Egyptian pyramids found by infra-red satellite images
bbc.co.uk
bbc.co.uk
OK, back to a rainy day in Chicago and trying to understand Puppet.
It seems we've reached the point where there's an xkcd for every situation (on HN at least) now. Maybe a corollary to rule 34[1] is needed.
[1] http://www.amazon.com/Pulling-Strings-Puppet-Automated-Admin...
Not sure if this is the exact technique they are using in this article, but it's what we featured in an exhibit on Egypt he worked on.
Seems like these techniques are going to radically change how we find new archaeological sites. Tech. project idea: Build some tools to help archaeologists learn and share from each other with this data. Build a world wide database of IR imagery just a few meters below the surface?
To my knowledge, the first people to use remote sensing data in an archeological context used radar (SRTM, a synthetic aperture radar mapping mission that flew on the space shuttle). Radar can penetrate the land to a depth of ~meters depending on lots of factors.
They discovered the lost city of Ubar, which was a trading city (ca. 3000 BC) in the Arabian peninsula that had been lost to the desert.
They discovered it because trails that had formerly led into Ubar gave off stronger radar reflections.
Later on-site digs confirmed actual ruins. This was in 1992. A link:
http://photojournal.jpl.nasa.gov/catalog/PIA01721
The person who blurbed the book you found, Charles Elachi, was a key member of the team that designed the radar instrument that found Ubar.
All of the SRTM data is online somewhere. The desert turns out to be a really good place to look for stuff. Less clutter.
And mount to DIYDrones for added awesome.
I am very curious as to what else they find through these excavations
Many presenting puzzles yet to be solved.
Not really. It'd be much more fascinating if you found relics of ancient civilisation which weren't concentrated in that part of the world.
The earliest egyptian pyramids were ~2600BC, corresponding with the rise of civilizations in China (http://en.wikipedia.org/wiki/Yellow_Emperor) and Peru (http://en.wikipedia.org/wiki/Caral). We've found a lot more iconic relics of Egyptian civilization from that time period, however.
Thanks for the great link!
That soil has to come from somewhere, anyone know where?
Which also explains why the ocean is blue.
Yeah, I have to: those poor underground buildings... they just don't hold a candle to infra-red images from space, do they?
Come on BBC, "show up"? We need a Ballmer-like "Editors! Editors! Editors!" chant right about now.
How can you see a mud brick under sand because it is "much denser than the soil that surrounds it"?
This is detectable in the light that is reflected back.
It's not dissimilar to how an ultrasound scanner is used to look at a baby in the womb. In fact, ultrasound is used in archaeology as well to do this sort of stuff, obviously on a smaller scale.
This is the wikipedia page you want: http://en.wikipedia.org/wiki/Infrared_spectroscopy
Although that page discusses things at very different scales to what we're talking about here, (while I am not a physicist,) the principles are basically the same.
What I think is really going on is thermodynamics. Suppose I bury a big stone pyramid under the sand. Stone is (I assume) a much better conductor of heat than sand. When the sun comes up after a cold night, it heats the sand, but the sand on top of the pyramid has its heat conducted away more efficiently than the sand far from the pyramid, so it'll show up as slightly cooler when imaged with the infra-red satellite.
As for how deep does heat actually go, I would say, that if earth wouldn't have any temperature of its own, it would go all the way down. The process just takes extreme amounts of time. Empirically it takes time for earth to freeze at winter (if you live north enough) and likewise one cannot dig the ground has melted at the late of spring. Other empirical example would be rock near a campfire, they will stay warm long time after the fire goes down. Earth is just a very big rock.
While the ground doesn't freeze at Egypt, they certainly have some seasons, with different average temperatures, to warm up or cool down the deep ground temperature. So within time they should be able to see temperature differences of objects buried deep into ground. Assuming the resolution of satellites is good enough.
Other question would be how much interference does the warm sand over these objects cause. As the sand is somewhat flat, it probably has black body like radiation curve and removing it should be easy, but there always will be some static from these processes reducing the total resolution.
Well all in all, I really don't know how they do all this.
I don't know, just formulating another hypothesis for the fun of it.
No I didn't read the article.
I'm not sure that a priori means what you think it means.
I use it here in the same sense as "an a priori estimate" as opposed to the more common logical use of something being apparent without requiring study but only the application of reason.
I take it you're more a logician than a Latin student. If the later then I guess you'll probably correct me?
Are you sure now, let me know.
--
Aside I've had chance to read teh article and there was no mention of taking near-IR images at day and night. So presumably it's my language use that's getting me heavily downmodded?
Actually I think you were downmodded for not reading the article and then asking a question that could have been answered by reading the article.
Except I read the article and watched the video and neither answered the question ... so if any of these people had read it they would have known the article didn't answer the point. So it's just pettiness?
IMO part of the benefit of social media such as this site is that others are willing to digest news and information to enable one to get a quick overview of a topic.
As specific heat capacity is inverse proportional to density, sand and pyramids react to temperature changes differently. In desert temperature changes between day and night are huge causing sand and pyramids to have different temperatures. As thermal radiation is infrared in temperatures near human body temperatures (didn't check the exact temperatures but pyramids should fit in infrared spectrum), sand and pyramids will show up in different 'colors' in infrared mapping of area.
This is probably the basic idea behind these findings, of course what they are doing certainly goes beyond this level of explanation with use of infrared spectroscopy.
Anyone have a better idea how this process works?
I don't know whether you've gotten a lot of votes or not so I don't know if your answer makes sense to other people as well.
Why do you think you don't need permission to take pictures of a country from space? I think there are certain areas in all countries that they would want to keep secret, and if you allow people to photograph in certain areas and not in others, that's exposing where these areas are (which is an invitation for governments to spy on those areas).
But, the closest I could get: UN General Assembly, resolution 41/65, of 3 December 1986: Principles Relating to Remote Sensing of the Earth from Outer Space.
Principle IV: These activities shall be conducted on the basis of respect for the principle of full and permanent sovereignty of all States and peoples over their own wealth and natural resources, with due regard to the rights and interests, in accordance with international law, of other States and entities under their jurisdiction. Such activities shall not be conducted in a manner detrimental to the legitimate rights and interests of the sensed State.
I'm not sure how remote sensing could violate jurisdiction over wealth and resources, but it does not mention territory.
And then there's principle XII: As soon as the primary data and the processed data concerning the territory under its jurisdiction are produced, the sensed State shall have access to them on a non-discriminatory basis and on reasonable cost terms. The sensed State shall also have access to the available analysed information concerning the territory under its jurisdiction in the possession of any State participating in remote sensing activities on the same basis and terms, taking particularly into account the needs and interests of the developing countries.
If prior permission to perform the sensing was required, provisions stipulating that the data should be shared would be redundant, I think?
Source: http://www.oosa.unvienna.org/oosa/en/SpaceLaw/gares/html/gar...
History repeats itself. I wonder what we can find in our past that will inform our future.
(although, one might say, the main thing that one learns from the study of history is that people do not learn from history)