A U.S. mission to land astronauts on the surface of Mars will be unlike any other extraterrestrial landing ever undertaken by NASA. 

Although the space agency has successfully landed nine robotic missions on Mars since its first surface missions in 1976 with the Viking Project, safely bringing humans to Mars will require new technologies for flight through the Martian atmosphere. But these technologies and systems can’t be comprehensively tested on Earth beforehand. 

Since 2019, a team of NASA scientists and their partners have been using NASA’s FUN3D software on supercomputers located at the Department of Energy’s Oak Ridge Leadership Computing Facility, or OLCF, to conduct computational fluid dynamics, or CFD, simulations of a human-scale Mars lander. The OLCF is a DOE Office of Science user facility located at DOE’s Oak Ridge National Laboratory.

The team’s ongoing research project is a first step in determining how to safely land a vehicle with humans onboard onto the surface of Mars. 

The arrival of OLCF’s Frontier supercomputer could not have come at a better time for the project. With exascale computing power (a quintillion or more calculations per second) now a reality, the team could afford to reintroduce the desired physical modeling and other lessons learned over the life of the project. In 2023, the team focused on the ultimate simulation they had hoped for years earlier: a truly autonomous, closed-loop test flight leveraging the world’s most powerful supercomputing system.

While the eight main engines are used to control pitch (up-and-down rotation) and yaw (side-to-side rotation) as the guidance system aims for the designated landing zone, POST2 also issues commands to instruct FUN3D to periodically fire four reaction control system, or RCS, modules arranged circumferentially around the backside of the lander to perform roll corrections in flight. 

 “These capabilities will be critical for assessing the controllability of future vehicles,” said Georgia Tech’s Alex Hickey, who led development of the RCS modeling.

The team’s long-term goal became a reality in late 2023, as OLCF staff assisted in coordinating a careful sequence of high-priority jobs over a two-week period at scale on Frontier.

“For the first time, we were able to return to the original question of safely controlling this type of vehicle in autonomous flight,” Nielsen said. “In a typical aerospace CFD simulation, one might compute a second or two of physical time. Here, Frontier enabled us to successfully fly 35 seconds of controlled flight, descending from 8 kilometers (about 5 miles) altitude to about 1 kilometer (0.6 miles) as the vehicle approached its landing phase.