Boris Smeds vs The Evil Dr Doppler

Here’s an article with lots of interesting things to say about data communication, system testing, and the way modern space exploration works. I may recommend it during CS-244 Data Communication & Computer NetworksTitan Callinghow a Swedish engineer saved a once-in-a-lifetime mission to Saturn’s mysterious moon [risks].

In short: Cassini is at Saturn, and about to launch the Huygens probe into Titan’s atmosphere (splashdown 14th January 2005). The communication link between Huygens and Cassini was not thoroughly tested before launch. Some thoughtful engineer realised this might be a problem, and after some pushing against resistance, managed to test Cassini’s response to how they expect the signal from Huygens to look. Surprise suprise, Houston we have a problem. Turns out, the original engineers took account of doppler shift in the carrier wave, but not in the encoded data. D’oh! Problem is encoded in firmware, can’t be fixed after launch. Double d’oh! So instead, they’ve altered Cassini’s trajectory to eliminate the doppler shift. Hurrah for Boris Smeds!