Gemini 8

Launch, orbit & landing data: Designation  02105 / 66020A Launch date - time  16 Mar 1966 - 16:41:02 UT Launch site  CC, LC19 Launch vehicle  Titan 2 GLV (#GT-8) Payload  Gemini SC8 Size (m)  5.6 long - 3.0 dia Mass (kg)  3789 kg Flight Crew  Armstrong, Neil A. (CDR) Scott, David R. (PLT) Call Sign  Gemini 8 Backup crew  Conrad C., Gordon R. Earth orbit on Mar 16.8:    - Perigee / Apogee  159 x 265 km    - Eccentricity  0.008    - Inclination  28.91°    - Period  88.60 min Landing date - time  17 Mar 1966 - 03:22:28 UT Landing location  25.23N, 136E (Pacific Ocean) Flight Duration (d:hr:min)  0:10:41 Nbr orbits  6,5 Distance (km)  284.8 thousand

Launch Crew

Mission details:

• First succesfull docking with unmanned target "Agena" satellite (GATV 8) on Mar 16.97; during the docking both spacecrafts get in uncontrolled stagging because of problems with the spacecraft control system; crew was forced to undock; crew regained control of their spacecraft by using reentry control system, which prompted in a early landing.
• Gemini 8 (1966-20 A) and Gemini 8 adapter module (1966-20 C) separated Mar 17.13

Agena in orbit - Credit: NASA.

First successful docking with an Agena target vehicle was immediately followed by a major space emergency. A stuck thruster on Gemini put the docked assembly into a wild high speed gyration. Near structural limits and blackout, Armstrong undocked, figuring the problem was in the Agena, which only made it worse. Finally he shut the main Gemini reaction control system down and regained control with the reentry control system thrusters, using 75% of that system's fuel. Although the crew wanted to press on with the mission and Scott's planned space walk, ground control ordered an emergency landing in the mid-Pacific. The crew spent all night in the water before being picked up by a US Navy destroyer.

Official NASA Account of the Mission from On the Shoulders of Titans: A History of Project Gemini, by Barton C. Hacker and Charles C. Alexander, Published as NASA Special Publication-4203 in the NASA History Series, 1977.

The target launch vehicle lifted from pad 14 at 10 o'clock in the morning. Its trajectory was at first low and to the right (south) of the intended flightpath. The sustainer engine rammed the target back on track. In a little more than five minutes, the Atlas had done its job. Now it was Agena's turn. After a short coast, its secondary propulsion system burst into life. The crucial test for the Agena came with the firing of its main engine, and the engineers crossed their fingers and held their breaths. But it worked. The engine ignited and carried the target into a 298-kilometer circular orbit. Planners had wondered if the Agena could so position itself that astronauts could catch it. The answer was yes!

With one up and one to go, attention turned to 19. Fourteen minutes before the Atlas-Agena lifted, Armstrong and Scott slid through the spacecraft hatches into their couches. As the flight-preparation crew helped harness Scott to his parachute, they found one of its catches full of glue. Backup command pilot Conrad and McDonnell pad leader Guenter Wendt began digging it out. Just a little thing like that, Scott thought, "might have cost us a launch," but he could not help smiling as he watched Conrad sweat over the job. The catch came unglued and Gordon, the backup pilot, tried the fitting a few times to prove to Scott that it was working. Learning of the Agena's nearly perfect orbit, Armstrong said, "Beautiful, we will take that one."47

Gemini 8 - Art concept of Astronaut in Maneuvering Unit during EVA - Credit: NASA.

After the first hurdle had been vaulted, the next challenge was catching the target. Procedures were much the same as those for Gemini VI-A, although this time there was no friendly target to point its attached transponders toward the spacecraft's radar. Armstrong and Scott began the chase 1963 kilometers behind the Agena.

Thirty-four minutes into the flight, the Sun set and, in the engulfing darkness, the crew could see brilliant fires streaming from their spacecraft's thrusters. As the radiator in the adapter expelled water, the thrusters fired to compensate for a sideward turn. The Carnarvon, Australia, tracking station told them the radiator was not much of a problem and passed to them the Flight Director's "go" for a day's flight.

Over the Pacific, the two astronauts had some time to sightsee. Molokai, Maui, and Hawaii hove clearly into view. Armstrong tried to see Karnai and Oahu, but cloud banks obscured them. Minutes later, Scott said to his partner, "We're going over Baja California now. Can you been it?" But Armstrong had his eyes on the Los Angeles ship basin in the other direction, and his response was, "Oh, look at all those ships!" Armstrong then spotted the Rogers Dry Lake bed. He looked for, but was not certain he found, Edwards Air Force Base, where he had spent seven years piloting experimental airplanes. Over Texas, both men wanted to see if they could spot their homes, but work preempted this scenic interlude. At the low point of their first circuit of Earth, Armstrong aligned the inertial platform for a height adjustment maneuver. At 1:34 hours elapsed time, he touched off a five-second burst of the thrusters for a small retrograde change in velocity, to lower the apogee slightly. Armstrong noticed a problem in cutting off residual thrust. This resulted in varying computer readings and made it difficult to tell the exact deceleration obtained.

Astronauts Scott and Armstrong inserted into Gemini 8 spacecraft - Credit: NASA.

Nearing second apogee (2:18:25 hours), Armstrong fired the thrusters to add 15 meters per second to their speed. Again, tail-off residuals made it hard to get a computer reading. After this maneuver, Armstrong and Scott pulled their food from the ceiling. Although Armstrong's chicken and gravy casserole had been mixed with water for half an hour, it was still dry in spots and not much like home cooking. But he finished it and washed it down with fruit juice to keep from dehydrating. Then he tried a package of brownies, which were stuck together and crumbly. They were hard to eat without scattering weightless scraps all over the cabin.

Astronaut David R. Scott in Gemini 8 spacecraft during countdown - Credit: NASA.

Armstrong and Scott then began the rendezvous radar test. They did not expect to get radar contact as quickly as Schirra and Stafford had, but the Westinghouse development team had promised target acquisition at 343 kilometers. The radar locked on solidly at 332 kilometers, which was good enough.

Over the Tananarive tracking station, 3:48:10 hours after launch. Armstrong nosed the spacecraft down 20 degrees and applied the aft thrusters for an in-plane (with the target) velocity change of 18 meters per second. This gave them a nearly circular orbit close to 28 kilometers below that or the target. The spacecraft was now in position to start the terminal phase of rendezvous.

Astronaut Neil A. Amrstrong in Gemini 8 spacecraft during countdown - Credit: NASA.

When the Agena was at the proper angle (10 degrees) above them, Armstrong aligned the inertial platform for the translation maneuver. Then he pitched Gemini VIII's nose up 31.3 degrees and canted the vehicle 16.8 degrees to the left. At 5:14:56 hours, ground elapsed time, the command pilot fired his aft thrusters, later making two small corrections. High over the Coastal Sentry Quebec tracking ship, stationed near Antigua Island, at 5:43:09 hours, he braked the spacecraft. Since he could see the Agena, Armstrong judged his braking action by eye as Scott called out radar range and range rate. At a distance of 46 meters, relative velocity between the two vehicles had been canceled. The second rendezvous in the Gemini program had been achieved.

For 36 minutes after rendezvous, Armstrong's delicate maneuvering kept his spacecraft on station with the target vehicle. As the command pilot drove, Scott inspected the Agena - checking antennas, docking lights, and the like. Finding it hard to see all of the target's instrument panel displays near the docking cone, he used the telescopic sight of a hand-held sextant. But a really good look would have to wait until they were docked, when these instruments would become a second dashboard. Meanwhile, Armstrong studied the general appearance of the Agena. It seemed stable, and he nudged the spacecraft to within a meter (about three feet) of the target. Then, at 6:32:42, Keith K. Kundel, CapCom on the Rose Knot Victor, radioed, "Go ahead and dock."
Armstrong eased Gemini VIII toward the target at a barely perceptible rate of 8 centimeters (3 inches) per second. "About two feet (60 centimeters) out," he told the Rose Knot Victor. In a matter of seconds, Armstrong gleefully reported, "Flight, we are docked! It's . . . really a smoothie - no noticeable oscillations at all." For a moment, the flight controllers in Houston could not realize that they had really done It. Then pandemonium broke loose, with back slaps, hand shakes, cheers, and tremendous grins.

Because there had been some difficulty in verifying the Agena's uplinked stored program commands for the planned docked yaw maneuver and in loading the target's velocity meter, the flight controllers suspected that Agena's attitude control system might be misbehaving. In fact, Lovell, on the remote link through Tanarive just before the spacecraft passed out of communications range, told the crew, "If you run into trouble and the attitude control system in the Agena goes wild, just . . . turn it off and take control with the spacecraft." With this warning raging in their ears, Armstrong and Scott began their docked chores.

The Agena was designed to obey orders from the spacecraft, as well as from ground control. Scott commanded the target's attitude control system to turn the vehicle combination 90 degrees to the right. It took five seconds less than the full minute expected. Scott next dialed an order to start the Agena's tape recorder and looked over toward Armstrong. As he did, his gaze skimmed the control panel in the spacecraft. Something had to be wrong - Gemini VIII should be in level flight, but the "ball" indicator showed a 30-degree roll. He knew there was no use checking the horizon out the window, as they were passing through Earth's shadow. There would be no help from the ground tracking stations either; they were still out of communications range.

Agena Target Docking vehicle seen from Gemini 8 spacecraft - Credit: NASA.

While Armstrong struggled with the controls, Scott photographed the interaction between the two vehicles out of his spacecraft window. The command pilot soon reported that the OAMS propellant had dropped to 30 percent, a strong clue that a spacecraft thruster might be causing the trouble. While Armstrong fought the controls, Scott cycled the target vehicle switches off and on and off again. Then Armstrong jiggled the spacecraft switches as well, to see if they could isolate the problem. Nothing they did seemed to have any effect.

Agena Target Docking vehicle seen from Gemini 8 spacecraft - Credit: NASA.

Almost immediately, suspicion about a spacecraft control problem became an established fact as the spacecraft rolled even faster. "And then we really took off," Armstrong and Scott later reported. Gemini VIII soon came into acquisition range of the Coastal Sentry Quebec. James R. Fucci, CapCom aboard the ship, was concerned and perplexed. He could not get a solid electronic lock-on, but a blinking light signal indicated that the craft had undocked. Unaware that the spacecraft was rolling, so the antennas could not remain in position, he put in a call to the crew to try to find out about these strange signs he saw on his console.

Fucci: Gemini VIII, CSQ CapCom. Com check. How do you read?

Agena Target Docking vehicle seen from Gemini 8 spacecraft - Credit: NASA.

Fucci: Okay. We got your SPACECRAFT FREE indication here. . . . What seems to be the problem?

Armstrong: We're rolling up and we can't turn anything off. Continuously increasing in a left roll.

Fucci: Roger. (37 seconds later) Gemini VIII. CSQ.

Armstrong: Stand by.

Scott: We have a violent left roll here at the present time and we can't turn the RCS's off, and we can't fire it, and we certainly have a roll . . . stuck hand control.

After backing away from the Agena, the spacecraft had started to whirl at a dizzying rate of one revolution per second. Armstrong suspected that the maneuvering thrusters were about finished. He and Scott were also having trouble seeing the overhead panel dials; their physiological limits seemed near. They were dizzy, and their vision was blurred. Something had to be done. "All that we've got left is the reentry control system," Armstrong said. "Press on," Scott responded. The two men began to throw switches to cut out the OAMS and cut in the reentry control system. Armstrong tried his hand controller - nothing. Scott tried his - still nothing. They started switching circuitry again - maybe something had been set in the wrong position.

Agena Target Docking vehicle seen from Gemini 8 spacecraft - Credit: NASA.

Armstrong steadied the motion and then turned off one ring of the reentry control system to conserve fuel. He then carefully reactivated the maneuver thrusters; now they were able to tell that No. 8 had "failed on" - that is, it had stuck open!

Using the reentry control thrusters meant that the Gemini VIII mission would have to come to an end as soon as possible. That was a mission rule. True, the spacecraft was operating in a backup mode - but it was the prime mode for reentry. If these thrusters developed leaks, the crew would have absolutely no means of getting the spacecraft into position for the critical retrofire that would return them to Earth. Attitude control before and after reentry was essential to reenter the atmosphere safely. Here was a case where the fail-safe maneuvers that Headquarters had insisted on early in the program were impossible - there was virtually no maneuverability left in the orbital thrusters. Armstrong and Scott also remembered, wistfully, that Kraft, the flight controllers, and engineers had nursed other missions to completion. Could the same be done for them now? This was but a fleeting hope, as the Hawaiian tracking station communicator told them to get their spacecraft into position for reentry.

Agena Target Docking vehicle seen from Gemini 8 spacecraft - Credit: NASA.

John Hodge, in his first trial as chief flight director, now had only one choice left - which contingency recovery landing area would be best? If he waited much longer, it would take a full day (or 15 revolutions) for the crew to reach a splashdown point from which they could be quickly recovered. Since the orbital track had precessed westward, landing during the sixth or seventh orbits would have to take place in the Pacific Ocean. When the Landing and Recovery Division recommended a touchdown in the seventh circuit, Hodge agreed.

Kranz had dropped by to listen to the spacecraft and target docking. Since Hodge had been at the flight director's console for 11 hours, he and Kranz decided that the second shift should report for duty immediately, catch up on all information, and direct the final Phases of the mission. Had the flight continued for three days, reentry would have taken place on Kranz' shift, anyway, and he and his men had more practice in recovery procedures than Hodge and his group.

Agena Target Docking vehicle seen from Gemini 8 spacecraft - Credit: NASA.

Many other engineers and program officials also heard about the spinning spacecraft while out of touch with minute-by-minute developments. Mueller, for instance, had remained at Cape Kennedy only through launch and the early phases of the mission. Then he took off for Washington to attend the annual Robert H. Goddard Memorial Dinner, sponsored by the National Space Club. The pilot of the NASA aircraft heard what was happening over the plane's radio and informed Mueller. They returned to Florida, where Merritt Preston met Mueller's party with a motorcycle escort, the prelude to a hair-raising ride to the old Mercury Control Center in time for spacecraft retrofire.

Gemini 8 spacecraft hoisted aboard the U.S.S. Leonard F. Mason - Credit: NASA.

As a rule, McDonnell (the spacecraft contractor) sent several of its experts from the Cape to Houston after launch and first orbit to be available as troubleshooters. On 16 March 1966, a NASA Gulfstream left Florida for Texas with about 14 passengers, among them several high-ranking McDonnell engineers. Over New Orleans, the pilot cut in a commercial radio broadcast to the cabin. The announcer was talking about an imminent recovery in the Pacific. This was all the startled passengers beard, since the news announcement ended there. Something had obviously gone wrong, but what was it? There was nothing to do but wait until they got to Houston.

Raymond Hill, McDonnell's Gemini manager at the Cape, recalled that his company's policy changed radically after "I . . . was caught with my pants down." In the future, senior McDonnell officials - Hill, Walter Burke, John Yardley, and Robert Lindley - would not be in transit at the same time during a flight. Hill stayed at the Cape, Burke went to Houston for the first day of the flight and then back to St. Louis, and Yardley and Lindley went to Houston and stayed until the mission was over. McDonnell specialists, who had previously remained in St. Louis to handle test set-ups and to answer questions by telephone and teletype, were shifted, along with their subcontractor counterparts, to Houston to work directly with GPO systems engineers during the mission.

Meanwhile, Navy recovery forces in the Pacific were swinging into action. A destroyer, the U.S.S. Leonard F. Mason, steamed at flank speed toward the expected landing point 800 kilometers east of Okinawa and 1,000 kilometers south of Yokosuka, Japan.

With Gemini VIII now flying over the southern latitudes. Kranz had only three tracking stations in position to keep in touch with the crew - Coastal Sentry Quebec, Rose Knot Victor, and Hawaii73 The spacecraft was in darkness over the Congo when Kranz's Houston flight controllers began the final countdown for retrofire. Through the remote stations, Scott reported, "Props OFF," and Armstrong said, "Hang in there." Seconds later, Scott said, "Okay. Four retros bed in AUTO RETROFIRE. . . ."

Armstrong was worried that he and Scott might land in some remote wilderness where they would be hard to find. He later said he had been thinking of the steamship Andrea Doria, which had gone down in the Atlantic on 26 July 1956. Although the liner's radios were operating, it had taken the rescue vessels a day and a half to find the sinking ship. He wanted Scott to doublecheck his every move - "I keep thinking there's something we've forgotten about," he said, "but I don't know what it is." Scott answered reassuringly, "We've done everything, as far as I know." Over China, Gemini VIII slipped down in the fringes of the atmosphere.

Everything clicked off properly during descent. As they neared a landing, Armstrong asked his partner, "Do you see water out there?" Looking into the first faint light of dawn, Scott replied, "All I see is haze." Then his voice quickened, "Oh, yes, there's water! It's water!" Less than two minutes later, Scott yelled, "LANDING - SAFE." The flight had lasted 10 hours 41 minutes 26 seconds.

The crew went quickly through the postlanding checklist, putting switches and valves in their correct positions. Then antennas were extended so they could communicate with the recovery forces. "Naha RESCUE 1, Naha SEARCH 1," Scott called, but no answer came. They were not very worried, however, as Houston Flight Control had told them the rescue planes would get to them shortly and the Mason should reach them in three hours. This meant their landing had been very close to the contingency touchdown point.

Several aircraft, including two HC-54 Rescuemasters - one from Naha Air Base, Okinawa, and' the other from Tachikawa Air Base, Japan - had raced to fetch the crew. The HC-54 from Naha got there first. Suddenly the pilot shouted, "I got it!" He had seen the spacecraft, with its main parachute in full bloom, drifting to the ocean's surface. Three pararescuemen were equipped and ready to jump. Armstrong and Scott saw one of the three as he parachuted down. Because of the waves, the frogmen had trouble hooking the flotation collar to the spacecraft. The rough sea also made them queasy, a feeling shared by the astronauts. But the swimmers persisted and secured the collar within 45 minutes of spacecraft landing. Demonstrating excellent cooperation with NASA and careful planning, the Department of Defense recovery forces had reacted to the emergency landing as though it were normal. Armstrong and Scott had few complaints about recovery in this remote area.

Three hours later, as promised, the Mason pulled alongside and fastened a line to the spacecraft. Climbing the Jacob's ladder in sea swells of 4 to 5 meters was hard, but they made it. On deck, the tired astronauts managed smiles and greetings for the welcoming sailors. Still feeling nauseated, the Gemini VIII crew headed immediately for sick bay. Medical personnel helped them strip off their pressure suits. Their undergarments were soaked with sweat. They were thirsty, but clinical examination showed minimal dehydration. The Mason reached Okinawa the next day, and the two astronauts flew on to Hawaii, then home.

Once the manned phase of the Gemini VIII mission was over. Hodge and Kranz turned back to the target vehicle. Because Scott had the foresight to pass the control of the target back to the ground, there was a chance to put the Agena through its paces and see how it reacted to commands. There was still hope that the Agena for Gemini VIII might be used as a passive target for Gemini IX or X.

External links:

• AmericaSpace: 210317-Remembering Gemini VIII, OTD in 1966 (Part 2)
• AmericaSpace: 210316-Remembering Gemini VIII, OTD in 1966 (Part 1)

Astrophilately covers:

Launch cancel Patrick Air Force

Rendezvous with Agena - White Sands cancel

Prime Atlantic Recovery Ship "USS Boxer" (LPH-41)

Second Recovery Ship "USS Cochrane" (DDG-21)

Second Recovery Ship "USS Myles C.Fox" (DD-829), Back 'B636'.

Second Recovery Ship "USS Goodrich" (DD-831), Back 'B640'

Gemini lands in the Pacific