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Unmanned Spaceflight.com _ Phoenix _ MARDI microphone
Posted by: elakdawalla Sep 18 2008, 03:52 PM
http://www.livescience.com/blogs/author/leonarddavid/ that "the Phoenix lander team is going forward with turning on the spacecraft’s microphone."
I'm working on finding out more details. (For instance, I want to know if this also means they'll get to use the camera itself, maybe get a different perspective on Holy Cow, if the camera's pointing the right way.) In the meantime, http://www.planetary.org/programs/projects/planetary_microphones/mars_sounds.html what Bill Nye and others would sound like on Mars before they asphyxiated.
Yay!
Emily
Posted by: Stu Sep 18 2008, 03:56 PM
That's fantastic news! Being able to play kids the sound of the wind blowing on Mars would be brilliant! As you so eloquently put it, "Yay!" 
Having said that... and without wanting to blow on anyone's chips here ... is this a sign that the Phoenix team is maybe sensing that the sand is really rushing through the hourglass now, and the time has come to start trying cool and unusual things..?
Posted by: ugordan Sep 18 2008, 04:24 PM
It's probably the realization that at this point, turning MARDI on can't jeopardize the success of the mission anymore so they might as well do it. I don't see it as running against the clock. I'm glad they decided to turn it on, was hoping it would happen sometime during the extended mission.
Posted by: fredk Sep 18 2008, 05:03 PM
I wonder if it will be sensitive enough to hear wind directly? Maybe some cavity somewhere on Phoenix will resonate in the wind and make a whistle or hum? Maybe the sound of the solar arrays flapping in the wind would be easier to hear, if it could carry directly through the body of Phoenix?
Posted by: elakdawalla Sep 18 2008, 05:18 PM
It's hard to know what, if anything, it'll hear; it was intended to listen to descent noises (whoosh and all that), so is probably pretty insensitive to the level of sound that currently prevails at the landing site -- but we'll see. We also have to see if it still works or not. So -- hope, but don't expect, to hear anything!
--Emily
Posted by: ElkGroveDan Sep 18 2008, 05:22 PM
It would be great if they could acquire audio during soil sampling and ice scraping.
Posted by: ugordan Sep 18 2008, 05:27 PM
The motors in the robotic arm should produce a buzzing sound when operated, right?
Posted by: elakdawalla Sep 18 2008, 10:21 PM
OK, here's a challenge for someone(s) with a facility for 3D visualization. The question is, what would MARDI be looking at if it took an image right now? More specifically, could it see any of the ice patches in Holy Cow? Attached is an image of the underside of the lander, in which you can see MARDI (it's the thing covered with a blue cover, actually a glove, just like the glove the technician is wearing!) I've tried to puzzle it out but am afraid of errors and am hoping a couple of people here can try to figure it out independently. Also relevant: its FOV is 66 degrees.
--Emily
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Posted by: Astro0 Sep 18 2008, 10:39 PM
Perhaps we'll hear this... 
mardi_1stsound.mp3 ( 25.1K )
: 1083
Sorry...couldn't resist. 
Posted by: djellison Sep 18 2008, 11:01 PM
OK - If Phoenix is like a clock...
Solar Panels are at 2.30 and 8.30
The arm is mounted at about 1.30
MARDI looks to be at about 7 - sort of behind where the elbow of the arm was when folded flat.
http://www.lockheedmartin.com/data/assets/14819.gif
http://www.lockheedmartin.com/data/assets/14845.jpg
I would GUESS - the area marked green...possibly getting a corner of one bit of the exposed stuff - but with MARDI being pointing slight away from straight down, I'm not confident.
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Posted by: PDP8E Sep 18 2008, 11:47 PM
doug,
In the second image you posted above ( http://www.lockheedmartin.com/data/assets/14845.jpg) it appears the telltale 'cord' has the bend (or similar) that we have seen from the first Sol it was deployed....
cheers
Posted by: dshaffer Sep 19 2008, 01:13 AM
Solar Panels are at 2.30 and 8.30
The arm is mounted at about 1.30
MARDI looks to be at about 7 - sort of behind where the elbow of the arm was when folded flat.
http://www.lockheedmartin.com/data/assets/14819.gif
http://www.lockheedmartin.com/data/assets/14845.jpg
I would GUESS - the area marked green...possibly getting a corner of one bit of the exposed stuff - but with MARDI being pointing slight away from straight down, I'm not confident.
Doug - I had thought that MARDI was fixed-focus (probably at Infinity) - so anything a few feet away would be out-of-focus, no?
Posted by: elakdawalla Sep 19 2008, 01:15 AM
You would think that, but actually it does pretty well at short distances. See the bottom of http://www.planetary.org/blog/article/00001485/.
--Emily
Posted by: dshaffer Sep 19 2008, 01:22 AM
--Emily
Thanks - I had missed that BLOG entry.
Mardi has an excellent depth of field.
Posted by: mcaplinger Sep 19 2008, 03:33 AM
FWIW, MARDI is just about exactly behind the met mast as seen from the SSI, and it's pointed 22 degrees outward from nadir.
Posted by: Paul Fjeld Sep 19 2008, 03:59 AM
If the camera's 22 degrees pointing out, and slightly away, to the west, from the nearest jet, then I don't think MARDI can see the HolyCow plume effect. I make the centerline of the camera about 18 inches from the nearest jet in the science deck plane (I think X/Y). The camera is below the deck some 5 inches, and that's about 3 feet (?) from the surface. A little trig tells me they'll miss it by half a foot, guessing the size of each "skating rink" to be maybe a foot and a half in diameter(??)
That's back of the envelope, so it's just a guess.
Posted by: elakdawalla Sep 19 2008, 04:09 AM
OK, I've got http://planetary.org/news/2008/0918_Phoenix_Mission_Receives_OK_to_Listen.html for all of you! Enjoy.
--Emily
Posted by: djellison Sep 19 2008, 07:11 AM
Round up a bit. 66 deg FOV, 22 deg out-from-Nadir pointing.
That means 22 degrees of FOV inside of Nadir from the camera, and 44 degrees outside of Nadir.
Assuming a height of, say, 100 cm...
I make it 40cm of terrain inside a point directly under MARDI and 96 cm of terrain outside it ( Tan Theta = Opposite (the distance on the ground) over Adjacent ( the height of Mardi above the ground ) )
Posted by: climber Sep 19 2008, 09:53 AM
Now that we "know" where Mardi is, can we determine the mike position relative to the incoming (main) wind and weather it'll pick up the wind strait or be shadowed by Mardi itself?
Posted by: mcaplinger Sep 19 2008, 01:33 PM
The microphone is more or less omnidirectional, and pointed in the same direction as the optics. You can see it in photos of the instrument; for example http://www.msss.com/phoenix/mardi/illustrations/phx_mardi2.jpg (you probably knew this already.)
I don't know where the prevailing wind is from.
Posted by: ustrax Sep 19 2008, 02:06 PM
Now...wouldn't it be great to capture another DD sequence with a wooooosh as soundtrack?...
Posted by: Paul Fjeld Sep 19 2008, 04:37 PM
That means 22 degrees of FOV inside of Nadir from the camera, and 44 degrees outside of Nadir.
I think your arithmetic is wrong. The centerline of the camera is moved out 22 degrees. So straight down you get 33 degrees inside and outside of nadir. When you move the centerline out, it's 33 - 22 degrees inside of nadir.
Posted by: jumpjack Oct 2 2008, 07:12 AM
It would be really cool to hear Phoenix digging Mars soli!
I stay tuned for news... Pleas keep us informed!
Posted by: ElkGroveDan Oct 2 2008, 01:45 PM
Glad to see the Swiss Military were part of the MARDI team.
Posted by: Decepticon Oct 3 2008, 12:35 AM
When can we expect science return?
Posted by: CosmicRocker Oct 4 2008, 04:36 AM
There was a small comment about when the microphone might be turned on in http://www.jpl.nasa.gov/news/phoenix/release.php?ArticleID=1886.
It sounds as if this experiment has a rather low priority. Is that because the event might trigger a fault?
Posted by: centsworth_II Oct 4 2008, 05:06 PM
Could they be planning to turn the microphone on only after there is insufficient power for digging? I was hoping to hear the sounds of Phoenix scrapping the surface of Mars. I suppose the next most interesting sound would be the solar panels creaking in the wind.
Posted by: Deimos Oct 5 2008, 02:21 AM
SSI and MECA-OM are noisy.
I don't think the microphone is being deliberately delayed. It is just not the highest priority thing to work on--using equipment in a "new" way after months of thermal cycles is something that needs to be approached with care. There is special concern during RA use. That's not to say it won't happen, but I'd be surprised if it happened first.
Posted by: mcaplinger Oct 9 2008, 12:47 AM
Does anyone know where the SSI exposure times might be tabulated? I need them to compute some exposure times for another instrument on the surface that may be operated soon
Posted by: 1101001 Oct 9 2008, 01:00 AM
Like this?
From http://www.met.tamu.edu/mars/vitals.html
From http://www.met.tamu.edu/mars/
Posted by: mcaplinger Oct 9 2008, 02:33 AM
No, like what exposure time a specific image was taken with.
Posted by: elakdawalla Oct 9 2008, 02:37 AM
Exposure information can be found in the header for all the JPEG images. Attached is a .csv file (zipped) with the metadata from all the JPEGs available to date, stripped from the headers using Midnight Mars Browser.
--Emily
Posted by: mcaplinger Oct 9 2008, 02:46 AM
Thanks for the CSV file! Apparently very few extent JPEG viewers can read the EXIF tags for some reason.
Posted by: elakdawalla Oct 9 2008, 03:14 AM
Hmm. If I want to see a header, usually I just open the JPEG file in a text editor. --Emily
Posted by: Skyrunner Oct 9 2008, 09:08 AM
http://www.irfanview.com/ works a treat. Just hit the 'image information' button or press 'i' and hit hit the 'comment' button or press 'c'.
Posted by: Juramike Oct 15 2008, 02:33 PM
But seriously, when is the microphone going to be activated?
The recordings of Martian sounds would make a dramatic backdrop for every image of Mars ever captured.
I'd hate to have the only sound sent to Earth be a 5-second clip of a solar panel snapping off from frost.
[/vent]
Posted by: mcaplinger Oct 15 2008, 04:19 PM
Let me try to lower your expectations. The audio is only digitized at 8 KHz (telephone quality at best), so even if it does work, IMHO it's not going to "make a dramatic backdrop" to anything.
Posted by: ugordan Oct 15 2008, 04:27 PM
Please say it's not 8 bits/sample!
Posted by: djellison Oct 15 2008, 05:16 PM
It's not 8 bits/sample
(you said please)
If it's roughly the same as the '98 one, the ADC is 12bit.
Prepare to be unamazed by the quality. http://www.planetary.org/programs/projects/innovative_technologies/planetary_microphones/mars_microphone.html
Posted by: ugordan Oct 15 2008, 05:39 PM
I am indeed unamazed, but at least the sample depth is 12 bit. 8 bits is pretty much useless and very noisy for any appreciable dynamic range.
Posted by: mcaplinger Oct 15 2008, 05:56 PM
It's got nothing in common with the Planetary Society microphone, but it's not 8 bits.
"DSP561xx processors are noteworthy because they include a sigma-delta codec on-chip. The sigma-delta codec provides linear, analog I/O with 16-bit resolution over a bandwidth of approximately 4 kHz. Motorola states that the codec has a signal to noise-plus-distortion ratio of greater than 60 dB. "
As always with ADCs, though, caveat emptor about how many of the stated bits are actually significant...
Indeed.
Posted by: fredk Oct 15 2008, 06:31 PM
Well, I wouldn't say that we exactly need high-fidelity surround-sound here! Do we expect much Martian sound above 8 kHz? Obviously higher signal-to-noise improves our chances of hearing anything at all, but I for one would be thrilled to hear even a sub-telephone-quality recording of the creaking of the solar panels flexing in the wind.
Posted by: Stu Oct 15 2008, 07:20 PM
http://www.gargaro.com/MaRvInWaVs/angry.wav of the first sounds to be recorded by the mic...
Posted by: ConyHigh Oct 15 2008, 09:35 PM
http://www.popularmechanics.com/science/air_space/4287469.html?series=60
Smith talks about using the microphone.
Posted by: fredk Oct 21 2008, 04:04 PM
From http://news.bbc.co.uk/1/hi/sci/tech/7680981.stm
Posted by: MahFL Oct 21 2008, 05:22 PM
Bang a few pots....I like it.
Posted by: Enceladus75 Oct 23 2008, 01:05 AM
I really hope that they get the microphone up and running before Phoenix kicks the bucket. Even just a few minutes of hearing the whisper of the Martian winds would be pretty cool.
Posted by: CosmicRocker Oct 26 2008, 05:49 AM
Thanks, fredk. I enjoyed that article. This lander's mission was really quite complicated, was it not? Since Phoenix is not a rover, it was interesting to see how the team assigned priorities. Organics, isotopes, ions, and whatever else they hoped to find, this has been a really fascinating planetary adventure.
I want to see another one. Hearing something will be fun, but it's not the highest priority on my agenda. I am fully prepared to begin banging pots at any time, if that is required.
Posted by: tedstryk Oct 31 2008, 08:00 PM
Does anyone know if they ever got a chance to use the microphone? Also, is it still being considered (although banging with the arm is obviously out of the question?). It seems that when they are back up and running, while the most obvious source of noise is gone, it might be worth giving it a go now (in other words, they don't have nearly as much to lose considering so many of the instruments are out of operation).
Posted by: 1101001 Oct 31 2008, 10:28 PM
The http://twitter.com/MarsPhoenix (October 29) gave an indication or two that it might be tried before too long, but then the storm hit.
If they had done it I think it would have been reported on Twitter or a news release.
Posted by: 1101001 Nov 5 2008, 11:46 PM
This is somewhat old news -- at least 24 hours old -- but I just saw this topic and thought it should be reported here:
http://www.planetary.org/blog/article/00001724/
[...]
They attempted to use the MARDI camera, including its microphone, somewhere around sol 146 (give or take a couple sols). It did not respond. But Barry thought that perhaps they hadn't allowed sufficient time for the instrument to warm up before commanding it to take data. Barry said he has "become a true believer in trying to get the microphone on" ever since Veronica McGregor passed him a message that had been received on the Phoenix Twitter feed from a blind man who pointed out that he never had a chance to see the pictures from Mars; sound would allow him, and others like him, to experience a foreign planet for the first time. Barry said he has instructed the team to include an attempt to use the microphone somewhere in the terminal science mode sequence, but he wasn't sure where it fell.
[...]
Posted by: Shaka Nov 5 2008, 11:53 PM
The things we take for granted... 
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