Earth Science Director Dr. Karen St. Germain presents to the 12th Session of the UN-Global Geospatial Information Management Committee of Experts

Narration: Karen St. Germain

Transcript:

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I'm really thrilled to be coming to you virtually today. I wish I could be there in person, but I'm happy to to have a few minutes to talk you through the importance of geodesy and what it really means to NASA's Earth science. So I'm going to share my screen with you today and just just walk through our interest in geodesy and global observatories.

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So first, let me take a moment to tell you about NASA's Earth Science. Nasser Earth Sciences is a pretty unique program in the world. Is end to end from investing in new technologies that can tell us about the Earth system to flying those those new technologies and satellite systems, to funding a research and analysis program that robustly explores the information content in that we get from those flight missions.

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And of course, that rests on top of a world class data and computation capability. And then in some ways, most importantly, taking all of that data, that understanding and the models that that that that allows us to develop and putting that into service for the betterment of mankind. We have an applied sciences program that tries to tailor the earth science information we get from our missions and from our science to the needs of people who have to make decisions at all levels of government, private sector, and even individual citizens.

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So most people think of me think of Mars or or even the Webb telescope when they think of NASA. But they might not know is that the planet we study the most is our own home planet Earth. And of course, the reason for that is obvious. This is the planet that holds everyone we know and everyone we love.

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So we study this planet. We study our home planet Earth to understand how its systems work, the atmosphere to the oceans, the land and even the cryosphere to really understand how that earth system is changing and help our citizens understand how they might plan for the future. So you're looking at our Earth science fleet today. We have about 25 different missions flying.

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Some of them are satellites that are as big as a coach bus and others are CubeSats that are the size of a shoebox or even we have instruments on the International Space Station all looking down at Earth. On this chart, this the missions that are coded in blue or green are missions that are on orbit. And those that are orange or gold are missions that we have in various stages of development for future capable 80.

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Now, just talk for a minute about our NASA's Space Geodesy network. We have we have capabilities on orbit and on the ground around the world to contribute to the International Geodesy effort. We we have a number of different techniques for making geodetic measurements. And you see those listed over on the right. And two of the major outcomes of these observations are the international terrestrial reference frame and also precision orbit determination.

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And I'll talk more about those in just a couple of minutes. But we're undergoing an effort right now to reinvest in our geodetic network to make sure that we have these key observations for generations to come. And, of course, our nascent observing system is part of a larger global geodetic observing system. So, you know, geodesy is inherently a global science because it's about the the position in the motion of Earth.

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And so we so it relies on strong international participation and partnerships. And we're really proud to be part of that international community. All right. So I'm going to I'm going to peel back layers of the onion for you here in the next 20 minutes or so. Are NASA's science missions or are driven by priorities that are established by our National Academies of Science?

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The way this works is every year, sorry, every decade, the National Academy undertakes at our request what we call a Decadal Survey. And what's Decadal Survey does is it identifies the most pressing, open science questions about our home planet. It gives us guidance for what missions we should go and build and what our science focus should be. And in the last decade, you also emphasized the critical nature of partnerships, both national and international and innovation, for meeting the demand for future information about our Earth system.

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In this most recent decadal, the Academy identified key questions and the observations that would be needed to answer those questions in the in the areas of climate variability and change, whether in air quality water cycle ecosystems and natural resource management, as well as solid earth dynamics and hazards. So we'll walk you through in the coming slides is how geodesy supports much more than just the solid earth dynamics and hazards, but actually has an impact on every one of these key, key question and observation areas.

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So shortly after the Academy Road to the the Carter Report for Earth Science, they released a report on the Geodetic Infrastructure that would be needed to enable that earth science. And I really love this pyramid. That's a that I took from this this national Academies report, because it really helps you understand how this geodetic infrastructure enables everything we do.

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So let's start at the bottom of the pyramid. The infrastructure itself, in the various geodetic techniques, as well as the software used to process the data and archive and the expertize. Those are really fundamental. Those are foundational. Those key underpinning observations. But from those observations, we go up to to the next level, the terrestrial reference ring. And this is really important because we're trying to establish a reference frame in a world where everything was moving, the surface is moving relative to the the the center of mass of the earth and not in a uniform way.

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The center of mass itself is moving. And, of course, the entire earth is moving. So to establish a reliable terrestrial reference frame is no easy feat. But. But the key measurements from the geodetic infrastructure. The the underpin this coordinate system and and orient us for all of the measurements that we make on top of another. Another level above that are the primary geodetic products.

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So once you have this reference frame to which everything else can be referenced, then you can start developing products like precise, precise positions and orbit determinations. You can you can establish key attributes of the Earth itself, the rotation in the in the gravity field and so forth. So the there's a set of primary geodetic products that are built up from the observations and the reference frame.

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And it's only once we have those capabilities that we can start talking about earth science missions that make measurements against that reference frame and enabled by those primary geodetic products like precise orbit determination, the kinds of earth science missions that are really dependent on this capability are those that measure changes in the Earth's gravitational field itself, or make positional or movement measurements such as altimetry, which is a time of flight measurement from the satellite to the surface of the earth and back radio, Occultation and Genesis reflections and so forth.

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So these the the geodetic infrastructure enables us to now envision these Earth orbiting missions. These missions then give us the ability to make geophysical observations, to measure deformation in land or in ice, to measure sea surface height, to measure land and vegetation, topography and changes in the distribution of mass on earth. Those geos, physical observables, are the fundamental things we need to know to enable the science itself, which is at, for me, at the top of the pyramid.

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So once we can make all those geophysical observations, we can. Then it's only then that we can finally start answering key science questions about what is driving sea level change and and how will the rate of sea level change likely evolve over time? What's happening with the water cycle? How is the water cycle change or how it changes in the water cycle manifesting themselves in changes in the carbon cycle and so forth?

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So those so you can see when you start from the bottom up how the geodetic infrastructure enables us to fundamentally answer some of the most pressing questions of our day. And I say that these are the most pressing questions in many of you in the room, probably know why these are the most pressing questions. But I'll just give you one data point.

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You know, every year the the World Economic Forum issues its Global Risks report and environmental questions, environmental issues and concerns have in recent years dominated the top of the list of risks to global well-being that risk widely recognized around the globe, is driving an unprecedented demand for the kinds of information that we can provide from our Earth orbiting missions and the science they enable.

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So when I look at the geodetic infrastructure and everything it enables, I feel a real sense of urgency that is ultimately tied to the demand for the kinds of insights we get from Earth observation. Now, let's look ahead, because, you know, we we've had a geodetic infrastructure for quite some time. And and now we're pushing to improve that geodetic infrastructure.

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And this chart, again, from our National Academy of Science links those fundamental earth science observables to the positional accuracy that we need from our geodetic infrastructure. And you can see that in several key areas, including sea level rise or sea surface height and including crustal strain, that that can help us foresee geological hazards in those areas. In particular, we have a demand for ever in improving positional accuracy down in the one millimeter to three millimeter range.

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Now the International Terrestrial Reference frame, I've talked about this and this is just to to give you a sense of what this looks like. The reference frame is a is an accurate, stable set of positions and velocities that can then serve as reference points around, you know, on the surface of the earth around the world. And of course, the points are represented on the on the map on the left.

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And the velocity fields are represented on the map on the right. And you can see that there is particularly in in certain locations around the world, significant horizontal velocity. And that is fundamentally why we have to be so vigilant about the the observations, the geodetic observations that underpin our ability to to to establish this reference frame. And now I'm going to show you a little a little animation here.

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So, of course, we're looking at our Earth system. This is the fleet of satellites that are either contributing to or benefiting from the the global geodetic reference frame and making some of those key observations. This these vectors are showing you the station position and velocity. Of course, these are not to scale, but they're showing you the different kinds of motion that are happening on the surface of the earth today.

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And now, if we dove inside the Earth's core and go all the way to the center of mass of the earth, you'll see an animation here of how the center of mass of the earth has moved over the last three decades. And, of course, you know, this is measured in in millimeters. And you can see that this motion ranges over tens of millimeters.

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And, of course, as you might imagine, our satellites are orbiting this center of mass of the earth, and they're making positional measurements of, for example, sea surface height. And so you can understand how an error in our understanding of how the center of mass of the earth is, is, is behaving would translate directly into an error in our measurement for C of C sea level.

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So really understanding not just how the surface of the earth is moving, but also how the center of mass is moving again is fundamental to the accuracy of the measurements we are trying to make key missions that rely on space geodesy and I am sharing these with you. Some of these are our existing missions that measure, again, mass change or weather, ocean topography, and some of them are missions that we are building for the future, like Nizar and SWOT, which will which will launch later this year.

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Incidentally, the swap mission will give us the first in an incredibly precise inventory of inland freshwater around the globe. So we're really excited for for these new missions that are coming up. And now I'll just dove in and show you a couple of examples of the kinds of science that we've been able to do. Again, because we have this this critical infrastructure.

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The first highlight is global sea level rise. And you can see here that sea level has been rising at a rate of about three and a half millimeters per year. But you can also see that it is accelerating. And we only know this because we have a 25 year track record of making these very precise measurements from space and the different colors, the different segments on this sea level curve represent different satellite systems.

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We would not be able to stitch this record together from satellite to satellite without an incredibly stable reference rate. You may be wondering what the Wiggles are in this curve, and those are just the annual cycles that reflect among other things, the amount of freshwater that gets trapped in the form of ice and snow on land in winter.

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So sea level actually fluctuates with the with the seasons tracking the North Atlantic winter season.

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It's another ambition, the grace the grace follow on the gravity, recovery and climate experiment that allows us to understand why sea level is rising. And and this is a particular example here. The the Grace Mission, which measures movement in mass. And so you're seeing an animation here of ice that is leaving Greenland and Antarctica. That, of course, is freshwater.

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That's getting added directly into our oceans. And Greenland and Antarctica alone, our response will be responsible for about a third of the total sea level rise we've seen over the last several decades. And again, it's this ten year record that that allows us to really understand what's going on here and why. And, of course, understanding is critical to predicting for the future.

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Now, just to be very specific about how important SLR in particular, that's the satellite laser ranging technique is to the grace follow on mission. If we didn't have this particular correction to the gravity to our measurements of the changing gravity field, we would underestimate Antarctic ice loss by about 45% just in the last several years. So this has been a critical correction for us.

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And and we really so we really rely on the these the ongoing infrastructure and reference frame to make these key corrections so that we get the get the estimates correct. Right. Let's see. I can't I this it's there we go. And there's one new this is just an emerging application that, again, would not be possible without without the reference frame and precision orbit determination, which is, you know, we with with every major event, we learn a lot and we and the, the tsunami is as a result of, uh, of volcanic activity.

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The volcanic eruption is no different. So we learned a lot about how we can see real time impact on G and assess signals, generate heated by shock waves and tsunamis. So we're prototyping a new capability to see if we can if we can provide an early warning for these kinds of events in the future. So, again, you know, there's there's all the the applications that we know about, but new and emerging applications all the time.

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So now going to look to the future of Earth science. So I've been talking with you about capabilities that we have today in systems that we are just about to launch that are enabled by the geodetic infrastructure, but I mentioned that we have this we just completed we completed in 2018, this Decadal Survey. So we are just now starting to build those next generation systems.

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And this is a this is a a slide that describes the what we call the Earth System Observatory. This is a holistic election of missions that will view the Earth as a whole system from the atmosphere, clouds, precipitation and aerosols to what's happening on the surface with surface biology and geology and surface deformation. And then how mass is changing on a large scale?

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That's not only the glaciers and land ice that I mentioned earlier, but also water depletion in underground aquifers, for example. So this is a system that we're just starting the investments in for the future. And and these systems will make measurements that are more accurate than we've ever had before. And again, is a compelling reason why we are simultaneously continuing our investment in Geodetic Observations and just to bring this all the way home, tying it back to the the UN game Integrated Geospatial Information Framework.

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I think there's now at this point broad recognition that earth observation, climate science and sustainability are all intimately dependent on the kind of geospatial information framework and the kind of of of geodetic infrastructure that we that we are currently investing in and that we think is so fundamental to our future. So with that, thank you for giving me the opportunity to speak with you today, and I hope you have a great conference and and will look forward to continuing to provide the world class science that that NASA's Earth Sciences provide has been providing for decades and meet the demand for actionable information well into the future.

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Thank you very much.