One additional Mercury astronaut, "Deke" Slayton, did not fly in this program due to a heart irregularity.
The Mercury capsule has been described as appearing like a television picture tube. It is conical, with a rounded bottom 74" in diameter,and a short cylinder in place of a peak, total length of 114 inches. The round bottom is the heat shield protecting the single astronaut during re-entry. The astronaut sits (actually, lies) with his back to the shield. The capsule in orbit weighed between 3100 and 3900 pounds depending on payload.
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