- And then move on to Karl Stapelfeldt who will be giving our ExEP Science and Gap List Update.

- Okay, hi, Knicole. Good morning, everyone, or good afternoon, depending on where you are. So I'm Karl Stapelfeldt, I'm the chief scientist in the Exoplanet Program Office at the Jet Propulsion Laboratory. That's where we implement the directions from NASA headquarters for NASA Exoplanet Programs. I work on this along with Eric Mamajek, what I wanna do in the talk this morning is to tell you about some science issues raised by the Astro2020 Decadal Survey that are relevant for our program and give you an update on the science gap list, which is one of the key documents I think ExoPAG members should be aware of for interacting with us and in your proposal process. So Astro2020 has been very good to us, at least in terms of the large missions, they've seen it our way. Here's a list of the various themes that they mentioned and questions that they mentioned in the main report. And these are now central to the definition of the next large space mission on the scale of HST or JWST. Well, this is a very exciting outcome for ExoPAG, for the exoplanet researchers in the field worldwide. It's something that was a long time coming. We've been trying to build toward this for 20 years with both the Astro2010 recommendations, seeding the ground for this, we've gotten a great benefit from Kepler making it possible to know the planets are out there. All the technology focused work that's been done to make such missions possible. Lots of mission studies that have happened over the past 30 years. And finally, you know, the HabEx and LUVOIR teams for their science cases, pushing this over the top and getting us this outcome. So this is really impressive because the decadal steering committee only had three exoplanet scientists amongst 18 members. They have made our science the focal point for the next big mission. It's really exciting, and I want to remind you that in Europe, the Voyage 2050 report for ESA came out and they listed a mid infrared parameter for trust real planets as a priority for study in their area as well. So there's a lot of great things coming along with, of course, what JWST is doing. So it doesn't stop with Astro2020. So there are questions that are raised, questions that were unanswered yet by the HabEx and LUVOIR studies that the community can now start thinking about. And they're defined a little better now. So here's one question. What is the definition of a science yield that detected exoplanet that we wanna use for the upcoming architecture trades? And you can see here in these plots by Rhonda Morgan about the different options that are available. There's a partial spectrum in the red optical that shows the detectability of water vapor. There is a more complete spectrum across the visible wavelengths. And then there is a spectrum going all the way down to the ultraviolet and capturing the ozone one. And so these have been used in different ways by the HabEx and LUVOIR reports, and we need the community to come to some kind of agreement about what is the right metric for measuring these future mission architecture options that we'll eventually be trading. So please start to think about that, ExoPAG and other community members. Open question number two is what do we do for getting the masses of our exoplanets detected with direct imaging? The reflected light observations themselves, of course, don't provide masses. We need supporting observations with radio velocity or astrometry. And masses are hugely important to understanding what we're looking at in the exoplanet spectrum that we're seeking. So the Exoplanet Science Strategy from the National Academy of Sciences asked for an EPRV initiative to get these masses and the implementation of that is still pending. But in the course of that study, it was realized in about 30% of the LUVOIR and HabEx target stars are too hot or too fast rotating to be able to get high precision EPRV measurements down to the desired limit of earth-sized planet in the habitable zone of a sun-like star. So what do we do to address this? This realization came after the LUVOIR and HabEx reports were finished. So the options are listed there. We could live without mass info for this fraction of the targets. We could try to develop astrometry capability on board, the flagship mission itself, if that's feasible, it needs to be studied. And then also we can talk about having a separate astrometry mission if we wanna bite the bullet on the cost to get these additional masses that aren't likely to be provided by RV. So this is a programmatic issue for exoplanets and the thoughts of the community on this really need to be developed. Okay, question number three, it's still a science gap that we have in each of these areas. We have uncertainties in eta Earth and exozodi, it still affect our ability to project what the future flagship mission architectures can actually do. We've made enough progress to be able to select this future mission, but the uncertainties now have to be balanced across the risks to the mission yields, the costs, and the technologies. What can we do beyond what all the smart people have been thinking of these past years? What new approaches could we take to reduce the uncertainties in these two key parameters? And it's great that ExoPAG has had a SIG 2 working the eta Earth issue and the proposed new SAG on exozodiacal dust are ways of keeping the discussion going on these two important areas. So I hope that that would happen. Another list for the future flagship mission is the question of the targets for the mission, the six meter telescope. We have from the ExoPAG SAG 22 report specifying what kind of information we'd like to have on the target stars. And so now that that the scope of the mission has settled, we need about 25 targets characterized. We need about 100 habitable zone searched that will amount to well over 100 targets to get enough completeness. We wanna be able to start looking and doing precursor and preparatory science on those targets, but those targets are relatively narrow set. We don't have flexibility to go and shift and choose a set of targets that would explore exoplanet evolution over age, or do a lot of targets in A stars and compare them to M stars. It's actually relatively restricted as this plot on the right from Eric Mamajek shows. And so we don't have the six meter target list yet, LUVOIR and HabEx list are not exactly the right one for this. And so for the past year or so, Eric Mamajek and myself have been working to build a target list that would be value added versus what has been done in the past. And we're on the verge of being able to release this to the community and post it at next site in the next month or so. So that target list we hope could provide some basis for precursor preparatory science work, but the community over the next decade or so. So that target list is more than just a target list for scientists to work on. It's also an opportunity to communicate where we're going with this future flagship mission. And so that the community engagement on this is something that we're calling where we explore. And we cannot look at just any target star out there and seeing planets in the habitable zone. There's only a select group where this is possible. And so we wanna raise awareness of that, I think in the community, in the public, about where are the places that we're gonna go take them along with us to try to find a habitable planet environments at a substantial cost. Let's focus the public's imagination on those destinations and build excitement for this feature discoveries and along the way explain our methods and telescopes. So we've started to prototype information about the target star list at the exoplanet program office. We've got a descriptive content being built on the most promising targets. Something, of course, that we're gonna put this out for public release in multiple ways we're still discussing. And so we have some initial stabs at this and we'll give you a lot more information at the Pasadena AAS. So that's my discussion of science topics related to the decadal. I wanna switch now to talking about the science gap list. This is something that we've had a lot of help from the community in helping to define. And I wanna tell you about it if you're not familiar with it. There are three documents that consists of our science gap list. And science is written into the program charter for exoplanets as the thing that defines our decisions, activities, and approaches, it guides them. And so we have to have those goals written down somewhere, and these are documents where this happens. And so these three documents are co-authored by myself and Eric Mamajek. They're reviewed by headquarters and the ExoPAG executive committee members. And, of course, any other community member who wants to send us feedback. So what are these three documents? There's the gap list itself that has 14 research areas where additional work would either enhance the science return of current and upcoming NASA missions, or provide the information needed to design future missions. This is not any possible interesting thing in exoplanet science. It's what really affects NASA's mission set for exoplanets. And we update this every year. One of the documents is a relatively static boilerplate document describing how the exoplanet program works, who does what in the science area. And the third and largest document is an appendix that provides the context for the science gap list of the state of the field and what knowledge we need to inform that ExEP objectives and how that becomes expressed in the science gap list. So these documents have been available online for years now. And for you folks, the important thing about them is that they are documents you can use when writing your science proposals in the NASA Exoplanet Research Program, XRP, they are explicitly referenced as ways to describe how your proposal connects to NASA's goals. And, of course, review panels can use them as guidance too, but they're free to do whatever they want. This is not a limiting step for what people can select for science. So a gap looks like these five elements, a title, a description, what is the capability we need to meet our objectives as defined by the decadal surveys and other community documents. What is the capability we have today in that particular area? What is going on right now to try to close these gaps? And, of course, what's really, what matters the most is what are the things that we need to do that haven't started yet? And that's your job community to go and find out what those could be, conceive them and propose them. So the program gap to be relevant to ExEP, it needs to be affecting a broader range of things, not just one area of the program, for example, is very important to the Roman mission to know the micro lensing rate in the near infrared north towards the galactic bulge, but that doesn't have broad implication to other parts of other missions, for example. And so that's not a gap that we track, but it is of course a gap for Roman science. So what we've done in the past year is we solicited input on the last version of the science gap list starting right after the XRP proposal deadline had concluded. We gave the community over the summer to give us inputs on this. And this year we received 37 unique gap lists suggestions from EC members and members of the community. This is a great set of inputs and helps make sure that your program scientists are reflecting what the community is interested in and that the program does the right things. Thank you everyone for the time you've spent giving us these inputs. So we reviewed them during the fall and we delivered a draft revise gap list to our headquarters program scientists, you know, Hannah and Doug, just before the holidays. Now it was a tricky issue about what to do versus Astro2020, because the report didn't come out until we were well through the revision process. And we're kind of fixed in our schedule because we wanna have a fresh gap list in February when the new ROSES proposal calls come out. So we added some references to Astro2020, that it exists and its recommendations exist. But I think the full impact of Astro2020 hasn't penetrated all the way down yet through the gaps. And of course not into our appendix document either. So we can look forward to that full impact taking place in the next year's revision. We've kept the list of gaps at 14. So the status of the document is that the final version was cleared for external release by JPL just yesterday. And it'll go out for the signatures by the management types for this week. It'll be posted in another few weeks later this month in time for that XRP ROSES proposal call, it will remain static during that time. So we have a lot of details on the modifications that were done, and I don't have time to go through these individually. They're all listed here in these charts for reference. So when you find this presentation online, you can go back and see what changes we did. I've highlighted the ones related to Astro2020 in red. And so you can see them going by here. If you aren't familiar with our gap names, these are the definitions of them going by here quickly. So they span not just things related of course to the future mission, but how do we get the follow-up for tests that we need to make good targets for JWST? How do we talk about simulating the mission yields for the future missions? And how do we get ready to interpret spectroscopy from these future missions? So that's the revisions that have taken place. And I wanna remind you that the gap list is still a living document. In 2022, we're gonna follow the same process and schedule as last year. After the XRP proposal deadline, we'll issue another call for updates to the science gap list. We'll have an open comment period through September, 2022, work on the revisions in the fall and have a new edition by January, 2023. And we're also gonna be updating this much larger science plan appendix document, the current version is from 2018, to reflect what the decadal survey has said and to reflect lots of progress in the field through all the research that you do. So thanks again for supporting everyone that the existence and development of the science gap list. And I look forward to your questions on this or any program science topics, thanks.

- And you stayed perfectly on time . I was just gonna give you five minute warning. So, yeah, let's jump right in. We have several questions. We'll start off with one that was asking will where we explore the community engagement activity include intentional inclusion of an outreach to underrepresented groups.

- Well, that is part of what the agency as a whole intends to do across all disciplines in astrophysics. As Hannah was describing, we have the intention to increase that level of outreach to all those communities. But in our program now already in Southern California, we have significant outreach already to the Hispanic community here. We can always be doing more. So, yes, I'm hoping that we will be able to do better with that as we fully implement what the decadal has told us we need to do.

- All right, thanks. So we have another top question now. The top one here regarding the need for masses, is there a sense of the cost difference between options two and three native astrometric capability on the flagship and a dedicated astrometry mission versus a dedicated space-based RV mission that could overcome the ground-based RV limits.

- So I think we don't have a full picture of this, that both of these studies need to be done on the modifications to the flagship and a dedicated mission. The issue for the dedicated mission is you might think something as large as SIM as needed to do this, but if you don't have to do searches and you can spend a lot of time on just the targets or the reflected light imaging mission has detected planets, it might be possible to do this on a smaller platform and use very ultra precise central rating of an image within pixels, down to millions on a pixel sort of levels to be able to do this astrometry. And it's actually been proposed at several different scales, including even there've been proposals to do such a thing on a SMEX platform and smaller, but we haven't really looked at that, you know, with a lot of technical scrutiny. So I think we don't know the answer to this. It could be that the dedicated mission is more expensive. That's why I put the dollar signs down there, but I think the question hasn't been studied enough to really know.

- All right, and next question then, we have time. Can you clarify, to be an exoplanet program gap, to be relevant it needs to be cross cutting. So what boundaries must it span?

- It needs to affect multiple elements of NASA's exoplanet portfolio, which are not all inside the Exoplanet Exploration Program, for example, JWST, is not in the Exoplanet Exploration Program. So if you've got an issue that affects the science recurrent from JWST, you know, or from tests, or from ground-based telescopes that are supporting NASA missions, that's where it rises to the program level instead of being an issue for just one project. So that's what we mean by cross cutting.

- All right, and then there's one more question, we have time. So I think this goes back to the community engagement ideas. So setting realistic expectations on what we could learn about potentially habitable worlds with current and future observatories has been a major challenge in recent years. So what else might the community do to get everyone, scientists and the public, on the same page?

- Well, there are lots of details that need to be made more broadly known. The cattle presented this very nice figure from the LUVOIR report, for the spectrum from like the ultraviolet up to two microns for an exoplanet. And that is something we really wanna get, we'll be excited to have, but it's not gonna be achievable for all the targets, because these missions have been designed, the two versions recently studied, only really to provide complete spectra out to one micron and beyond that as sort of bonus areas. So I think people need to understand that the wavelength range of the spectra we're gonna get is gonna be different for every target because of their relationship of where the planet is, relative to the inner working angle of the starlight suppression system. So that's part of making everyone's expectations more realistic, and there are numerous other examples of this. The most important of these, I think is gonna be uncertainty in what we can say about how spectral signatures translate into whether a planet is habitable. And especially if you wanna make a claim about whether it has life. So the community has made some good thoughts of its own known on this. There's a recent group that has a white paper on the uncertainties in interpreting spectra like this. Also, I think that this is an obligation for the science team for the future mission, whenever it is constituted a few years from now to have a quite strong public facing presence on what we can really do and still make that exciting to the community and the public.

- Awesome, I think we can sneak in this last question that popped up. So regarding the stars that are rapid rotators or hot, can we simply eliminate them from the target list?

- So that is a good question. I didn't list that as an option. So we could choose not to observe those planets and those systems, but that would be giving up the chance to see spectrum around some of our best targets. Those are the brightest stars, typically the earlier type ones. They're the ones that therefore are gonna have the brightest reflected light planets. And so some of the highest signal to noise spectra. So I think it's still desirable to look at those, even if we can't interpret them as well as the other planets around cooler stars. We don't have the option of plugging in a different 30% of targets, because other way to do that, we would need to have a better inner working angle, a bigger telescope. And so that would be more costly. So I don't think we're gonna leave on the floor for comparative planetology purposes, a set of really good spectra. There will be larger planets in those systems we might be able to get masses for. I don't think we're gonna ignore those targets if the telescope has the capability to get the spectrum.

- All right, yeah, thank you, this is great. Let's thank Karl for his time. There's some applause for you and .