After much refinement, endless wind-tunnel, spin-tunnel, heat, and drop tests, and trajectory work on primitive computers, the cone-shaped, blunt-bottomed Mercury capsule was finished. Faget added a thick ablative heat shield (the concept of which had been described in 1920 by rocket pioneer Robert Goddard and later fine-tuned by Eggers) made of an aluminum honeycomb and several layers of fiberglass. The outer layer of the shield would absorb some of the heat and burn away, or ablate, protecting the capsule itself during reentry.
