'M Equals 1': The All-Up Mission of Gemini XI (Part 1)

Not all astronauts get on with one another, but if there ever was a crew whose members could be described as best buddies, it would be Gemini XI’s Charles “Pete” Conrad and Dick Gordon. Their friendship pre-dated their NASA days, back to a time in the late 1950s when they served together aboard the aircraft carrier U.S.S. Ranger. A decade later, as astronauts, their camaraderie endured and they earned a reputation for being fun-loving, cocky, irreverent … and intensely focused. Nowhere was that focus more tightly maintained than on Gemini XI, a three-day mission in September 1966, during which Conrad and Gordon pushed the United States a step closer to landing on the Moon.

In less than 18 months, Project Gemini had accelerated NASA—literally—to dizzying heights. On Gemini 3 in March 1965, the two-man craft had been trialed with astronauts for the first time. Three months later, in June, Gemini IV crewman Ed White executed America’s first spacewalk, after which the Gemini V and Gemini VII crews pushed the world space endurance record to eight and 14 days. Rendezvous and precision maneuvering with unmanned target vehicles in orbit, together with ever more ambitious spacewalks, were performed by the crews of Gemini VI-A, Gemini VIII, Gemini IX-A, and Gemini X. On the penultimate mission of the series, Conrad and Gordon were tasked with performing a rendezvous and docking with an unmanned Agena-D target … on their first orbit of Earth. The necessity of completing this exercise at such an early stage in the mission would prove critical for Project Apollo, in which the Command and Service Module would have to approach, rendezvous, and dock with the ascent stage of the returning Lunar Module.

“There was a lot of concern that it wasn’t going to be successful,” Dick Gordon told Neil Armstrong’s biographer, James Hansen, in First Man. “For the Apollo application, the desire was to rendezvous as rapidly as possible, because the lifetime of the LM’s ascent stage was quite limited in terms of its fuel supply.” To achieve a first-orbit rendezvous and docking, Gemini XI had to meet a two-second launch window on 7 September 1966. In addition to performing a lengthy spacewalk and experiments, Conrad and Gordon would physically tether their Gemini to the Agena in order to evaluate the possibility of keeping vehicles flying in formation without fuel inputs or control actions. They would also establish a world record of 850 miles for the highest altitude achieved at that time by human beings.

In March 1966, Conrad and Gordon were assigned to Gemini XI, with Armstrong and “rookie” astronaut Bill Anders announced as the backup crew. Conrad’s assignment was inextricably linked to the mission’s demonstration of achieving high altitudes. In mid-1965, he learned of plans to fly the spacecraft around the Moon and, even when such a mission was rejected by NASA Administrator Jim Webb, pushed vigorously to use some of his Agena fuel to carry Gemini XI into a high orbit. Among the earliest champions of Conrad’s scheme were the scientists—flying to high altitude, he argued, would allow the astronauts to acquire high-resolution imagery of weather patterns and possibly benefit other experiments. Fears that the Van Allen radiation belts might scupper such a mission were allayed when Conrad sent Anders—a qualified nuclear engineer—to Washington, D.C., to devise and argue ways of avoiding them.

With the high-altitude objective approved, another key target was tethering Gemini XI to the Agena as a means of establishing better station-keeping between two spacecraft in formation. McDonnell engineers recommended a nylon or Dacron line, no longer than about 160 feet, could produce a reasonable amount of cable tension. Ultimately, the cable chosen was about 100 feet long and the only major concern was figuring out how to free Gemini XI from the Agena in the event of problems. It was decided to fire a pyrotechnic charge and, should that fail, to snap a break line in the tether with a small separation velocity.

The elephant in the room, however, was achieving rendezvous with the target on Conrad and Gordon’s first orbit of Earth. Within NASA, it was known as an “M=1” rendezvous, and it had been suggested several years earlier by Richard Carley of the Gemini Project Office, in response to Apollo managers’ concerns that such a practice was needed to produce a close approximation of Lunar Orbit Rendezvous (LOR). There was much skepticism that it would work, to such an extent that William Schneider—deputy director for Mission Operations at the Manned Spacecraft Center (MSC) in Houston, Texas—bet the review board’s chairman, James Elms, a dollar that a first-orbit rendezvous could not be done with the required economy of on-board propellant.

As if this was not enough, spacewalking remained a worry. “Neutral buoyancy” training, whereby astronauts were submerged in a water tank, their suits carefully counter-weighted, had been trialed for the first time in mid-1966 and was already being billed as the closest analog to the real thing. Astronaut Gene Cernan, who endured a particularly harrowing EVA in June 1966, was the first to utilize the new training aid and found that it did approximate his efforts and difficulties in open space.

By the end of the summer, Gemini XI sat patiently on Pad 19 at Cape Kennedy, Fla., primed for liftoff on 9 September. A minute leak in the first-stage oxidizer tank of the Titan II rocket produced a 24-hour delay, but when Conrad and Gordon were en-route to the pad on the 10th it became clear that their Agena target was experiencing pre-launch checkout problems with its autopilot. The countdown was halted as engineers scrambled to rectify the glitch, but were unable to do so in time to meet the “launch window” and the attempt was scrubbed.

Early on 12 September, the astronauts were sealed inside their spacecraft and their Agena target roared into space atop an Atlas booster at 8:05 a.m. EDT. The first stage of the mission was underway. Now came the big test: launching Gemini XI within its incredibly narrow, two-second window. “Rocketeers of the Forties, Fifties, and early Sixties,” wrote Barton Hacker and James Grimwood in their seminal work On the Shoulders of Titans, “would have been aghast at the idea of having to launch within two ticks of the clock.” But, aghast or not, Conrad and Gordon’s Titan II thundered into orbit at 9:42:26.5 a.m. EDT, just half a second into the two-second window.

Six minutes later, on the edge of space, Mission Control notified them that their ascent and Titan II performance had been “right on the money” and they were cleared for the M=1 rendezvous with the Agena. Their first step was the Insertion Velocity Adjust Routine (IVAR) maneuver, whereby Conrad corrected their orbital path and placed them on track to “catch” the Agena, then about 300 miles from them. Next, Conrad performed an out-of-plane maneuver and the two men switched on their rendezvous radar … and, just as predicted in their training, they received an immediate electronic “lock-on” with the Agena. At the time of the maneuver, they were out of communications range with the ground, but when contact was re-established they were barely 60 miles from their target.

Guided by Capcom John Young, seated at his console at the MSC in Houston, the astronauts moved ever closer. At one stage, with only 25 miles between the two spacecraft, they were almost blinded as the Agena flashed into view with orbital sunrise above a glorious Pacific Ocean. The men scrambled for sunglasses as Conrad eventually pulled Gemini XI into position, within 50 feet of the target. As they passed over the California coastline a little more than 85 minutes after launch, Conrad and Gordon had pulled off the improbable: they had achieved the world’s fastest-ever rendezvous in orbit. Moreover, their propellant tanks still brimmed with 56 percent of their fuel reserves.

William Schneider lost his bet with James Elms. “I never lost a better dollar,” he said.

As for Conrad and Gordon, they were exuberant at their triumph. They called Mission Control and sent a message directly to Flight Director Chris Kraft. “Mr. Kraft,” they radioed, “would you believe M equals 1?”

On 12 September 1966, he certainly did.

The second part of this article will appear tomorrow.

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