It's a shame your comment was downvoted, jeffbee. I thought it was insightful and I upvoted it. There has indeed been tremendous loss of knowledge with two (and

It's a shame your comment was downvoted, jeffbee. I thought it was insightful and I upvoted it. There has indeed been tremendous loss of knowledge with two (and counting) generations of engineers working on this technology and retiring with their work mostly lost to time, both at our national labs and in the private sector.