Guest:  Charles (Charlie) Precourt; Topics:  Artemis, SLS, solid rocket boosters (SRBs), SRB propellant, lunar return timelines, human lunar lander, Gateway, Gateway lunar orbits, plus much more.

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We welcomed Charlie Precourt back to the program to discuss his work on Artemis to return to the Moon plus the portion of Artemis involving his company, Northrup Grumman (N-G).  For more N-G information, see their Artemis website at  www.northropgrumman.com/space/nasas-artemis-program.  Our discussion focused the N-G mission to support the NASA Artemis Program, the SLS (more about that later), returning to the Moon timelines, The Gateway and Gateway low energy stable orbits and more.  Our discussion started off by talking about the upcoming wet dress flights, testing, and the solid rocket boosters. For sure you want to hear the Charlie's introductory commentary as it was key in setting the focus for our 60 minute discussion. 

As I have been doing with other recent shows, I will once again use the tags/key words as a summary of our discussion topics.  For your convenience, I am repeating them here:

"Tags/Key Words:  Charlie Precourt, Northrup-Grumman, Artemis, SLS, NASA, SLS boosters, solid rocket boosters, recovering SRB's, Orion, human landers, mission performance facts, lunar habitats, SRB safety, SRB propellant,  launch dates, timelines, The Lunar Gateway, Gateway orbits, 5 segment booster, abort escape feature, SLS for humans and cargo, SLS Block 1B, SLS Block 2, SLS capabilities, deep space mission analysis, SLS acoustic signature, vibration modification, lunar return 2024 landing, SLS inventory for seven flights, launch costs and operations analysis," SRB detonation vs. deflagration.

Additional topics I zeroed in on included the upcoming test/demo flight with SLS known as Artemis 1 for later this year.  Our guest had much to say about this test fight, SLS in general and Artemis, Orion, plus a possible 2024 human landing on the Moon.  Listen to how our guest said they were building SLS different from building it one vehicle at a time as was done in the past.  He said the first three were already built, they had four engines ready with more on the way.  Once the subject of the SRBs came up, we started getting listener questions about them.  Listener Paul wanted to know how SLS SRBs were different from those used during shuttle flights.  Another listener wanted more information about the five segments plus the propellant burned for the new SRB as compared to the propellant used during shuttle flights.  Listener Joe wanted to know if the SLS SRB would be recovered.  Charlie's answer this question was no.  Listen to his explanation of the recovery economics and the why the boosters will not be recovered at this time.  Another listener wanted to know if there will be other uses for SLS down the road.  Our guest talked about potential human and cargo flights, the SLS Block 1 B and the still to come larger Block 2 version of the rocket. 

Our guest was asked about SLS costs and the rumored very high operating costs.  Charlie explained operating costs as being separate from the development cost but that just comparing operating costs in dollars to perhaps another rocket was not a valid comparison.  He talked about evaluating the mission capability, the qualities an SLS brings to the mission, change in velocity needed for some missions, how big a payload could be pushed regarding a specific mission and more and overall rocket to mission capabilities.  When all factors were considered, the operating cost for an SLS launch was in the proper perspective.  Charlie spent time explaining this analysis to us at different times during our interview.  Please share your thoughts with this analysis by posting on our blog about it. 

One listener asked our guest to compare riding on the SLS to the ride Charlie had on shuttle and those SRBs.  Charlie did not think the ride would be much different and said that SLS vibration would not be a big deal. This led to several questions asking him about the SLS acoustic signature, vibration control, and sound wave dampening.  Don't miss his commentary on these questions. Fremont John called to inquire about the SLS SRB design, wanting to know if SLS SRBs were sensitive to temperatures as was Challenger.  Charlie talked about the fix to the boosters after the Challenger accident and the fact that SLS boosters would not incur the same sort of problem. 

The Gateway came up and Charlie said that the Gateway requires a low energy orbit which he discussed in detail.  Dr. Jurist sent a note in asking about a continued interest in a Marine Corp SUSTAIN type of military launch vehicle on the order of the previous Ares 1 design.  Alexandra sent in a note asking about SRB safety since you could not turn the engines off once the firing started.  Our guest had much to say regarding this question comparing liquid rocket motors to SRBs in terms of safety and turning them on and off.  I suggest you listen carefully to what our guest had to say to turning off a rocket engine in flight and solid rocket boosters in general.  Our guest did mention that the ultimate safety would come from an abort feature which SLS has.  Our guest continued talking about SRB detonation and then told us about detonation vs. deflagration.

Listener James in Los Angeles once again brought up SLS suggested launch costs.  This time around Charlie went deeper into the operational cost analysis formula he mentioned earlier.  This was an import mini-discussion in our program today. Our last caller was Gene from Pasadena talking about lead times with SLS, having more than two at any time and related items. 

Please post your comments/questions for Charlie Precourt on our blog for this page.  He can be reached through me or through Northrup Grumman.