The Kontakt rendezvous and docking system

The two manned craft intended to land Soviet cosmonauts on the Moon, the LOK lunar orbiter and the LK lander used a rendezvous and docking system called Kontakt. This was developed in some competition to the system IGLA (described elsewhere at this Web site) used on Soyuz/Progress/Salyut. Very little is known about Kontakt, especially its radio system for homing and guidance during rendezvous and docking. This article is an attempt to locate antennas for the system on images of LK and LOK and to try to draw conclusions from these antennas.
 
 

LOK shown at Kaluga museum. Credit: © Mark Wade

Antennas on LOK possibly related to Kontakt

There are three four-turn helices with a diameter of 10-12 cm (indicating a frequency of 800-960 MHz). Two are facing forwards and one backwards. A detailed image of the antenna at the front of the spacecraft shows that the helix is fed at the circumference and not at the center. The antenna gain of a four-tun helix operating in the axial mode is 11.7 dBi and it has a beamwidth that is 52 degrees wide.

Antennas and other devices on LK possibly related to Kontakt

In the figure we can identify four antennas and two other devices that could possibly have something to do with the Kontakt system
 

• The low gain canted turnstiles over a ground plane (A) can be seen at six places. Four pointing radially outwards from the docking unit at the top. One pointing forwards from the docking unit and one pointing backwards from block E. This type of antenna can be seen on many vehicles including around the waist of LOK. It can be a used for the 922/768 MHz system for command and telemetry used on many other Soviet/Russian spacecraft such as Soyuz and Progress. The six antennas provide a compete omnidirectional coverage - something that is absolutely essential for the command link.
• The conical helices were intended to probably deploy upon landing and are most probably also for the 922/768 MHz system.
• The type C antennas that are called "Homing system antennas" probably belong to Kontakt and most probably transmit beacon signals that the direction-finding array antenna on LOK can receive. It is interesting that both the elements of direction-finding "X-shaped" antenna on LOK and this homing antenna on LK are very small compared to e.g. the type A and D antennas, indicating a much higher frequency than those operate on.
• The four-turn helix "D" that can be found also on LOK is probably for receiving range and range rate signals from LOK that are retransmitted over the "C" antennas once the direction-finding antenna on LOK has located the LK.
• The alignment sensor/fine adjustment sensors seem to have something to do with final pitch, roll, and yaw alignment just prior to contact. Whether they are optical devices or not cannot be judged at this time.

Antennas used during homing and proximity operations

The figures below are intended to illustrate these situations.