Looking Back at the Gemini IX Spacecraft, courtesy NASA/Eugene Cernan

Gemini 9A and NASA’s Second Spacewalk

Bullock Museum
6 min readJun 8, 2020


Paving the way for the first man on the Moon

On June 5, 1966, Gemini 9A astronaut Gene Cernan became the second American — and only the third person — to complete a spacewalk. Nearly everything about the Gemini 9A mission and his spacewalk was new and unknown to him, to his crewmate Tom Stafford, and to NASA. The main purpose of the spacewalk was to test ways in which astronauts could maneuver in open space, including a jet pack called an Astronaut Maneuvering Unit (AMU).

Before NASA’s Apollo Program could land a man on the moon, the Gemini Program tested and perfected the skills and technology to make it possible. Between April 1964 and November 1966, Gemini flew thirteen missions. Gemini 9A was plagued with problems and setbacks from the get-go. Its original crew, Elliot See and Charles Bassett, were killed in a plane crash during a training activity on February 28, 1966. Their untimely deaths promoted the backup crew, Stafford and Cernan, less than three months before the scheduled launch date.

Astronauts Gene Cernan and Tom Stafford moments before climbing into the Gemini 9A module for the third time. After two failed launch attempts, Stafford was handed a large match as a joke to “light the fuse” on the rocket. Courtesy NASA.

It would take three tries before the mission launched. The first launch was postponed because the vehicle they were supposed to rendezvous with failed to make it into orbit and another vehicle had to be prepped and launched. The second launch was scrubbed due to a computer glitch in the last minute before takeoff. On June 3, 1966, Gemini 9A finally made its way into space for their three-day mission.

They successfully rendezvoused with the other spacecraft, only to see that a shroud over its nose had not fallen away after launch — docking would be impossible. Their new task became testing different rendezvous scenarios, like finding the other spacecraft if the radar system didn’t work and they had to rely solely on math and the stars to guide them. They also tested the procedures an Apollo crew would need to employ to rescue a lunar module stuck in low orbit.

View of the rendezvous vehicle with the shroud still partially attached. Cernan and Stafford nicknamed it the “Angry Alligator.” Courtesy NASA.

The change in plan and added tests left Cernan and Stafford physically and mentally fatigued and had burned fuel at an alarming rate. It was decided they would postpone the spacewalk, giving them a day to rest and conserve fuel. The next day, they spent nearly four hours prepping for the spacewalk — going through an 11-page checklist, dropping themselves into a lower orbit, and plugging Cernan’s suit into the umbilical that would feed him oxygen, communications, and electrical power.

Test subject Fred Spross from the Crew Systems Division wearing the AMU, Gemini spacesuit, and an Extravehicular Life Support System chest pack, May 1966. Courtesy NASA.

Cernan compared his spacesuit to wearing a Macy’s Thanksgiving Day Parade balloon with steel pants. To help protect him from extreme conditions outside of the module as well as the AMU’s tiny rockets firing at 1,300 degrees, his suit consisted of 14 layers — several more than Stafford’s. These layers included a chain link restraint layer to maintain the shape of the pressurized suit, seven layers of mylar for thermal protection, a special layer to shield him from hits by dust-sized meteors, and heat-resistant leg coveralls made of fiberglass and ultrafine superalloy. It was already difficult to move in before pressurizing it for the spacewalk.

Cernan’s first task once outside the module was to test the viability of using the umbilical to help move around. It failed the test. Cernan spent most of the time tumbling out of control as the umbilical took on a life of its own, rebounding toward the spacecraft and trying to lasso itself around Cernan. Without anything else to stabilize himself, he had no control over the umbilical much less the ability to use it to pull himself along. He likened the experience to “wrestling an octopus,” and gave up after 30 minutes, reporting to Mission Control that future spacewalkers would need some form of propulsion for control.

Cernan during his spacewalk with the umbilical floating in front of him. Courtesy NASA/Tom Stafford.

Already exhausted from his fight with the umbilical, Cernan turned his attention to his spacewalk’s main event — testing the AMU. There were 35 steps to go through before it was ready to fly, many near impossible in zero gravity while wearing a clumsy spacesuit and thick gloves. Trying to turn a lever or valve would send his body turning the opposite direction. Pulling on the telescoping arms was like “straightening wet spaghetti.” When he finally got the AMU prepped, he strapped himself into its small saddle seat and swapped the umbilical for the oxygen and power contained in the AMU.

After an hour and half in space, Cernan took a break to assess his situation. His breathing was so heavy that his visor had completely fogged over — he was using his nose to clear a small window. His normal heartrate had tripled. His earlier struggle with the umbilical had ripped apart the back seams on the seven inner insulation layers of his suit, leaving him with a triangle of exposed skin that was now seriously sunburned. He was also sweating so much that, when he finally took his suit off on Earth, technicians would pour more than a quart of sweat out of it. And his switch from the umbilical left him with severely degraded communication with Stafford via a line-of-sight radio on the AMU. For Cernan’s safety, it was decided that the AMU test flight should be scrapped, and he should return to the module.

Unstrapping from the AMU and making his way back to the module door were easier, but he needed every bit of his waning energy to climb back in. The space inside the module was so small that Cernan, with a lot of help from Stafford, had to compress himself into a painful, crouched position. Describing it later he said, “Air could not get to my lungs, spots danced before my eyes, and incredible agony lanced through me as I clung to the edge of consciousness.” After two hours and nine minutes and almost two revolutions around the Earth, Cernan was back in the module with the rest of the day to relax before returning home. But first they jettisoned the unused, ten-million-dollar AMU because its explosive fuel package posed too much of a risk during reentry.

On the morning of Monday, June 6, Cernan and Stafford re-entered Earth’s atmosphere. They splashed down right on target, about 350 miles east of Florida. Each of Gemini 9A’s successes and failures were a learning experience that got us that much closer to the Moon. The AMU was not tested on another Gemini mission nor was it used during the Apollo program, but a similar technology called a Manned Maneuvering Unit (MMU) was used during three missions in 1984. Tom Stafford went on to command Apollo 10 and serve as the Chief of the Astronaut Office, the most senior position an active astronaut can hold. Gene Cernan served as pilot on Apollo 10 and commander on Apollo 17, during which he became the last man to walk on the Moon. (Check out an amazing virtual flyover of the Apollo 17 landing site here.)

Cernan was the last man to walk on the Moon, seen here during the Apollo 17 mission. Courtesy NASA.

Texas has deep roots in the United States space program. Houston is home to NASA’s Lyndon Baines Johnson Space Center, many astronauts have made Texas their home after leaving NASA, and three of the 12 men who walked on the Moon were Texans. To learn more about Texas’ connection to NASA and see an unused AMU on loan from the Johnson Space Center, visit the Bullock Museum.

This post is contributed by Angie Glasker, Curator, at the Bullock Texas State History Museum.

Support for the Bullock Museum’s exhibitions and education programs is provided by the Texas State History Museum Foundation.



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