Mark,

I've never heard of Lowther. His use of the jargon indicates he is probably an aeronautical engineer. I searched the NASA employee index and came up empty. He's not a civil servant or an on-site contractor at any NASA center. His criticism of Zubrin of not using 6-DoF is interesting. Nobody would use 6-DoF for a pre-Phase-A study of a Mars mission which is what Zubrin does. However a Master's level aeronautical engineer who is mainly a G-and-C guy would often use 6-DoF for stability study. He might be an airplane guy working for Boeing or Lock-Mart. That's the best I can do. Sorry

Gary