A suitcase-sized satellite may unlock the secrets of the early universe

The big bang may have started everything we know and love, but there wasn’t much to show for it at first. After that monumental release of initial energy, it took around 150 million years before the first stars began to coalesce. This “cosmic dark age” was comparatively quiet, but far from silent. A delicate signal from this era—known as the 21-centimeter line due to its wavelength in a vacuum—is technically detectable, although very difficult to observe from Earth.