Sen installed the probe frame outside the shield at the fourth hour.
It was a ring of angle iron, bolted to the interface chamber’s floor in front of the outer shield, with six arms reaching through ports in the shield’s glass toward the boundary’s rim, and a seventh, shorter, with a small hammer tip and a gripper. At the end of each of the six, a probe tip. Fine, pointed, ceramic-sheathed. Each tip tied by a cable to its own gauge on the frame’s outer face. Six gauges in a row, at eye height.
Each tip read the boundary’s temperature and its shift: how far the boundary’s edge moved, toward the tip or away. The seven distributed sensors mapped the whole rim; the six tips marked a line. One particular line. The line where the collar would grow: where crown, seam and root iron would condense together on the seed ring, layer by layer, as the gradient turned.
Sen set each tip by hand. Reaching through the shield’s ports with her chapped fingers on each arm, sliding it forward until the tip’s gauge showed it was a fraction from the boundary’s edge. Then locking it.
“Six,” she said, when she was done.
