In 1958, the US launched Gordo the squirrel monkey 300 miles above Earth; he endured 8.3 minutes of weightlessness and 40 g during re-entry, but died after his capsule sank at sea

On December 13, 1958, about 68 years ago, Gordo, a squirrel monkey, was strapped to the nose cone of the Jupiter rocket PGM-19 and launched from Cape Canaveral, Florida.The Jupiter was the U.S. Air Force's operational missile, but the biological test flight itself was organized under the Army Ballistic Missile Agency, with the U.S. Navy responsible for training Gordo and monitoring his physiological signals before and during the flight. The rocket reached an altitude of approximately 600 miles (965 km), well beyond low Earth orbit's typical boundary, though the flight itself was suborbital. As per the records of historical launches maintained by NASA's Kennedy Space Center, Gordo endured 10 g forces at launch time , was weightless for 8.3 minutes, and endured 40 g re-entry forces, with no problem at all to any of his vital organs. Then, in a twist of irony befitting a Cold War-era space program that was run on duct tape and bravado, a flotation device failed to work properly, and Gordo ended up sinking into the ocean. He received little public recognition afterward.

A one-way ticket to space

Gordo's flight was not conducted by NASA. It was a joint military effort: the Army Ballistic Missile Agency managed the biological test program, the Air Force operated the Jupiter missile and launch facilities at Cape Canaveral, and the Navy handled the animal's training and medical monitoring. NASA, established only two and a half months earlier, in October 1958, played no organizational role in the launch itself. According to the same NASA archives, the mission was considered "partially successful," a highly charitable phrase for describing the results of an experiment whose main "result" was the death of the subject while returning to Earth.

However, the information he collected- that a live mammal was capable of surviving the particular stresses involved in launch, weightlessness, and re-entry- became a direct contribution to Project Mercury, the program that would eventually send American astronauts into space. In other words, a forgotten monkey may have done all the work to make Alan Shepard and John Glenn look like natural geniuses.

Eight minutes that changed everything, and killed him anyway

The whole idea behind shooting Gordo into space was not just "can a body survive space," but "would weightlessness mangle a body's organs so badly that a human pilot may not be able to cope?" NASA's own history office says that Navy physicians who were monitoring his breathing and heart rate found that his vital signs provided evidence that a man could physically survive a ride like that. This was a huge scientific relief.

It was a bizarre tragedy at the same time, because Gordo answered the biggest unanswered question in human space travel and then drowned before anybody could say thanks. But there were no explosions or guidance errors involved. The problem was simply a leak. A basic floating system, something even a life jacket could have done, failed during the splashdown process, causing Gordo’s spacecraft to sink into the ocean about 1,500 miles off the coast of Cape Canaveral, never to be seen again.

Able and Baker's more fortunate flight

Five months later, in May 1959, there was another attempt by the U.S. Army, this time using two monkeys called Able and Baker on a Jupiter rocket. As reported by Slate, both monkeys returned safe and sound and became famous overnight, with Baker spending decades at a naval research facility in Florida and being showered with bananas. The disparity cannot be missed, that while one monkey silently drowned and died and was never heard of again, two survived and received their own fan club.

Why this still matters

It is worth remembering that space exploration in the 1960s was often experimental and uncertain. Historians of the early space program, including NASA's own history office, have documented that pre-Mercury biological test flights carried significant technical risk and a low margin for error, particularly in recovery systems. Gordo's flight is a reminder that the achievements celebrated as "the golden age of American spaceflight" rested on outcomes that were, for a period, genuinely uncertain, and not equally fortunate for every participant.