Human Rating A Spacecraft

Given some of the recent talk about human rating commercial spacecraft, we have to say that it is a relief to read a post by a real rocket scientist and Shuttle Program manager, Wayne Hale, in his blog post, Human Rating A Spacecraft. A few excerpts follow:

“Armchair authorities like to discuss the “big ticket” items in the Human Ratings Requirements: redundancy requirements for fault tolerance, or minimum factor of safety for structures as examples. Real rocket builders know while those are important, the real key to safety and success is very much more affected by the quality of parts and myriad individual steps in workmanship of the end product. These are measured against thousands of individual checks against the appropriate standard. So you must realize the vast majority of standards and requirements do not show up in the NPR 8705.2B Human Ratings Requirements document, they must be searched out in a hundred subordinate documents.”

“…the builder must comply with what the independent technical expert requires.

I can remember one shuttle issue with the agency tribology expert (that’s lubrication to most folks). The technical expert would not budge a millimeter (0.254 inch) in requiring servicing of a part almost inaccessible deep in the bowels of the orbiter. The agency technical experts have absolutely no incentive to back off on their standards. They are independent of the program. They are not concerned with cost or schedule, only with compliance. Compliance brings about safety, why would we want them to do anything less?

How will that fit with a lean, entrepreneurial commercial organization with a profit/loss bottom line? Heck if I know.

So on about the fourth page of the Human Ratings Requirements document you can read that before work starts on a spacecraft design, a meeting is convened of the technical authorities to tell the program manager what standards and specifications the new vehicle will have to meet.

Don’t forget the legend that is stamped on the top of the front page:  Compliance is Mandatory

(Via Post List[Wayne Hale’s Blog].)

1 comment to Human Rating A Spacecraft

  • Adam K

    Wayne is absolutely correct. The real requirements aren’t in the NPR, it’s in the sub documents. This leads to increased cost and schedule delays in design. Then it transfers to the vehicle cost.