Spacecraft Crashes Into Satellite

Juha-Matti Laurio writes "A robotic NASA spacecraft designed to rendezvous with an orbiting satellite instead crashed into its target. Unbeknownst to engineers at the time, DART's main sensor mistakenly believed it was flying away from the satellite when it was actually moving 5 feet per second toward it, investigators found."

Comments

Re:Oddly familiar

[FTL]

If an engineer makes a mistake, it's the job of the manager to have in place a system whereby the mistake is caught. Engineering failures which reach the light of day are also managment failures. Management failures are management failures. If something happens, no matter how it happened, it's always going to be a managment failure.

So yes, you are right. It's always the manager's fault. By definition.

Top Down Design?

[Ohreally_factor]

One wonders if this failure is due to a design philosophy similar to the top down design that has doomed the shuttle.

From the Feynman report:

The usual way that such engines are designed (for military or civilian aircraft) may be called the component system, or bottom-up design. First it is necessary to thoroughly understand the properties and limitations of the materials to be used (for turbine blades, for example), and tests are begun in experimental rigs to determine those. With this knowledge larger component parts (such as bearings) are designed and tested individually. As deficiencies and design errors are noted they are corrected and verified with further testing. Since one tests only parts at a time these tests and modifications are not overly expensive. Finally one works up to the final design of the entire engine, to the necessary specifications. There is a good chance, by this time that the engine will generally succeed, or that any failures are easily isolated and analyzed because the failure modes, limitations of materials, etc., are so well understood. There is a very good chance that the modifications to the engine to get around the final difficulties are not very hard to make, for most of the serious problems have already been discovered and dealt with in the earlier, less expensive, stages of the process.

The Space Shuttle Main Engine was handled in a different manner, top down, we might say. The engine was designed and put together all at once with relatively little detailed preliminary study of the material and components. Then when troubles are found in the bearings, turbine blades, coolant pipes, etc., it is more expensive and difficult to discover the causes and make changes. For example, cracks have been found in the turbine blades of the high pressure oxygen turbopump. Are they caused by flaws in the material, the effect of the oxygen atmosphere on the properties of the material, the thermal stresses of startup or shutdown, the vibration and stresses of steady running, or mainly at some resonance at certain speeds, etc.? How long can we run from crack initiation to crack failure, and how does this depend on power level? Using the completed engine as a test bed to resolve such questions is extremely expensive. One does not wish to lose an entire engine in order to find out where and how failure occurs. Yet, an accurate knowledge of this information is essential to acquire a confidence in the engine reliability in use. Without detailed understanding, confidence can not be attained.

A further disadvantage of the top-down method is that, if an understanding of a fault is obtained, a simple fix, such as a new shape for the turbine housing, may be impossible to implement without a redesign of the entire engine.

Re:Oddly familiar

[Ohreally_factor]

Bullshit!

Why even bother with engineers if that is your attitude? Why bother having projects at all? Let's just funnel money directly into defense and aerospace contractors' pockets, and make it easier for them to pay off the politicians. It'll be a whole lot more efficient, and, in cases like the shuttle, won't lead to any loss of life.

I've posted this link elsewhere, but it bears repeating.

And WTF is a "newspaper deal"?

Re:Oddly familiar

[Billosaur]

It's the job of critics and engineers to say things like that constantly and then land a newspaper deal when (if) it happens.

Did you happen to read those quotes? It points out the disconnect between the engineers who design the system and build, and know what it is and isn't capable of, and the PHB management that is bowing to pressure from above in rushing things into production without adequate regard to safety or overlooking the safety objects of the engineers. Columbia and Challenger were direct results of management looking at something pointed out by engineers and blatantly ignoring the facts, under pressure to keep the shuttle running.

BTW, this isn't the 1920's, so anybody getting a "newspaper deal" is in for a rude shock when they get the check.

Re:Disband NASA

[Ohreally_factor]

Unfortunately, the faulty design was due to the screw ups of a private contractor, so there goes your "private sector" argument.

Re:Disband NASA

[xoyoyo]

Snore. And out come the free enterprise loonies. The only trouble with your argument is that free enterprise is already perfectly able to indulge in space exploration and, well, hasn't. You can rent time on a launch pad, you can rent space in a rocket. There are many excellent engineering companies who can build more or less any satellite or other space craft you want. But there's no return on doing anything more ambitious than communications satellite. What exactly is the private sector going to do with a Mars probe, say? Sell ad hoardings on the side? (Didn't Beagle II do this?) It's better to regard what NASA and ESA do as a public infrastructure project rather than as competition for private enterprise. The work NASA is doing (mostly competently) is more like building the channel tunnel than a profit-based business. We tried building the tunnel through the private sector, but Eurotunnel has been bailed out by the giovernment and the banks so many times that it's actually ended up costing us far more than it would have done if we'd done it the old fashioned way, even assuming the usual obscene project over-run costs of a public project.

Re:Disband NASA

[GreggBz]

Yes, Yawn. I'm all for the X-Prize and private endeavors into spaceflight, but really, what's been acomplished? They are decades behind. Last I heard, Space Ship One barely managed to reach a sub-orbital altitude and return safely. This is comporable to what the X-15 did in 1960 and is so far removed from the complexety of a single shuttle mission (not to mention Apollo) that it's totally outragous to think the private sector is somehow doing better because they didn't screw it up.. Actually, they did screw it up, just not enough to kill anyone. Besides Rutan, everyone else is still doing test fire's or has had their unmanned rocket explode on the launch pad. It will be a long while before they can reach orbit relatively safely and repeatadly. Will they make less mistakes on their way there? No but that's ok because space is really hard. Meanwhile, NASA has contributed an enourmous amount to planatary scinece and space exploration in the past decades despite seemingly wary public support and a dimished budget. It really is amazing what they've accomplished. Their paradigm has been rightly adjusted to focus on science and exploration. They pursue one of the noblest of human endeavors (and if you don't understand why science and understanding the universe is noble, well..) and in my mind are pretty detached from political and corporate bullshit and burracracy. To bad some of you don't want to pay attention.

Three words:

[MacEnvy]

Military-Industrial Complex.

If you think Boeing, Raytheon, and Lockheed are merely private contractors, you've not been paying attention. They are as integrated into the current system as they can be while still retaining the title of "corporation". This is part of what Eisenhower was warning us about - when the private sector controls and influences the public sector in an industry, they become intermingled in ways that do not inspire greatness. And it becomes dangerous for the autonomy of the state from private control.

NASA, while purportedly a civilian agency, is obviously tremendously influenced by not only the military but also those private contractors. It's pretty amazing that Scaled Composited was able to even get a bid in on the recent manned capsule designs - and they almost didn't. Notice that their proposal wasn't accepted, though. Whether it wasn't as good (doubtful) or whether there are other barriers to entry (probable) is up for debate.

Re:Ah.

[Rob T Firefly]

They should never have rejected the dried-frog-pills allowance in NASA'a budget.

Re:Oddly familiar

[spun]

LOL! Wish it worked like that, I'd love to find a meritocracy in industry. From what I see, it's who you know that determines how far you go. That whole "Work hard and you'll make more money!" idea is just a scam perpetuated by rich knobs so they can make more money off of you. Look at corporate CEOs. They run a company into the ground, fire all the employees and scuttle off with their "golden parachutes," only to get hired by their buddies on the board of a different scam-poration where they do it all again. I guess it is a meritocracy, those who are better at screwing over their fellow man get ahead.

People who believe in meritocracies are just holding on to the idea in order to prop up their sense of self worth, and to keep from having to feel empathy for those who are less lucky. "OOhh, look at me! I got where I am through hard work. Forget that daddy got me into an Ivy league school and my chums there got me a job I don't deserve and can't do well. I did it on my own! Anyone who isn't successful is obviously a lazy git who deserves nothing."