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Upside-Down Sensors Caused Proton-M Rocket Crash
Michi writes "According to Anatoly Zak, the crash of the Russion Proton rocket on 1 July was apparently caused by several angular velocity sensors having been installed upside down. From the source: 'Each of those sensors had an arrow that was supposed to point toward the top of the vehicle, however multiple sensors on the failed rocket were pointing downward instead.' It seems amazing that something as fundamental as this was not caught during quality control. Even more amazing is that the design of the sensors permits them to be installed in the wrong orientation in the first place. Even the simplest of mechanical interlocks (such as a notch at one end that must be matched with a corresponding projection) could have prevented the accident."
A review of the quality control procedures used by the contractors responsible is underway.
What seems more amazing is that a simple software check pre-launch (i.e. "do all the sensors think they are pointed up?") was not part of the SOP. Given that their exact function is orientation detection, skipping the opportunity for self-test via that function is somewhat baffling.
Obligatory: It's not rocket science!
Perhaps the thinking is, as long as the arrow isnt pointed at you it's probably safe.
Yes, the real, original Murphy's law apparently came from Col. Stapp, who was testing rocket sleds for the rocket program.
I should note that the putative original Murphy's Law reads, "If there are two or more ways to do something, and one of those ways can result in a catastrophe, then someone will do it." . The website goes on to say "This is a principle of defensive design, cited here because it is usually given in mutant forms less descriptive of the challenges of design for lusers. For example, you don't make a two-pin plug symmetrical and then label it `THIS WAY UP'; if it matters which way it is plugged in, then you make the design asymmetrical."
Highly appropriate to the topic, I might say. If only they had labeled, with the arrow, the words "up", and put another arrow down, with the letters "dn" for "down", then none of this would have happened.
For those who wish to nit-pick my attention to detail and editing, also, I will for further irony include the wikipedia link, as well: http://wikipedia.org/wiki/Muphry%27s_law
Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
Amusingly, when someone actually attempted to track down who murphy was, and where the law came from.... http://en.wikipedia.org/wiki/Murphys_law
So this is potentially, very much related to the original usage.
"I opened my eyes, and everything went dark again"
...aren't so amazing when you look at the track record of Russian manufacturing.
Before we Americans point too many fingers, let's not forget NASA is not immune to similar mistakes.
My favorite is Cole's Law...
What seems more amazing is that a simple software check pre-launch (i.e. "do all the sensors think they are pointed up?") was not part of the SOP. Given that their exact function is orientation detection, skipping the opportunity for self-test via that function is somewhat baffling.
Obligatory: It's not rocket science!
The sensors in question were for angular velocity. Given that pre-launch the craft doesn't have any (peculiar) angular velocity, the sensors would return the correct results (zero) no matter how they were installed.
"None can love freedom heartily, but good men; the rest love not freedom, but license." --John Milton
An old joke:
A militia (communist police) station has been ordered to conduct an intelligence test. It consisted of a board with three holes: a circle, a triangle and a square, and three corresponding blocks. The next days, the commandant announces: I'm very proud of our station: all of you passed the test! 5% have shown exceptional intelligence, 95% exceptional strength!
The creatures outside looked from Alt-Right to Antifa; but already it was impossible to say which was which.
The US once sent a probe all the way to mars, only to have it fail because the ground computer was in imperial units while the orbiter was in SI units.
Getting everything correct is hard... really hard. For most projects you have elaborate "fail gracefully" modes which rely on external agents to notice the problem and take action. A doctor or pilot can take appropriate action, but it's hard to do with rockets.
For comparison, I wrote the software for the altimeter that goes into some 747 aircraft. Total of about 21,000 lines of C, about 40% comments so figure 12,000 lines of code. The testers (and I) worked really hard to find all bugs in the system, knowing that a mistake could knock a plane out of the sky. There were elaborate internal checks both in software and process, and Boeing did their own testing on top of ours. Everything passed, all requirements were met, things looked good.
The device had 1 bug, found after installation. A software typo which wasn't caught by QA even though it had a specific testing requirement. No one was negligent, it just slipped by despite best efforts.
Multiply this by all the devices in an aircraft, and add in the other engineering disciplines like electronics and mechanical. It's really hard to get everything right all at once, and on the first try.
If only they had labeled, with the arrow, the words "up", and put another arrow down, with the letters "dn" for "down", then none of this would have happened.
Except that "dn" upside-down is indistinguishable from "up". Murphy strikes again?
Accept Eris as your Fnord and personally sate her