Proteins are nature’s machines, performing tasks from transforming sunlight into useable energy to binding oxygen for transport through the body. These functions depend on structural arrangement of atoms within the protein, which was, until recently, only possible to measure statistically, in easily crystallized samples via conventional X-ray diffraction. In the past decade, X-ray Free Electron Lasers (XFELs), a new type of X-ray source, have begun to come online. Using ultra-bright, ultrafast X-ray pulses of the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory, this technology allows us to measure not only static pictures of protein structure but to record “molecular movies” of proteins in action. Series: "Lawrence Livermore National Lab Science on Saturday" [Science] [Show ID: 33432]