Geology surveys in Afghanistan don't just rely on the trusty map and hammer. John Brozena of the Naval Research Laboratory discusses how geologists there have mapped mineral deposits from planes carrying various sorts of cameras as well as gravity and magnetic sensors.
Copyright © 2010 National Public Radio®. For personal, noncommercial use only. See Terms of Use. For other uses, prior permission required.IRA FLATOW, host:
You're listening to SCIENCE FRIDAY, from NPR. I'm Ira Flatow.
The recent news that below the surface of Afghanistan lies a treasure trove of minerals got us wondering. You know, that's a bad idea. It got us wondering: Just how do they know that?
It used to be that the only way a geologist could find out what kinds of rocks and minerals were in the hills was to throw on some sturdy boots, grab a hammer, a pair of binoculars, a Rite-in-the-Rain notebook and a map and hit the trail, if there was a trail.
But geology has come a long way since the prospectors out West. Today, we can map the hidden minerals from a plane 50,000 feet above the ground, which is what a team of geologists has been doing in Afghanistan, where, if you wanted to, it's not too safe to hike around hammering rocks, unless you have a squadron of soldiers with machine guns following you around.
So how does all that stuff work? How can you tell what kind of ore lies beneath a mountain range without digging it up? Joining me to talk about that is my guest, John Brozena. He is chief scientist of Project Rampant Lion. That's a geophysical survey of Afghanistan. He's also the head of Marine Physics Branch at the Naval Research Laboratory in Washington. And welcome to SCIENCE FRIDAY, Dr. Brozena.
Dr. JOHN BROZENA (Chief Scientist, Project Rampant Lion Head; Marine Physics Branch, Naval Research Laboratory): Oh, well thank you.
FLATOW: How much of what we've heard this week is really new information, and how much has been known for a while?
Dr. BROZENA: Well, it's a combination of quite a few things. And let me correct one thing. You mentioned 50,000 feet. There were two separate airborne surveys during 2006. Ours was in a P-3, a naval aircraft, a research-configured P-3, and our was at sort of 20,000 to 30,000 feet. The second aircraft, equipped with different sensors, was flown at about 50,000 feet. That was the WB-57.
So there's information from several programs between those two aircraft. But what you need to think about when you're looking for all these minerals or thinking about all these minerals is that geologists fuse information from every source that they can get.
So a great deal of this information came from old Soviet maps. You may have heard that the workers within the Afghan Geological Survey, during the time of the Taliban occupation or control of the country, hid the maps that were made during the Soviet period and brought them forward and gave shared them with U.S. Geological Survey, who then worked with us and the WB-57 folks to put together airborne surveys to supplement the on-the-surface maps.
And so when you're thinking of how you would go about looking for all these minerals or finding them, it's really a combination of every piece of information you can integrate, and we've contributed to one part of that.
FLATOW: Well, share with us the secret of how, from 20,000, 30,000 or 50,000 feet, you can get below the surface and know what's down there.
Dr. BROZENA: Well, our sensors system - and we had a very large group of sensors on the P-3, these I should mention these are former submarine chasers. It was their primary function in the Navy at the time, and the Naval Research Laboratory and its - the Navy Scientific Development's Squadron 1, VXS-1, have a couple of P-3s that are stripped out of all their military hardware, all the sensors for submarine warfare, and all the weapons systems have been removed. And they've been turned into research trucks that can carry lots of different kinds of equipment.
We had gravity, magnetics, hyper-spectral let's see, what else...
FLATOW: Well, let's break each one down.
Dr. BROZENA: Okay.
FLATOW: What can you tell from a gravity sensor?
Dr. BROZENA: A gravity sensor detects variations in mass, local mass variations, which could be either density or amount, like a mountain. And so if you take a topographic map and try to remove the topographic variations, you're left with a good estimate of the density variations in the earth beneath you.
And that's related to both the combination of geologic structure and the materials that are in the area, and that's one type of remote sensing. It's not definitive. You have to calibrate against some ground truth. You have to integrate that information with other things. But knowing the regional densities and density variations tells you quite a lot of information.
The gravity is used primarily for sedimentary basins, looking for oil and gas, as opposed to minerals. You've been hearing in the newspaper about minerals possibly in Afghanistan.
FLATOW: Right. Right. And...
Dr. BROZENA: The gravity sensor is more appropriate and it was onboard the aircraft looking for sedimentary basins. And in fact, we there were known sedimentary basins around Afghanistan, and what we did was define their extent and their geometries. And there are a couple that look fairly perspective, that the USGS is working on, trying to come up with estimates of potential oil and gas within Afghanistan. And they may have a fair amount of gas and even perhaps a bit of oil.
FLATOW: And what about the minerals, that were sensors for the minerals. Which kinds of sensors would detect the minerals?
Dr. BROZENA: Okay, well, the gravity does contribute something, because if it gives you the real - the regional geologic context, the folding and faulting and things like that that are important for mineralization.
Then the next primary sensor that would be used would be the magnetics, which, from its sound, detects the variation in the magnetic field locally, around space. And that tells you about a lot about the minerals or the materials that are in the area.
It there's different amounts of magnetic field that are associated with different types of materials, and in combination with the gravity and the ground truth, again, it's a good way to do initial searches for either likely areas for minerals or direct detection.
In the case of something like iron ore, it has a huge magnetic signature directly, and so you can actually see the extent of an ore deposit if you get close enough to it.
One of the problems we had was flying at 20,000 to 30,000 feet. We're a long ways away from some of those things, so their signatures are attenuated. But in the case of a very large ferrous metal deposit, it's you still pick up signatures.
FLATOW: Mm-hmm. And what about imaging? Hyper-spectral imaging, I've heard about. Tell us about how that works and what you might find with that.
Dr. BROZENA: Well, hyper-spectral imaging, if you think of a normal camera as dividing the visual spectrum into three colors, red, green and blue, and then mixing them to make the various colors that you see on a photograph, a hyper-spectral imager divides into many more colors, essentially, many more bands.
The one that we were using on the P-3 divided visual range plus a little bit of the infrared into 72 bands. And so you're looking for emissions, or lack of emissions within each of those bands. And those are diagnostic of, again, materials. But the thing here is you're looking only at the surface. It's you can only see what's on the surface with any type of imaging like that, and...
FLATOW: Is this an ongoing project, this Rampant Lion, something that's over? Will it keep continuing and looking...
Dr. BROZENA: It's continuing. Rampant Lion is a developmental project at the Naval Research Laboratory that's not particular to platform or sensors. It's a way to put together multiple sensors on whatever platform's appropriate for a particular problem.
So we've operated in Colombia, in Iraq and Afghanistan. We're hoping to operate in the future with other countries, as well, and we have quite a lot of interest in different places in Africa and...
FLATOW: Are there military applications? For example, if you can see anomalies on the ground, could you see where troops might be hiding in caves and things like that?
Dr. BROZENA: Not with the gravity or magnetic sensors. One of the other instruments we carry is a high-resolution photogrammetric camera, which is just a visual camera, but with very high resolution, and each pixel is georegistered - that is, you have a latitude, a longitude and the height of every pixel. So you can zoom in and look at things with that, and that has quite a lot of applications.
As a matter of fact, we returned to Afghanistan in 2008 for support of some of the war efforts there, although some of that data is also being contributed to the economic and civil infrastructure of Afghanistan.
You have to think this is not just minerals and oil and gas exploitation, but the ability to build roads, dams, bridges and pipelines, and you really need good engineering data for that. And a lot of the data we collect is useful for that.
For instance, we got a lot of interest from people that are working on the airports around Afghanistan, the obstructions. So it's - the equivalent of the FAA in Afghanistan wanted to have avoidance of obstacles around airports, and they're using our photographs for that.
FLATOW: Well, while I have you here - and we have about a couple of minutes left - I can't avoid asking you a question I've asked many times, and I've seen in pictures in National Geographic, maps of the oceans, and you see mountains underneath the water. Is it true that the mountains under the water actually push up the ocean and little bit, and that's how you map what's underneath the surface?
Dr. BROZENA: It's not actually pushing up. It's pulling the water towards it, which makes a bump on top. There's a more intense or more gravity over the top of the extra mass of a sea mount, and that attracts water towards it, and it piles up, and you have a bump there.
FLATOW: And you can detect that how much of a bump, a few centimeters big?
Dr. BROZENA: Anything from a few centimeters to maybe up to a meter. We do a lot of this from a satellite, but we also do it from aircraft, with precise radar and laser altimeters.
FLATOW: So what we think of as the actual flat sea surface is really a myth?
Dr. BROZENA: Oh, well, there's yes, that's absolutely true. Sea surface or sea level has bumps and hollows all over it, and as you back off into space and look with these precise altimeters, you can see those bumps and hollows.
FLATOW: And so if there was a giant as there is a mountain range under the Atlantic, if we could theoretically motor along that in our yacht or something, we would actually see the seawater being higher in that spot?
Dr. BROZENA: No, because you're only looking at a couple of feet of bumps, and it's spread out over many miles. So it's not visible to anybody from the surface. You really have to do precise measurements to see these bumps.
So you're seeing a reflection of whatever's underneath the water. It's related to the bumps and hollows of the topography. You get the same thing on the surface, but it's very subdued so, you know - centimeters and perhaps up to a meter in height.
FLATOW: But your instruments are able to reconstruct that?
Dr. BROZENA: Very much so, and I'm sure you've seen the National Geographic maps that it's useful we work for the Navy, and we can use that to detect sea mounts that haven't been mapped and even estimate their size. There are people working on that.
FLATOW: And how far down can you look?
Dr. BROZENA: It's not really looking far down. You're looking at the surface of the ocean, and that's reflecting what's far down.
FLATOW: So the Marianas Trench would be visible?
Dr. BROZENA: Very much so, and it shows up as a big trench in the water. It's, again, probably a few maybe more than a meter deep, and it's a huge signature because it's such a deep hole, the Marianas Trench.
FLATOW: Wow.
Dr. BROZENA: Yeah.
FLATOW: You know, you can't look at the ocean again, the mythology of above sea level.
(Soundbite of laughter)
Dr. BROZENA: Well, you also have to think of the same bumps and hollows, sea level continues across land. You just don't happen to have a sea there to be reflected. But if you had a network of canals crisscrossing all over the land surface, you'd see there would be bumps and hollows in that, in the same way that there is the ocean.
FLATOW: Fascinating. Thank you for taking time to be with us today, John.
Dr. BROZENA: My pleasure.
FLATOW: John Brozena is the chief scientist at Project Rampant Lion. That's the Geophysical Survey of Afghanistan. He's also head of the Marine Physics Branch at the Naval Research Laboratory in Washington. Have a good holiday weekend.
Dr. BROZENA: Well, thank you very much. Same to you.
FLATOW: You too.
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