PS I've just followed up with this NASA link:
https://sservi.nasa.gov/wp-content/u...p-20171130.pdf
Some fascinating information embedded in what is one of the worst PowerPoint presentations I have ever seen!
The author has clearly not read any of Edward Tufte's books:
He's had a go at NASA before - "
PowerPoint Does Rocket Science--and Better Techniques for Technical Reports"
https://www.edwardtufte.com/bboard/q...1yB&topic_id=1