Propellant Consumption-Optimized Lunar Landing Using Signals from Circumlunar Satellite Navigation

The paper reviews a possible lunar mission architecture, where lunar modules are integrated on the lunar Orbital Station (OS), placed in a high lunar orbit (HLO). It discusses the concept of transfers from HLO to an intermediate low lunar orbit (LLO), transfer to a descent orbit, landing at a designated point on the Moon, and return to the OS. An approach was defined, and algorithms were determined and run in simulations for rough and fine control during various phases of the flight. An approach was defined for implementing propellant consumption-optimized descent from LLO to the designated landing target, the lowest possible value for the braking burn required for the descent was defined. Algorithms were developed for quasi-optimal descent during braking phase using measurements from lunar navigation satellites, with the braking burn value which is close to the optimal landing. Relationship between the braking burn and the ratio of the engine thrust to the mass of the Lunar Ascent/Descent Vehicle (LADV) was studied. Relationship between the braking burn of the quasi-optimal landing and the ratio of the engine thrust to the mass of LADV was studied. An approach to and control algorithms for providing operator support for lunar landing were developed, which provide the capability to visually asses the suitability of the landing target from the standpoint of landing safety and, if need be, the ability for the operator to intervene into the control process in order to move the landing target to a safer site.