Slashdot Mirror


The Forgotten Huygens Experiment

jdray writes "An experiment onboard the Huygens probe didn't run as planned because someone forgot to turn it on. The team lead for the experiment has put eighteen years of his life into the project, just to watch it not happen after a seven year ride to its destination on Titan."

36 of 556 comments (clear)

  1. Only one word can be used to describe this... by sjrstory · · Score: 5, Funny

    1. Doh
    Doh (d)

    Interj.

    a) A Gen-X colloquialism conveying an overall feeling of frustration.

    b) Used to express a feeling one has after realizing they have been tricked, misled, scammed, swindled, etc..

    c) Used to boast or chide the victim of such tomfoolery

    d) Coined by the animated sitcom character Homer Simpson in the mid to late eighties, "Doh" is similar to other one word, one syllable explicatives in that it is a quick and succinct summary of one's aggravation, but differs in that it was an accepted substitute to similarly censored words.

    1. Re:Only one word can be used to describe this... by rokzy · · Score: 3, Informative

      D'oh comes from a Laurel and Hardey character. but Homer's version is a lot quicker because animation time is valuable.

    2. Re:Only one word can be used to describe this... by NearlyHeadless · · Score: 3, Informative
      Although it's been mentioned before on Slashdot, it's nice to remember the total data loss that was avoided by averted by Boris Smeds discovering a huge problem early enough to do something about it.

      (I was reminded of this by a story on NPR this morning.)

  2. Redundancy... by Burb · · Score: 3, Insightful
    I understand that half the camera pictures were lost because they were transmitted on channel A. Interestingly enough, an article in New Scientist quoted one of the mission planners as being scathing about the scientists' choice to use the 2 channels for increased bandwidth...

    This post is from memory. Please feel free to correct errors and ridicule me for factual inconsistencies.

    --

    1. Re:Redundancy... by Anonymous Coward · · Score: 4, Informative

      David Southwood (the ESA head of science) was the one who said so - he said "That's scientists trying to screw the system. We don't have redundant systems to get more data down, we have redundant systems for redundancy." http://www.newscientist.com/channel/space/mg185248 33.700

    2. Re:Redundancy... by arkanes · · Score: 3, Informative
      Science is about quality not quantity, so they were wrong to do that.

      This is totally false, as an scientist will tell you. Quantity is a characteristic of quality. In this case, splitting the data stream is actually the best choice, because you get both redudency of the communications infrastructure, but you also get redundency of data. The thing to remember is that there was a limited communications window and increasing bandwidth meant that the quality of the data they were going to get back would be greatly increased. They didn't affect redudency because, while they didn't get exactly the same data, they got a working subset of it.

    3. Re:Redundancy... by Tablizer · · Score: 4, Informative

      Perhaps it could be illustrated as follows:

      Assume a probe has the bandwidth to send a total of 8 images on two channels, 4 on each channel, on the way down. Each image will be represented by the digits 1 through 8.

      With exact redundancy:

      A: 1357
      B: 1357

      With alternating redundancy:

      A: 1357
      B: 2468

      With exact redundency, if you receive both channels, you only get 4 total images in the end. With alternating redundancy, if both channels work, you get up to 8 images in the end. But if one fails, you still get 4, just like under exact redundancy. Thus, it seems like the better choice because you get twice as many images if both channels happen to work, but both techniques still send only 4 images if one channel fails.

  3. In a strange way, it makes me feel better by WegianWarrior · · Score: 5, Funny

    I forgot to turn on my cellphone this morning, and missed a call from someone dear to me. Still, reading this makes me realise that somewhere out there, someone is feeling even worse over forgetting to turn something on.

    --
    Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
    1. Re:In a strange way, it makes me feel better by chimpo13 · · Score: 5, Funny

      I forgot to put my condom on.

      Sincerely,

      Your Father

    2. Re:In a strange way, it makes me feel better by krumms · · Score: 3, Funny

      I am a bastard, you insensitive clod!

    3. Re:In a strange way, it makes me feel better by martingunnarsson · · Score: 4, Funny

      At least you got turned on...

      --
      Martin
  4. Shit happens. by KiloByte · · Score: 4, Insightful

    ... especially in this field of work. If you have a project this big, the chance that nothing will go wrong are simply infinitessimal. Do you remember the last time when you wrote a program of 100 lines without doing a single error?

    We should really praise the gods that the rest of Huygens mission was a grand success.

    --
    The creatures outside looked from Alt-Right to Antifa; but already it was impossible to say which was which.
    1. Re:Shit happens. by grozzie2 · · Score: 5, Insightful
      Do you remember the last time when you wrote a program of 100 lines without doing a single error?

      I may not have got it all right on the first go around, but you can rest assured, i got it right after the testing and before it was deployed...

      In my primary field of work, 'shit happens' is just not an acceptable excuse, I'm a pilot. We use checklists precisely for that reason, to make sure that shit doesn't happen. Every flight has a few phases where even one minor screw up can have serious consequences, so we have checks and balances built into the system to make sure that small screw up does NOT happen.

      I know the software folks here on /. always want to make excuses about 'its hard' and 'its to complicated', but, it's actually not hard, and not to complicated. complex systems are designed and built every day in the aerospace field, systems that many lives depend on. We take it for granted that they are properly designed with failsafe modes, they can deal with problems on the fly, and they do not puke up and die when things become abnormal. Same goes for our crews, they train extensively to make sure they fully understand all operational modes, and they can deal with them. Once that's all done, we write books full of checklists, to make sure the details do not get missed at a critical time.

      'I forgot' or 'shit happens' is just not an excuse. In reality, it's an admission of unprofessional conduct. Billions of euros spent, many many man years of effort, and you want to take 'forgot' or 'shit happens' as an acceptable excuse? there is no acceptable excuse, those are just admissions of shoddy management and operations. Those are terms that are not even in the vocabulary of true professionals.

      Every time I read here on /. about how 'professional' programmers seem to think that it's to hard to actually take the time and effort to write failsafe code, and test it as such, I ask myself how many people would die if thier attitudes were used developing the flight management systems in our aircraft.

      Thanks to government regulations, i can only fly 9 days a month, that leaves me with a lot of time to operate my other business. We do software development, embedded systems for mission critical applications. We do deploy equipment into life critical situations, so, for our work, 'shit happens' and 'i forgot' just dont exist in the vocabulary. We use checklists to ensure that all testing covers all forseeable abnormal conditions, up to and including partial failure of various hardware. for your typical 'desktop' developer, equivalent testing would be along the lines of making sure programs handle gracefully things like having the hard drive removed from it's computer while the program is still running. They may not function at full capacity anymore, but it's not reason enough to have the thing just puke up and crash, it needs to fall into a failsafe mode that's prepared to deal with the detail of 'no local storage available anymore'. the code to handle this scenario will likely not 'get it right' on the first try, but, it'll surely be right before the product goes into release.

      Looking at the money spent, and the multitude of man years spent on developing the lander for this mission, to hear that a significant experiment was lost becase somebody forgot to turn it on, is just beyond comprehension. this goes way beyond unprofessional, and well past the line we would draw for 'incompetent'.

    2. Re:Shit happens. by JaredOfEuropa · · Score: 5, Insightful
      I know the software folks here on /. always want to make excuses about 'its hard' and 'its to complicated', but, it's actually not hard, and not to complicated.
      [...]
      We do deploy equipment into life critical situations, so, for our work, 'shit happens' and 'i forgot' just dont exist in the vocabulary. We use checklists to ensure that all testing covers all forseeable abnormal conditions, up to and including partial failure of various hardware.
      You're right... up to a point. The amount of robust coding, testing, and many other things like security, are always subject to a balance of costs and benefits. Rigorous testing is expensive, and in many software applications it might be wise to, say, not do a complete regression test on a minor release since the cost of that test outweighs the risk of a bug slipping through.

      In your field of business, I imagine you cannot easily deploy quick fixes (to embedded systems), and major bugs in life critical situations are obviously not acceptable. So you do rigorous tests and code reviews. In my line of business however, bugs are acceptable. Sometimes a bug makes it into production... users will moan, and we'll have to spend a bit extra on writing and deploying the fix, but the cost is lower than doing a full test on every release.

      I agree with you that software developers should realise the importance of testing, and take a critical look at their own testing and coding procedures... often it isn't that hard or expensive to make real improvements.
      --
      If construction was anything like programming, an incorrectly fitted lock would bring down the entire building...
    3. Re:Shit happens. by Oxygen99 · · Score: 3, Insightful

      Well. Precisely. Coding is hard, but not any more so than designing a building, an aircraft or an automobile. However, neither is it any less hard, so why is software engineering not accorded anything like as much respect as other disciplines? Do you see Airbus outsourcing airtcraft designs to the far east to save a few Euro's? No. Yet for some reason management always believes software can be written cheaper and quicker.

      Admittedly lives don't depend on 90% of the software any of us here writes, but that isn't to say it isn't complex or demanding and requires complex, demanding testing to ensure high standards of reliability.

      If those resources aren't allocated, then I'm afraid 'Shit Happens' is very definitely an excuse.

      --
      I had a dream, bright and carefree, but now there's doubt and gravity
    4. Re:Shit happens. by Doomdark · · Score: 3, Insightful
      It's never about costs. Mistakes ALWAYS cost more than thorough testing.

      Well, that's kind of nitpicking. Although "time is money" is just a slogan, it does point to the fact that both timeline and money are constraints that affect test coverage that can be done. And cost/benefit analysis should be done for testing as well as for implementation: proper amount of testing to do is a compromise based on many things (type of system, expertise of implementers, aggressiveness of implementation/release schedule etc. etc.). So I would argue that it's ALWAYS about cost, in broad sense (delaying a release costs money -- that's the main reason to avoid delays).

      And finally, there are cases where defects just are cheaper to have, than doing rigorours testing. Like everything in software engineering, impact of defects is relative; there are no absolute guidelines.

      --
      I like paying taxes. With them I buy civilization -- Oliver Wendell Holmes
  5. Human error by Mikmorg · · Score: 3, Funny

    Lets just hope noone forgets to turn on the anti-missile lasers on the orbiting satellites. Bigger mistakes can happen. :)

    --
    Codito, ergo sum.
  6. losing data? by Maegashira · · Score: 5, Funny

    i spent 23 years of my life to get a girlfriend. i deleted all my pr0n for her. now she is gone. life is truly a misery.

  7. D'oh by Hognoxious · · Score: 4, Funny

    I never understood why the apostrophe is there. What letter has been omitted? Maybe Homer somehow believes that saying "some water" in French is swearing or something.

    --
    Confucius say, "Find worm in apple - bad. Find half a worm - worse."
    1. Re:D'oh by El+Kevbo · · Score: 4, Funny

      Try small-town Quebec. That's where real french is spoken.

      Uh, wouldn't it be France where real French is spoken?

    2. Re:D'oh by SamSim · · Score: 5, Informative

      Roughly five to ten O's have been omitted. Homer's trademark expression was voice actor Dan Castellaneta's interpretation "[ANNOYED GRUNT]" (which is how "D'oh!" has always been written in scripts for Simpsons episodes). It's based on the "Dooooooooooh!" from the Laurel and Hardy routines, only shortened considerably. Source

    3. Re:D'oh by Anonymous Coward · · Score: 4, Informative

      The french spoken in France and elsewhere is quite modern...in small town Quebec they speak a 200-year-old variant almost...it's quite unpalatable to the french ear really.

  8. somebody send him... by worf_mo · · Score: 5, Funny

    ... a link to today's /. poll

  9. Nothing was lost, all data is safe by thesp · · Score: 5, Informative

    The article isn't quite correct. A fuller description would take a while to type, so I summarise:

    Two redundant radio channels were used to get data from the lander to the orbiter, which relays the data to earth. The signal for the orbiter to start listening on the high-sensitivity channel, channel A, was never given. The data was transmitted redundantly on both channels, except for images and the output of the Doppler wind speed experiment. Fortunately, all was not lost, as scientists donated radio telescope time around the earth to search directly for the A signal, despite it not being relayed via the orbiter. Thanks to this increase in sensitivity, the data acquired was good enough to fulfill all objectives of all experiments.

    So everyone can relax and get one with the analysis...

  10. Don't worry by Illserve · · Score: 3, Funny

    I'm sure they'll have plenty of time to try again.

    They send these missions all the time don't they?

  11. What about the grad students? by Jonathan · · Score: 3, Insightful

    I assume (like practically all scientific projects) grad students were involved in the design. While the failure to turn on the experiment may be an embarrassment to the primary investigator, how does it affect the grad students? Do they just leave the "results" section of their dissertations blank? Do they need to restart their graduate research with another project?

    1. Re:What about the grad students? by imsabbel · · Score: 3, Insightful

      This probe lauchned years ago. Every grad student involved in building/designing would long now have his PhD...

      --
      HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
  12. No problem... by Gallowsgod · · Score: 5, Funny

    Find the person who was responsible for this, send him or her up there to turn it on, and tell them not to expect any overtime for it. In fact, the costs for sending them up should be taken out of their salary.

    Might sound a bit hard, but it's the only way they'll learn.

    --

    The belief in a biblical god is an ignorant one
  13. Latest results from analysis by zrq · · Score: 5, Informative
    The Huygens team held a press conference this morning and presented some of the results of their analysis so far.

    The first scientific assessments of Huygens' data were presented during a press conference at ESA head office in Paris on 21 January.

    Results include:
    • Geological evidence for precipitation, erosion, mechanical abrasion and other fluvial activity says that the physical processes shaping Titan are much the same as those shaping Earth
    • Huygens' data provide strong evidence for liquids flowing on Titan. However, the fluid involved is methane.
    • ... while many of Earth's familiar geophysical processes occur on Titan, the chemistry involved is quite different. Instead of liquid water, Titan has liquid methane. Instead of silicate rocks, Titan has frozen water ice. Instead of dirt, Titan has hydrocarbon particles settling out of the atmosphere, and instead of lava, Titanian volcanoes spew very cold ice ...
  14. three words for you... by Suchetha · · Score: 4, Funny

    off. site. backup.

    women come, women go, but pr0n is forever

    Suchetha

    --

    learn from yesterday, plan for tomorrow, party tonight
    or one out of three ain't bad
  15. Re:Sad :-( by supergiovane · · Score: 4, Funny
    Damn that's sad. Don't they have checklists for these things??

    Sure they have!

    1. Spend 18 years planning a space mission.
    2. ???
    3. Profit!

    They just realized what was at point 2.

    --
    Signatures are for stupids.
  16. Re:Shame they were only black and white. by Speare · · Score: 5, Insightful

    Black and white sensors have higher resolution, just as black and white film has higher resolution. Resolution is more than the number of pixels, it's the valuable ability to resolve actual data with those photosensors.

    Your little consumer digicam that did not cost a hundred thousand dollars is arranged with cheap little colored filters, cutting out over half of the photons that arrive in the camera, just so you can get the right shade of pink on your girlfriend's tummy. Scientists would rather collect all the photons they can, thanks.

    Scientists do use filters now and then. Spirit and Opportunity use black and white cameras, but they can use something like NINE different filters to block out all frequencies except certain bands of interest. They don't just select Red, Green, Blue, but also various bands of near and far Infrared and Ultraviolet too. Those probes were designed later, and were going to be used on a longer mission, where power and available light energy would be greater. Huygens was built earlier, and going to a distant and dark moon where they'd be lucky if the probe lasted a couple of hours.

    Is their logic still a mystery to you?

    --
    [ .sig file not found ]
  17. Blackadder did it too.. by adeyadey · · Score: 4, Funny

    Edmund Blackadder: Right, let's get the book. Now; Baldrick, where's the manuscript?

    Baldrick: You mean the big papery thing tied up with string?

    E: Yes, Baldrick -- the manuscript belonging to Dr. Johnson.

    B: You mean the baity fellow in the black coat who just left?

    E: Yes, Baldrick -- Dr. Johnson.

    B: So you're asking where the big papery thing tied up with string belonging
    to the baity fellow in the black coat who just left is.

    E: Yes, Baldrick, I am, and if you don't answer, then the booted bony thing
    with five toes at the end of my leg will soon connect sharply with the
    soft dangly collection of objects in your trousers. For the last time,
    Baldrick: Where is Dr. Johnson's manuscript?

    B: On the fire.

    E: (shocked) On the *what*?

    B: The hot orangy thing under the stony mantlepiece.

    E: You *burned* the Dictionary?

    B: Yup.

    --
    "You lied to me! There is a Swansea!"
  18. Re:Shame they were only black and white. by mikael · · Score: 3, Informative

    They use monochrome images for a very good reason.

    To capture a colour image using CCD arrays, there are the cheap, the expensive and economic ways. The cheap way (consumer cameras) is to place itty-bitty colour filters over the entire CCD array. In this way each cell captures either red,green,blue or white.
    The expensive way is to have separate CCD chips for every wavelength of light you want to capture.

    However, when an image is captured by a CCD array, there is a very small amount of bleed from one CCD pixel into it's neighbours. You can compensate for this by making use of image process techniques like convolution/sharpening. But these methods are completely useless with the cheap way of capturing colour images (each of RGBW will have blended with its neighbours of a different colour).

    This can be done with the expensive way (professional digital cameras), but you are restricted to three wavelengths of light.

    Alternatively, you can have one CCD chip, and a series of calibrated colour filters that can be swapped over. In that way you, have a low energy budget of one CCD chip, and the flexbility of analysing a scene in multiple light wavelengths, each of which can be processed separately.

    --
    Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads
  19. Slashdot post is wrong by Anonymous+Writer · · Score: 4, Interesting

    This is what the slashdot post says...

    An experiment onboard the Huygens probe didn't run as planned because someone forgot to turn it on.

    But I got this out of your linked article...

    Huygens was programmed to transmit telemetry and scientific data to NASA's Cassini Saturn orbiter for relay to Earth using two redundant S-band radio systems. Channel A was the sole path for an experiment to measure wind speeds by studying tiny frequency changes caused by Huygens' motion. In one other deliberate departure from full redundancy, pictures from Tomasko's descent imager were split up, with each channel carrying 350 pictures.

    As it turned out, Cassini never listened to channel A because of a software commanding error. The receiver on the orbiter was never commanded to turn on, according to officials with the European Space Agency.
    ...
    Even the lost wind measurement data will be made up, thanks to a remarkable effort on the ground to monitor a faint carrier signal broadcast by Huygens - the equivalent of a cell phone call at a distance of 751 million miles - using a network of 18 radio telescopes around the world. That data, which not as precise as the Doppler information that was lost, should fill in the blanks.
    And I also found this article online. Here's an excerpt...
    Atkinson had a Doppler wind experiment onboard the probe which landed on Saturn's moon Titan after dropping from the Cassini spacecraft. Atkinson and other team members estimate they had put in nearly eighty- man years to bring that experiment to a conclusion this past weekend.

    However, a command to turn on the instrument being used by Atkinson's team was not in the command sequence. The entire experiment was lost. There is some hope that some transmitted data was picked up by radio telescopes back here on earth, and if so, then an Earth- based version of the Doppler experiment may still be possible. ...
    The Cassini mission, he says, has been incredibly successful, and he says eventually they'll get the wind measurements they needed, but definitely not how they planned, and he says it will take a long, long time.

    The reports are confusing and I can't tell what happened. Was there a measurement device onboard the Huygens probe gathering data and transmitting it (like the Slashdot story suggests), or was the data supposed to come from the measurement of the signal from the Huygens probe in relation to the Cassini orbiter?

    If it was the former, is the data not as good because the Earth radio telescopes didn't pick up the entire signal, because there was signal degradation, or because they have to piece all the data together from all the different radio telescopes? If it was the latter, is the data not as precise because of the proximity from the transmitter to the receiver?

    Either way, the Slashdot post is wrong. If it was a measurement device solely on the Huygens probe, it was turned on- it was the relay onboard the Cassini orbiter that wasn't turned on. If the data was meant to be gathered from the proximity of the transmitter to the receiver, then the experiment wasn't onboard the Huygens probe but was actually meant to be a collaboration between the probe and the orbiter.

  20. Re:Shit DOES happen...and HAS happened. by penguinsula · · Score: 3, Informative
    Complex system interactivity and tight coupling have caused accidents in many industries and in the transport sector.

    Charles Perrow has an excellent analysis of those type of accidents in Nuclear Plants, Petrochemical industries, Aircraft & Airways, Dams etc.

    (Normal Accidents: Living with High-Risk Technologies, by Charles Perrow, Basic Books, NY, 1984.) http://oak.cats.ohiou.edu/~piccard/entropy/perrow. html

    Most of these accidents and failures were not the result of lack of money or due to operator error. In this case, I doubt it was a simple as forgetting to push a button on a control panel. This is not an excuse, but a reasonable explanation for a whole range of accidents involving complex systems.