In 1301 the painter Giotto di Bondone saw a comet so striking he later painted it as the Star of Bethlehem. Nearly seven centuries later the European Space Agency named a spacecraft after him and sent it straight into that same comet. This deep dive covers the turbulent birth of the Giotto mission after NASA pulled out of the joint International Comet Mission in 1979, the rejected HAPPEN proposal, the outdated GEOS satellite blueprint that had to be scrapped, the rocket musical chairs before a solo Ariane 1 launch on July 2, 1985, and the liquid helium incident that chilled the probe below minus 20 Celsius on the pad.

The episode explains the Halley Armada, with Soviet Vega probes acting as pathfinders to locate the hidden nucleus, and the Whipple shield of one millimeter of aluminum, a gap, and 12 millimeters of Kevlar that turned hypervel ...