Edward: Hm. I wrote about this more than a year ago:

Have modern space engineers forgotten the importance of keeping things simple?

Nice that others are catching up. :)

Manley touches on software, but not very deeply. I have additional thoughts on software problems. The 1960s had limited capability computers, so the software was the minimum needed to navigate to and land onto the Moon. Modern software tends to be large and complex. Add to that the tendency to have multiple sensors for navigation, guidance, and control, and I think we can see that modern software has a lot to sort through. There may even be some hubris involved. The lander that didn’t account for the drop-off of the terrain when it flew over the large crater that was its landing site had a fatal flaw in its error detection, where it ignored the altitude data, because the assumption was that a rapid drop of the terrain was a sign that the software interpreted as an obvious error in the data stream. The engineers had not updated the software for the new conditions when the landing site was changed from a large plane to the interior of a large crater.

Modern software engineers are putting in far more complexity, giving more room for unintended features (bugs) to crop up. Perhaps they think that they are adding flexibility and robustness, but the complexity give places for the team to get bit in the butt.

In the 1960s, less was more (as Hollywood often says), which really means less can be better. Stick to the basics and Keep It Simple.

Manley’s other points about the differences between 1960s landers and todays give good explanations as to why we cannot just land more Surveyors on the Moon. Essentially, it is time to do real work, not the basic preliminary test landings that the Surveyors made.