Spacecraft structure of Gemini program

In order to control the spacecraft accurately, the designer installed several rocket engines for Gemini, so that it can move forward, backward and sideways in the orbit to change the orbit. Complex tasks require two people to fly the spacecraft, which makes the spacecraft bigger. Moreover, the space flight time of Gemini spacecraft usually takes one to two weeks to determine whether the human body can withstand long-term weightlessness, so it needs a lot of electricity and energy. In order to meet this requirement, Gemini spacecraft added equipment cabin and installed power supply system, propellant storage tank and other equipment.

At that time, the ordinary chemical battery used was low in power and short in life, which was not enough to maintain long-term flight, and the solar cell technology was not mature, so the designer adopted the fuel cell, which released energy by the chemical reaction of fuel and converted it into electric energy output.

With two astronauts, plus additional support systems, materials and propellants, the Gemini spacecraft weighs twice as much as Mercury. To send it into space, the Cosmos launch vehicle used by Mercury has been powerless, and the Hercules 2 launch vehicle has become the launch vehicle of the Gemini spacecraft. After a long investigation, the designer found that the probability of the launch vehicle exploding during launch was extremely small, so Gemini canceled the escape tower and adopted the ejection seat as a life-saving measure in an emergency.

One of the main contents of "Gemini" plan is to realize spacewalk. Considering that designing another transition module for spacewalking will inevitably increase the weight and volume of the spacecraft, the designers of NASA adopted a simplified design, without installing a special transition module for extravehicular activities, and directly used the cockpit as the transition module. There is a rectangular hatch on the side of Gemini spacecraft, which has excellent sealing performance and can be opened and closed in space. When performing extravehicular tasks, astronauts first reduce the oxygen pressure in the cabin and use the oxygen supply system of the spacesuit to breathe. When the hatch is opened, the oxygen in the cabin is lost and the activity outside the cabin is carried out. When returning to the cabin after completing the mission, close the hatch and release oxygen again to pressurize the cabin.

In the way of recycling, the spacecraft dropped the equipment cabin on the track before returning, then ignited four thrust braking rockets in the engine compartment, pushed the spacecraft into the loading track, and finally dropped the engine compartment. The cockpit re-enters the atmosphere alone like a mercury spacecraft, and when it descends to a low altitude, the parachute is opened, and the astronauts splash down on land (or sea) together with the cockpit.