ESA Lunar Lander: Approach Phase Concept and G&C Performance

Abstract

The ESA Lunar Lander mission is tasked with landing safely on the lunar surface near the lunar South Pole. The mission aims to demonstrate the capability of performing soft precision landings and autonomous hazard detection and avoidance (HDA) during the descent and landing phase. The final portion of the descent and landing phase is the approach phase, during which time the spacecraft is steered to the final landing site via the GNC, while providing a vehicle attitude for sensor observations of the landing site and surrounding terrain. An HDA subsystem is active during this phase and uses data from a camera and a Lidar to assess the safeness of the terrain around the landing site and select a safe landing site for GNC targeting. The GNC drives autonomously the vehicle to perform a soft landing at the landing site, performing trajectory diverts when new landing sites are selected by HDA. This paper describes the GNC concept and architecture for the approach phase of the descent and landing portion of the Lunar Lander mission, with emphasis on the details on the guidance and control (G&C) algorithms and the achieved G&C performances. The performance of the G&C subsystem is demonstrated through Monte Carlo simulation campaigns on a functional engineering simulator, with both the GNC and HDA algorithms active. Nomenclature= reference propulsive acceleration, computed by the guidance. = reference and navigated position and position error, respectively. = reference and navigated velocity and velocity error, respectively. = rotation matrix from frame to frame . = parameter of a z-transform. = reference and navigated attitude and attitude error, respectively. = reference and navigated angular rate and angular rate error, respectively. = torque commanded by the attitude control.

Attainable Landing Area Computation of a Lunar Lander with Uncertainty by Reachability Analysis

“…of the unique stabilizing solution S(t i ) of the algebraic Riccati equation (19) such that the eigenvalues of A(t i )B(t i )K(t i ), i ∈ I are negative. A linear interpolation has been applied to the K(t i ), i ∈ I to obtain a time-continuous control law.…”

“…Table 3 shows the range of the error for each state and specific fuel consumption. The uncertainties for the initial state are obtained from [19] by imposing the values with the same proportion. The uncertainty for the specific fuel consumption of the main engine σ SFC is around %2 [20], but in this paper taken as %3 with a conservative assumption .…”

Ground Testbed Development of Navigation System for Lunar Lander

“…The ESA also had researched about design for lunar landing phase, and related technologies and algorithms for ESA Lunar Lander (Ref. [4,5]). In order to perform safety landing, hazard detection and avoidance, autonomous guidance and navigation, and terrain mapping were considered for key technologies, and algorithms and sensors configuration was designed based on each landing phase and altitude.…”

Innovative hazard detection and avoidance guidance for safe lunar landing

“…10 ESA has also been developing 3D imaging lidar for 2018 lunar landing missions. 11 A conceptual scheme of using millimeterwave phased array radar was put forward to support hazard detection and navigation measurement for Mars landing mission. 12 Matthies et al 13 reviewed the sensor options for landing hazard detection and discussed the landing hazard detection approach based on stereo vision and shadow analysis.…”