Gold Foil Bus — 2 museum-grade prints in this palette. IXPE fulfilled a decades-long ambition to measure X-ray polarization from orbit — a parameter that reveals magnetic field orientation and emission mechanisms invisible to imaging or spectroscopy alone. The Crab Nebula first-light result validated pulsar wind nebula models that had relied on indirect inference since the 1960s. NuSTAR proved that hard X-ray astronomy could move beyond coded-aperture imaging to true focusing optics — a breakthrough that opened supernova element mapping, black hole spin measurement, and solar flare microphysics. The mission's first-light image of Cassiopeia A revealed titanium-44 emission, directly tracing the radioactive ashes of the explosion that created the remnant.