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Eyes on Earth Episode 100 – EROS 50th: Our Legacy

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As USGS EROS turns 50 this month, our Eyes on Earth podcast also marks a big moment: Episode 100. To celebrate, we bring together some treasured moments from previous episodes in which people inside and outside of EROS share their thoughts on EROS and its role in the world of remote sensing, including as keeper of all Landsat satellite data.




Public Domain.



It's been said that EROS is an incredible asset to the state that most people don't know about. Why is that?


I guess because we quietly do our work out here on the prairie and keep our nose to the grindstone.


Hello, everyone. Hello, everyone. Hello, everyone. Hello, everyone. 


Hello, everyone, and welcome to another episode of Eyes on Earth. Our podcast focuses on our ever-changing planet and on the people here at EROS and across the globe who use remote sensing to monitor and study the health of Earth. This happens to be the 100th episode of Eyes on Earth. And because we are also celebrating the 50th anniversary of EROS this year, we're doing things differently. This episode presents clips from previous episodes that highlight the incredible work done here at EROS. We started with a clip from the very first episode. That was Dr. Tom Loveland, former chief scientist at EROS, capturing pretty well the work ethic here. As part of that inaugural episode, Dr. Loveland also summarized the mission at EROS and described why it is located here on the prairie in southeastern South Dakota.


Our primary mission is to be the central archive and distribution center for civilian images of the Earth. That was why we were envisioned in the 1960s and why we ultimately had a building put out here and established to start providing the intelligence needed to understand the condition of the Earth's natural resources. In the broadest of senses, when the idea to have a fleet of Earth-observing satellites orbiting the Earth was first proposed, there was a need to have a location in the center of the United States that could track those satellites as they passed across the land surface of the United States. And so that essentially meant a corridor between about Grand Forks, North Dakota, down to Kansas City. Somewhere along that line would put us in a position to see coast to coast. So that's that's why we were in a location that was a potential site. The exact reason why we're here is because of both politics, the influence of Senator Karl Mundt, a close friend of then President Nixon, and as well the very aggressive efforts of the Sioux Falls Development Foundation to identify a parcel of land that met the government's needs and to offer that land and a building to be the home of this new satellite record.


Since EROS is the home of the Landsat archive, we took Eyes on Earth inside the Radome for an episode to see how the antenna works that gets all that data. Mike O'Brien, ground station engineer, describes the antenna once we get inside the Radome. Okay, we're inside the dome now, and it looks like the antenna is already moving. 


Yep, it's prepositioning for a pass. What it is doing is it's setting up to look at the horizon where the spacecraft are coming up over the horizon. And then it'll start to follow it as soon as it can see it and then will lock onto the signal of the spacecraft and follow it from beginning to end. Inside of the reflector itself, the reflector's extremely smooth. It's 10 meters. It weighs about 8,000 pounds. It has 8,000 pounds of counterweights on the backside of the antenna. It makes this antenna extremely well balanced. I can move this antenna around with my hands when I turn off the brakes. There's two structures I want to point out inside of the reflector. There is a large structure that is attached to the reflector itself. That's where all the image data is received. It's a higher frequency. So all the pictures that we get come through that structure. Now at the end of the four bars, there's another smaller structure out here, and that is the S-band feed, or the low rate. And we do command and control here. So we check that spacecraft's temperature, voltages, we tell the spacecraft when we want it to turn on, when we want it to turn off, all that stuff. All that happens through the low rate, which is the structure out of the end of the four legs here.


The influence of EROS internationally is evident in our conversations for this podcast, including how the work we do saves lives. Here's Greg Stensaas, USGS EROS, mentioning those collaborations.


At EROS, we've been working with international partners since the beginning of Landsat. We've had the Landsat ground stations around the world that we continue to partner with today. Those partnerships have turned into a very good relationship and collaboration, but also have led us to engage with many countries like Germany or the DLR, the space agency there; Brazil; ISRO in India, the Indian Space Research Organization. We're collecting data and downlinking it here at EROS. In many, many other collaborations, everybody has recognized that we need to move into an environment to get ready to use these datasets together.


Other international partnerships include the International Charter Space and Major Disasters and the Famine Early Warning Systems Network, also known as FEWS NET. Mike Budde, USGS liaison to the International Charter, described how EROS got involved with the International Charter. And then host Steve Young asks Chris Funk, a research geographer, about how Landsat helps FEWS NET monitor cropland. 


We had a role during the tsunami in Indonesia in 2004. Brenda Jones, a former employee at USGS, was really instrumental in EROS's involvement in the charter and holds a somewhat legendary status among its members. She was very active at the beginning, and she did some organization in support of that tsunami in Indonesia in December of 2004, where Landsat data was used to show the impacts before and after the tsunami event. And it was shortly after that the USGS became a official member of the charter. I think we'll continue to respond to more and more disasters because they're becoming somewhat commonplace and happening more frequently. 


It sounds like FEWS NET relies in part on satellite systems like Landsat. How can something flying 400 miles above the Earth tell you about crop conditions across the planet?


Really just the same way, if you're looking out of your car and - like, driving out here this morning looking out of my car, I noticed that there are a lot of fields that didn't have corn in them, which I guess is because of the rains have been exceptionally wet this year. And satellites like Landsat give us this amazing ability to, you know, literally see like we would with our eyes almost, you know, the land surface of the Earth. And if you're skillful at working with that data and know where and when to look, that's part of the secret, you know, you can almost always tell when there's been a really major disruption in crop ring activity. I really can say confidently that the information that we provide is used by others to send lifesaving aid to people, and some of whom would perhaps have died without our help.


It cannot be overstated how important the open data policy was to researchers, and many of them mentioned that in our conversations. Here's Kristi Kline, previous Landsat archive project manager, and Barb Ryan, former associate director of geography for the USGS, talking about how that policy came about. 


We actually had a photo processing lab here at EROS that would take the data and create that print, and then we would mail those off to whoever the user was. Users had to pay for that service. When I started here, we were still selling Landsat data, and because of Barb Ryan, we actually put all that data out for free. And that started in fiscal year 2008, and that year we went from selling 25,000 products a year at our highest to distributing over a million a year for that first year. Now, of course, we distribute up to 20 million a year.


Even when the government sold the data at $400 or $500 a scene, and I think it was maybe 2001 that it was the peak of data sales, we were selling about 53 scenes a day. Now 53 scenes a day, 365 days a year - I mean, we were taking in, you know, probably 4 and a half or 5 million dollars, which, you know, it's a significant amount of money to any federal agency. But if you did a study, and we did, about who was actually buying those 53 scenes a day, number one, other federal agencies. Number two, universities, largely paid for, you know, by the National Science Foundation. And then number three, contractors that were largely financed by the Defense Department. We were just taking money from one pocket and putting it into another. And so that was the argument. We said, just stop. Now that we can deliver the data over the web, it will save the government money. You could finally start to do national - regional, national or global assessments, whether it was forest cover or land cover change. I mean, you just couldn't do these large area assessments if you had to buy the data at $400 or $500 a scene. Some of these analyses would require, I don't know how many hundreds of thousands of scenes. And so it was maybe a third of the cost of the satellite. So these global analyses did not get done.


Curtis Woodcock from Boston University and longtime member of the Landsat Science Team, explains the value of the open data policy from the researchers' point of view. 


Well, in 2008, we got free access to the data in the Landsat archive and started using the data we needed rather than the data we could afford. That's hugely important. Just to give you an example, at the time we got access to the archive, only about 7 or 8% of the images that had ever been collected had been processed and used. People had to be incredibly selective and only pick the very best images, which mostly meant no clouds. So the taxpayers had spent billions of dollars to collect massive amounts of data that we, users, couldn't afford to get. Now we use virtually all the data, sorting through each image from whatever good observations are available and making use of those. So that's been a sea change. It's really about finding change. And if you're going to compare images through time to find change, there has to be consistency in what's being measured. In essence, the observations affected by clouds and shadows and snow really are like noise. And if you include them in your analysis, all they do is confuse your analysis, which is a polite way of saying they ruin what you're trying to do. And so the better we can screen out these bad observations, or noisy observations, the better it is for everybody downstream as well. And so EROS deserves a lot of credit and the USGS because the quality of the processing of data has gone way up, in addition to making the data freely available.


Part of increasing the quality of the data is something called collections. In separate episodes, Chris Barber, research physical scientist, and Dennis Helder, retired from South Dakota State University and now a part time contractor at EROS, talked about the importance of that and the expertise at EROS. We'll then hear from Barb Ryan one more time.


Twenty-plus years ago, monitoring the land surface with Landsat data was a bit of a challenge because data was expensive and computer storage was expensive. A half a dozen, a dozen, 20 images for your study period was about all you could handle for cost and storage. Some big projects, maybe 100 images, maybe 200 images. And today, data is free. Computer storage is inexpensive. So the idea of, well, let's look at all the images for the United States and look at how land cover is changing across the United States and the land surface is changing. Using all the inputs becomes an idea that could, you know, it's cost effective and it's storage effective, and why not? Before collections, the problem was that there was inconsistent data through that historical record. So if you wanted to do monitoring over time, especially with any kind of automated method, it's really important that you're measuring the same thing and measuring with the same measurements all the time. 


EROS has always had a tremendous expertise on the geometric side of things. In other words, they can put the pixels in the right place, and they were world leaders in that. And so by asking SDSU through my work to do the radiometric side, that brought a balanced approach to the imagery itself. Are the pixels the right value, and are they in the right place? And so we tried to build up that capability at SDSU to complement EROS's ability that way. So that was, I think, the benefit to working together with the university, where we could focus more on the research going on and EROS could focus more on how to operationalize that and get it out into the products and then get the products out the door. It's a great relationship. And more recently, like about four years ago, EROS stood up the EROS Cal/Val Center of Excellence. We call it ECCOE. And now EROS has got a team that has expertise in both areas and can work even more effectively, not only with the university partners, but worldwide, that relationship has continued to keep, in my opinion, the EROS Center as the premiere calibration center on the planet.


The Landsat program is thought of as the gold standard for the world. And while other governments, other agencies, other entities, including those in the private sector, can come in with wonderful assets, the fact that we've got the fabric and the foundation built with the Landsat program is just absolutely essential. You can compare the data from one satellite to the next through the Landsat program, and that is just something that needs to continue into the future so that you can have that gold standard for all other countries and all other organizations to compare like data to what's collected through the Landsat program.


A few more researchers mentioned the importance of the open data policy, as well as the depth of the archive. In this segment, you'll hear from three EROS researchers: Francis Dwomoh, Roger Auch and Heather Tollerud.


We can go back far into history. Landsat has been around since 1972, so we can, you know, track these changes at a scale that is relevant to the people as well as provide historical context to these changes. And when you are working in developing countries, Landsat, which is provided by the USGS free of charge anywhere in the world, is significant because you don't have to bother about, you know, what is the budget for buying data. Now it's freely available - the entire archive, and that has been a very rich resource for doing all of this. Without that, we would not be talking about any of this research.


Even though it's 400 plus miles in space, we can get those readings that the sensor is capturing from the Earth and make something such as land cover maps from that. And then we can take those land cover maps and do analysis of it and see trends of changes, or the leading types of changes, or the rates of change and things like that. That's one reason why it's important to keep satellites like Landsat going, because then we can increase the temporal span and change processes that may take longer than 30 years. We can start seeing, whereas we just have 10 years of observations, we may not see or understand those kind of change processes.


Making use of all the data that's available that we can bring together into a good format is really powerful. It can see patterns that you wouldn't be able to see if you were just trying to pick one time of the year, and what's happening then, because you can see how it changes through the seasons and between the years and across space. So the sort of large dataset, dense time series approach is really powerful. 


Nothing added to the depth of the Landsat archive quite like the Landsat Global Archive Consolidation, or L-G-A-C, also referred to as "el-gac." LGAC exemplifies our concern for gathering all the data possible into one place to ensure its quality. Here's Todd Taylor, Contract Task Lead for Sustaining Land Imaging Partnership Support, describing the project.


For one thing, it's added 6.6 million images to the archive. And it's growing. Many of these are unique scenes, scenes that did not exist in the USGS archive but existed in the international Cooperators archive. What this does is it gets those unique scenes available to the public who can use them. A lot of these areas that have collected images are over rainforests, which clouds are an issue there. So every pixel, every bit of data that we get that's cloud free is valuable somewhere. Someone will be able to use that for research projects going forward. 


It was also nice throughout our first 100 episodes to continually hear good things about positive working relationships with the people at EROS. Here's Volker Radeloff, University of Wisconsin in Madison; Mary O'Neill, formerly at SDSU; Steve Covington, former Landsat 5 flight manager; and Zhe Zhu, University of Connecticut and former EROS employee. 


And were you aware that we had this Corona imagery available here at EROS, or how did you become aware of that? 


Well, I knew we can order it through the National Archives. And then when we started ordering more, I learned that the actual imagery is at EROS and all the scanning is done here and so. And then at some of the meetings I go to where we talk about land cover, land use change, and some of the contractors were there and they recognized my name and said, "Oh, you are one of our bigger users." So we started chatting, so. This morning I had a chance actually to see the scanning operation and go down in the archives. It's very impressive to see. 


I was going to ask you what you thought of that. You saw not only the scanning but the film archive, so. 


It's immense. Yes. And it is so neatly organized and everything. And clearly the film's in good hands here.


We would take students here quite often for tours, for presentations, meetings. And one of the big things we did was to take advantage of your advanced image processing capabilities. You had better capabilities than we had at SDSU, so we often took folks down here to work in your Data Analysis Lab, or DAL as we called it. And that was especially true for a lot of visiting scientists we had from around the world. Another big interaction between our two institutions was the Geographic Information Science Center of Excellence, which was established in 2004, at SDSU, but it really was a joint program between SDSU and EROS. And that center had two co-directors, one from SDSU and one from EROS. That program is now part of the Geography and Geospatial Sciences Department at SDSU. Many SDSU graduates have worked here in the past and are still working here as EROS employees. You've hosted many summer internships for students and summer sabbaticals, including one I did back in 1993, which was a lot of fun. And on the flip side, a lot of EROS employees also serve as adjunct faculty for SDSU. So it's a synergistic relationship.


The biggest contribution of working at EROS earlier was it got me the job later, to work on Landsat 7, so that was all good. But it also meant that I had a very good working relationship with the staff at EROS. And as you may know, EROS is the project office for Landsat. So all the Landsat mission development, production, archiving, distribution, all happens through management at EROS and a lot of the work done in EROS. And so even though the missions are actually flown out of NASA Goddard Space Flight Center with a USGS crew, because it's 1500 miles away, it was really important, I think, especially in those early years, to have that relationship with RJ Thompson and Tracy Zeiler and Kristi Kline and Jim Lacasse, Brian Sauer and others to handle a level of trust necessary for USGS to feel confident to fly these missions at all, let alone 1,500 miles away. So EROS has been, and USGS in general have been so supportive of the Landsat program and what it's done. Of course, they started archiving data back in the  early missions in the early '70s. And so having the opportunity to work with them from a distance, from Goddard to EROS, was very important. And the crew there really jumped on the bandwagon in support for flight operations, but secondly, are second to none in the world, really, world-renowned for their work as a ground station and archivist of Earth observation data. So it's been great working with them all along. 


There are a lot of connections at EROS, and a lot of people, when I talk about I may cry sometimes. Like Tom Loveland, he's the person who got me into EROS, and I worked with him. Such a nice person - he's like the academic father to me, always caring about my research and also gave me the great vision for my research. And there are a lot of people I'd like to mention like Jess Brown, Heather, Qiang Zhou, Suming Jin, George Xian - there's so, so many people there. And if I want to name all the people, give out the name, I might not even finish within like 15 minutes. But all those people, I still keep very close connections, and we are still working closely on papers, projects, LCMAP, and NLCD on the urban detection, deep learning, machine learning method. I think EROS is a big Earth observation research hub, and lots of exciting research is going on here at EROS, and I just feel like I'm so fortunate to have worked at EROS for two years and know all those great people there.


Before we finish this compilation episode, we'd like to emphasize that we are open to the public again for tours. Here's the outreach coordinator, Ann Tripp. What can people expect to see and learn about when they come out here to EROS to take a tour?


Well, the first thing that you're going to see is we have got an amazing display and model of the Landsat satellite. You're going to learn a lot of history about the Landsat program and what is going on with it today. You're going to hear about what we do with the imagery that's collected from the satellites and how it's used to benefit mankind and preserve our natural resources. You're going to get to see a lot of satellite imagery along with just learning a little bit more about the amazing work that happens here.


You know, about the time that we got all used to seeing aerial imagery and astronaut imagery of the Earth and so on, it started to become a little ho-hum. But then we get an instrument up there that can see in other parts of the spectrum that our eyes can't. Oh, no, there's still a world of mystery for you, and amazement. And that's kind of cool. Landsat allows us to see things that we couldn't see ourselves. 


Thank you, listeners, for joining us on this 100th episode of Eyes on Earth. Check out our EROS Facebook and Twitter pages to watch for more episodes. And you can subscribe to us on Apple Podcasts.


This podcast, this podcast, this podcast, this podcast, this podcast is a product of the U.S. Geological Survey, Department of Interior.

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