NASA’s Space Chimps

Before the first American astronauts went into space, they were preceded by a pair of chimpanzees.

Mercury-Redstone 2, which carried the chimp Ham on a suborbital spaceflight, on display at the California Science Center in Los Angeles

In the aftermath of World War II, the US shipped a number of captured Nazi V-2 rockets to the White Sands missile range in New Mexico. Here, a group of scientists led by the German V-2 developer Wernher von Braun hoped to utilize the rocket as a means of sending humans to space.

But of course nobody was really sure that anything could survive at all in the weightless environment of space or at the accelerations necessary to get them there. So the first tests were simple: technicians strapped a Rhesus Monkey into the nosecone of a V-2 and fired it off. Sadly for the monkeys, though, none of them survived—they all either died when the rocket malfunctioned and hit the ground as the parachutes failed, or landed out in the desert where they could not be quickly found and succumbed to the heat. The first successful mission didn’t happen until 1952, when two monkeys and two mice were recovered alive after their flight.

In 1958, NASA was formed, and a short time later Project Mercury was announced, with the goal of putting a human into space. By this time, NASA had already obtained a number of young wild chimpanzees from Cameroon who would serve as living test dummies for Mercury flights. For hours each day, the space chimps were taught to push buttons and throw levers in response to various cues—correct actions won them a banana pellet, while incorrect moves got them an electric shock on the soles of their feet.

By the end of 1960, the Mercury spaceship was ready for full-on flight testing. The first manned missions were to be sent aloft atop a Redstone missile which was not capable of reaching orbital speeds, and so they would consist of a short 15-minute ballistic flight—up, and then right back down again. For the first “chimped” suborbital test flight, designated Mercury-Redstone 2, a three-year old named Ham (for the “Holloman Aerospace Medical” center where he was trained) was selected. Ham was chosen largely for his calm disposition and his excellent skills during training.

Mercury-Redstone 2, with Ham aboard, was launched on January 31, 1961. The Redstone booster rocket malfunctioned and burned its fuel much quicker than planned. This not only unexpectedly put the Mercury spaceship at a higher speed than planned, but it subjected Ham to 15.7 g’s of force at re-entry instead of the anticipated 12 g’s, and when it landed in the Atlantic Ocean the capsule suffered damage which caused a leak, necessitating a quick rescue. When Ham was brought aboard the recovery ship, the waiting press wanted to take some photos of him sitting in his flight couch, but upon seeing it again the normally good-natured chimp began screaming and squirming to avoid being strapped back into it. Apparently he did not think the experience was a pleasant one.

But Ham’s successful test flight was enough to certify that the Mercury spacecraft was ready for a manned flight. After a series of delays, Mercury-Redstone 3 placed Alan Shepard and his Freedom 7 capsule into space during a 15-minute suborbital flight in April.

Ham, meanwhile, continued to be used by the Air Force as a test subject for several different projects. In 1964 he was retired and given to the Smithsonian National Zoo in Washington DC. But his lifetime among humans as a space chimp had not prepared him for life in a chimpanzee troop, and he became a social misfit who was unable to socialize or get along with the other chimps. In 1981 he was sent to a small zoo in North Carolina where it was hoped he would do better, but he died in January 1983 from heart and liver disease. He was 26 years old.

Ham’s skeleton was given to the US Air Force for research, and was later donated to the National Museum of Health and Medicine in Silver Spring MD. The rest of his remains are buried at the International Space Hall of Fame in Alamogordo, NM, near the Holloman Air Force Base where he was trained for his flight into space.

Mercury-Atlas 5, the spaceship that took the chimp Enos on an orbital flight, on display at the North Carolina Museum of Science and Life in Raleigh

After Gus Grissom made the second suborbital Mercury-Redstone launch in July 1961, it was decided that NASA was ready to attempt an orbital flight. This necessitated placing the Mercury spaceship atop an Atlas booster rocket, which was far more powerful than the Redstone. And once again it was planned that the test flight would be made by a chimp. Enos, who was five years old, had an entirely different personality from Ham. While Ham had been congenial and easy-going, Enos had a reputation for being headstrong, uncooperative, and grouchy. Because he could be such a dick, he had quickly earned the unofficial nickname “Enos the Penis”. (Years later, the legend arose that his nickname referred to a habit of publicly masturbating himself, but this was not true.) Enos, however, also demonstrated a quick intelligence and a good aptitude for learning what was required of him, and that was enough to win him a place on the Mercury-Atlas 5 test launch. He was scheduled for a three-orbit flight.

The mission had troubles right from the start. There were several delays due to weather. When the mission was finally launched in November 1961, there was a defect in one of the electrical inverters and a fault in one of the Mercury’s thrusters that resulted in improper attitude control–which in turn caused the internal cabin temperature to soar to over 100 degrees. The control panel being used by Enos also malfunctioned, and was delivering electric shocks to his feet no matter what he did during the flight (he received 76 shocks in all). Frustrated and angry, the chimp tore off all of his medical sensors, including a catheter that had been inserted into his femoral artery. The mission was cut short and was brought back to Earth after just two orbits. Then the Mercury capsule landed off-course, and it took almost an hour for the recovery team to find it and another two and a half hours to get the occupant out, during which he damaged his control panel by pounding on it, apparently trying to escape. Upon his recovery, Enos was understandably a very sullen and hostile chimp. 

NASA considered the test flight a success, however, and in February 1962, John Glenn and the Friendship 7 spaceship orbited Earth three times. Upon his return Glenn was honored with a visit to the White House where, he recalled later, President Kennedy’s five-year-old daughter Caroline greeted him with the question, “Where’s the monkey?”

Enos’s post-flight life was much shorter than Ham’s. A few months after returning to Holloman for further testing, he developed a case of dysentery caused by the Shigella bacteria. At that time, this was untreatable by antibiotics, and America’s second space chimp died in November 1962.

It’s not clear what happened to Enos’s earthly remains. One story has it that, like Ham, his skeleton was kept by the Air Force and his organs and hide were sent to the Alamogordo Space Hall of Fame for burial—but no researcher has ever been able to find either one. Another version states that Enos’s body was given to the Smithsonian Institution, but there is no record of that either.


2 thoughts on “NASA’s Space Chimps”

  1. At least these chimps survived their space ordeal – poor little Laika was not so lucky. I have long thought that if I ever discovered an asteroid, I’d name it after the USSR’s ill-fated space dog – last time I checked, it has not yet been done.

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