Prediction and Validation of Landing Stability of a Lunar Lander by a Classification Map Based on Touchdown Landing Dynamics’ Simulation Considering Soft Ground

In this paper, a method for predicting the landing stability of a lunar lander by a classification map of the landing stability is proposed, considering the soft soil characteristics and the slope angle of the lunar surface. First, the landing stability condition in terms of the safe (=stable), sliding (=unstable), and tip-over (=statically unstable) possibilities was checked by dropping a lunar lander onto flat lunar surfaces through finite-element (FE) simulation according to the slope angle, friction coefficient, and soft/rigid ground, while the vertical touchdown velocity was maintained at 3 m/s. All of the simulation results were classified by a classification map with the aid of logistic regression, a machine-learning classification algorithm. Finally, the landing stability status was efficiently predicted by Monte Carlo (MC) simulation by just referring to the classification map for 10,000 input datasets, consisting of the friction coefficient, slope angles, and rigid/soft ground. To demonstrate the performance, two virtual lunar surfaces were employed based on a 3D terrain map of the LRO mission. Then, the landing stability was validated through landing simulation of an FE model of a lunar lander requiring high computation cost. The prediction results showed excellent agreement with those of landing simulations with a negligible computational cost of around a few seconds.

Soft-Landing Dynamic Analysis of a Manned Lunar Lander Em-Ploying Energy Absorption Materials of Carbon Nanotube Buckypaper

With the rapid development of the aerospace field, traditional energy absorption materials are becoming more and more inadequate and cannot meet the requirements of having a light weight, high energy absorption efficiency, and high energy absorption density. Since existing studies have shown that carbon nanotube (CNT) buckypaper is a promising candidate for energy absorption, owing to its extremely high energy absorption efficiency and remarkable mass density of energy absorption, this study explores the application of buckypaper as the landing buffer material in a manned lunar lander. Firstly, coarse-grained molecular dynamics simulations were implemented to investigate the compression stress-strain relationships of buckypapers with different densities and the effect of the compression rate within the range of the landing velocity. Then, based on a self-designed manned lunar lander, buckypapers of appropriate densities were selected to be the energy absorption materials within the landing mechanisms of the lander. For comparison, suitable aluminum honeycomb materials, the most common energy absorption materials in lunar landers, were determined for the same landing mechanisms. Afterwards, the two soft-landing multibody dynamic models are established, respectively, and their soft-landing performances under three severe landing cases are analyzed, respectively. The results depicted that the landers, respectively, adopting the two energy absorption materials well, satisfy the soft-landing performance requirements in all the cases. It is worth mentioning that the lander employing the buckypaper is proved to demonstrate a better soft-landing performance, mainly reflected in reducing the mass of the energy absorption element by 8.14 kg and lowing the maximum center-of-mass overload of the lander by 0.54 g.

Instruments Operations, Science and Innovation in Expedition Support: EuroMoonMars-Etna campaign 2021

<p>An expedition EMM-Etna to simulate the Lunar and Martian volcanic and soil environment will be carried out at Mount.Etna’s Cratere del Laghetto in Sicily, near Catania Italy by the EuroMoonMars TUDublin and LEAPS ExoMars groups. This scouting campaign intends to train in using instruments to be used on MoonMars landers and rovers, with a perspective of ARCHES DLR telerobotics campaign to be conducted in June 2022, and in preparation for ExoMars rover instruments (PANCAM, CLUPI and spectrometers) science and operations.</p> <p> </p> <p> </p> <p> </p> <p>Figure 1: Lunar Lander and REMMI Rover for Sample Analysis</p> <p>The aim of this EMM-Etna expedition is to investigate and analyse the terrain with the use of different scientific instruments. The topography of the landscape will be photographed using a 360° panoramic camera and drone; it will be processed, and a 3D model developed. The terrain will also be investigated using the REMMI Rover, the abilities of the rover to operate and transport equipment will be monitored. This will further develop the knowledge available of the terrain and help future expeditions to identify different landmarks. The use of a Radio Jove Antenna will permit the team to monitor transmissions from both the Sun and Jupiter. This will allow different cosmic events or changes in the celestial objects to be studied and explored. On site a selection of different samples will also be collected and examined using the REMMI Rover. An Ocean Optics UV-Vis-NIR spectrometer will a be operated  in order to evaluate the existence of biological compounds and substances within these samples and in the area itself. It is key to understand the molecular makeup of one’s surroundings when in an unknown environment. By analysing samples collected, spectroscopy can be used to identify and determine a diagnostic for each substance. This process will be monitored by a Logitech camera to ensure it is carried put correctly. A selection of photographs will be captured of each sample using a portable optical microscope. This will allow an in-depth analysis of the microscopic structure of each collected sample. The use of all of the instruments mentioned above is key in the investigation and research into the Moon and Martian-like volcanic environment that is Mount Etna.</p> <p>We would also like to thank Prof I. Pagano's team from the University of Catania and Dr A.Wedler's team from DLR Deutsches Zentrum für Luft- und Raumfahrt for their support in organising this expedition.</p>