Preliminary design of a Lunar landing mission

G.Guglieri, F.Quagliotti, M.A.Perino

 

This paper provides an overview of a preliminary design procedure for the terminal descent of a lunar lander as result of parametric analysis and trade-off.

After almost 30 years, there is a renewed interest in exploring the Earth's nearest neighbor, the Moon. Recent orbital missions (Clementine and Lunar Prospector) were successfully completed. Surface landing missions are also planned for the next decade with the supervision of space agencies even supported by private investors.

Humans and robotic systems visited Earth's natural satellite in the past. During these missions only a small fraction of the Moon's surface was explored and limited samples from those explored areas were returned to Earth. Much remains to be learned about the Moon. As a matter of fact, from what scientists have learned from Apollo and other unpiloted missions, it is known that the Moon may offer resources that could be used in the future to support the exploration activities of the neighboring areas of the solar system.

As a general remark, the Moon Descent and Landing Module (MDLM) contributes as a system to the successful achievement of the mission objectives providing to the payloads a safe Moon surface access, then the basic services needed to set the payloads in the proper initial conditions required to start their nominal operations.

The GNC and propulsion subsystems play an important role in the MDLM design and mission accomplishment together with a high level of system automation and autonomy especially regarding to soft and precision landing phases. Although some tolerance for the landing site accuracy is accepted, there is still a need for GNC. Correct landing attitude and descent rate are two of these needs. Landing attitude is predominately controlled by RCS while the descent rate is controlled by thrusting power. Obstacle avoidance and landing site terminal correction are provided by RCS thrusters.

The preliminary mission design was performed following the analysis of mission and the design requisites, the definition of the RCS architecture and the simulation of system performances. An optimization procedure based on a genetic algorithm was implemented. Finally, the response of the vehicle for the reference descent profile was reproduced with a comprehensive higher order simulator including a realistic representation of the attitude control system.