NASA is planning to send humans to Mars by the 2030s – and landing on the surface will be considerably trickier than landing a rover like Curiosity. To solve the problem, NASA researchers are using the world’s fastest publicly-ranked supercomputer.

Mars’ atmosphere is a hundred times thinner than Earth’s, meaning that what might be a gradual descent through Earth’s atmosphere looks more like a plummet on Mars.

“You can’t use parachutes to land very large payloads on the surface of Mars,” said Ashley Korzun, a research aerospace engineer at NASA, of the planned human exploration vehicle, which she likens to a two-story house. “The physics just break down. You have to do something else.”

So instead of parachutes, NASA engineers have turned to another solution: retropropulsion, whereby the vehicle would use engine power to decelerate as it descended toward the surface. “Instead of pushing you forward, retropropulsion engines slow you down, like brakes,” said Korzun.

But, as always, it’s easier said than done – and for the doing, NASA is turning to the Summit supercomputer, a massive system at Oak Ridge Leadership Computing Facility (OLCF) that delivers 148.6 Linpack petaflops and leads the current Top500 list. 

Summit is running computational fluid dynamics code – FUN3D – to model the aerodynamic effects of the descent through the Martian atmosphere. Researchers are closely examining turbulent flows across a wide range of time intervals and distances.

“FUN3D and the computing capability itself have been completely game-changing, allowing us to move forward with technology development for retropropulsion, which has applications on Earth, the Moon, and Mars,” Korzun said. “We can’t match all of the relevant physics in ground or flight testing on Earth, so we’re very reliant on computational capability. This is really the first opportunity – at this level of fidelity and resolution – that we’ve been able to see what happens to the vehicle as it slows down with its engines on.”

“We would typically wait 5 to 6 months to get an equivalent answer using CPU technology in a capacity environment, meaning lots of smaller runs,” said Eric Nielsen, the senior research scientist at NASA Langley who is leading landing simulation project. “On Summit, we’re getting those answers in about 4 to 5 days. Moreover, Summit enables us to perform 5 or 6 such simulations simultaneously, ultimately reducing turnaround time from 2 or 3 years to a work week.”

The team is also producing high-resolution visualizations of the descent using the quantitative data produced by the simulations.

“The visualization is a big takeaway from the Summit capability, which has enabled us to capture very small flow structures as well as really large flow structures,” Korzun said. “I can see what is happening right at the rocket engine nozzle exit, as well as tens of meters ahead in the direction the vehicle is traveling.”

The team hopes that the results will inform the real-world testing – such as wind tunnel testing – that will begin within the coming years as NASA begins to turn its Mars dreams into realities.

To read OLCF’s original article discussing this research, click here.