7K-L1 Zond Program

Having won the "first race" in the space race, the Soviet Union was going to keep its priority in the future, and the design idea, spurred on by recent successes, did not stand still. On the agenda was the question of organizing a manned flight to the Moon, and the first to fly this Soviet cosmonauts.

Unlike the Americans, who didn’t set the lunar flyby as an independent goal and performed them only as test flights during the preparation of the landing on the moon, in the USSR there were a number of projects specifically for flying around the moon. The projects envisaged a single flight over the reverse side of the moon, the field of which bent the ship's trajectory and sent it back to Earth. No transition to orbital lunar orbit was planned. This made it possible to drastically reduce the mass of the lunar ship, since during such a flight, only a small amount of fuel was required for trajectory corrections. In view of this, a super-powerful carrier was not required to launch the ship.

In March 1959, under OKB-1 under Sergei Korolev, preparations began for the creation of a new spacecraft, which was to replace the Vostok at the next stages of the development of Soviet cosmonautics. Initially, the project, known as the "North", did not include the astronaut's landing on the surface of the Earth's natural satellite - it was just a flight around the moon. Unlike the future of the "Union", the ship "North" provided for a much larger volume of the descent vehicle. By summer, the designers developed the main parameters, which formed the basis for the design of the future ship.

It was necessary to change the concept, and in 1962 in response to the American program "Apollo" Mikhail Tikhonravov's department OKB-1 proposed a whole space complex consisting of the ships "7K", "9K" and "PC" and intended for the flight of the moon. First, the ship "9K" (upper stage) was to be launched into the near-earth orbit, then three (maximum - four) ships of the "PK" (tanker) with fuel and oxidizer were sequentially attached to it.

After the completion of the refueling, the ship "7K" was to start with the crew, who, after docking with a refueled upper stage, formed a ship to fly over the moon. If all five launches were successful, then a manned spacecraft (23 tons in weight) using the LRE of the 9 K upper stage would be transferred to the flight pattern of the moon. The entire flight should not take more than 7-8 days.

For that time, such a scheme looked very complicated, because no one ship with the crew ever flew to orbit, the docking system was not worked out, without which it was simply impossible to implement the project. True, she also had her own positive side: for the launching of ships into the near-earth orbit, it was possible to use the spent and sufficiently reliable R-7 carrier rocket. And yet, for the flight of the moon, this program would require long-term developments and a large complex of flight-design tests.

As a preliminary stage, the program "Soyuz 7K-L1" was conceived. The spacecraft developed under this program was intended for a manned flight around the moon lasting 6-7 days. Since there was no provision for access to the lunar orbit, the ship did not have a powerful propulsion system, and the return to Earth was provided by a maneuver in the gravitational field of the Moon. With accurate calculations and correct deduction, the inclusion of the engine for return was not required at all.

On March 7, 1963, Sergey Korolev presented the draft project of the Soyuz space-rocket complex. The complex, in particular, included another modification of the R-7 rocket carrier under the name "Soyuz" and the Soyuz-A spacecraft intended for orbiting flights and flying around the Moon. The ship was equipped with rendezvous and docking systems, and also allowed refueling during the flight. At the same time, Chief Designer OKB-52 Volodymyr Chelomei proposed his project of flying the moon along a loop-shaped trajectory by the Lunar "LK". Moreover, the ship was to be taken out to near-earth orbit and transferred to the flight trajectory to the Moon by a three-stage UR500K rocket (Proton-K) and a special upper stage developed in the same OKB.

On October 13, Nikita Khrushchev was dismissed, and OKB-52 Chelomey was "overboard". The leadership of the lunar program was completely transferred to Sergei Korolev, and moreover he was able to use all the developments of Chelomey on a manned flight to the Moon and, in particular, the UR-500K missile for his tasks. So, on the basis of two projects being developed in OKB-1 and OKB-52, the Soviet program for the fly-around of the Moon was born, under the designation "UR-500K-L1" ("UR-500K-7K-L1"). On December 15, 1965, it was approved and became the main lunar fly-by program of the USSR.

The government of the USSR formed the opinion that V.N. Chelomei with the project "UR500K-LK1", despite its obvious merits, will not be able to ensure the priority of the USSR in a manned flight of the Moon. Creation of a flying ship was assigned to OKB-1 under the leadership of S.P.Korolev. At the same time, to accelerate the work, the use of the UR500K LV was suggested. Chelomey with the addition of the upper stage "D" as the fourth stage of S.P.Korolev.

Then the work was carried out within the framework of the project “Union” - on October 25, 1965, by decision of Afanasyev, at the meeting of the Military Industrial Committee, the project was transferred from Chelomey OKB-52 to Korolev Design Bureau 1. S.P.Korolev presented a new project, named "UR500K-L1", on December 15, 1965. It was approved and became the main lunar flying program of the USSR.

The implementation of the program of the manned flight of the Moon by the UR-500K complex (Proton-K) -7K-L1 provided for a considerable amount of research on the experimental development of each of the constituent parts of the complex. In particular, it was envisaged to develop a regular flight scheme along the Earth-Moon-Earth route with the help of 7K-L1 unmanned ships built on the basis of Soyuz spacecraft. The weight of the ship was about 5,350 kg, the weight of the descent vehicle was 3,100 kg, the useful volume of the vehicle was 2.5 m. After the launch, the Proton-K rocket carried the ship along with the upper stage D (fourth stage) to the satellite's transition orbit with parameters : apogee ~ 220 km, perigee ~ 180 km, inclination - 51.5°. After that, the engine of block D was switched on by the command of the program device, and the ship switched to the flight path to the Moon.

In addition to solving purely technical issues, it was necessary to study how the congestion on returning with the second space velocity and the radiation situation on the lunar track affect the living organisms. This time, according to the advice of scientists of the Academy of Sciences, for the "biological indication" of the route into space, decided to send turtles (Testudo horsfieldi Gray): they do not need a large supply of oxygen, they can be in a lethargic state for a long time. Turtles were placed in special cases, where they were practically deprived of mobility. they can for a long time be as if in a lethargic sleep.

Sergey Korolev, who did not trust the products of OKB-52 by Vladimir Chelomey, in 1965 ordered another version of the manned flight of the Moon. In this case, the 7K-L1 spacecraft would be put into orbit in an unmanned mode. The crew was to launch into orbit on the ship "7K-OK" with the help of the Soyuz rocket. After the ships were docked, the cosmonauts had to go into the spacesuits "Yastreb" from the "7K-OK" household compartment to the descent vehicle "7K-L1" through the open space and a curved tunnel in the support cone of the emergency rescue system. After that, the ship "7K-OK" should be automatically undocked, and the ship "7K-L1", having dropped the docking node with the support cone, start to the Moon. Later, experiments were conducted on a special Tu-104 plane to investigate the possibility of transfer of two cosmonauts in spacesuits from the ship 7K-OK to the ship 7K-L1. As a result of these studies, the version with a crew change in the Earth's orbit was rejected.

Based on the previous studies on the themes “Soyuz” and H1, as well as having familiarized with the work of OKB-52 V.N.Chelomey on the LV UR500K and the ship LK-1, S.P. Korolev on December 15, 1965 at a meeting of chief designers presented Avia project of the ship L1 for flyby of the Moon. According to this draft, it was supposed to fly around the Soyuz spacecraft in a lightweight version. The launch of the ship from the near-earth orbit would be carried out using the upper stage “D”. The launch of the “blocking vehicle” complex into a low earth orbit should have been carried out by the UR500K carrier.

The advantage of the project of S.P.Korolyov over the project of V.N.Chelomey was that OKB-1 already had experience in the development and creation of manned spacecraft "Vostok" and "Voskhod" and the successful work on the program "Soyuz" conducted by wide front in this time period. In addition, a certain role in the decision to start work on project L1 was played by S.P.Korolyov’s great authority.

Like the project LK-1, the L1 program provided for circling the moon and returning to the Earth a spacecraft with a crew of two people. Because of the short timeframes allocated for the implementation of the program, it was envisaged to make maximum use of the existing ground base, documentation and material part of the Soyuz program. The hard limits imposed by the UR500K carrier and the “D” block limited the weight of the ship L1 to 5.1–5.2 tons. For these reasons, the designers were forced to relieve the Soyuz in every possible way, while maintaining its reliability indicators. So, in particular, the household compartment, part of the CA systems (including the reserve parachute system) and part of the PJSC systems (one of the four sections in each wing of the solar panels and the backup LRE close-to-corrective remote control) were removed from the ship. Substantial changes were made to the design of the Soyuz, allowing it to fly around the moon. The orientation and motion control system of the onboard equipment complex, the radio communication system with the Earth were upgraded, and a sharply directed antenna was introduced. The number of jet nozzles that control the movement of the SA on the descent section in the atmosphere has been increased. The heat shield of the SA was refined for heating during descent with the second space velocity.

At the atmospheric launch site, the ship L1 was closed by an aerodynamic fairing specially designed for this purpose. In the event of a carrier accident, it was proposed to divert the SA using an emergency rescue system (SAS) with a more powerful remote control than the Soyuz spacecraft. Since the domestic compartment of the Soyuz vehicle was absent on apparatus L1, the capture of the descent vehicle by the fairing lodgments at the moment the SAS propulsion system was turned on had to be carried out by a special support cone docked in the upper part of the aircraft. Through the hatch in the head fairing, the passage in the center of this cone and the hatch in the SA astronauts at the start got into the ship. Before turning on the “D” block, in the near-earth orbit, the reference cone was dropped.

The astronauts' training under the program L1 began long before the first copies of the ship were ready. At first, they were carried out on the ground analogues of the Soyuz AS, equipped with new control devices, among which the indicator field used for the first time was highlighted. The astronauts noted the convenience of working with the new equipment, but also complained about the tightness of the SA, which was supposed to spend seven days of flight.