Hopefully everyone realized that this article is from 2004 and Huygens completed its descent onto Titan in January 2005. The problem discussed in the article was successfully fixed, saving the mission, but an unrelated problem (also with the telemetry) means a modest chunk of data was lost:<p>> Huygens was programmed to transmit telemetry and scientific data to the Cassini orbiter for relay to Earth using two redundant S-band radio systems, referred to as Channel A and B, or Chain A and B. Channel A was the sole path for an experiment to measure wind speeds by studying tiny frequency changes caused by Huygens's motion. In one other deliberate departure from full redundancy, pictures from the descent imager were split up, with each channel carrying 350 pictures.<p>>As it turned out, Cassini never listened to channel A because of an operational commanding error. The receiver on the orbiter was never commanded to turn on, according to officials with the European Space Agency. ESA announced that the program error was a mistake on their part, the missing command was part of a software program developed by ESA for the Huygens mission and that it was executed by Cassini as delivered.<p>>The loss of Channel A means only 350 pictures were received instead of the 700 planned. All Doppler radio measurements between Cassini and Huygens were lost as well. Doppler radio measurements of Huygens from Earth were made, though not as accurate as the expected measurements that Cassini would have made; when added to accelerometer sensors on Huygens and VLBI tracking of the position of the Huygens probe from Earth, reasonably accurate wind speed and direction measurements could still be derived.<p><a href="http://en.wikipedia.org/wiki/Huygens_(spacecraft)#Channel_A_data_lost" rel="nofollow">http://en.wikipedia.org/wiki/Huygens_(spacecraft)#Channel_A_...</a>
Amazing work by a tenacious and talented engineer. Great story.<p>(Question: What does his nationality have to do with it though? Seems like an odd addition to the headline.)
Perhaps I missed it when I read the article: Why did he originally have the hunch that the radio wouldn't work when Doppler shifted?<p>Also, I guess something like Manchester encoding wasn't use because of the data rate limitations? IIRC Manchester encoding is self-clocking, which seemed like the issue here.
> In proposing this more complex test with simulated telemetry, Smeds "had to argue with those who didn't think it was necessary," recalled JPL's Mitchell. Smeds was persistent and continued championing the test even after it was initially rejected. In the end, with the backing of Sollazzo and Huygens's project scientist, Jean-Pierre Lebreton, Smeds's plan was accepted because it was easy to do, even though hardly anybody seemed to think it was worth doing. On such seeming trivia US $300 million missions can turn: the simpler carrier-signal-only test, Mitchell noted, would never have uncovered any problems.<p>Is there any place you can go to escape the forces of willful ignorance?
"An Alenia Spazio spokeswoman said that none of the company's officials were available to comment because of a company-wide summer vacation period." Typical Italian... (I'm Italian myself btw)
<i>Alenia Spazio’s insistence on confidentiality may have played a role in this oversight. NASA reviewers were never given the specs of the receiver. As JPL’s Mitchell explained to Spectrum, “Alenia Spazio considered JPL to be a competitor and treated the radio design as proprietary data.”</i><p>I am surprised that NASA would allow a piece of hardware on a spaceship that they do not have the specs for. Unless NASA/ESA do very extensive testing, this seems like a terrible practice.