Probe Crash Due to Misdesigned Deceleration Sensor 374
squirrelhack writes "Seems as though the Genesis spacecraft was able to launch from earth, travel through space, avoid aliens, and cruise back into the atmosphere to be caught by stunt pilots waiting patiently with their helicopters. Alas, the brakes didn't work because a sensor was designed upside down.
Yeah (Score:4, Informative)
I read the same story here [yahoo.com] earlier today, and it also says that it was installed backwards.
Re:wtf (Score:5, Informative)
The sensors, which are estimated to be less than an inch (2.5 centimetres) wide, were apparently installed in a circuit board in the wrong orientation - rotated 180 from the correct direction. But the problem stemmed not from the installation but the design, by Lockheed Martin, based in Bethesda, Maryland.
no such thing as... (Score:1, Informative)
Re:Mirror? (Score:2, Informative)
17:18 15 October 04
NewScientist.com news service
Sensors to detect deceleration on NASA's Genesis space capsule were installed correctly but had been designed upside down, resulting in the failure to deploy the capsule's parachutes. The design flaw is the prime suspect for why the capsule, carrying precious solar wind ions, crashed in Utah on 8 September, according to a NASA investigation board.
The sensors were a key element in a domino-like series of events designed to release the parachutes. When the capsule - which blazed into the atmosphere at 11 kilometres per second - decelerated by three times the force of gravity (3 Gs), the sensors should have made contact with a spring.
"It's like smashing on the brakes in your car - you feel yourself being pushed forward," says NASA spokesperson Don Savage.
The contact should have continued as the capsule peaked at a deceleration of about 30 Gs. Then, when the capsule's deceleration fell back through 3 Gs, the contact would have been broken, starting a timer that signalled the first parachute to release.
"But it never made the initial contact because it was backwards," Savage told New Scientist.
Wrong orientation
The sensors, which are estimated to be less than an inch (2.5 centimetres) wide, were apparently installed in a circuit board in the wrong orientation - rotated 180 from the correct direction. But the problem stemmed not from the installation but the design, by Lockheed Martin, based in Bethesda, Maryland.
They still have to find out why that design error was not caught," says Savage. The mission's Mishap Investigation Board will continue to investigate the problem.
"This single cause has not yet been fully confirmed, nor has it been determined whether it is the only problem within the Genesis system," says the board's chairman Michael Ryschkewitsch. "The board is working to confirm this proximate cause, to determine why this error occurred, why it was not caught by the test programme and an extensive set of in-process and after-the-fact reviews of the Genesis system."
So far, Savage says, the design flaw does not seem to be shared by NASA's Stardust mission, which will use a similar parachute system to deliver samples of a comet to Earth in January 2006.
The $264 million Genesis mission launched in August 2001 to study the composition of the early Solar System, which is thought to be reflected in the solar wind.
Re:There is a bright side (Score:3, Informative)
The primary limitation is the maximum weight we can get to the Earth/Moon Lagrange points. Once at the L-points, the cargo pretty much travels one gravity slingshot to the next with nearly no fuel expenditure.
If anyone is interested, I believe this is also known as a soft orbit transfer. IIRC, this technique was inveneted to rescue a mission that had suffered a pretty catastrophic failure.
Re:no such thing as... (Score:5, Informative)
From Dictionary.com:
3 entries found for deceleration.
decelerate Audio pronunciation of "deceleration" ( P ) Pronunciation Key (d-sl-rt)
v. decelerated, decelerating, decelerates
v. tr.
1. To decrease the velocity of.
2. To slow down the rate of advancement of: measures intended to decelerate the arms buildup.
v. intr.
To decrease in velocity.
References (Score:5, Informative)
For them dropping the NOAA sat:
http://www.space.com/spacenews/businessmond
(first link I found)
Climate Orbiter:
http://www.space.com/news/mco_report-b_
Re:wtf (Score:1, Informative)
I'm a designer, it makes sense to me. I have to be careful that my work is right, and hope that if I do make a mistake, someone catches it, and doesn't just build to print.
Very much like the origins of Murphy's Law! (Score:2, Informative)
read about the whole story: http://en.wikipedia.org/wiki/Murphy's_law [wikipedia.org]
(note that the sensors were wired backwards as opposed to installed backwards)
Re:wtf (Score:4, Informative)
So the failure was in design, not installation. The net result still being it ended up backwards.
At least that's what I'm reading.
Re:There is a bright side (Score:5, Informative)
Seriously, a solar or even a high earth orbit is fine for storing waste indefintely. Don't need to waste delta vee directing it into a star. Stuff is heavy.
Re:It just shows that you gotta test (Score:1, Informative)
There is no "deceleration" (Score:3, Informative)
Re:no such thing as... (Score:3, Informative)
I mean, look at the definition:
1. To decrease the velocity of.
This is meaningless. Decreased with respect to what? I can select a reference frame where the velocity has increased, not decreased! This "definition" is bogus. A forgiveable error, seeing as the dictionary authors are not physicists, but still an error.
The real, physical definition of acceleration is a CHANGE in velocity. An increase or a decrease. Change is universal. Change can be measured in any reference frame. In some frames, the change is negative, while in others it is positive. No matter which, it is always called acceleration.
Nobody is disputing the usefulness of the term "decelerate," but the OP was quite correct that there is absolutely no distinction between the two.
Re:Alphaware ... (Score:4, Informative)
I hate to tell you this, but NASA HAS been using proven parts in spacecraft, there is a strong push for COTS (Commercial Off-The-Shelf) Hardware, it's much cheaper than designing every op-amp from scratch. But this COTS stuff has to be beyond military spec, it has to be rad-hard, withstand severe thermal and vibrational stresses, etc. It's easy to make a reusable op-amp or logic gate in a desktop computer, but for a satellite they have to be MUCH more rugged.
Regarding this accelerometer, not sure why it had to be different, but like I said before, it definitely needed to be rad-hard, endure strong vibrational and thermal extremes, and still function flawlessly upon re-entry. That's not easy to design, and there are 100000000 things to go wrong, one of which is that it's installed backward.
Now as to the reason they don't re-use spacecraft designs is that every craft has different operating parameters. Some are very far from Sun and Earth, and need higher-gain antennas (ie, parabolic dishes that can retract) and RTG's (solar panels become inefficient beyond Jupiter). Some operate close to Earth orbit and use solar panels and smaller antennas. Some will never re-enter earth, some will burn up on re-entry when their use is finished, and some need to survive re-entry intact. Some craft close to the sun (eg SOHO) need special rad-hard thermally-shielding designs. The inclusion or exclusion of each of these items will drastically change the structure of the craft.
So basically, each mission is so different that it's very unfeasible to come up with a reusable 'strawman' design from which to start all NASA craft. And this is just considering operating environment, power, and communications. That's not even including the scientific instruments, all of which need specialized heating or cooling or shielding or vibrational-isolation requirements, etc.
Re:Symmetrical parts baaaaad (Score:2, Informative)
Massive peer review? (Score:2, Informative)
I'm geeky enough to check sensors for correct orientation, and motivated enough to do it for free.
-Dan
Congress, NASA, JPL also to blame (Score:3, Informative)
When the final report comes out, we will presumably learn why the sensor was not fully tested -- where was the decision made and why. Until then, all we have is the proximate cause, not the root cause.
The MCO failure was NOT merely LM's bad propulsion database. JPL's navigators saw the errors building and did not act. And JPL did not adequately staff the navigation operations console. And the reason was the emphasis on "cheaper".
The NOAA satellite really was LM's fault, and they will pay for it.
Re:There is a bright side (Score:2, Informative)
"The scientific theory I like best is that the rings of Saturn are composed entirely of lost airline luggage." - Mark Russell
Re:Redundant logic (Score:2, Informative)
The problem is that if you have 2 firing switches, then the chances of at least one going off accidently doubles. Redundancy is perhaps best where at worse failure simply means a loss of an single instrument rather than catastrophic side-effects, such as a premature chute opening.
did you know that a Mars Rover has a single CPU
I remember reading about this. They actually calculated the cost of the risk based on past failures of similar CPU's from the same company. For example, it may only have a 1-in-10 chance of failure, but would increase costs by 20% if they redundicated it (is there such a word?)
Re:There is a bright side (Score:2, Informative)
The problem of course, rears it's ugly head when the plastics are buried under 75,000 tonnes of refuse and zero air and water get in/on to it. Like so many other things, they sit there and remain intact, future evidence for archaeologists studying our society.
Two Things... (Score:4, Informative)
1) Some plastics are designed to decompose.
2) Most plastics that aren't designed to decompose... don't. Instead they undergo weathering by the elements and 'vanish' as they are ground down by sun, wind, rain, and snow into plastic dust which then remains in the environment [eurocbc.org] for hundreds/thousands of years. This is a worldwide problem. [bbc.co.uk]
This flies against all the enviromentalists saying they will stay here forever
It flies against nothing. Just because something is too small for you to see does not mean that it is 'gone'. Weathering does not equal decomposition. Choice quote from the BBC article [bbc.co.uk]: "...this study suggests that practically everything really is made of plastic these days - even the oceans."