Gemini 10 (officially Gemini X) was a 1966 manned spaceflight in NASA's Gemini program. It was the 8th manned Gemini flight, the 16th manned American flight and the 24th spaceflight of all time (includes X-15 flights over 100 km).
Mission Insignia
Mission Statistics
Mission:Gemini X
Number of Crew Members: 2
Launch:July 18, 1966
22:20:26.648 UTC
Cape Canaveral LC19
Landing:July 21, 1966
21:07:05 UTC
26 44.4' N, 71 57' W
Duration:2 days, 22 hours
46 minutes, 39 seconds
Orbits: 43
Distance:1,968,823 km


The crew of Gemini 10 were John Young and Michael Collins. Young had flown once before on Gemini 3 flight, the first manned Gemini flight.


Gemini 10 was designed to try and achieve the objectives planned for the last two missions--rendezvous, docking and EVA. As well as this it was also hoped to dock with the Agena Target Vehicle from the Gemini 8 mission. This Agena's battery power had failed many months earlier and this would demonstrate the ability to rendezvous with a dormant object. It would be also the first mission to fire the Agena's own rocket, allowing them to reach higher orbits.


The Agena launched perfectly for the second time, after problems had occurred with the targets for Gemini 6 and 9. Gemini 10 followed 100 minutes later and entered into a 159.9 x 268.9 km orbit. They were 1800 km behind the Agena.

Rendezvous Number One

Collins discovered that he was unable to use the sextant for navigation as it did not seem to work as expected. At first he mistook airglow as the real horizon when trying to make some fixes on stars. Then the image didn't seem right. He tried another intrument that they had on board but this was not pratical to use at it had a very small field of view.

They fortunately had a backup in the form of the computers on the ground. They made their first burn to put them into a 265 by 272 kilometres orbit. However Young didn't realise that during the next burn he had the spacecraft turned slightly which meant that they introduced an out of plane error. This meant tow extra burns using 60% of the fuel on board by the time they docked with the Agena. It was decided to keep the Gemini docked to the Agena as long as possible as this would mean that they could use the fuel on board the Target Vehicle for attitude.

They made the first burn of the Agena engine was 80 seconds long and put them in a 294 by 763 kilometres orbit. This was the highest a person had ever been (until the next mission when Gemini 11 went to over 1000 km). This burn was quite a ride for the crew. Because the Gemini and Agena docked nose to nose, the forces experienced were eyeballs out as opposed to eyeballs in for a launch from Earth. The crew took a couple of pictures when they reached apogee but were more interested in what was going on in the spacecraft--checking the systems and watching the radiation dosage meter.

After this they had their sleep period which lasted for eight hours and then they were ready for another busy day. First order of business was to make a second burn with the Agena engine to put them into the same orbit as the Gemini 8 Agena. This was at 20:58 UTC on 19 July and lasted 78 seconds and took 105 metres per second of their speed, putting them into a 294 by 382 km orbit. They made one more burn of the Agena to circularise their orbit to 377.6 km.

EVA Number One

It was now time for the first of two EVAs on Gemini 10. This was to be just a standup EVA, where Collins would 'stand' in the open hatch and take some photographs of stars as part of experiment S-13. They used a 70-mm general-purpose camera to image the Southern Milky Way in ultraviolet. After orbit sunrise, Collins then photographed a colour plate on the side of the spacecraft (MSC-8) to see whether film reproduced colours accurately in space. They reentered the spacecraft six minutes early when they both found their eyes were irritated. After repressurising they ran the oxygen at high rates and flushed the environment system.

Young and Collins were both tired after the exercise of the EVA and slept well on their second 'night' in space. The next 'morning' they started preparing for the second rendezvous and another EVA.

Rendezvous Number Two

After undocking from their Agena they thought they sighted the Gemini 8 Agena. It however turned out to be their own Agena 5.5 km away, while their target was 176 km away. It wasn't until just over 30 km away that they saw it as a faint star. After a couple more correction burns they were station keeping 3 metres away. They found the Agena to be very stable and in good condition.

EVA Number Two

48 hours and 41 minutes into the mission, the second EVA began. Collins first task was to retrieve a Micrometeorite Collector (S-12) from the side of the spacecraft. This he accomplished with some difficulty (like those experienced by Cernan on Gemini IX-A). However it floated out of the cabin some time during the rest of the EVA and was lost.

He next travelled over to the Agena. He tried to grab onto the docking cone but found this impossible as it was smooth and had no grip. He used the gas gun to move himself towards the Gemini and then back to the Agena. This time he was able to grab hold of some wire bundles and retrieved the Micrometeorite Collector (S-10) from the Agena. He decided against replacing it as he could lose the one he had just retrieved.

He last task on this EVA was to test out the gas gun. However this stopped working and meant they finished the EVA after only 25 minutes. After some difficulty closing the patch due to the 15 metres of umbilical cord it took eight minutes to close the hatch. It was jettisoned along with the chestpack used by Collins an hour later when they opened the hatch for the third and final time.


There were 10 other experiments that the crew performed during the mission. Three were interested in radiation. MSC-3 was the Tri-Axis Magnetometer which measured levels in the South Atlantic Anomaly. There was also MSC-6, a beta spectrometer, measured potential radiation doses for Apollo missions, and MSC-7, a bremsstrahlung spectrometer which detectd radiation flux as a function of energy when the spacecraft passed through the South Atlantic Anomaly.

S-26 was interested in the ion and electron wake of the spacecraft. This provided limited results due to the lack of fuel for attitude control, but found that electron and ion temperatures higher than expected and it registered shock effects during docking and undocking.

Once again S-5 and S-6 were performed. These were Synoptic Terrain and Synoptic Weather photography respectively. Both had good results though were affected by the windows on the spacecraft being dirty. There was also S-1 which was intended to image the Zodiacal Light. These were of little use as the film used was only half as sensitive as Gemini IX-A and the dirty windows lowered the transmission of light by a factor of six.

They also tried to do D-5, a navigation experiment. They were only able to track 5 stars, with six needed for accurate measurements. The last experiment was D-10 to investigate an Ion-sensing Attitude Control system. This was to see if it was possible to find the attitude of the spacecraft from the flow of ions and electrons around the spacecraft in orbit. This system was found to be accurate and responsive.


The last day of the mission was short and retrofire came at 70 hours and 10 minutes into the mission. They landed only 5.6 km away from the intended landing site and were recovered by the USS Guadalcanal (LPH-7).


The patch is simple in design by highly symbolic. The main feature in a large X with two stars orbiting around it. This represents the Agenas but could also show Castor and Pollux in Gemini or the two crew members.

Capsule Location

The capsule is on display at the Kansas Cosmosphere and Space Center, Hutchinson, Kansas. When the restoration of the Gemini 6A capsule is completed, then Gemini 10 will be restored in full view of the public. At the end of this restoration it will be put back on full display at the Cosmosphere. One of the hatches is displayed at Virginia Air and Space Center, Hampton, Virginia.

External links

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Gemini 9A
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Gemini 11