46 years ago today, veteran astronaut Gus Grissom, first American spacewalker Ed White, and rookie Roger Chaffee were killed in a cabin fire during an Apollo 1 launch pad test. The first majorly fatal accident in NASA's history, the fire was caused in part by the cabin's pure oxygen atmosphere and a number of other dangerous design flaws that were corrected over the 20 month delay that followed the incident.
Today, NASA posted a picture of the trio for its image of the day, and we'd all do well to remember them too. That they died was certainly a tragedy, but their sacrifice and the sacrifice of those like them helps pave the way for safer, more cautious, but still ambitious feats of human engineering and exploration. And where would we be if we didn't poke and prod at the limits of our own Earthly world despite the risks involved? So here's to three heroes who helped build the foundation of modern spaceflight.