Artemis I: how digital simulation played an important role in the success of the mission

With Jim Woodburn, Chief Orbital Scientist at AGI, an Ansys subsidiary, discover how digital simulation played an important role in the success of the Artemis I mission and how it prepares for the return to the Moon.

The success of the first mission of the Artemis program back to the Moon is the result of multiple factors. Among these, the multiphysics numerical simulation that played a role in the design and modeling of this mission “Explains Jim Woodburn, Chief Orbital Scientist at AGI (Analytical Graphics, Inc.), an Ansys subsidiary.

To understand the interest and the usefulness of numerical simulation, it is necessary to know that this tool is ” a means of calculating and predicting complex physical phenomena impacting the characteristics and performance of a system “. Specifically, the software make it possible to virtually test an almost infinite number of scenarios, which would otherwise be impossible, both from a technical and economic point of view and within a reasonable timeframe “. In this context, it is possible to explore and test many avenues without degrading the physical prototype or compromising design costs and deadlines “.

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In addition to reducing costs and development times, simulation also makes it possible to create predictive behavior and optimize product maintenance by detecting potential failures before they occur “.

As part of this first Artemis mission, NASA wanted to use digital simulation to allow ground teams to ” ensure smooth communication between the rocket and NASA stations “. The purpose of this mission was to qualify this new manned space transport system and to test Orion and its service module inside its flight envelope and to see under what conditions and how it could operate in very varied flight configurations.

Reliable communications ensure the safety and success of Artemis missions

It was therefore important throughout the mission, which lasted just over 25 days, that the ” communications between the ground and the various elements of the mission are optimal in order to receive data from Orion, the SLS launcher and its upper stage, and to send command instructions “. It should also be kept in mind that Orion is the first vehicle designed to transport humans ready to venture this far from the Earth and the Moon. Hence this need to ensure that communications in both directions are optimal in all modes of spacecraft operation. Effective communication links are needed to improve the safety of those on board and to support Artemis’ goals of building a space economy and continuing human exploration in increasingly remote regions of our Solar System.”

The NASA communication network is divided into two networks: the Near Space Network (NSN), “ which connected both Orion and SLS during the pre-launch and launch phases “, and the Deep Space Network (DSN), “ used for communications beyond thelow earth orbit “. The two networks worked together to provide navigation for Orion via three-way Doppler tracking. As part of Artemis I, the teams from Marshall Space Flight Center, responsible for RF (radio frequency) communications, used the electromagnetic simulation software 3D Ansys HFSSas well as the software Ansys Systems Toolkit (Ansys STK), in order to analyze the ” contacts between spacecraft and ground stations, visualize flight paths and antenna radiation “. With the help of these two softwares, the flight controllers could thus know where the spacecraft were and predict their trajectory throughout the mission “.

On this Artemis I mission, the SLS also carried several secondary payloads, including a dozen shoebox-sized spacecraft named CubeSats that were jettisoned on the way to the Moon. Some of these mini-satellites were intended to assess and measure various physical parameters essential to a prolonged life around and on the Moon. In order to ” simulate the accuracy of the trajectories of the different CubeSats and therefore ensure that enough follow-up passes were planned to meet the requirements of each CubeSat mission “, NASA used the software Orbital Determination Tool Kit from Ansys (OTDK). With Ansys ODTK, it is possible to perform ” pre- and in-flight simulations of CubeSats trajectory and navigation to provide highly accurate orbit estimates “. This is particularly the case for the BioSentinel missions, ” intended to study the effect of radiation on the organism in space using yeast as a model “, or the LunIR project, developed by Lockheed Martin Space, which “ will make it possible to map the surface of the Moon in order to determine potential landing zones for future manned missions “.

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If digital simulation has helped a lot in the preparation and success of the Artemis I mission, it will also be essential ” to determine the most efficient means of transporting people and materials from Earth to the Gateway and then to the surface of the Moon,” highlighted Jim Woodburn.

In addition to the unmanned and manned missions, the Artemis program indeed provides for the construction of a space station in orbit (Gateway), which will serve as a starting point towards a base on the lunar soil where the astronauts will be able to live and work. Of course, creating a habitable environment on the Moon poses many challenges related in particular to atmospheric conditions and the supply of energy and food resources. The SLS launcher, the centerpiece of the program, will play a key role in supplying the missions. Eventually, this launcher will be able to transport nearly 47,000 kilos of goods to the Moon thanks to a translunar injection (TLI, lunar transfer from a low circular parking orbit around the Earth). The presence of ice on the Moon could also be a source of water supply in the future.

Specifically, the simulation is “and will continue to be used to define in particular the optimum location and orientation of elements of the lunar infrastructure, such as the solar panels used to produce energy on the Moon”. Thus, Ansys software will allow ” d‘perform virtual explorations of the surface of the Moon in order to identify the most suitable regions for ice extraction, but also to plan future excursions for the crew and the rovers’. Thanks to electronic payment simulation we can therefore consider thousands of scenarios, identify potential problems and implement effective solutions to remedy them upstream of the first manned missions and, thus, guarantee maximum safety for the crews “.

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