Rocket exhaust on the Moon: Unveiling the surface effects

For NASA, the exploration of the Moon has always been a fascinating endeavor. With the Artemis program, the space agency is planning to take lunar missions to new heights by establishing a sustained human presence on the Moon. To achieve this goal, a deep understanding of how future landers interact with the lunar surface during landing and liftoff is crucial.

Landing on the Moon is a complex and challenging task. Unlike Earth, the Moon lacks an atmosphere and has low gravity, making the descent of spacecraft a unique and difficult endeavor. To counteract the Moon's gravitational pull, spacecraft employ rocket engines to control their descent. However, this process creates supersonic plumes of hot gas that interact with the lunar surface, causing various hazards and potential risks.

When a spacecraft lands or takes off from the Moon, the intense forces generated by the rocket engine plumes can have significant consequences. These forces kick up dust, eject rocks, and create visual obstructions and dust clouds that can interfere with navigation and scientific instrumentation. Moreover, the plumes can erode the lunar surface underneath the lander, posing risks to the stability of the lander and the safety of astronauts.

To better understand and predict the interactions between rocket engine plumes and the lunar surface, researchers at NASA's Marshall Space Flight Center in Huntsville, Alabama, have developed new software tools. These tools are designed to simulate and predict plume-surface interactions for various NASA projects and missions, including the Human Landing System and Commercial Lunar Payload Services initiative. 

One remarkable achievement of the NASA Marshall team is the simulation of the Apollo 12 lander engine plumes interacting with the lunar surface. Through their simulation, they were able to closely match the predicted erosion patterns with the actual landing event. The simulation shows the fluctuating radial patterns of shear stress, which is the lateral force applied over a surface and a leading cause of erosion when fluids flow across it.

To achieve such accurate simulations, NASA utilized the power of supercomputers. The Pleiades supercomputer at NASA's Ames Research Center in California's Silicon Valley played a crucial role in running the simulations. Over several weeks of runtime, the simulations generated terabytes of data, providing valuable insights into plume-surface interactions.

The framework used for these simulations is called the Descent Interpolated Gas Granular Erosion Model (DIGGEM). This framework was funded through NASA's Small Business Innovation Research program, emphasizing the agency's commitment to technological advancements in space exploration. The DIGGEM framework, along with the Loci/CHEM+DIGGEM code, has been refined and optimized through direct support for flight projects within NASA's Exploration Systems Development Mission Directorate.

The insights gained from these simulations and software tools play a crucial role in minimizing risks associated with future lunar missions. By predicting cratering and visual obscuration, NASA can ensure the safety of spacecraft and crew during landing and takeoff. These advancements are not only essential for the Artemis program but also for future Mars landers and other off-world missions.

In conclusion, the study of plume-surface interactions is a critical aspect of lunar missions. NASA's research and simulations conducted at the Marshall Space Flight Center provide valuable insights into how rocket engine plumes interact with the lunar surface during landing and liftoff. By understanding these interactions, NASA can minimize risks and ensure the success of future missions, including the ambitious Artemis program. With the aid of supercomputers and advanced software tools, the agency continues to push the boundaries of space exploration and pave the way for human exploration of celestial bodies beyond the Moon.