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Taking the Long View From Space

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Get caught up on the latest in land remote sensing, the future of Landsat, and more with Barbara Ryan, USGS Associate Director for Geography.




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Jon Campbell

Hello, and welcome to another edition of CoreCast. I'm Jon Campbell. Today, we are pleased to have with us Barbara J. Ryan, the USGS Associate Director for Geography. Barb will help us get up-to-date on developments at the Survey in the field of land remote sensing, an activity that involves observing the earth from outer space.

Barb, I'm going to start with a pretty basic observation myself. I imagine that it will come as a bit of a surprise to many of our listeners, not all of whom are space experts - at least we hope not, because that would limit our fan base - the surprise is that the USGS has any role in space. Most people associate the USGS with maps and seismographs, expertise about earthquakes and water resources, and if they've been listening to CoreCast or other recent science news, USGS research about polar bears. Now before we even begin to talk about space, let's get down to this term "land remote sensing." What exactly is "land remote sensing" and does it have to happen from space?

Barbara Ryan:

Thanks, Jon, and let me say that it's a real pleasure to be here and do this CoreCast. I'm actually quite excited about it. If we talk about remote sensing in its simplest terms, I think it just refers to observing anything from afar. Certainly, earth observation from space gives us a synoptic or an "all at one time" view. Comparisons of earth observations over time provide a context for something the Director is very interested in, that's identifying global change. Essentially what we in the Geological Survey want to do, and historically have done, is assess the Nation's natural resources. Today we're adding a remote sensing component. So it's an observation from afar. Clearly, land remote sensing implies "from space." But I think one could argue that our historical reliance on aerial photographs also pertains generically to remote sensing.


So, to make sure that we cover the full range of land remote sensing, let's imagine that I went up in a hot air balloon, say, at the Albuquerque Balloon Festival, and I take along a pocket camera and take pictures of the ground. Is that also remote sensing?


Yes, absolutely, the concept is really that simple.


How has the USGS come to operate land observing satellites in outer space?


I tell you, for me, this is really just a phenomenal view into our past. It was actually one of our previous directors, Bill [William T.] Pecora - he ultimately became Deputy Secretary at the Department of the Interior, under Stewart Udall - who really convinced the Secretary and the Department that the time was now right to start looking at the Nation's, the world's land masses.


This was back in the sixties?


1966. Stewart Udall issued a press release with that very quote: "The time is now right" for us to use space-based technology to help us with natural resource problems that are compounded by urban growth and changes to the landscape. Now, that might not be a word-for-word quote, but the point is, those issues are every bit as relevant today - 40 years later, 41 years later - as they were back in 1966. It was that vision that started the wonderful legacy that we have with the Landsat satellites.

I think Landsat has been successful in spite of, not because of, the policy environment that has been associated with that program. Interior conceived the mission; NASA built and launched it. In a few years it went to NOAA, then it went to the Air Force, then it went to the private sector, and in 1999, it came back - I would say, it came back home - to the Geological Survey to operate both Landsats 5 and 7. We have always had a role in the ground processing segment all the way back to Landsat 1. The tremendous archive that we have at the EROS Center facility in Sioux Falls, South Dakota, has been our historic legacy to that program.


So we've learned that the survey has a long history in land remote sensing. But, once the agency goes to all this trouble to understand land conditions and land change, what does that tell us about the state of the land and global environmental issues? In other words, what's the benefit of this increased science understanding for the general public, that mythical average Joe or Jill?


For the Geological Survey, we are one of the few agencies that have coast-to-coast, border-to-border responsibilities for providing information to help resource managers look at the natural resources. Whether it's our work in Geography based on Landsat imagery that ultimately produces land cover and land characterization maps of the earth; or whether it's Water's monitoring streams, water quality, nationwide; or whether it's Biology's terrestrial and aquatic monitoring; or Geology's surficial monitoring - there is no other agency that has coast-to-coast, border-to-border responsibilities for monitoring the Nation's natural resources. No state is interested in a national mandate; they are confined by their borders. No university actually owns this monitoring. Individual professors come and go and exert tremendous leadership, but the U.S. Geological Survey really has the niche for monitoring the Nation's land resources.

If we look at our land cover efforts in Geography - in fact, something you coined, Jon, a map that we produced entitled "Geographic Face of the Nation" - it was our 1990's dataset that showed 21 or 22 different land cover categories. Combining that 1990, 91, 92 dataset with the 2001 dataset and with the 2010 dataset, we'll have roughly a decadal look at how the Nation's landscape is changing. And in fact, we've coined this as a "Census of the Nation's Land Resources." You can see, from these land cover categories, how our agricultural lands are changing through time; how forests lands are changing through time; how urban areas are, in most instances, growing out into the countryside. You can actually come up with very dedicated metrics and measurements that can quantify the degree of landscape change.

Just real quickly, about why it's so important to the Geological Survey and linkages to the other disciplines. As we start to see urban growth and look at measures of imperviousness [impenetrable, constructed surfaces], a surrogate measure for urban growth, then the implications that that would have on water quality are immense for these areas and the Nation's streams. So it is a wonderful information asset that underpins much of the other science that's done, not only in Geography, but across the whole Geological Survey.


We've talked about the Survey's role in gathering land information. Do other people across the globe have access to this information? Is it useful to them as well?


Particularly Landsat. Let's talk about that middle resolution. We say "middle resolution" because it's about 30-meters. Each pixel is about 30 meters in size. It's not high resolution like our commercial satellites provide, and it's not low resolution like the weather satellites provide that are on the scale of 250 meters to a kilometer in resolution. For this middle resolution imagery, we've got data for every piece of land in the world and, in fact, even some imagery off the coasts.

So every inch of the globe, except right at the Poles, is covered with Landsat data and it feeds into global land cover data. Although we don't have national land cover data statistics globally yet at 30-meter scale, the world is clamoring for that. As resources become more available not only here in the United States, but in other countries, I think you will start to see 30-meter land cover data for the whole globe, largely built off Landsat data.


Would this global interest in Landsat be the reason why you went to India recently?


It is. A recent conference in Hyderabad, India, was the IAF, the International Astronautical Federation, which has just accepted the U.S. Geological Survey into its membership. We were being voted in at that particular conference, the World Congress of the IAF in India, and we were there to talk about a couple different things. One, our role in some international committees including CEOS, the Committee on Earth Observation Satellites. We're chairing that effort this year.

But we were also there to announce a report [A Plan for a U.S. National Land Imaging Program] that the President's Science Advisor John Marburger has just released, which essentially brings the entire Landsat program back home to the Geological Survey. It argues for, not only having the historic responsibilities for the ground processing systems and the archive that we've talked about already, but it says, you know, we really need more consistent leadership for this program to design future satellites and have the responsibility for building and launching those future satellites. So it's a rather substantial recommendation that comes back to the Geological Survey and the Department of the Interior.


Is the USGS involved in any other international organizations that promote remote sensing?


Yes. In addition to the CEOS. The Geological Survey chaired that [CEOS] this year. Our CEOS plenary meeting is in a few weeks in Hawaii. The chairmanship will be turned over to South Africa and the space agency there for a one-year tenure or a one-year chairmanship. What's coincidental about the [CEOS] chairmanship is that it coincides with another very, very important meeting that will be held later in November in Cape Town, South Africa, called GEO, the Group on Earth Observations. It's an organization of 70 plus countries and, I don't know how many, 46 or so, participating organizations from around the world. All the UN organizations are represented. These 70 participating countries come together and say: how can the world community do a better job of integrating space-based observations and in-situ, ground-based or ocean-based, observations so that we can address nine societal benefit areas for the globe. Those societal benefits are, as one might expect, global change, agriculture, disasters, energy, ecosystems, and biodiversity - key issues that [government] ministers of the world are interested in.


Now, my last question is probably aimed at people have heard about Landsat before. Folks that are familiar with, or cognizant, let's say, of the world of remote sensing may have heard some pessimistic notes about Landsat 5 and Landsat 7, that both of these satellites have had some technical difficulties. All of these experts know that Landsat 5 is pretty old as far as remote sensing satellites go. So I was wondering if you could give us your take on the future of space activities for USGS.


Sure, and I'm really glad you asked that question, Jon, because I actually think the future is quite bright. You know, we talked about the President's Science Advisor John Marburger's report that was done on behalf of the Office of Science and Technology Policy. That really says that the country needs a dedicated commitment to terrestrial observations, much like NOAA has exerted for oceanic and atmospheric observation. So I think that the future is quite bright.

I don't want to downplay, though, the challenges that you alluded to with Landsats 5 and 7. Landsat 5 was launched in 1984, so it's 23 years old. In March, we will be going on its 24th year. That is an engineering feat, in and of itself. I don't believe there's another civil satellite that has been on orbit and successfully collected data for the length of time that that satellite's been in orbit. If our dear friend Jay Feuquay were here, he's deceased now, but he would say that satellite is old enough to drink. (laughter) We joke a lot about that.

Landsat 7 also has had its share of problems, though I guess I would have to say, it certainly has surpassed its design life for most satellites of three to five years. Landsat 7 was launched in 1999, so we are going on seven or eight years for that satellite. It has something called a scanline corrector problem or venetian-blind effect so it's got some pieces of each image, particularly out near the perimeters of the scene, that are missing. For all the data that's there, it's radiometrically, geometrically pure. But, out near the edges of the scene, there are actually data missing from this anomaly. So we are keeping our fingers crossed that Landsat 5 and Landsat 7 will stay on orbit until we can get Landsat 8, or sometimes called the Landsat Data Continuity Mission, launched at the end of 2010 or 2011.

In the event neither of these two satellites Landsat 5 or Landsat 7 stay on orbit, we are also working with - through CEOS, this Committee on Earth Observation Satellites that I spoke about - we're working with other space agencies around the world, where we might be able to use some of their assets to come in and fill in holes that would exist in our dataset if we do go into a data gap.


That's something of a contingency plan?


Yes. Now I'll tell you the bottom line: there is no other asset that could come in and totally replace Landsat. There are other satellites around the world that collect similar kinds of data, but they tend to be more localized in their data collection and there are few satellites that actually have global daily collection algorithms like Landsat does. We are keeping our fingers crossed that we don't go into a data gap situation, but we do have a contingency plan if we do.


Okay, that sounds good. Barb, we are at the end of our time, and I'm glad to say we could end on a positive note. Thanks very much for your help in helping us understand more about USGS and its role in land remote sensing from outer space. This is Jon Campbell for the USGS CoreCast, podcasting from high atop the USGS National Center Tower in Reston, Virginia. CoreCast is a product of the U.S. Geological Survey, Department of the Interior. Any replay, rebroadcast, or other reuse of this program is strongly encouraged.

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