten small, precisely metered tanks to run parallel selections. Progress reaches about 0.6% nitrogen tolerance. A side inquiry into Eridian food proves untenable for humans due to toxic metals, so Grace sticks with “coma slurry.”

Approaching the Blip-A’s orbit, they spin down. Using the Petrovascope, Grace catches the dim flash of Rocky’s preprogrammed engine beacon, aligns via telescope, and, though out of radar range, targets the ship. Rocky pulses the beetles to orient, then they begin a 200-second burn at 15 m/s² for a ~3 km/s intercept.