Issue 59

Jack’s Astro Corner: The Gemini 76 Story – First-ever Rendezvous & Proximity Operations (Part 1 of 2)

AN ASTRO HISTORY ESSAY: Up to now, my Jack's Astro Corner essays have been astrodynamics related. This article is more of an astro “history” essay capturing the year 1965. In that year the Gemini spacecraft and crew of two along with 1000's on Earth helping them were put into action to prove out some of the key…

AN ASTRO HISTORY ESSAY: Up to now, my Jack’s Astro Corner essays have been astrodynamics related. This article is more of an astro “history” essay capturing the year 1965. In that year the Gemini spacecraft and crew of two along with 1000’s on Earth helping them were put into action to prove out some of the key concepts needed to enable Apollo to head for the Moon for mankind to set foot, explore and return safely. Perhaps the highest priority was proving two spacecraft could rendezvous (meet up), enter proximity operations (loiter with each other) and dock (connect). I call this RPO&D. This Jack’s Astro Corner topic will be two articles, a Part 1 that will focus on the Gemini happenings in 1965 up through October. The emphasis will be on 25-28 Oct 1965, wow, that’s 57 years ago almost to the date. The second article in this two-parter will pick it up and cover Nov and Dec 1965. TWO PART SERIES: In this Part 1 essay, we examine early efforts by Gemini 4 and 5 to accomplish some RPO basics. Spoiler alert, the RPO goals for those missions were not achieved and, in the case of Gemini 4, huge lessons were learned. October 1965 arrived with great excitement as Gemini 6 was poised for launch and the on-orbit task to chase down an uncrewed Agena target vehicle and complete an RPO and then dock. The Gemini 7 crew was assigned the December 1965 14-day endurance mission to prove the crew could function for 14 days in space, the longest anticipated Apollo mission. Allow me to go back and review Gemini 4 and 5. Then we shall experience 25 October 1965 and see what happens and dive deeper into the subsequent innovation and decision to relentlessly pursue the prize of a first-ever RPO in space. THE GEMINI PROGRAM KICKS OFF WITH RPO GOALS: Gemini 10 & Apollo 11 astronaut Mike Collins summed up Gemini perfectly “Project Gemini served as a bridge between the rudimentary Mercury capsule and the sophisticated Apollo spacecraft, a bridge between President Kennedy’s bold statement and the national capability to execute it.” Gemini 3 proved the 2-seat spacecraft was ready and agile. Gemini 4 followed in June 1965. In this mission, the first multi-day (four days) manned mission for the US, a station-keeping exercise was added: Astronauts James A. McDivitt and Edward “Ed” H. White would attempt to close and hold station with the final stage of the Titan II which had followed them to orbit. This was essentially a short duration but good RPO first step. Gemini 4 did not carry a radar, meaning computer aided rendezvous calculations could not be made. McDivitt and White did their best to turn around and close back in on the Titan upper stage. They truly proved the non-intuitive nature of orbital mechanics is very unforgiving. McDivitt attempted to fly Gemini toward the target, thrusting directly at it. The upper stage pulled further away as they kept trying to thrust towards it. Kepler and his orbital motion laws were winning. A ton of learning took place and the flight and mission operations crews benefited a great deal. Also of significance was that astronaut Ed White did conduct the first ever spacewalk in the history of the US space program (see VIDEO). As I was finishing this article, I learned that on 13 Oct 2022 James McDivitt passed away at the age of 93. He was an accomplished AF test pilot and astronaut who besides commanding the Gemini 4 mission would go on to command Apollo 9 in early 1969 and prove the Lunar Module was ready for the Moon. Gemini 5 was next, and lifted off in August 1965. Carrying the Gemini radar for the first time, the crew ejected an RPO evaluation pod which was intended to act as a rendezvous target. You might say an RPO “dance partner.” Unfortunately, problems getting the Gemini 5 fuel cells up and running resulted in cancellation of the rendezvous with the deployed partner (see Gemini 5 mission VIDEO). RPO and docking was a critical “prove it” goal with Gemini and things were off to a terrible start. 1965 was slipping by and in the race for the Moon it seemed the Russians were in the lead. BE A WALLY! Next up was Gemini 6 with Wally Schirra and Tom Stafford. Prior to launch day, Wally Schirra dove deep into astrodynamics to understand the aircraft test pilot skills he was gifted with would not be the way to go. He learned orbit mechanics and how to make the Gemini fly in accordance with the space nuances of the “satellite paradox” (slow down to speed up). In his autobiography book “Schirra’s Space” said “Our mission was to do a rendezvous, a difficult task. Frankly, in those days we didn’t know how to do a rendezvous.” Schirra goes on to credit fellow astronaut Buzz Aldrin who did his PhD work at MIT in RPO astro. Wally was ready and armed with astrodynamics know how. GEMINI 6 READY TO GO, BUT… OK, let’s experience launch day 57 years ago. On the morning of 25 October 1965, the pace of activity and excitement at Cape Canaveral was pegged! At Launch Complex 14, the Agena that would serve as the target for the first ever orbital rendezvous was readied for flight on its Atlas booster. Just a mile to the north, at LC 19, stood Gemini VI atop its Titan II rocket. At 0945, astronauts Thomas P. Stafford and Walter “Wally” Schirra climbed into their Gemini capsule, preparing to track down and fly in close formation with the Agena RPO and docking target. Just minutes later, at 1000, the Atlas/Agena climbed into the blue Florida sky. In n the span of six short years, the Agena had flown an amazing 140 times on national security related flights. Although this was its first manned spaceflight support mission, watching it soar skyward had become as commonplace as watching a train leave the station. Minutes later as the vehicle became a dot to the naked eye, the Agena target was released and took over the last propulsion needs to achieve orbit. The flight controller reported the separation, and then began to relay downlink data indicated something very wrong. The Agena appeared to be wobbling. The main engine did fire as expected, but NASA and Air Force officials from the blockhouse in Florida to Mission Control in Texas became nervous. Then, the range reported sure signs of failure: radars were tracking the Agena: all five pieces of it. Yikes, that was not what was expected. Fifty minutes into flight, Carnarvon tracking station in Australia should have picked up the Agena coming around the other side of the Earth. There was nothing there. Back at the Cape, Stafford and Schirra exited their Gemini capsule. There was no target. There would be no rendezvous, and therefore no launch from the Titan pad at LC 19. I’m sure someone said “give me a break.” What next? Ugh…Gemini was still floundering as it tried to gain traction on achieving RPO and docking. WE HAVE AN IDEA: Looking on at the Cape were two McDonnell Douglas contractors, Walter Burke and John Yardley. With unknown months of potential delay, Burke asked Yardley “Why couldn’t we launch another Gemini as a target instead of an Agena?” He recalled a previous study of a rapid-fire launch demonstration by Martin, the Titan II contractor. Listening in on the chat were Frank Borman and James Lovell, the Gemini 7 crew next in line for a 14-day long duration mission in December 1965. Burke further detailed his idea, going so far as to sketch out a concept where Gemini 7 could be fitted with an inflatable cone as a docking mechanism. Borman drew the line on spacecraft modifications and pushed back. But Burke and Yardley continued to brainstorm the overall concept. The two McDonnell engineers then tracked down George Mueller (NASA’s manned spaceflight chief in Washington, DC) and Charles Mathews (NASA’s Gemini program manager) and explained their radical thought. The two NASA officials were pessimistic. There had been chatter amongst Cape leaders to devise the rapid-fire demo and few months back and now, two months later, the demo plan was dusted off. It had features that might help make Burke and Yardley’s idea work. Still stinging from the day’s failure, but not giving up on their new idea, Burke and Yardley described the details of the rapid launch demo to NASA’s leadership and said that if two Titan’s could be launched from LC 19 in under a two weeks span (the length of the Gemini 7 mission), a back-to-back mission was definitely doable. DETAILS EMERGE, MAYBE IT’S A GOOD IDEA: Meanwhile, NASA was dealing with the yet to be understood Agena problem and trying to sort out what to do. Knowing that determining and correcting the Agena problem could take many months; several in the agency’s leadership immediately began to focus on the upcoming Gemini 7 flight. Burke and Yardley left Florida for Texas. Once in Houston, Texas, the day after the Agena failure, they began to discuss their plan with Robert Gilruth, the director of the Manned Spacecraft Center (MSC). Gilruth listened politely, but said to Burke, “Walter, you know things aren’t like that in real life.” Burke, pressed Gilruth-yes it might be challenging, but what from an engineering point of view was preventing it from being done? At this point, Gilruth brought in his wingman backup. He asked his deputy George Low what he thought about the concept-Low replied that he was very intrigued by the idea, but did point out one potential issue: the Gemini tracking system was not designed to handle more than one Gemini spacecraft at a time. Still optimistic, Low asked Flight Operations Director Chris Kraft what he thought of the plan. Kraft first replied, “You’re out of your minds. It can’t be done.” Of course, “Has he lost his mind?” had been one of the first thoughts that came to Kraft when he heard Kennedy’s speech to Congress in May of 1961. Now, like then, Kraft gave it more thought and gave the idea a chance. Astronauts when asked about the plan of course loved it. Suddenly, what seemed to some as a totally ridiculous idea began to make a lot of sense. RPO was the bridge to the critical objective of docking. On the other side of the ocean, the Russians appeared to be taking no holiday in their quest for technological dominance. The end of the decade was nearly a mere four years away. NASA was now seriously considering the Burke-Yardley idea to keep up the momentum and go do a dual Gemini RPO test flight. The Cape team now looked into a fast-paced strategy involving a nine-day pad turn around. The initial assessment was that it could be done, although the tracking and control operations of two Gemini’s in orbit was still a question mark. Kraft gathered his team in mission control and introduced the Burke-Yardley plan. Motivated, focused, and relying on their detailed systems insight, one engineer quickly figured out how to solve the tracking problem: the Mercury tracking system was still in place and could be used to handle Gemini 7 while Gemini 6 was in orbit. Rapidly things were falling in place, and even Kraft, who at first considered this a totally outrageous idea, was becoming convinced the plan could work. A little more than 48 hours had expired since the Agena launch failure. GETTING THE GO: On the afternoon of October 27, the top NASA officials convened in Washington to formally consider the Burke-Yardley proposal. NASA Administrator James Webb listened intently as the point-counter-point discussion evolved. Webb was intrigued-but he needed to know the bottom line: would it work? Webb phoned George Mueller, his administrator for spaceflight, and asked the question. Mueller then passed that question to Gilruth in Houston. To add a bit of pressure, Mueller also informed the MSC director that if the plan was viable, Webb wished to immediately pass it along to President Johnson. Gilruth responded that he thought it was still a good plan, but wanted 30 minutes to convene his experts, including Kraft and Deke Slayton, chief astronaut, to take a vote. Mueller gave Gilruth 15 minutes. The concept had been discussed in Houston a mere 24 hours. Gilruth went around the room. The vote was unanimous: GO! (Note: no PowerPoint slides were built and they did this rapid decision making without the Internet-this is an attempt at humor). GEMINI “76” IS GO! On Thursday, 28 October 1965, only three days since the failure, a press conference was convened at the Lyndon B. Johnson Ranch. Press Secretary Bill Moyers announced to the national news media the details of an ambitious plan: NASA would launch two Gemini spacecraft into orbit on back-to-back missions and carry out the first ever orbital rendezvous. The combination mission would become known as “Gemini 76.” So, on the 57th anniversary of this late October 1965 3-days of failure, ideas and taking a chance, the plan for the Gemini 76 dual-Gemini RPO mission was in full swing. UNTIL NEXT ISSUE: OK, we will stop here and hold you in suspense as we enter into November 1965 and all the “wheels turning and churning” as everyone seeks to accomplish a dual-Gemini mission. Until next time when Part 2 is unveiled in “the Flash” (Hummm, I better start writing) stay awesome in your space duties.

Agena target space vehicle central to the planned Gemini 6 rendezvous mission.

Gemini “76” rendezvous and proximity-operations formation-flying illustration.