 YouTube as well. So now we'll click go live and join the folks there too. All right, we are at the top of the hour. So let's go ahead and get started. So hello everyone, and welcome to the June NASA Night Sky Network member webinar. We're hosting tonight's webinar as usual from the Astronomical Society of the Pacific in San Francisco, California. We're very excited to welcome our guest speaker, Dr. Elliot Quadert from Princeton University. Welcome to everyone joining us on YouTube. We're very happy to have you with us. These webinars are monthly events for members of the NASA Night Sky Network. For more information about the NASA Night Sky Network and the Astronomical Society of the Pacific, check the links in the chat, which I'll put in in just a couple moments. But before I introduce Elliot, here's Dave with just a couple of announcements. Awesome. Hi, everyone. Happy solstice, first of all. Happy summer for those of you, I assume, most of you, or if you're in the hemisphere or a happy winter, or happy, I suppose, for the southern hemisphere. Welcome. And for those of you along the equatorial regions, congratulations on another beautiful day. Let's see here. I've just got a couple brief things to tell you about. Just if you liked our last summer social hangout, we have another one coming up Wednesday, July 13th, 2022, which will be planning for International Observe the Moon Night, which is going to be held on October 1st this year. We just want to know what your plans are for International Observe the Moon Night, and what are you doing something special in your communities, your general plans, and what are your favorite moon observing activities? We're discussing all things sooner on July 13th, and we'll be joined by Kayla Berry from NASA's International Observe the Moon Night planning team. And we may have a few other special guests, so we'll have more about that in our next newsletter. So watch out for that. I'll put the link to that in our Zoom chat. That's really the big thing. Oh, of course, I am obligated to remind you to post and report on your events to the Night Sky Network calendar as we are near the close of quarter two for reporting. And we'll be having some prizes and toolkit shipping out by the middle of next month after those have been turned in. And of course, one last thing is I just really hope that you have clear skies and a clear view of the east and the southeast for tomorrow morning or for the next few days or week or two, or, you know, as we can see this beautiful show of five planets and a crescent moon, which that's this week. So, yeah, let us hope for some great views, everyone. And with that, Brian, back to you. All right. Thanks, Dave. For those of you on Zoom, you can find the chat window and the Q&A window at the bottom edge of the Zoom window on your desktop. Just kind of hover your cursor down there and they should pop up. Please feel free to greet each other in the chat, making sure that you select everyone in the little button and so that it doesn't just go to the host and the panelists. If you have any technical difficulties, you could also let us know in the chat. Please put all your questions in the Q&A window. Don't be shy about putting those in early. There's a lot of content here and so we might actually get to some of your questions during the program. So if you've got something that you really want to hear about while Elliot's talking, go ahead and pop it in the Q&A and we'll see if we can get it answered while we're on that particular topic. You could also send us an email for any challenges at night sky info at astrosociety.org. So I'm going to hit the record again here. So again, welcome to the June webinar of the NASA Night Sky Network. This month, we welcome Dr. Elliot Quatter to our webinar. Elliot is a professor of astrophysical sciences in the Charles, a young professor of astronomy at Princeton University. He's an astrophysics theorist who works on a wide range of problems, including stars and black holes, plasma astrophysics and how galaxies form. He's received a number of national awards for his research and he's an elected member of the American Academy of Arts and Sciences and the National Academy of Sciences. So please welcome Dr. Elliot Quatter. Thank you. It's great to be here. It's really neat to see on the chat where everybody is joining from. So what I was asked to do today and I'm excited to tell you a little bit about is to give you an overview of the astronomy decadal survey that was performed in 2020, roughly. So my goals really are to explain to you why we do this kind of survey, what its goals are, what the process is and what some of the recommendations were that came out of this particular exercise. I was one of about 20 people that were on what's called the Steering Committee. The name of that is meant to convey that we sort of steer the process of the entire decadal survey which in total involved hundreds of people and as you'll see large swaths actually of the entire professional astronomical community in the U.S. So do feel free if you have questions as we go. Feel free to ask so that they get answered along the way. So in short, a decadal survey is a prioritization exercise for how the United States government spends its money in science and astronomy in particular for what we're talking about today. And the history of this actually goes back to 1964. Astronomy was the first field to do this prioritization exercise and since then it's been widely adopted by many different scientific communities from planetary science to other areas of physics to areas of biology, etc. And the basic motivation for it is the idea that by coming together as a community, the science community can sort of speak with one voice about what it thinks the most important science questions and the most important facilities, telescopes largely is what we're talking about today, what the most important telescopes to develop are that can actually address those science questions. And by having it be a prioritization process where the community comes together and does this in a systematic way, it really allows the community to speak to the federal government with one voice and say these are what we think are the most pressing science questions. These are the telescopes that we think should be built to address those science questions. And that really amplifies the impact of those recommendations because it's this sort of coherent speaking with one voice that the community is able to do. So many, if not most of the large telescopes that you know and love, the Hubble Space Telescope, the Very Large Array, the Chandra X-ray Observatory, the James Webb Space Telescope, the soon to be launched Roman Space Telescope, the currently being built Verreroobin Observatory, these are all telescopes that were recommended as part of previous decadal surveys. So I'm listing here the year in which some of these were done. So it's roughly every 10 years that it's done and then what the particular recommendation was. It started out because it was in the early 1960s. There actually wasn't a huge amount of space astronomy. There was some, but it was mostly a ground-based effort. So the original one was actually just focused on ground-based astronomy, but as time has gone on, of course, the importance of space astronomy has grown. And so the current efforts encompass both observations from the ground and observations from space. And so this is again some of the history where you can see the impact that these efforts have had leading to many of the most important and scientifically productive telescopes in operation still today. The Very Large Array, Hubble, Chandra are all still in operation. So who does it? The decadal surveys are sort of commissioned by the parts of the federal government that support scientific research. So that's NASA for space-based efforts and the National Science Foundation and the Department of Energy for ground-based. But they don't themselves, NASA and the NSF and the DOE, don't themselves sort of carry out the prioritization exercise. Rather, they look to the National Academy of Sciences to carry out that task. So for those of you who don't know, the National Academy of Sciences was started actually by Abraham Lincoln when he was president. He signed the charter that established the National Academy of Sciences and it was established with the explicit goal of providing independent advice to the federal government on matters of science and later engineering, medicine, and related discipline. So it's an independent entity separate from the National Science Foundation or NASA, which provides sort of independent and peer-reviewed advice to the federal government. It does this in many, many, many different areas and the decadal surveys, these prioritization exercises are one example of the functioning of this advice that the National Academy of Sciences provides to the federal government. And this is a peer-reviewed study. So we, as it said on the first slide here, we ended up writing a report that was over 600 pages long. That report was peer-reviewed. It actually was by far the most intense peer-review process that I've ever been a part of. I've written hundreds of journal articles that have all been peer-reviewed, but this peer-review process was much more rigorous. You were required to respond in detail to every single comment, criticism, a request for a change, etc. that a huge number, something like 20 different people provided reviews of the report. So there was like a three-month period where all we were doing was reading the criticism and, you know, some compliments, but of course mostly focusing on the criticism and suggestions for changes and revising the document in response. Okay. So one reason for stressing this that it's NASA and the National Science Foundation and the Department of Energy that are the, so you can think of them as the constituents, right? They are the primary users of this advice. And so one thing that's important to recognize is that you'll notice I have not put up here universities or the American Astronomical Society. So the Decadal Survey process really is one that's focused on providing advice to NASA, NSF, DOE about how to spend money, how to optimally spend the federal government's, you know, scientific dollars to get basically the most science for a certain amount of money. And what that means is that certain topics that are extremely important for the functioning of universities such as how we educate undergraduate students and graduate students, those are addressed a little bit in the Decadal Survey, but not very much because that's not really the primary goal of this prioritization exercise. It's not about how to optimally teach undergraduate students astronomy. It's about how to prioritize the use of the federal government's money. So that's just important in terms of thinking about the topics that I'll tell you that we addressed. There'll be some that you may think are missing. And in many cases, the reason that they're missing is because it's really not part of the purview of this particular prioritization exercise. So indeed, a very important part of this process is that there's a complicated negotiation between the federal agencies and the National Academy of Sciences on what is the scope of this prioritization exercise? What are we supposed to address? And what are we not supposed to address? And this is all public. You can go read what's called the statement of task that sort of gets at what are the topics to be addressed? And what are the topics that really shouldn't be addressed because they're outside the purview of this particular exercise? And so part of what we did in this process is you do spend a lot of time thinking about what it is specifically that the NSF and NASA have asked you to focus on because you want to be responsive to what they're the most interested in hearing advice on. So distilling this statement of task down into a few bullet points, I would say roughly can be summarized as follows. So one is to review the sort of state of the field. What is the current state of the scientific enterprise, the current state of our understanding in all of astronomy and astrophysics? And in so doing, identify what are the most exciting and compelling science challenges for the next 10 or 20 years? In addition, having identified those compelling science areas, the primary goal of the Decadal Survey, this prioritization process, is to identify strategies for how to actually go about answering those science questions using facilities that can be developed over the next 10 or so years. And part of that includes really prioritizing, saying, you know, this is the most important thing that can be done in the coming decade to advance our scientific understanding. And although our advice is to the U.S. Federal agencies, of course, part of this has to take into account the international scientific landscape, the fact that very large projects are often international. Or in addition, right, we don't necessarily want to duplicate if the European Space Agency, which is Europe's analog of NASA, if they're launching a telescope to do a particular science, then we don't necessarily want to duplicate that. We want to find something that's complementary. And so understanding that international landscape is very important. The other thing that's somewhat unique to the United States, that's different from other countries, is that in the U.S., there's actually a large private investment in scientific research, and in particular, in astronomy. There's a lot of telescopes, ground-based telescopes, that are primarily funded by private universities, not federal investment. And so that balance between what the federal government funds and what private universities fund is a sort of important one to bear in mind as part of our process. One of the things we grappled with a lot as part of this survey is that large astronomical projects really don't take a decade anymore. To develop, they take much longer than that. The James Webb Space Telescopes, which Space Telescope Singular, which has so spectacularly launched and seems to be working beautifully, right, took over 20 years to come to fruition. And so really calling it a decadal survey is a little bit of a misnomer now, because the projects take a very long time to develop. But we don't want the scientific community to be waiting for 20 years to get science out. And so there's a balance between projects that might take 20 years to come to fruition and ones that might only take a few years to come to fruition. And part of the goal of this prioritization process is to really understand that balance, the health and vitality of the scientific community relies on having telescopes that are producing data now, while at the same time building ones that will make breakthrough discoveries on a 10 or 20 year time scheme. Elliot, we have kind of an interesting question that came up. Karo asked, does it help the lobby legislators to obtain funding for research? So I think in general, the answer to that is yes, namely that the lobbying both by you as, you know, individual constituents of a particular house representative or senator to support basic science research is certainly important. And then also there's a large effort by the American Astronomical Society and related astronomical societies to lobby more broadly on behalf of the recommendations of the Decadal Survey to sort of bring those recommendations to the attention of the House and Senate subcommittees on science. And so part of what many people who are involved in the Decadal Survey process actually end up doing is going to Washington DC and pitching the conclusions of the Decadal Survey process to relevant lawmakers in the federal government. And so that actually is an important part of the process. So after the process of prioritization is done and the 600 page report is finished, an equally important part of the process is keeping those recommendations in the eye of the federal government for the coming decade. So that they actually continue to capture the attention of the relevant funding committees and committees in the House and Senate and so have a chance of actually coming to fruition. So that actually is a very good question and it's an important part of the process. You know, there are a couple of other things that I'll emphasize about the process. One of the things increasingly is to have off ramps. You know, if projects are ballooning in cost or time to completion, to have clear guidance to NASA and the National Science Foundation about when they might no longer want to continue to do a project because it's not scientifically worth the dollars that it's taking. I think that's a very important thing for the scientific community to acknowledge is right. We're not going to do all projects at all costs. We have to make difficult decisions. And so that's part of the prioritization process. And then lastly, as I'll come to in a second, another part of the this prioritization process is increasingly to recognize the human element of doing science. And so to provide an assessment of sort of the health of the profession overall and the individuals who are actually doing the science and what can be done to have the most scientifically productive workforce, the most well trained workforce issues like that. I just was noting the comment in the Q&A. Okay. So here's kind of a flow chart idea of how the process works. The process really is driven by the entire astronomical community. So early on in the process, which took over two years to complete overall, there was a call for input from the scientific community, which led to the writing by the members of the astronomical community of science white papers and then what we're called program or project white papers, which are basically just members of the scientific community saying, you know, this is what I think is the most exciting science question that can be addressed in the coming decade. And then this is an example of a project that could try to address that question. Each of these white papers was on average something like 10 pages long. So if you do the multiplication, right, that's 5,700 pages, 3,000 pages of these white papers. So it's a huge investment by the astronomical community overall in trying to identify exciting science and exciting projects that can carry out that science. And then what happens is that there are different panels, science panels, and then project or program panels that distill all of that input and try to identify a small number of priority science questions and a small number of projects that can address those priority science questions. And then lastly, there's one overall main committee called the steering committee, which consists of about 20 people. That is the committee that I was part of in this last decadal survey, the 2021. It was co-chaired by Rob Kennekat and Fiona Harrison. So they sort of led the overall effort. And there were about 20 scientists and engineers who were on this primary committee who took all of this input from the community and from the science panels and project panels and came up with the prioritized set of what we think the most exciting sciences and what we think some of the most exciting projects to address that science would be. And so it all kind of flows from the community through these different groups, ultimately, to the steering committee who makes the sort of final set of recommendations. Elliott, our names are always kind of the bane of things like this. So George asks, what does SOPSI panel mean? Yeah, so SOPSI is the panel that was tasked with looking at the state of the profession. So SOP stands for state of the profession and SI stands for societal impact. So this is the panel that was tasked at looking at the sort of health of the scientific workforce, the diversity of the scientific workforce, what can be done to improve that. And I'll talk a little bit more about that. So that was sort of a separate panel from these science panels and these project panels. Good question. So this just gives you a list of the science panels. What areas were they in? So sort of covered all of astronomy from cosmology, dark matter, dark energy, the Big Bang, through to black holes and neutron stars, to the sun, to exoplanets, astrobiology, the solar system, not directly exploration of the solar system with satellites. So that, you know, things like sending Mars landers, that's actually the purview of a different CATL survey, which is the planetary science to CATL survey, but things like the Hubble Space Telescope observing Jupiter or Saturn or Uranus is very much within the purview of the astronomy to CATL. So those were the science panels. They gave input in terms of scientific priorities to these more project oriented panels, which consisted of trying to do projects from space, projects on the ground at optical or infrared wavelengths or radio wavelengths. Increasingly astronomy is not just done by observing light, it's also done by observing gravitational waves and particles, neutrinos and high energy particles called cosmic rays. So there was a panel devoted to that. And then there were two panels that were a little different in kind. One was called the Enabling Foundations for Research and I'll explain what that did. And the other was this state of the profession and societal impacts, the SOP-C panel that we just talked about. Elliot, we've got a couple more questions here. Yep. So at some point we might need to let you make some progress here, but Stuart's wondering what it is that you mean by exciting science. You know, what's exciting to one person might be different than someone else? Is that based on what's theoretically possible or practical achievements? Right. So that's a great question. And everybody has, you know, a different sense of what is the most exciting science? What are areas that are the most ripe for progress? And so part of the goal of this kind of process is to think through different answers to that question of what the most exciting science is. And, you know, I think in practice, the answer to that question is not completely divorced from what is scientifically possible and what is technologically possible. So in many ways, I think the areas of science that are identified are things like what is dark matter? Where we know there's a really big question, it's actually been around for a while, but it's still a really pressing question that underlies a lot of our understanding of cosmology, the history of the universe itself. We'll talk a little bit later about searching for life on other planets, right? That's a question that we're really now only for the first time in scientific history able to address using, you know, clear, well-defined observational programs we're able to tackle that science questions. So those are some of the examples, but it's, you know, I think the truth is that there is something very much subjective about this. And that's why there's a lot of different people involved in the process because one is trying to take the pulse of the entire astronomical community in identifying in a fair way what many different people in the community find to be really exciting science questions. And I believe that you answered this question in your, the last answer, Carl said, is acceptance of proposed research based on completion of analysis of all prior data gathered data. And so you alluded to that as far as basing this on past missions or past research. Yeah, so I think very much the goal in identifying these priority science areas is to try to identify either questions where new technology is allowing us to address things in ways we couldn't before or where there have been new breakthroughs, either observational or theoretical, that have created new questions that we really didn't have 10 or 15 years ago. And those are the kinds of questions that sort of bubble to the forefront out of this kind of process. So it very much involves synthesizing what's been done and what is known and then looking forward. Okay. So I want to say a little bit about this enabling foundations. These two panels were new in this decadal survey. They had never been sort of separate prioritization processes in any decadal survey before, not just in astronomy, but in any area. And so one of the things I think that many of us were proud of is recognizing these enabling foundations and the state of the profession as things that were important to address on the same footing and with the same importance as what's the next big telescope that we should build. And so the way to think about the enabling foundations for research is sort of things that aren't telescopes, but that are really important for research. Things like what fraction of the federal government's funding goes to supporting people to do science, to actually analyze data from telescopes versus goes to building new telescopes. What's the right balance that we should strive for? How do we actually archive all the amazing amount of data that we have from the Hubble Space Telescope and that we'll be getting from the Webb Telescope and from the Vera Rubin Observatory? How do we archive that in the most useful way that the entire scientific community, any indeed any member of the public can access, right? The federal government through taxpayer's money is paying for these instruments and so the data should be publicly accessible to anybody, not just members of the astronomical community. And so those are some examples of these enabling foundations for research where there was a lot of thought into how to ensure that the most research can get done by having sort of the right backbone, the right research infrastructure in place to enable telescopes to do the most science. And then the state of the profession and societal impacts sort of the goal and the view of this panel is stated very nicely I think in this quote that was at the heart of the report written by this panel and that the steering committee very much took to heart and it's that the pursuit of science and the pursuit of scientific excellence is inseparable from the humans who animated, the people who do the science, the people who were involved in the scientific process. So we should not think of science as this sort of robotic enterprise that just yields amazing images, but it extrably has a very strong sociological component to it. It involves people, it involves people working within the particular confines of the society that we live in, and that very much shapes the scientific enterprise and thinking about it in that way is very important both for understanding where the scientific community is doing things well and understanding where the scientific community may not be doing things as well as it could. So there's another question here. Are projects selected not always to be done at a major university or institution? I think that's a great question and that's I think that's actually very much one that we talk a lot about and struggled with in the sense that we want the projects that are supported by federal resources, by government dollars, again taxpayer dollars, we want them to lead to science that benefits the entire scientific community, not just to be completely honest, not just people like me who are at Princeton University, which is an extraordinarily privileged and wealthy institution with a lot of access to resources that most universities don't have. And so I think that that has led to the prioritization of projects that have as part of their output data that can be widely used by the scientific community by people at any institution, be it a major research university like UC Berkeley or Princeton or be it a small liberal arts college that doesn't have PhDs, that primarily trains undergraduate students and where it's the undergraduate students who are involved in research. And so that a goal very much of some of the projects that are highlighted is to ensure that the entire scientific community benefits from the projects that we prioritize. So great question. Okay, so I'll just say that this panel on the state of the profession grappled with a lot of questions that show up not just in the scientific community but that our society as a whole is grappling with. It grappled with the fact that the astronomical community, the research community and astronomy, the demographics of that community are not at all representative of the Democrat demographics of the United States overall. And so what can be done to ensure better participation in particular by women and underrepresented minorities in the scientific enterprise? How can we strengthen programs that draw in a broader range of people into the scientific process? And so those are the kinds of questions that the society for that the panel on the state of the profession grappled with and tried to identify recommendations that could really improve the sort of health and vitality of the astronomical profession on those fronts. Another one that they dealt with that I wanted to highlight because I think it's something that the amateur astronomical community is also very concerned with is issues about light pollution, both light pollution that we're used to, street lights, things like that, and new sources of light pollution like Starlink, which are increasingly problematic both for professional astronomers and for amateur astronomers. And so how to mitigate the impacts of those was another area where there was a lot of focus from the state of the profession panel. And indeed, they and we as the primary steering committee, we met with representatives from SpaceX and other companies that are launching these satellites into space and tried to sort of engage them on minimizing their impact on both the professional and amateur astronomical communities. Okay, so I want to highlight the sort of science areas that were identified as being sort of capturing areas where we think there's going to be a lot of progress in the next 10 to 20 years. And those take the form of both broad science themes. And then within those broad science themes, somewhat more specific science questions, questions that really drove a lot of the specific project recommendations that we ended up highlighting. So those science themes were grouped into three broad areas. So there are all of these science panels that I emphasized here came up with actually they each came up with five different they came up with five different science questions and then the steering committee overall grouped those into these themes and then more specific questions within those themes. There's another question in the Q&A, was there is there was surveys done? Was there an opportunity for amateur astronomers to somehow participate? That's a great question and honestly, I should know the answer to that and I don't remember whether as part of the process there was outreach to the amateur astronomical community. I believe that there was but I would have to go double check exactly what form that took so I can do that afterwards and get back to you. But great question. Okay. So the science themes, one of which is a theme that we called cosmic ecosystems. And this really captures the science behind Carl Sagan's famous quote that we are all star stuff. This is this idea of the interconnected universe that stars produce the heavy elements necessary for life and they eject those heavy elements back out into space and indeed most of those heavy elements get ejected out of galaxies out into intergalactic space before they later flow back into galaxies form new generations of stars and planets and ultimately end up as the iron in our blood and the oxygen we breathe and the rare earth metals that make our technological civilization our phones and my MacBook Pro here actually work. And within that broader science theme, the area in which there has been the most progress in the last five or 10 years and one where we think there will be more in the coming decade is really understanding how galaxies grow by gathering up gas from their surroundings. Galaxies pull gas into them and that becomes the fuel for later generations of star formation and planet formation and the growth of galaxies. There's another question. Was any research designated to removing or cleaning space debris left over the past 80 years? That also was definitely a topic that was grappled with namely how to minimize the chance of collisions of satellites or collisions between debris created by satellites that have been their scientifically productive lives and other things. So this is a huge worry. I don't think there are any good solutions. I think this is an area where there's a lot of hand-wringing and a lot of concern but not one in which there's been a huge amount of progress partially because a lot of the problem increasingly is driven by the increasing use of space for commercial purposes. So that's driving a lot of the difficult problems in this area. Good question. Another one of the major science areas that we identified as being particularly exciting is a good example of science that really has only fully emerged in the last decade. This is the idea that I already alluded to, that astronomy is now done not just with light but it is now done by directly observing gravitational waves. That's what the gravitational wave view of the universe is. What the LIGO and Virgo telescopes opened up starting in 2015 through the present day and likewise we can now observe the universe in neutrinos and hynergy particles, not just in light. So those different ways of looking at the universe, new messengers have revealed new ways of doing astronomy, new types of astronomy really, and in so doing they're also revealing new physics, right, involved in the collision of two black holes that LIGO has detected. That's allowing us to test Einstein's theory of gravity in ways we never knew possible before. There's another question, how does dark matter become involved in the process of star formation? That ties into this cosmic ecosystems theme. Dark matter is not directly involved in the process of star formation. By the time you're forming stars, dark matter, the gravity of dark matter is actually not that important, but dark matter is critical for the process of galaxy formation. The gravity of dark matter on the scale of a galaxy as a whole dominates over the gravity of normal matter, and so the gravity of dark matter dominates how gas gets pulled into galaxies, which sort of sets the stage for where stars form, where planets form in the universe. Overall, the dark matter creates a kind of backbone that sets where gas accumulates to subsequently turn into stars and planets, but once you're forming a star in that region of space where a new star is forming, the gravity of the dark matter is no longer that important. So good question. And then the last science area that we highlighted was sort of the idea of really exploiting the remarkable advances in understanding and indeed detecting planets around other stars to really understand those other planetary systems, both how they're different from our own solar system, how they're similar to our own solar system, different or similar as the case may be. So that's sort of the idea of understanding other planetary systems in context, both relative to each other, because we now know of many thousands of planets around other stars, both so both in context relative to each other and also relative to the solar system, which is the planetary system that we of course have the most detailed knowledge of. And within that broader science theme, the scientific question that is the most likely to see transformative progress, which will impact not just the astronomical community, but I would say will really impact the entire world in terms of changing how humanity perceives our place in the universe is this search for planets like the earth in the sense of being potentially habitable. And so one can use that phrase potentially habitable in many different ways. The one that's the easiest to define would be capable of having liquid water on its surface. There is no guarantee at all that that's the only definition of the habitable planet, but it's the easiest one to start with because it's grounded in what we know about the earth and the solar system. And so that drives a lot of the interest in the astronomical community is just trying to find other planets that could have liquid water on those surface. So rocky surfaces that might have oceans. So going from the science areas to actually identifying projects, of course, is very difficult. There's a lot of factors that have to be balanced. I would say chief among those those factors that have to be balanced is sort of a balance between small, medium and large projects. You don't want to put all your eggs in projects that will take 20 years. That's not good for developing a vibrant scientific community. You want a scientific community that has lots of small projects, which are going to get results a year from now, while at the same time trying to do the super ambitious things like build the James Webb Space Telescope. And so that small, medium and large exists both in the space of dollars, in the space literally of the diameter of the telescope, and also in terms of time scales near term versus longer term. There's a lot of other things that we had to balance in thinking about how to go from science to projects. I've listed a few others here that I'm happy to answer questions about if people have them. So this shows kind of a mapping from the science areas that I emphasize to you, to some of the specific projects that were prioritized. So those projects that were prioritized include a new large infrared optical and UV telescope in space, new extremely large telescopes, ELTs as they're called on the ground, a next generation version of the very large array, the radio array that has been used to do so much amazing science in the radio part of the electromagnetic spectrum, through to other things like continuing to develop the technology to detect gravitational waves. There's a question, can planets around Red Dwarf stars harbor life as we know them? And indeed, that's one of the questions that drove the recommendation as I'll mention in a second of building a new generation of very large telescopes, these ELTs on the ground, is specifically to try to answer that very science question. So I think it's fair to say that at the end of this multi-year process involving hundreds of hundreds of people distilling many exciting science areas down to a set of projects to be prioritized, there was really one question that at the end of the day most strongly influenced the recommendations that we made. And that is this idea of trying to continue the remarkable progress in the study of planets around other stars and in particular to push that search for planets around other stars into the realm of trying to answer through direct observations of planets around other stars, whether there are planets that might have liquid water on their surface, whether there are planets that might have oxygen atmospheres, that might have evidence of photosynthesis, and thus that might have evidence for the possibility of life similar to that that developed here on it. And the push to try to answer that question really drove the most ambitious, most difficult in terms of engineering, timescale, and cost of the projects that we recommended. So just to set the stage for this, we've basically learned over the last 20 years that all stars to first approximation host planets, indeed on average, each star like the sun probably hosts several planets, just like our own solar system does. But a smaller fraction of planets appear to host earth-like planets, and by that I mean rocky planets, so planets that have not just gaseous like Jupiter but that are rocky and that have surface temperatures that might be compatible with having liquid water. And the major technique that we prioritized as part of the 2020 Decadal Survey was the idea of trying to directly see planets around other stars. And the way to do that is shown in this animation. So you develop techniques where you actually block the light of the star, sort of like what happens during an eclipse of the sun by the moon. And by blocking the light of the star, you're able to see the very faint planet that is otherwise hidden by the incredibly bright source of light that is the host star in that system. And the goal here is to directly see the light from the planet and to actually take a spectrum to be able to characterize the composition of the atmosphere of planets around other stars, to look at whether or not those planets have water, whether or not they have oxygen in their atmosphere is whether or not they have ozone, whether they might have photosynthesis, questions like that. We want to be able to answer those questions directly using astronomical observations of planets around other stars. This technique is done using a coronagraph, so which is sort of an engineered version of an eclipse where you build into the telescope a way of blocking the light of the star and seeing the very faint planets that are orbiting around the star. And to do that, we need to build larger telescopes than we have today, both on the ground and in space. And the need for larger telescopes is really driven by three different factors. We need big telescopes because planets like the Earth in the sense of rocky and temperate may be rare. And so we need to look at a lot of stars to have a chance of finding them. So that drives towards bigger telescopes that can survey more stars. The other two reasons that we need bigger telescopes is that blocking the light of the host star is difficult. That requires high angular resolution, which means large diameter telescopes. And lastly, the planets are very faint relative to the star, and so you need really big diameter telescopes to gather enough light to directly see the planets. And so the primary recommendation on the ground that we made is to build a new generation of telescopes that are sort of like the big 10 meter diameter telescopes that exist today, but instead have diameters of 20 or 30 meters. So these are telescopes that have a total diameter of something of order 30 meters or so. There are two such projects led by U.S. consortia, U.S. groups. One is called the Giant Magellan Telescope and one is called the 30 meter telescope. And our recommendation was to try to pursue building both of those telescopes, but at a minimum to definitely try to do one. And for the U.S. federal government to invest enough resources to ensure that at least one of those large ground-based telescopes will come to fruition. And indeed, these ground-based telescopes are the ones that can directly answer the question that was asked a minute ago, which is, can we see planets that might have Earth-like temperatures orbiting cool red dwarf stars, M stars? And that can be done from the ground. It doesn't require growing to space, but it does require building bigger telescopes than what we have today. And so that's part of what we recommended. Another major ground-based telescope that we recommended is to start technology development for building a successor to the very large array. And the goal of that is actually to directly see planets as they form. So this is sort of theoretical, theoretical example of what one might see. This is what one can currently see using the Alma array that's in the Atacama Desert in Chile. And this is what the next generation, very large array, would see. Each of these rings here that you see in this image is actually traced out by a planet in this hypothetical planetary system. So with a new radio array on the ground, one would actually be able to see planets like the Earth in the act of forming and really understand the planet formation process itself, which is a very difficult process. In space, the primary recommendation or highest priority recommendation is actually to build what is basically a successor to the Hubble Space Telescope. So you may know that the James Webb Space Telescope is not going to observe like Hubble at optical or UV wavelengths, but rather it observes in the infrared part of the electromagnetic spectrum to detect light from very, very distant redshifted objects. But to detect Earth-like planets around sun-like stars, what we need is basically a much larger version of Hubble in space. So something like a seven or eight meter diameter telescope that observes at the wavelengths that Hubble observes at, rather than at the infrared wavelengths that JWST observes at. And so that indeed is our primary recommendation because that will advance this goal of really understanding and trying to directly detect planets that potentially could be habitable. Okay, so I'll simply end by saying that astronomy has succeeded in many ways over the last decade because we have observed the sky not just at wavelengths that our eyes can see, optical wavelengths, but we've actually observed in the entire part, the entire electromagnetic spectrum from the radio all the way through to the x-rays and gamma rays. And indeed, part of the success of astronomy in unraveling the workings of the universe has been the realization that different parts of the electromagnetic spectrum give us very different information about the objects that we look at. These are three images of the exact same object in the sky, a cluster of galaxies, visible x-ray and radio, and those images tell us very, very different things. And so our recommendation is to NASA, to NASA, is that at the same time as it prioritizes building a new infrared optical UV follow-on to the Hubble Space Telescope, a larger version of Hubble, it has to at the same time start the technology development for building new infrared telescopes and new x-ray telescopes in space. And that has to be done now because it takes decades for the technology to develop to the point where one can actually do a mission, and we need to simultaneously advance the technology for all of these different missions so that in 20 or so years, we won't just be looking at the universe in the visible part of the electromagnetic spectrum, but we're able to have this full multi-wavelength view of the night sky. Okay, so I'll end there. There's lots of other things that we prioritized, but I'll end there in the interest of time and say, I hope I've given you a feel for, first of all, why the scientific community does this process of prioritization, the decadal survey process, how we go about doing it, and what some of the specific recommendations, both scientifically and technologically, in terms of future telescopes, that the most recent astronomy decadal survey actually prioritized. So I'd be happy to answer any additional questions that you have now. Yeah, we've got a couple there in the Q&A, and the one thing that I might mention with thinking about the high-energy telescopes is our speaker next month is someone on the New Star team, which has been doing X-ray astronomy for 10 years. So thinking ahead to something a better instrument with greater, much more capable than the existing ones, we've learned so much, and yet there's so much that we still have yet to Yeah, that's exactly right. So that New Star observes high-energy X-rays and has really transformed our understanding of black holes and neutron stars. And so that's a great example where, in addition to building this sort of successor to Hubble, one wants at the same time to be pushing forward the technology to develop better X-ray telescopes, things like New Star, things like the Chandra X-ray observatory. There's a question in the Q&A about, do we understand how we can detect black holes that aren't in a galaxy but are roaming out there in space? The answer is we do know one way of detecting sort of free-floating black holes, and that's through the process of gravitational lensing. So occasionally that a black hole that's floating out there in space will pass between us and a background star, and it will cause the brightness of the star to go up and then go down as the black hole passes between us and the background star. And that process of gravitational lensing is our best hope for directly seeing black holes that sort of don't have any gas falling into them that aren't at the center of the galaxy. And there, in fact, just earlier this year, the most compelling example for a black hole discovered using this technique of gravitational lensing was announced through observations by the Hubble Space Telescope. So that's our best bet for doing that. There's a couple other questions in the Q&A that I can address. Is a Dyson Sphere good signature for intelligent life? So there's this idea for those who don't know, the Dyson Sphere is the idea that a future very, very future, very technologically advanced civilization might evolve to the point where it builds basically a sphere around its host star to capture all of the energy produced by a star and harness all of that sunlight, basically for solar power, to power the functioning of the technologically advanced civilization. And so there have in fact been searches using infrared observations for, so the idea is that if you had a sphere made of metal around the sun at the distance of the earth, that would be a bright infrared source in the night sky. And so there have been searches for bright infrared sources that would represent Dyson Spheres. There haven't been any detections. You definitely would have heard of it had there been a detection of that. There hasn't been one. And of course, it's a huge outstanding question whether any technological civilization, can it could actually get to the point where it could build something like that? We're incredibly far from being able to do that today. And in my pessimistic moments, it's not at all obvious to me that we will reach the point where our technology will enable us to do that before bad things have happened on earth. And then the last question in the Q&A is the inclusion of quantum physics becoming becoming part of present astronomy research. There are a couple of different answers to that question. So all I mean, there is a sense in which quantum physics is part of everything we do in astronomy, right? Every time we observe atoms and the spectral lines from atoms were using quantum physics to understand atomic structure and what stars and galaxies are made of. I think you probably are getting at a version of the question which is, does our understanding of quantum gravity, so the theory that would unify quantum mechanics and gravity, is that becoming a part of astronomy research? And indeed the answer to that is yes, that the attempts to unify the theories of quantum mechanics and general relativity in a quantum theory of gravity, we do not have such a theory today, but there's a lot of active research trying to develop such a theory. And that is really at the forefront of our understanding of cosmology as a whole, sort of the evolution of the universe writ large, and our understanding of things like the acceleration and the expansion history of the universe ties into that idea of a quantum theory of gravity. And there are also ideas that observations of black holes might be able to detest, to test, not to test, to test quantum theories of gravity. So those are senses in which we're trying to use astronomical observations to actually test sort of basic laws of physics, in this case, about the union of quantum mechanics and gravity. So great question. Any other question? I think that the one item that did show up in the chat, which I thought was interesting, something that I had wondered about too is that it was suggested or asked, what about putting a liquid mirror telescope out in space? And there would be some engineering things. But then I also pondered whether or not if you could do that, would that be a self correcting one? And so you could avoid the, it would be self healing if you had some micro meteorites pass through it. Yeah. So there has actually been a lot of research into that also into the idea of putting one on the moon. And part of the interest in that is to piggyback on human exploration of space. So there's interest in going back to the moon. And so one wants to use the, all of the engineering effort in going to the moon to push science forward as well. And one way to do that would be to build a telescope on the moon. Radio telescopes on the moon would be very interesting, but another idea has actually been to have a liquid mirror telescope. So I honestly don't know all that much about it, but I do know that that's an area in which there's quite a bit of interest and research. The other one is actually there are interesting ideas for inflatable dishes. So if you're observing at radio wavelengths, then your reflecting surface doesn't have to be an amazing mirror in the sense that it has to be if you're observing at optical wavelengths. The mirror only has to be as good as the kind of wavelength of light that you're observing at. So at radio wavelengths or far infrared wavelengths, you could actually get away with something that's sort of like an inflatable balloon making up the dish. And so there are interesting ideas for that from an engineering standpoint of actually trying to make that work. So I know there's a lot of research going on into that as well. So many things in it. It's so much creativity and imagination that goes into it. And I think that that's where that human element that comes in that you were mentioning that they're really emphasizing and bring that to bear. So that's all for tonight. Thank you so much, Elliott, for joining us this evening and thank you everyone for tuning in. You can find this webinar along with many others on the Night Sky Network website in the Outreach Resources section. Each webinar's page also features additional resources and activities. This will be posted on the website within the next few days. Also join us for our next webinar on Wednesday, July 20th when Dr. Brian Greffenstetta from Caltech will bring us up to date on New Star, a space-based X-ray telescope now in its 10th year of operation, which I don't know, maybe it was in a decadal survey 20 years ago. I bet it was. Also join us on the evening of Wednesday, July 13th for another in our series of social events where you, the members of the Night Sky Network, share your ideas and good works. This one will be specifically on International Observe the Moon Night and we will have some guests as Dave mentioned earlier. So keep looking up and we will see you next month. Thanks everyone. Thanks for the great questions. Well, thank you so much for hanging in there longer than after seven o'clock. I know it's after 10 o'clock for you. No, my pleasure was fun. It's always fun to do these things. I enjoy it. Yeah, people had lots of lots of good questions. Yeah, no, I'm very happy