Phoenix sings!

By Phil Plait | May 28, 2008 10:36 am

You’ve seen the pictures, now listen to the soundtrack!

As Phoenix descended onto the surface of Mars, its telemetry signal was picked up by the European Mars Express orbiter. The ESA has just released a version of that signal converted to audio, so you can hear the signal.

At first I was confused, but now I understand: the pitch of the signal goes up because Mars Express was approaching Phoenix as it orbited Mars. That caused a Doppler shift in the signal, increasing the frequency (or shortening the wavelength if you prefer). Just like an approaching car or train whistle will apparently go up in pitch (change to a higher note) as it approaches, so did the signal from Phoenix as Mars Express sailed toward it.

For the public, there is nothing really to learn from this, and nothing of any great import to deliver. Still, why not? Not everything has to be earth-shattering. Sometimes things are just cool.

CATEGORIZED UNDER: Cool stuff, NASA, Science, Space

Comments (24)

  1. Alaa

    It is music to my ears: “Phoenix, the Bringer of Mars”!!! Where is John Cage when we need him :-)

  2. :) I think I’ll make it my ring tone.

  3. 01101001

    My dog came running.

  4. Pierre

    A train’s whistle does not go up in pitch when the train is moving at a constant speed directly towards you. It’s just higher. It’s when the train moves by you (or over you!) that you notice the difference in pitch.

    I haven not listened to the signal, but does the pitch actually goes up, or is just higher than expected? If it goes up, it means the phoenix’s speed was increasing with respect to Mars Express (at least, on the light of sight). If it was approaching at a constant speed, then the signal’s pitch would be higher but not necessarily going up. I suppose that the geometry of the two spacecrafts’ speed vector looked liked an acceleration?

  5. Sure, enjoy listening to the Phoenix signal. Meanwhile the toilet is busted on the space station. Where are your priorities? This is like Apollo 13 all over again. We need engineers on the ground scrounging up supplies found on the ISS to rig up a contraption and describe how to make it to the nervous crew floating there helplessly in space.

    For the love of Haleakala! Somebody do something!

  6. MK

    Hi Phil,

    Long time lurker, first time poster.

    These recent developments in our exploration of space has got me as thrilled, as enthused as you or any other space/science nut (I say that with all affection!) I was absolutly floored when the two rovers were successfully placed up there! (out there?) I also have high hopes that I will live long enough to someday see something similar to Phoenix land on Europa.

    What I don’t yet grasp (And it’s OK, I really don’t grasp quite a lot!) is the whole human space flight thing.

    I’ve known for some time that you are a strong proponent of putting a man on Mars. (Well, first getting back to the moon for the purpose of going to Mars, but nevertheless…) the thing I can’t find–and I recently did a search of your site, sorry if I missed it–was, why? Why do you feel men need to set foot on Mars? What will they do that hasn’t been or isn’t already being done?

    It has long been my contention that we will have learned to send a robotic probe to Mars, have it pick up some rocks and soil, and have it launch itself and return back to Earth long before we yet again set foot on our moon…much less Mars! So men on Mars might by then seem redundant at best.

    You’ve acknowleged the difficulties in the moon/Mars program. That it would take a very long time to figure out how to do it successfully, to overcome the extremely high hurdles. I personally have no doubt that it CAN be done. But, in the end, for me, it’s the “Why?” that matters.

    Why should we do this? Is it really just because we can? Because exploring is what humans do? Don’t we need a more concrete, a more scientifically sophisticated answer before we undertake such a monumental task? And again, if you have answered this and I missed it in my search please forgive me. I’d love to read it.

    Genuinely curious.


  7. MK,

    Because it’s there, and as humans, that’s all the excuse we’ve ever needed.

    Sure, there’s lots of other reasons, some more profound or of greater import than others, some absolutely imperative if we wish to continue as a species, but it really needn’t be any more complicated than this:

    Because it’s there.

  8. Couldn’t have said it better myself JanieBelle. Because it’s there.

  9. BovineSupreme

    If there’s a longer version (a couple seconds should be enough), we should totally try to get this on the charts.

  10. Pierre:


    Actually, unless the train is moving in a straight like directly towards you, the pitch is constantly changing. You just don’t notice it until it passes.

  11. You can’t stop the signal.

    This is very cool.

  12. gopher65

    MK says (paraphrased): “Why should be go deep into space?”

    There is only one real, practical reason and it is a doosy: necessity is the mother of all invention. In our history we have traditionally had two types of necessity, war and famine. Both have driven us to achieve, to strive, to invent.

    In the Western World we have limited (but not completely eliminated) those two factors from our internal societies. Yes there is still war, yes people are still starving, but you know what? It’s happening thousands of kilometres away, and people don’t reaaaaaally care if it isn’t happening to them. Oh we feel compassion and pity in spades, and we may even try and help a little bit, but we won’t throw ourselves at the problem like we would if it were *us* that was starving to death.

    So what’s left for us? We need to force ourselves into solving problems, because frankly we’re all naturally lazy. We have plenty of problems, but none of them seem urgent enough for us to act quickly and decisively. But when you toss someone up into a radiation filled vacuum in an aluminum foil shell, well, that seems pretty urgent. It gives us an immediate problem to solve, and to be creative in solving. The amazing things we develop and learn can then be applied to the rest of the problems that our society, and humanity as a whole, faces.

    In short, our society is lazy, and we need to trick ourselves out of procrastinating, just as we do on an individual level (or at least I do).

  13. NM

    Very nice, ESA.

    Now.. where’s the the promised EDL pictures?

  14. DustPuppyOI

    Hey Phil!

    Pardon me if you’ve already mentioned this link (couldn’t find any mention while quickly browsing your Mars/Phoenix posts), but the Mars Phoenix Lander has its own Twitter feed, in the first person!


  15. hambr

    At just about the half way mark, it sounds a sound bite from Pac Man

  16. KaiYves

    I agree. Sometimes stuff just IS cool.

  17. Reminds me of the Voyager Sound Recordings “Symphonies of the Planets” 5 disc set released ages ago. But not as hauntingly dark or lush. Still. Awesome.

  18. Stark

    MK –

    I’ll add on to what JanieBell said…

    In addition to the human spirit of exploration – humans can do things no robots will be able to do in the forseeable future. Namely, be creative, adjust to rapidly changing circumstances, and completely change the parameters of the mission should new information crop up. Basically, while we can send robot after robot to Mars they are all limited in what they can do. A human is not. A human on the ground with support of people on earth is far more likely to notice something truly interesting and be able to respond to it than a robotic rover is.

    Also, our planet WILL become hostile to human life at some point. It may not be for a very long time but it will eventually happen. Walking on another planet and getting home safely is the very first baby step to leaving this planet when it becomes neccesary to do so – just as the first reed rafts on the Nile 10,000 years ago were the first baby steps to ocean going passenger ships. You gotta start somewhere and Mars is far enough to be hard yet close enough to be do-able, and ineresting enough to be worthwhile with existing technologies. Using those existing technologies in new ways will, as history has shown time and time again, lead to new technologies with far reaching results for mankind.

  19. Crux Australis

    My senior Physics class just finished studying Doppler shift. This will be the intro to today’s lesson! :-)

  20. @CarrieP — Right on!!

  21. So when are they going to turn on the microphone?

    – Jack

  22. MK

    To all kind enough to respond…

    I didn’t say we don’t need to explore space. We do. I asked why do you want to put a man on Mars. No good answer–except for gopher’s humorous one–has been offered beyond the “we are humans and we can, therefore we should.” Someone even went boldly so far as to say there is no other reason necessary.

    Therefore, I leave today still genuinely curious.

    If you are not too busy Phil, I’d love to hear from you.

  23. Some Grad Student

    This is really confusing. Phoenix must be approaching the orbiter at less than 0.1% the speed of light. So the Doppler shift should be less than that order, and for a 8 kHz signal that’s 8 Hz. That would just be barely perceptible. Is there something that I missed? Or was the transmitted signal just changing pitch and someone at the ESA press office got a little overexcited?


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