Future spacecraft bound for the Moon or beyond will benefit from high-powered computer simulations that model the particulate mayhem set in motion by rocket thruster-powered landings. During descent, exhaust plumes fluidize surface soil and dust, forming craters and buffeting the lander with coarse, abrasive particles. This action presents a host of variables that can jeopardize a landing. A current understanding of those millions of interactions is based on data that is, in some cases, 40 to 50 years old. Much of the available data used in the design stage, including for the Mars 2020 mission, is based on Apollo-era data.

Landing-relevant data is very difficult to generate because such an experiment cannot be run on Earth. Existing mathematical models break down in these more extreme conditions when particles approach supersonic speeds. The new numerical algorithms enable such simulations.

The team is developing physics-based models that can be incorporated into codes used by NASA to help predict what will happen when a spacecraft attempts to land millions of miles from home. These include “messy turbulent flows” and simulating the behavior of fluids made of two phases of matter — in this case, solid particles suspended in a gas.

Apollo-era landings showed that disturbed surface material can spread up to half a mile, posing hazards not only to the lander itself, but also for neighboring vehicles or landing sites. Despite advances made in the years since, landings remain fraught with potential hazards. Eight years ago, a wind sensor on the Curiosity rover was damaged during its Mars landing. As NASA moves toward new crewed missions under the Artemis Program, this work becomes more vital. Not only do humans onboard raise the stakes, they mean larger payloads and subsequently, stronger exhaust plumes interacting with the planet’s surface.

The team uses models — best guesses based on all available data — to provide a framework NASA can use to better predict how different designs will impact the ground and the landing and adjust.

Watch the simulation on Tech Briefs TV here. For more information, contact Jim Lynch at This email address is being protected from spambots. You need JavaScript enabled to view it..

Topics:
Computer simulation Data Acquisition Emissions Entry, descent and landing Entry, descent, and landing Exhaust emissions Fluid Handling Satellites Simulation Software Simulation and modeling Software Soils Spacecraft Spacecraft Vehicle dynamics Vehicles

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    This article first appeared in the March, 2022 issue of Tech Briefs Magazine (Vol. 46 No. 3).

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    Transcript

    00:00:00 That's one. Contact [music] CAPECELATRO>> As the spacecraft's coming down towards the planet or towards the lunar surface you essentially have these, these rocket engine exhausts that is now interacting with with the surface of that planet or moon. NARRATOR>> It's important for researchers like Jesse and his students to understand how thrusters disrupt surface materials in such a way that could affect landing or damage the spacecraft. CAPECELATRO>> Trying to understand what is the crater depth, what is the crater size, what is the objective is almost entirely being based off of Apollo era data.

    00:00:43 That data is, is fairly outdated by now but also you can't simply translate what happened on the moon to uh, to Mars. If you want to do accurate, predictive modeling we really need to do simulations that, um that are running today on some of the biggest super computers, and so the idea is run these these very kind of smaller scale but higher resolution calculations and then upscale it, develop models from that, learn from that, and develop models that NASA can use in their code and that can actually stimulate a full landing site. We have to get to the bottom of understanding plume surface interactions.

    00:01:25 It's one of the key challenges that's associated with this and these challenges are only getting, becoming amplified as we move towards manned missions, and so in order to be able to do this we have to rely on numerical stimulation. NASA has recognized room surface interactions is not something that's just going to plague one individual mission, it's really, um going to be something they have to deal with for at least all the missions they have planned in the next 20 years. [music]

    00:02:20