Lunar human landing system architecture tradespace modeling
Introduction
In 2017, the United States government provided a clear direction for the US human spaceflight program for a return to the Moon by 2024 [1]. The focus of those efforts culminated in the development of the Artemis program [2], which forms the backbone of international collaboration for future human space exploration endeavors. The next steps for the US human spaceflight program, according to the policy at the time of writing this paper, will likely result in the establishment of a deep space Gateway and sortie missions at the lunar South Pole. Reusable systems will likely be employed in such architecture, to ensure sustainable operations over the long term. Architectural decisions such as system reusability need to be evaluated in the context of all other system-level engineering decisions, in order to develop an integrated plan for technology development. In a recent paper, we proposed a technology roadmap for lunar human landing systems, which are key building blocks for future exploration of the Moon [3].
Over the years, different human landing system architectures have been considered; multiple architecture studies were conducted. Those studies, however, are relevant to the specific assumptions and lunar exploration architectures proposed at the time of conducting the study. Since today we have new assumptions (such as having the Lunar Gateway in the lunar architecture and switching to reusable systems), there is a need for a new human landing system architecture study. Such studies are being performed by private companies – see, for example, the study by Aerojet Rocketdyne [4]; examples of other private companies that are likely concerned with architectural studies on human lunar landing systems are Blue Origin, Dynetics and SpaceX, as we can infer from NASA press releases [5]. Those studies, however, are usually either not publicly available or their public representation does not provide enough details on the respective modeling assumptions (as in case with [4]) which makes it difficult to fully understand the justification behind such study conclusions. Making well-informed system architecture decisions is important as they have a significant impact on the end outcomes of program cost and performance (as described in the well-known ‘80/20 rule’ in the context of conceptual system design [6]).
The goal of this paper is to address the gap of an open architectural study of human landing systems (HLS) for future Moon exploration. We develop parametric mathematical models to enable a comprehensive tradespace exploration of future (potentially reusable) HLSs. Open-source parametric models allow for a publicly available architectural analysis, within the framework of future lunar exploration programs. The mathematical models proposed in this paper can be reused and adapted for a range of planetary exploration systems, and are thus of general interest to the space systems engineering community. We achieve our goal in two stages:
- •
First, we develop a set of figures of merit (FOMs) and a general HLS model applicable to each of the three architecture types (1-stage, 2-stage, or 3-stage). The HLS model is used to calculate the mass properties of a specific HLS which are then used to calculate the respective FOMs. Using those FOMs as preliminary proxies for the HLS program cost, we conduct a Pareto analysis on the overall HLS architecture tradespace and narrow down architecture options to a few promising candidates.
- •
Second, we develop an HLS program cost model. This includes developing a refueling vehicle model to model the costs associated with delivering the HLS elements and propellant from Earth to the Gateway (the launch costs). The HLS program cost model is then used to perform the cost analysis on the HLS candidates identified at the first stage. As a result, one of the architectures is selected as having the lowest costs under the assumptions of this study.
The remainder of this paper is structured as follows. Section 2 of this paper describes the methodology used in this study. Section 2.1 provides an overview of HLS architectures; section 2.2 lists the main study assumptions; sections 2.3 defines the figures of merit used in the study; sections 2.4 and 2.5 develop the HLS and refueling vehicle models, respectively; section 2.6 is devoted to the HLS program cost model. Section 3 presents the results of the Pareto (section 3.1.) and cost (section 3.2) analyses. Section 4 summarizes the findings of the study and identifies opportunities for future work.
Section snippets
Methodology
We adopt a comprehensive architecting approach to tradespace exploration in this paper. We have discussed our approach in previous papers [7,8], including previous human spaceflight assessments [9,10]. The methodology can be briefly described as follows. We first provide a brief overview of the system under investigation – human landing system. We then narrow the focus of the study with a set of assumptions, which also set the limitations of our investigations and point out avenues for future
Pareto analysis
HLS architectures with different numbers of stages (1, 2, or 3 stages) and different types of propellant for each of the stages (LOX/LH2, LOX/CH4, or MMH/NTO) were explored. Pareto charts for different numbers of HLS system uses are shown in Fig. 2. The two axes of the upper-left chart are the total HLS wet mass in the Gateway orbit (the horizontal axis) and the total HLS dry mass (the vertical axis). Those masses are used here as proxies for the launch and production costs associated either
Conclusion
In this study, we performed a human landing system architecture tradespace analysis relevant to the current vision of lunar exploration which includes the Lunar Gateway in an L2 near rectilinear halo orbit and tasks a reusable HLS with delivering the crew from the Gateway to a landing site at the lunar South Pole and back to the Gateway. A set of parametric models including an HLS model applicable to the 1-, 2-, and 3-stage cases and an HLS program cost model were developed for the analysis.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References (17)
- et al.
Earth Orbiting Support Systems for commercial low Earth orbit data relay: Assessing architectures through tradespace exploration
Acta Astronaut.
(2015) 45th Space Congress ‘The Next Great Steps’: Space Policy Directive-1
Space Congr. Proc.
(2018)- et al.
NASA’s Human Landing System: the Strategy for the 2024 Mission and Future Sustainability
- et al.
Technology roadmap for future lunar human landing systems
Study recommends minimizing elements for Artemis lunar lander
NASA selects Blue Origin, Dynetics, SpaceX for Artemis human landers
- et al.
INCOSE Systems Engineering Handbook: A Guide for System Life Cycle Processes and Activities
(2015) - et al.
Systems architecting methodology for space transportation infrastructure
J. Spacecraft Rockets
(2013)
Cited by (1)
REACHABILITY-BASED APPROACH FOR SEARCH AND DETECTION OF MANEUVERING CISLUNAR OBJECTS
2022, AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022