The paper's author Dr. Phil Metzger is such a rockstar. He is The Expert on the mechanics of soil erosion by rocket exhausts, and writes a lot about the problem

The paper's author Dr. Phil Metzger is such a rockstar. He is The Expert on the mechanics of soil erosion by rocket exhausts, and writes a lot about the problem in an approachable way, https://twitter.com/DrPhiltill/status/1658507854859337737 https://twitter.com/DrPhiltill/status/1658507854859337737 It turns out that the rate & mechanics of erosion by rocket plumes is an unsolved problem that requires a new kind of model. To quote from his thread, In the Apollo era the thinking was that the rate of soil erosion is controlled by conservation of momentum. It turns out this is wrong. NASA researcher Leonard Roberts, the first person to research this topic, hypothesized that the soil grains steal momentum from the gas, which slows down the gas and thus reduces the erosion rate. It was this feedback that determined the rate. I argued some years ago this has to be wrong because the particles achieve their high velocities far downstream of where they are lifted off the surface, so momentum transfer does not provide feedback to control the rate that grains are lifted. He's going to be publishing his alternate model soon-ish. Can't wait to see what he has come up with.