Guest:  Dr. Haym Benaroya; Topics:  Returning to the Moon with humans, Artemis, lunar development action plan, hardware advancements, regolith and low gravity concerns, large rocket acoustic signatures and challenges, noise abatement blast wave, blast vibrations, low frequency vibrations and more.

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We welcomed Dr. Benaroya back to the program to discuss what is needed for humans to get back to the Moon, plus we asked our guest for his assessment on how we are doing in preparing for the lunar returns given the 2024 timeline or another close in targeted date.  In addition, later in the program we asked our guest about the acoustic challenges with a very large rocket such as Starship.  What causes them, what are the acoustic issues and how do they manifest in real time, how can sound be dampened or mitigated, and how can the launch company make the rocket vibration resistance but also protect local property within the vicinity of the blast wave. 

The first hour of our discussion focused on our return to the Moon.  Dr. Benaroya said he does not see evidence that the needed engineering, technology, and action plans are in play or being worked on. He said he looks for journal articles, professional papers and other sources to see what is being planned, what is being built, how known challenges are being dealt with and more. For example, he talked about the need for AI and robotics to be lunar regolith resistant but said he does not see that being worked on or developed for commercial readiness. He also pointed that if the plan is to cover the lander with regolith for shielding, astronauts cannot do that due to the regolith issues and concerns. He pointed out the delays in the lunar spacesuit program as indicated by GAO reports, one of which he mentioned on air.  He said regolith concerns are serious for robots too because the lunar regolith can cling to the robot and get into the workings and jam it up.  He was not seeing information on designing lunar regolith resistant robots which he said would be needed.  He mentioned many other areas of shortfalls from cislunar space development to the public private partnership arena, pointing out that for government and the privates to work together and stay on time, there are challenges just from that type of relationship.  He said he did not see noticeable progress in that area with.  When asked if he thought work was being done, perhaps just not that visible. He said he hoped that was the case.  Listen carefully to how he addressed these issues during the first part of our program.  I challenged it and asked him direct questions, wondering if the "emperor had no clothes" to borrow a literary phrase.  Listen to how Haym responded to my challenging questions.  Listeners sent in multiple emails about his concerns, including budget issues which our guest talked about and even compared to the Apollo era budgets as a percentage of the national budget, not just by the dollar amount.  Toward the end of the lunar part of our discussion, Todd asked Haym for the key indicators he would look for were we serious about a 2024 timeline.  Listen to the what our said would be his key indicators for progress reports.

A listener asked Haym a question from our most recent Open Lines show, wanting him to explain why we have to go to the Moon now especially since many Americans think the Earth is in climate peril or some other existential challenge.  Callers chimed in on this question too. For example, Ft. Worth John said we should go now because the project was funded, congress approved it so we should do it.  Haym had a more complete response which I urge you to listen to but he agreed with John.  I brought up national security and China concerns.  Why do you think we should go to the Moon now?  Let us know by posting on our blog for this show.

Before moving to another topic, Jerry asked about Martian regolith and said the rovers seem to cope with it ok, suggesting it might not be such a bad problem for the Moon.  Listen to how Haym responded to Jerry's question.  Before moving on, I asked Haym if there was a way for engineers to calculate a special type of opportunity cost that I asked him about relating to delay now and then look at expected value return after you start or do it now and look project value on the closer in timeline.  Listen to the actual question I asked Haym, how he responded and our general discussion about delaying projects and opportunity costs, including non-cash opportunity costs such as innovation which carries its own opportunity cost and worse. 

Our last program topic address the acoustic signatures of very large rockets such as Starship.  Haym explained some wound engineering to us, explained the problem, talked about vibrations, especially low frequency vibrations, and how each structure has a vibration frequency so if the Starship vibration wave comes close to a structure's frequency, goodbye structure.  This was a fascinating and detailed discussion sound waves, ocean waves created by sound for those proposing launch at sea on an converted drilling platform, plus lots more. For example, how far would a building or a person have to be to avoid damage from the sound and vibration.  How does the rocket survive the vibration, how can one mitigate these challenges.  Haym talked about the Saturn 5, the water used to dampen the noise and earlier concepts that never happened. We talked about the Robert Truax design concept for Sea Dragon that would launch from the ocean, plus the challenges for a Starship Point to Point program in that each landing and launching center would have to face sound mitigation challenges for the local region. Toward the end our guest was asked if SpaceX was working on this given its not a frequent discussion topic about SpaceX or with Elon.  He said he did not know but felt sure SpaceX had quality engineers and that they were working the problem even they were not talking about it.

Before ending the program, our guest summarized his discussion points for us. 

Please post comments/questions on our blog for this show.  You can reach Dr. Benaroya through me or through his Rutgers University faculty website page.