OUR MOST EXCITING DAY IN SPACE

At 9:00 Sheridan Park, Saginaw, Michigan time on Sunday morning, December 12^th  1965 - 60 years ago as of this writing, Walter Cronkite opened CBS news’ broadcast of the launch of Gemini VI(A) by cheerfully stating,

“Good morning, everyone, this ought to be our most exciting day in space…”

He was, of course, referring to the planned rendezvous between Gemini VII and Gemini VI. Yet, he had no idea just how true those words would become in less than 54 minutes. (Yes, I know his display says 41:40 here, but there were planned holds along the way)

 

Over his left shoulder was a TV screen and on it was a live picture of the GT-6A launch vehicle and spacecraft poised for ignition and in his voice was a note of gleeful excitement. In that spacecraft were Schirra, Stafford and about 301,771 pounds of highly toxic, corrosive propellants that would burn on contact. 

Sometime in the spring of 1965 a technician at the Martin Baltimore plant had removed one of the engine’s gas generators on vehicle 62-12561 for cleaning. As the check valve for the oxidizer inlet was separated, he placed a small plastic dust cover in the gas generator port in order to keep dust and dirt out. When the gas generator was later reinstalled, probably by different personnel, the little dust cap was overlooked and once the entire assembly was put back together there was no way to see the cap and there were no preflight tests that would indicate that it was there. The result would be that at about the same moment that the bolts blew and the Titan II began to rise, the thrust would have decayed to the point where the engine would shut down and the whole stack would come crashing back to Earth in a huge fireball garnished with a toxic orange cloud. Now, as Cronkite announced the this and that’s of the mission the clock counted down toward that disaster.

 

Schirra’s hands were on the “D” ring that when pulled would eject both he and Stafford simultaneously from the spacecraft. Once the erector had been lowered, ejection was their only way to escape. Stafford also had a “D” ring, but he had concluded long ago that he would leave the ejection up to his commander.

 

Most Gemini astronauts had little faith in the ejection system, feeling that their oxygen-soaked suits would light up like roman candles with the firing of the ejection rockets. Stafford referred to it as committing suicide to keep from being killed.

In the spacecraft the astronauts listened as the Test Conductor, “TC” Frank Carey counted off the final events. At T-minus 02:00 TC called that the big first stage pre-valves were opening. Now the oxidizer from the stage’s upper tank flowed down as far as the engines and waited for the ignition signal. At T-minus 01:30 the TC called that the Titan II was going onto internal power. Next at T-1:20 TC notified the crew that the engine gimbal test was taking place. In the cockpit the crew did not really need a notification. The action of the engines gimbaling through a pre-programmed pattern of movement was both felt and heard in the cabin. In fact it was a loud and obnoxious grind and groaning that shook the vehicle and really got their attention. Every crew commented on it during their post-flight debriefing.

 

Finally at T-00:35 in the count the second stage’s pre-valves were reported opening by TC. The crew heard the big valves open and also heard the “glug, glug, glug” of the oxidizer flowing down the pipe. The big bird was ready to light her engines.

 

From the Complex 19 blockhouse astronaut Alan Bean was serving as “Stony,” the blockhouse CAPCOM, and it was his job to count down the final ten seconds to the crew and call ignition. Bean counted down exactly as he was trained and when he saw the signal he called out, “Ignition.”

With an almost primordial scream like a giant monster coming to life the Titan II’s turbo pumps spooled up to speed and fed the hypergolic fuel and oxidizer into the combustion chamber. A great orange cloud of toxic smoke burst from the pad’s flame bucket as the near explosive burning of the propellants blasted from the twin Aerojet engines and the entire engine mount shook. At nearly that same instant the hand of fate reached out and saved the mission of GT-6A as a small cannon plug at the base of the booster shook loose and dropped out.

That plug was meant to pull out at liftoff 3.7 seconds after ignition, but it dropped out nearly immediately. To the malfunction detection system, that error was clear and the signal was sent at the speed of light to shut down the entire launch system. Instantly the engines were shut down, the thrust tapered off rapidly and soon all that could be heard was the low shrinking howls of the turbo pumps spooling down as if the monster was now falling asleep. Color TV cameras caught the toxic orange mist of what remained of unburned Nitrogen Tetroxide propellant, caused by the aborted engine start.

In the cockpit, Schirra’s clock had been started by the dropping out of the tail plug. This was an indication of liftoff, but if a liftoff of less than an inch had indeed taken place and then the engines had shutdown, the Titan II was no longer bolted to the pad and was about to topple over and explode— it was an ejection situation. Yet Schirra saw that things did not add up.

 

The actual liftoff was supposed to happen 3.7 seconds after ignition, not immediately at ignition. Additionally, none of his attitude needles were moving and he had no feeling in the seat of his pants that the vehicle was moving. Finally, the sound of the thrust had rapidly come up and then vanished just as rapidly.

 

In less than two seconds Schirra, the experienced test pilot and Mercury astronaut correctly calculated that they were still bolted to the pad. Glancing at his fuel pressure gages he saw that they were beginning to drop- he and Stafford were indeed still bolted to the pad.

 

“Shutdown Gemini Six!” the TC rapidly called to the crew, “Program reset!”

 

Now Schirra knew for sure he had not lifted off. His major concern now was the tank pressures. If they stopped venting, the crew may have to eject anyway.

 

Across the free world, hearts stopped as everyone waited for the worst and for the crew to eject. Instead, Schirra and Stafford did exactly the right thing— which was to sit tight and do nothing.

 

In less than three minutes the Test Conductor sent word up to the crew that the indication was that of a tail plug dropping out. Without doubt the technician who had installed that plug was probably feeling pretty bad for the next 24 hours— until it came to light that he had unwittingly saved the entire mission.

Oddly, the mission rules said that after a situation such as this, if the crew was to be removed by way of the erector it had to be up and in place within 15 minutes. Schirra thought that was dumb and when the ground told him it would take 20 minutes he happily agreed.

 

As those 20 minutes turned into 99 minutes, he advised that they should read the mission rules again. No one considered just how long it would take to fully safe the booster.

 

Again, oddly, there was plenty of experience with Titan II shutdowns. Test vehicle N-4 had a shutdown on Launch Pad 16 back on June 27^th, 1962 when it suffered a “severe start transient.” That issue actually blew the thrust chamber of one of the engines off the mount and shot out through the flame bucket. It landed “…several hundred feet…” away from the pad. 

N-4 was successfully launched on July 25^th of that same year. Also, GT-2 had a shutdown on December 9^th, 1964, just a year and four days prior to GT-6A’s shutdown. In that situation the ignition took place, and in the 3.2 seconds prior to the programmed blowing of the hold-down bolts and liftoff, the booster sensed a pressure drop in its primary hydraulic control system and instantly switched over to the back-up system. Since the engines were running, the malfunction detection system sensed that switch-over and it could not allow the vehicle to launch on just the back-up system, so it sent the shutdown command.

 

In both cases, the malfunction detection system did exactly what it was supposed to do and it saved the vehicle to fly another day. The fix required re-machining a component and the new part did not arrive at the Cape until January 9th and NASA had to slip the GT-2 launch to January 19^th.

 

Immediately following GT-6A’s shutdown, the launch vehicle sat there with two astronauts aboard plus its toxic propellants— some of which were currently venting into the surrounding atmosphere and to make the matter worse, about 1,830 pounds of that propellant had already been combusted into the pad’s flame bucket. The entire scene was horribly toxic and highly dangerous, but the ground crews now had to get the crew evacuated as quickly and safely as possible. 

It also had to be kept in mind that the booster and spacecraft were both bristling with live pyrotechnics. Scores of squibs, explosive bolts and linear shaped charges were everywhere. There was a slide wire that extended from the service tower to a safe area at the pad perimeter, but the crew had no way to get to it without the erector raised and in position. If they opened their hatches now, there was nothing but empty space. Getting to the slide wire required stepping into the erector’s whiteroom and then dashing to the doors opposite the elevator, go down a flight of stairs and across a short walkway to the service tower. Thus, the first problem to be solved was raising the erector.

 

Pad technicians clad in Self-Contained Atmospheric Protective Ensemble (or SCAPE) suits were at the pad within minutes of the word that the vehicle was stable. They first had to replace the steel grid decking around the engines and then had to go about ensuring that the atmosphere was indeed safe for the extraction crew to move in from their safe positions. That crew would then raise the erector. This whole process all took an agonizingly long time.

Schirra and Stafford were left there “…just breathing,” as Schirra reported to the TC. Their problem was that their spacesuits were at their worst when reclined there in 1G.

Schirra, contrary to what some other authors may say, was wearing the G3C suit, of the same model that Grissom and Young had worn and that suit had a single zipper up the back and along the spine. So, after being in that seat aboard GT-6A for nearly three hours, he was quite uncomfortable. Stafford, however, was wearing the newer G4C suit that had a double zipper up the back. By all rights he should have been in double agony, but he had thought ahead and ordered a long strip of wide foam rubber to run the length of his spine. That was inserted while he was suiting up- and now it paid off. Still, by the end of their entrapment in the spacecraft, Stafford had to resort to grabbing the hatch closure loop and occasionally pulling himself off the seat in order to tolerate the discomfort.

After the crew had been in the spacecraft for a total of three hours and 22 minutes the erector finally started to raise. It took six minutes and four seconds for the erector to reach the vertical position and come to a stop; Schirra was livid.

Just 30 seconds after the erector came to a stop a team of three engineers dashed to the base of the structure and headed up the stairs. The elevator was locked at the spacecraft level to afford the astronauts an alternative exit once the erector was in place. Therefore, the only way for the extraction crew to get up to the whiteroom level was a climb up the tower by way of 80 feet of caged rung ladder and then a series of stairs to the spacecraft level in the white room. Adrenalin must have been really pumping as the first member of the extraction crew made it to the spacecraft level in just two- and one-half minutes!

 

Quickly Schirra and Stafford were helped out of the spacecraft. Together they took the waiting elevator down to the pad level and were met by the emergency crew. This was an actual pad abort and the procedures called for the astronauts to be evacuated to the safe area near the blockhouse by way of the two armored vehicles that were waiting for them on the pad. So, although both astronauts were in good condition and by the time they had finished their elevator ride and Schirra’s temper had cooled down, they were directed away from the waiting astronaut van and into their assigned armored personnel carrier (APC) vehicle.

 

Once at the blockhouse safe area they were finally allowed to get aboard the astronaut van and head off to get out of their suits. The entire evacuation was shown on live TV as the Cape’s remote cameras followed the process.

 

In watching the events it is a sure bet that many out there in TV land considered that Cronkite’s opening statement was far too correct. This was indeed our most exciting day in space- but not for the reasons everyone had expected.