Simulation Helps Artemis Keep in Touch and on Track to the Moon

In the 1820s Baron Franz von Paula Gruithusen, a German physicist and astronomer, turned his small telescope toward the Moon and saw what he imagined was a city there, which he named Wallwerk. “Imagination will often carry us to worlds that never were,” said the American scientist Carl Sagan more than 150 years later. “But without it we go nowhere.” And in 2022, the first Artemis Moon mission launched, paving the way for humankind to not only return to the Moon after a 50-year absence – but to live and work there.

Artemis I is the first of three increasingly complex missions. The uncrewed mission is a test of NASA’s deep space exploration systems, including the Orion spacecraft that will carry astronauts from Earth to lunar orbit and back, the Space Launch System (SLS) rocket — the most powerful rocket in the world — and ground systems needed to support the launch and recovery of the spacecraft after its 1.3-million-mile journey. Future missions are planned to land astronauts on the Moon, deploy a spaceship in lunar orbit to act as a long-term gateway to the Moon, and to build a base camp on the Moon. What is learned from the Artemis missions could be used to explore destinations farther from Earth, including Mars.

Connect and Communicate

Artemis is a prime example of digital mission engineering (DME), which is defined as the use of digital modeling, simulation, and analysis to incorporate the operational environment and evaluate mission outcomes and effectiveness at every phase of the life cycle. Since its inception, every state in America has made a contribution to the success of the Artemis program, not to mention the systems being designed in Europe. The system complexity and collaboration involved are astounding, and Ansys is proud that our software has played several roles in the Artemis mission.

For example, the RF Communications Team at NASA’s Marshall Space Flight Center routinely uses Ansys HFSS 3D electromagnetic simulation software and Ansys Systems Tool Kit (STK), a physics-based modeling environment for analyzing platforms and payloads. For the Artemis missions, the team is using STK for all of its SLS communication link analysis, and to visualize flight trajectories, contact with ground stations, and antenna radiation patterns.

A depiction of the Artemis-1 trajectory constructed with STK Astrogator. The animation (right) captures the general structure of the Artemis-1 trajectory and illustrates the unique path the spacecraft follows, a path that harnesses the simultaneously combined gravitational influence of both the Earth and the Moon. Also sharing a ride up with the Artemis-1 spacecraft are several ride-share missions. Some of these missions utilize both the Astrogator capability set within Ansys Systems Tool Kit (STK) as well as the Ansys Orbit Determination Tool Kit (ODTK).

Seamless communications are critical, of course, to send and receive data at each stage of the mission — enabling flight controllers to send commands to the spacecraft and receive data from Orion, the SLS, and the rocket’s upper stage. Navigation, or tracking, services enable the flight controllers to calculate where the spacecraft are along their trajectory through space.

NASA’s communication network is divided into two networks: the Near Space Network (NSN), which links to both Orion and SLS during prelaunch and launch for Artemis I, and the Deep Space Network (DSN), which is used for communications beyond low-Earth orbit. The two networks work together to support navigation for Orion via three-way Doppler tracking. With two ground stations on Earth in contact with Orion simultaneously — one from each network — NASA can triangulate Orion’s location relative to the ground stations.

What’s Brewing in Artemis’ Secondary Payloads?

LunIR was developed by Lockheed Martin Space in Denver, Colorado. As it flies by the Moon, it will use a miniature infrared sensor to gather images and data about the lunar surface, such as material composition, thermal signatures, presence of water, and potential landing sites.

Other CubeSats will be used to map near-surface hydrogen, function as a space weather station, image the Earth’s plasmasphere, investigate an asteroid, observe the interim cryogenic propulsion stage with advanced optics, compete in NASA’s Space Derby, and even attempt to land the smallest ever (weighing just 700 grams) spacecraft on the Moon. The range of science being carried out by the CubeSats is indeed exciting, including several firsts for humankind.

However, what scientists will learn about safely sending a crew to the Moon and back from the broader mission is difficult to measure. Artemis I will fly farther away than any spacecraft built for humans has ever flown and return faster and hotter than ever before. It could lay the foundation for a space economy and for human exploration of ever-more-distant regions of our solar system — something Baron Gruithusen no doubt imagined hundreds of years ago.