^* Ham and Enos traveled in pressurized compartments and thus didn’t need pressurized spacesuits and helmets. Nonetheless, some prototype chimp suits had been developed, including the “SPCA Suit”—certified humane by the Society for the Prevention of Cruelty to Animals. “To prove that a suit was safe for a man, we were going to test it on a chimp, but to prove the suit was safe for a chimp, we had to test it on a man,” U.S. Spacesuits coauthor Joe McMann said in an email. “That was a mind boggler.”