Like birds returning to their nests, these feather-like grid fins help steer rockets back down through the atmosphere toward their landing zones.
In the 1960s, astronomers theorized that the Universe was filled with a mysterious mass that did not interact normally with light, which they named "Dark Matter." This theoretical matter is believed to constitute 80% of the Universe's mass, largely in the form of "halos" surrounding galaxies and galaxy clusters. However, even after six decades of searching, scientists have still not found the particle that constitutes this mass. Many candidates have been proposed in that time, including Weakly-Interacting Massive Particles (WIMPs), primordial black holes, and ultralight particles known as "axions."
