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Let's create a telescope the size of Earth.
People currently crowd source CPU time (bitcoin, seti at
home, folding at home). Now that people have wide access
to
sensors (cell phone) and an accurate position (gps)
everyone
can share their sensor data to create the largest sensor
array
ever. All the user contributed data will be collected and
synthesized into a common synthetic aperture image.
en.wikipedia.org/wiki/Aperture_synthesis
en.wikipedia.org/wiki/Sensor_array
Cellphone_20radio_20telescope
[hippo, Sep 15 2016]
Detect Earthquakes using Fitbit
Mentioned in my anno. Also "Crowdsourced Seismometry" right below this in the category. [notexactly, Sep 20 2016, last modified Sep 22 2016]
Planet-wide camera
[xaviergisz, Sep 20 2016]
Discover Habitable...he Professionals Do
[xaviergisz, Sep 20 2016]
(?) Diagram
https://en.wikipedi...agnetic_opacity.svg
[hippo, Sep 21 2016]
Diagram
https://commons.wik...agnetic_opacity.svg
Fixed [hippo]'s link for those on mobile, those using Imagus or similar, those who don't want to load a whole encyclopedia article just to see one picture, etc. [notexactly, Sep 22 2016]
[link]
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I may have heard of something like this around 2006, people with handyphones gathered audio from everywhere and then they were going to correlate this with earthquakes or something like that. The thing i might have thought about then was 'is the frequency response of the microphone sufficient?" |
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similarly, what are some visible range observables that go with handyphones. and, um, I may have either thought of this now, or previously, I have thought about could IP packet static be measured then correlated with something interesting to observe. i do not know if this means giant swathes of optical fiber detecting something, or a few million CPUs drifting slightly from some EM cause. |
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also, I am upvoting your idea. |
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[beanangel], regarding your first paragraph, see links at
[link]. Baked several times. |
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Hello, [FloppyHardDisk]! If you will put your links into the "links"
section below the idea text, they become actual working links... |
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like the prior art [xaviergisz] linked to in which [EdZ] proposed a
similar idea seven years ago. The cell phones are a new addition;
they don't solve any of the original problems. |
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I may be wrongly mistaken here, but doesn't aperture
synthesis require the position of the elements to be
known to within less than a wavelength of the light
being imaged? |
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So with reasonably accurate GPS you could get away
with imaging 10-metre waves, which are nearly the
longest wavelengths to which the Earth's atmosphere
is reasonably transparent (according to the linked
diagram). |
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I checked with Seth Shostak a few years ago about a similar idea: a crowd funded SETI project. |
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My question was along the lines of: |
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'...build a standard SETI kit, that anyone interested could purchase, install in their backyard or on the roof, connect to the web and contribute data directly to the project. The antenna would self align and track, and be under the control of SETI as part of a distributed computing project. The data could be time-stamped at very high resolution allowing bits from opposite sides of the world to form a virtual telescope...' |
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(part of) His response was: |
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1. The idea of amateur radio SETI is a good one, and has been pursued for a few decades by the SETI League (look them up).
2. Small antennas have very little sensitivity, but hey .. |
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//doesn't aperture synthesis require the position of the elements to be known to within less than a wavelength of the light being imaged?// |
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I believe it does, and it also needs sensors which can record the phase of the incoming signal as well as its magnitude. |
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I could be wrong, though. |
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// So with reasonably accurate GPS you could get away with imaging 10-metre waves, which are
nearly the longest wavelengths to which the Earth's atmosphere is reasonably transparent (according
to the linked diagram). // |
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Is it practical to receive such long waves with the small antennas in phones, assuming the radio
hardware is capable of receiving that band, which it currently isn't? |
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I thought the idea (this time I read it, anyway) was about using phone cameras. Put your phone on the
roof overnight with the app running, or something like that. Those wavefront coding-based cameras
(which have been in some iPhones, IIRC) might be able to capture phase information, or maybe future
versions of them could. Position of the sensor to within less than a wavelength could be solved by the
same method that FlightAware uses (and probably the other companies do too) to find the exact
position of each ADS-B receiver for multilateration. As I understand it, their multilateration only works
when there are multiple planes in the sky whose signals are being received by the same set of
multiple receivers, because it uses that to solve for not only the planes' exact positions, but the
receivers' exact positions too. (For that reason, you can move your receiver's antenna a bit without
telling FlightAware, and it will still be able to multilaterate.) Similarly, this idea could use bright stars
visible to multiple phones, at least conceivably. |
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How much could you achieve without wavelength
correlation? |
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Assume you have 10,000 cameras around the world (or at
least in one hemisphere), all pointed at roughly the same
area of sky. All of their low-res, low-sensitivity images
could be aligned using bright stars. Wouldn't the alignment
allow you to see much fainter stars? I don't think the image
would be any sharper, but the sensitivity might be higher. |
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Also, this could be used to provide a continuous (during the
night) image of the whole sky in realtime if the images were
stitched automatically. This could be used to accurately
count meteors, for instance. It would also give you a record
of any other transient phenomena (eg, a largish meteorite
hitting the moon; or a bright but short-lived nova) that
might otherwise be missed. |
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