Apollo 1 Plugs-Out Test Fire - ESA CAVES in Sardinia and Planck

From Apollo 1's fatal plugs-out test to ESA's underground CAVES training and Planck's sky map, this Trajectory episode shows how hard lessons drive spaceflight progress. NASA moved from Mercury into the clustered-tank Saturn I and the improved Saturn IB, pioneering all-up testing with a Block 1 Apollo capsule that splashed down 37 minutes after launch. The launch escape system was trialed on Little Joe, which developed a roll 26 seconds into flight, triggering a real abort that worked perfectly. A year later, the first crewed mission drew near. Concerns grew over flammable cabin materials and simulator lag, but a seemingly safe plugs-out test turned deadly. In a pure oxygen cabin sealed by an inward opening hatch, a spark caused a flash fire that killed Gus Grissom, Ed White and Roger Chaf