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Gemini 10
Part of Gemini

Agena in orbit

Agena in orbit
Credit: NASA

First free space walk from one spacecraft to another. First rendezvous with two different spacecraft in one flight. Altitude (763 km) record. Exciting mission with successful docking with Agena, flight up to parking orbit where Gemini 8 Agena was stored.

Launched: 1966-07-18. Returned: 1966-07-21. Number crew: 2 . Duration: 2.95 days. Location: Norwegian Technical Museum, Oslo, Norway.

Exciting mission with successful docking with Agena, flight up to parking orbit where Gemini 8 Agena is stored. Collins space walks from Gemini to Agena to retrieve micrometeorite package left in space all those months. Loses grip first time, and tumbles head over heels at end of umbilical around Gemini. Package retrieved on second try.

The Gemini X mission began with the launch of the Gemini Atlas-Agena target vehicle from complex 14. The Gemini Agena target vehicle (GATV) attained a near-circular, 162- by 157-nautical-mile orbit. Spacecraft No. 10 was inserted into a 145- by 86-nautical-mile elliptical orbit. Slant range between the two vehicles was very close to the nominal 1000 miles. Major objective of the mission was achieved during the fourth revolution when the spacecraft rendezvoused with the GATV at 5 hours 23 minutes ground elapsed time and docked with it about 30 minutes later. More spacecraft propellant was used to achieve rendezvous than had been predicted, imposing constraints on the remainder of the mission and requiring the development of an alternate flight plan. As a result, several experiments were not completed, and another secondary objective - docking practice - was not attempted. To conserve fuel and permit remaining objectives to be met, the spacecraft remained docked with the GATV for about 39 hours. During this period, a bending mode test was conducted to determine the dynamics of the docked vehicles, standup extravehicular activities (EVA) were conducted, and several experiments were performed. The GATV primary and secondary propulsion systems were used for six maneuvers to put the docked spacecraft into position for rendezvous with the Gemini VIII GATV as a passive target. The spacecraft undocked at 44 hours 40 minutes ground elapsed time, separated from the GATV, and used its own thrusters to complete the second rendezvous some three hours later. At 48 hours and 42 minutes into the flight, a 39-minute period of umbilical EVA began, which included the retrieval of a micrometeorite collection package from the Gemini VIII Agena. The hatch was opened a third time about an hour later to jettison extraneous equipment before reentry. After about three hours of stationkeeping, the spacecraft separated from the GATV. At 51 hours 39 minutes ground elapsed time, the crew performed a true anomaly-adjust maneuver to minimize reentry dispersions resulting from the retrofire maneuver. The retrofire maneuver was initiated at 70 hours 10 minutes after liftoff, during the 43rd revolution. The spacecraft landed within sight of the prime recovery ship, the aircraft carrier Guadalcanal, some 5 km from the planned landing point on July 21.

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.

After the premission review, the traditional meal, and the ritualistic suiting up, Young and Collins left the crew quarters on 18 July 1966 for pad 19 - to begin the most complex manned flight so far. They had been awakened at noon for a 5:20 p.m. takeoff, when a 35-second window offered the best chance for rendezvous with the two Agenas. The Atlas lifted its payload toward space at 3:39 p.m., just two seconds late. One hundred minutes later, the Gemini launch vehicle boosted the spacecraft skyward exactly on time. Except for a slight shaking and a buzzing in their ears, Young and Collins had a nice ride to start chasing their first target.

At entry into orbit, Gemini X trailed its Agena by 1,800 kilometers. Flight Director Lunney told the crew they were all set for a fourth-orbit rendezvous. Collins unstowed a Kollsman sextant to sight on selected stars for an attempt at optical navigation. Young pointed the spacecraft while his crewmate tried to find the horizon. Collins realized that he was using the wrong reference when he saw stars below the line. He had been mistaking the airglow, a band of radiant light from the upper atmosphere, for the horizon. Even after he corrected this, Collins could not get the lens of the sextant to work properly, as the optical image of the stars did not agree with what he had been taught. He laid the Kollsman aside and tried an Ilon instrument, but that was little help as the Ilon had a severely limited field of view.

Young and Collins checked their figures with Lunney, who had been watching their activities carefully through telemetry. When the trio found that the numbers did not agree with those of the ground computers, Gordon Cooper, the Houston CapCom, passed the word that the crew would have to use the ground computations. Young then fired the thrusters to adjust their orbit to 265 by 272 kilometers. When he aligned the platform for the terminal phase, the command pilot did not realize that the spacecraft was turned slightly. As he thrusted toward the target, Young needed two large midcourse corrections. The spacecraft path toward the Agena was not lined up properly. So he had to stop thrusting briefly and take off on a new track. The final translational maneuvers to reach the Agena cost nearly 181 kilograms of fuel, or three times more than any earlier mission. Five hours and 52 minutes after launch, Young reported a rigid dock.

Because too much fuel had been used, Lunney decided to omit docking practice - backing away and returning to the target's cone. Young and Collins wondered if the second rendezvous might also be canceled, but, some six and a half hours into the mission, the ground controllers started giving the crew the data they would need for the burn. Then, an hour later, the CapCom at Hawaii cleared them to try for second rendezvous.

The Agena main engine roared into life exactly on time. For 80 seconds, the target vehicle thrust the spacecraft upward, adding 129 meters per second to their speed. The crew, at the moment flying backward, had little to say about their reactions to a negative one-g force (a shove to the front of the body - "eyeballs out" - rather than a push on their backsides - "eyeballs in" - as during launch). They were thrown forward from the seats against the body straps. Young later described the first ride on a space switch engine:

"At first, the sensation I got was that there was a pop (in front of our eyes), then there was a big explosion and a clang. We were thrown forward in the seats. We had our shoulder harnesses fastened. Fire and sparks started coming out of the back end of that rascal. The light was something fierce, and the acceleration was pretty good. The vehicle yawed off - I don't remember whether it was to the right or to the left - but it was the kind of response that the Lockheed people had predicted we would get. . . . The shutdown on the PPS (primary propulsion system) was just unbelievable. It was a quick jolt. . . and the tailoff. . . I never saw anything like that before, sparks and fire and smoke and lights."

Gemini X reached an orbit that measured 763 kilometers at the top and 294 kilometers at the bottom. The Agena had pushed the spacecraft more than 463 kilometers above its initial apogee. Young and Collins now viewed Earth from a higher elevation than any human beings ever had. Instead of gazing at the Planet in wonderment, however, they confined their attention to their own little, artificial world. They watched spacecraft systems and kept an eye on the radiation dosage readings (which were within tolerable limits). During his technical debriefing, Young only reported, "We took some pictures at apogee. . . . I don't know where it was, but it shows the curvature of the Earth. . . . We took some pictures coming down hill. I think it was the Red Sea area." Thus, in rating one impression over the other - record high altitude versus Agena ignition - Young and Collins were more affected by the firing of the switch engine than they were by the unique vantage point they had reached. This lack of awe at their record height was caused, at least in part, by the fact that the switch engine blocked much of the downward view.

Nine hours into the flight, the pilots bedded down, sleeping fitfully. Both were still wondering if the second rendezvous would be done. Besides, neither was "really bone-tired," Collins said. Charlesworth's shift in Mission Control was busy that night, reviewing alternate plans for adapting the mission to fulfill its objectives.

When Young and Collins opened for business after 18 hours of flight, their spirits lifted as the CapCom at Carnarvon gave them the numbers for the next target vehicle firing. With the Agena/spacecraft combination faced about so the main engine would fire directly into the flight path, Young made a 78-second burn to reduce the velocity by 105 meters per second and lower the apogee to 382 kilometers. The pilots were again pressed forward in their seats, but this time they were impressed more by the firepower of the Agena than by its fireworks. "It may be only l g, but it's the biggest l g we ever saw! That thing really lights into you," Young commented.

Like rendezvous maneuvers in the past, the next Agena burn (and the final one with the main engine) aimed at circularizing the orbit. At 22:37 hours, the target drove the spacecraft along the flight path to add 25 meters per second to the speed. This brought the low point of the orbit up to 377.6 kilometers - only 17 kilometers below Agena 8.

Although rendezvous and docked maneuvers with the Agena were the high point of the first day, the crew also spent a good part of that time on the 14 experiments they carried. Twenty minutes after launch, the crew turned on a switch to start the tri-axis magnetometer (MSC-3). This device was used, as it had been in other flights, to measure the radiation levels in the South Atlantic Anomaly. Two other experiments were also devoted to radiation - MSC-6, beta spectrometer (mounted in the adapter to measure potential radiation doses for future missions), and MSC-7, bremsstrahlung spectrometer (installed in the cabin to detect radiation flux as a function of energy when the spacecraft passed through the South Atlantic Anomaly).

Some of the experiments had to be done outside the spacecraft. Before the third Agena burn, Collins got ready for his first exposure to outer space, a standup EVA. Preparations went well and the hatch opened easily. At sunset, Collins stood in his seat, setting up a 70-mm general-purpose camera for S-13, a photographic study of stellar ultraviolet radiation. Collins aimed the camera at the southern Milky Way, scanning from Beta Crucis to Gamma Velorum, and exposed 22 frames. The entire night pass was devoted to this task. Young helped Collins identify the stars, at the same time controlling the spacecraft and target vehicle combination. With the beginning of daylight, Collins began MSC-8, color patch photography, to see if film could accurately reproduce colors in space. The pilot did not complete this assignment, however, as his eyes began to fill with tears. Young had the same problem. They suspected at first that the anti-fog compound inside their faceplates was irritating their eyes. They closed the hatch at 24:13 hours, about 6 minutes early.

They had noticed a strange odor that they thought might have been the lithium hydroxide used in the environmental control system, but ground engineers finally concluded that their smarting eyes were caused by having both suit fans on at once. They turned one fan off and, at 30 hours elapsed time, began a second sleep period. Bone-tired this time, they rested well.

Young and Collins awakened to a "morning" of increased activity. In addition to normal systems check, the ground network also reminded them of the experiments expected this day - the S-26 ion wake measurement, to study the ion and electron structure of the spacecraft's wake (after it undocked from the Agena), S-5 synoptic terrain, and S-6 synoptic weather photography. The pilots also had to work in two maneuvers to help them catch up with Agena 8.

Their Agena switch engine had accomplished its task, and more. After being hooked to it for 39 hours, however, they were getting a little tired of looking at it. Young said that watching the Agena out his window was

"just like backing down the railroad track in a diesel engine looking at a big boxcar in front of you. . . . The big drawback of having the Agena up there is that you can't see the outside world. The view out of the window with the Agena on there is just practically zilch."

On freeing themselves from their Agena, the crewmen began preparing for Collins' exit from the spacecraft. Young now needed to make the final maneuvers to get the spacecraft close enough to the Agena 8 for Collins to reach it. Collins connected the 15-meter umbilical to his suit and then fastened it out of the way until time to use it.

"45:38. First sighting of Gemini VIII," Young said. "At this minute it's blurry." After the distance between the two vehicles had been calculated, the Houston CapCom (on the remote line through the Canton station) informed Young, "Your range, Gemini X, is 95 (nautical) miles (176 kilometers)." The crew then learned that what they had been looking at was their own Agena just 5.5 kilometers away. Houston offered consolation, "95 miles is a pretty long range," and Young answered, "You have to have real good eyesight for that." They didn't see the Gemini VIII Agena until it was 30 to 37 kilometers from them, looking to Young like "a dim star-like dot until the sun rose above the spacecraft nose." NORAD's constant care had paid off. They found Agena 8 just where it was supposed to be.

At 47:26 hours Young started the final closure, with Collins computing the figures for two midcourse corrections. The crew found the old Agena pretty stable, and Young moved in to stationkeep about 3 meters above it. In less than 30 minutes, he told the Houston CapCom that they were going down for a closer look at the micrometeorite collection package. Back in Mission Control Center, fuel usage during stationkeeping was being very closely watched. When it proved to be reasonable, Gemini X received a go for the next extravehicular exercise. "Glad you said that," Young answered, "because Mike's going outside right now."

Collins emerged from the spacecraft at dawn. Like Cernan on Gemini IX-A, he found that all tasks took longer than he expected. But he picked off the package from the spacecraft exterior. Next, he moved to the adapter to attach his zip gun to the nitrogen fuel supply. Back in the cockpit area once again, he held on while Young moved the spacecraft to within two meters of the Agena.

Collins pushed off from the spacecraft, floated freely in space, and grasped the outer lip of the docking cone on the target. As he clutched at the experiment package, he wished for handholds - or more hands. Cernan had warned him that it would be hard, and it was. He soon lost his grip on the smooth lip and drifted away from the package and from the Agena. He had to decide quickly whether to pull on the umbilical, coiling about like a snake, or to use the hand-held gun. Being about 5 meters away from the spacecraft, Collins chose the gun. It worked, and he propelled himself first to the spacecraft and then back to the Agena, using a series of squirts to get to the package. This time he clung to wire bundles and struts behind the adapter cone and grasped the S-10 experiment. Collins was supposed to attach a replacement device in its place, but he abandoned this idea, fearing he would lose the one he had picked up. Using the umbilical, he pulled himself hand over hand back to the cockpit and gave the S-10 package to Young.

So far, the umbilical had been snubbed so it would extend only 6 meters. The pilot now unsnapped the buckle that released the remaining 9 meters, intending to evaluate the gun. But the gun play stopped before it started. The Hawaii CapCom told Young, "We don't want you to use any more fuel (for stationkeeping)." Young replied, "Well, then, he'd better get back in." To Collins he said, "Come on back in the house."

Getting back into the spacecraft was surprisingly difficult. Collins had gotten himself tangled in the umbilical. Since the pressurized suit made it difficult to see or feel just where the line had wrapped itself about him, he had to wait while Young helped unwind him and got him back into the seat. But fuel remained the big question. Houston called them, "just . . . to confirm that you're not using any fuel." Young replied, "We've got everything shut off."

More was shut off than he realized. He soon discovered that the radio transmitter had also been turned off. By this time, Collins was back in his seat. Young reported that hatch closing had been easy. With the long lifeline coiling all over the cabin, Young thought it made "the snakehouse at the zoo look like a Sunday school picnic." A little over an hour later, the crew reopened the hatch and tossed out the chestpack and umbilical. This operation only took three minutes. McDonnell had done an excellent job on this righthand hatch.

Because of the time spent struggling with the umbilical, Collins and Young had to hurry to get set up for an important maneuver that would make the point of reentry more precise. They carried out an orbit-shaping activity exactly on time, at 51:38 hours. This retrograde firing, of 30 meters per second, brought the spacecraft perigee down 106 kilometers, making the orbital parameters safe for reentry. After another round of experiments - this time synoptic terrain and weather photographs taken as the spacecraft drifted through space - the crew began their third sleep period.

On awakening (about 63 hours into the flight) on homecoming day, Young and Collins spent more time on experiments and did their packing. Then, 70 hours and 10 minutes after liftoff, the crew felt the first retrorocket ignite as they passed over the Canton Island tracking station during their 43rd revolution. Reentry went remarkably well, with Young steering bank angles by computer solutions. Landing in the western Atlantic at 70:46 hours (4:07 p.m., 21 July 1966) was only 5.4 kilometers from the aiming point. The crew of the primary vessel, the Guadalcanal, watched the spacecraft hit the water. Once the swimmers had attached the flotation collar and positioned the raft, Young and Collins climbed out. They were lifted by helicopter to the deck of the recovery ship.

With that part of the mission completed, the flight controllers put the Gemini X Agena through its paces. Over a 12-hour period, the main engine was fired twice and the small engine once. Since the first maneuver was intended to study temperatures at higher altitudes, the controllers sent the Agena up to a 1,390- by 385-kilometer orbit. They watched it for almost seven hours and found that the temperatures varied little from those at lower orbits. The vehicle was then returned to a circular orbit (352 kilometers) that would make it available as an alternate target for later flights.

Gemini IX-A and X had successfully grappled with some of the specific needs of the Apollo program, acquiring operational experience while fostering healthy debates between the two programs on procedures and equipment. Perhaps the greatest benefit to Apollo was the demonstration and practice of several types of rendezvous. Each provided a storehouse of information. In addition, the orbit-shaping maneuvers to the higher altitudes established that the trapped-radiation hazards could be avoided on trips into deep space. Then, too, the very fact that one spaceborne vehicle could meet another, latch onto it, and use it as a kind of space tug offered many possibilities for such space flight concepts as shuttles, space stations, and space laboratories.

There had been problems, but missions IX-A and X had logged a combined total of three hours and 41 minutes open-hatch experience. Although the extravehicular hiatus between the fourth and ninth flights adversely affected both equipment and operational development, Cernan and Collins had shown that tasks outside the spacecraft were feasible. They found that all chores took longer than foreseen and that body positioning was difficult. During technical debriefings, each extravehicular pilot had pointed out the need for more and better restraints and handholds. These aids were being developed. Overall, perhaps, extravehicular activity remained Gemini's greatest problem. It was and is dangerous, difficult, and deceptive, despite its delights.

The ninth and tenth flights also took several steps forward in experiment performance. Despite operational constraints, usually brought on by limited fuel resources, each situation had been modified to wring the utmost from specific experiments. More and more, principal investigators were being brought in to help with modifications and to assist in rescheduling their tasks for later in the missions, if necessary. These realtime flight changes could not have been carried out in an unmanned flight and would not have been done in an earlier Gemini mission. So, in Gemini IX-A and X, the experiments program began to achieve maturity.

By the end of Gemini X, many of the men and women who had worked full time on the program had begun to have a strong feeling of anticlimax and to wonder about their next jobs. Some had already gone on to other fields, but Mathews tried to control this exodus and to hold enough together to finish the flights. Shortly after IX-A, he told his staff that the Gemini Program Office, as such, would not be continued. The people would be absorbed into other MSC activities - mainly Apollo and Apollo Applications. By early August, a personnel placement committee had begun work. It soon arranged four to six interviews for each of the 193 project office people. This allayed any immediate fears, but Mathews still warned his staff to refrain from making personal contacts for new jobs until the committee could complete its arrangements. There were two more flights in the Gemini program, but it already seemed to be heading into history.

More at: Gemini 10.

Family: Manned spaceflight. People: Collins, Young. Country: USA. Spacecraft: Gemini. Launch Sites: Cape Canaveral. Agency: NASA Houston.
Photo Gallery

Gemini 10Gemini 10
Credit: www.spacefacts.de

Gemini 10Gemini 10
Agena in high orbit
Credit: NASA

Gemini 10Gemini 10
Agena thrusting
Credit: NASA

Gemini 10Gemini 10
Young in orbit
Credit: NASA

1964 January - . LV Family: Titan. Launch Vehicle: Titan II.
1965 September 16 - . LV Family: Titan. Launch Vehicle: Titan II.
1965 November 3 - . LV Family: Titan. Launch Vehicle: Titan II.
1965 November 19 - . LV Family: Titan. Launch Vehicle: Titan II.
1966 January 6 - .
1966 January 17 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 January 25 - .
1966 February 2 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 February 28 - . LV Family: Titan. Launch Vehicle: Titan II.
1966 March 16 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 March 19 - .
1966 April 14 - . LV Family: Titan. Launch Vehicle: Titan II.
1966 April 22 - .
1966 May 3 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 May 13 - .
1966 May 25 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 June 1 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 June 7 - .
1966 June 7 - . LV Family: Titan. Launch Vehicle: Titan II.
1966 June 9 - . LV Family: Titan. Launch Vehicle: Titan II.
1966 June 9 - .
1966 June 13 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 June 15 - .
1966 June 19 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 June 20 - . LV Family: Titan. Launch Vehicle: Titan II.
1966 June 24 - . LV Family: Titan. Launch Vehicle: Titan II.
1966 July 1 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 July 18 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 July 18 - . 20:39 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC14. LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 July 18 - . 22:20 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC19. LV Family: Titan. Launch Vehicle: Titan II GLV.
1966 July 19 - . 21:44 GMT - .
1966 July 20 - .
1966 July 20 - . 23:01 GMT - .
1966 July 21 - . LV Family: Atlas. Launch Vehicle: Atlas SLV-3 Agena D.
1966 July 21 - .
1966 July 22 - .

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