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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."
Damn that's sad. Don't they have checklists for these things??
Martin
This post is from memory. Please feel free to correct errors and ridicule me for factual inconsistencies.
... 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.
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?
It would be fantastic if they could, but I think they are only talking about using the phase/doppler shift of the carrier signal to infer something about the location/movement of the probe. The high frequency data channel is probably lost in the noise.
:-)
As someone who has been involved in large coding projects (100,000 lines +) while I understand how easy it is for bugs to creep in, I do think the programming bug that effectively did not switch on the second channel should have been picked up on a project of this size/budget. Sadly, too often, the bigger the bureaucracy, the more mistakes like this you have - small keen teams often do better.
Regarding image quality on Huygens - in hindsight could that have been done better?
I realise there are constraints - 80's hardware, limited batteries, 8k bit channel, etc, but here are my casual observations..
Much higher resolution CCD's were available at the time - Cassini had a 1 megapixel unit. Low res data could have been transmitted during descent, but hi-res data could have been stored & broadcast after landing. As it is, the radio spent a lot of time sending identical images of the landing site. Another idea that gets a lot more out of a video data stream is variable jpg compression & only transmitting the signal difference between certain frames. That way you can use hi res CCDs then compress-until-it-fits the 8K data channel. When there is a lot of data/change in the pictures you compress a lot, but if certain cameras are not returning any or little change in the pictures, or if the picture has no detail, more channel space is available to send either hi-resolution or even pre-recorded data.
Furthermore, why the assumption that the probe will be destroyed on landing? Why not switch off Huygens when Cassini dissapears below the horizon, and switch it on for the next day? (titan's day is 16 days long..) The batteries lasted many hours after the landing, and the craft did cruise in standby mode for 16 days, so this might have been possible.
I think they could have returned all the data we got anyway up to the landing, and designed a 2nd phase with more data being sent, with little change to mission profile/weight/etc..
One thing I dont understand - why are the triplets out of sequence? The early pictures show the landing site! Is this just some artifact of the transmission process?
If I didnt know any better, I would say that final picture of the rocks was just a "joke" by the programmer, a frame to put in when the data/checksum fails for that camera..
"You lied to me! There is a Swansea!"
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?
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Main reason was to take pictures?
...but you probably won't understand those if you really think they send the expensive probe half way across the solar system just to take some snapshots.
No-no-no.
The reason pictures were received first and are getting most of the attention is because it's good PR. A lot of scientific data isn't pretty things you can oogle at, but just some measured numbers at chart. Describing atmospheric composition, pressure, and so on.
You assume that heavily penalizing the person responsible will actually prevent these errors. If this were true, your comment would have some merit. But I believe such a measure would actually be counter-effective. Since the person responsible quite likely did not *plan* this to go wrong, he did not actively deliberate the pro's and con's of such a failure. Therefore the only effect will be even more pressure, with an even larger chance of failure.