- We'll move on to our final speaker of the morning session, well, our first session, afternoon session, with an ExEP Technology update. We have Brendan Crill. This is another 30-minute time slot. And let's see, I see your desktop, but not your, there you go.

- [Brendan] That's nice.

- Yep. And I can hear you.

- [Brendan] Okay, excellent. So hello, everyone. I'm Brendan Crill, the deputy program chief technologist for ExEPT. It's great to be here, connected with you all once again. So on behalf of the ExEP Technology team, which includes Nick Siegler and Pin Chen, I'm excited to tell you about the wide variety of activities we're undertaking to develop technology for future exoplanet missions. So we're leading or facilitating many technology activities. We maintain a list of technology gaps that we need to close in order to enable or enhance future exoplanet missions. We facilitate strategic astrophysics technology grants that are aimed to develop technologies for these missions. We maintain space coronagraph testbed facilities that can be used by SAT-funded teams and flight projects. In advance of the decadal survey, we ran a small study to look at technology gaps related to nulling interferometry. We provide some support for the coronagraph instrument on the Roman Space Telescope, which as you heard from Vanessa Bailey on Monday, is really taking essential technology steps for high-contrast imaging in space. In ExEP, we've provide testbed support mainly, and we've also contributed a couple of masks. We've organized a modeling study, which is addressing key questions about coronagraphs on segmented space telescopes. We're managing an activity called S5, which is maturing starshade technology. And then also recently we commenced a fact-finding study to understand opportunities for ExEP to help in the search for technological life. So today, I'm gonna be describing the highlights of these activities, especially any important achievements in the six months since the last time we gathered. But I'll just start by acknowledging, though, the last time the ExoPAG met, of course, we were waiting to hear the recommendations of Astro2020, and we received those in November. And as many speakers in this conference have said, exoplanet science and technology is truly front and center. First, we have this recommendation for NASA to create a Great Observatories Mission and Technology Maturation Program to shepherd the preparatory work for future large missions. And then secondly, a mission specifically with exoplanet characterization capabilities is recommended as the first to come out of this program. So it's interesting to note that the recommendation itself, this text here focuses really on the science, doesn't overly specify what this recommended observatory should look like, doesn't even say six meters right here. Though, of course, there is plenty of discussion in the main text about this. I guess we heard in the discussion yesterday that it was not the intention to be overly prescriptive. So I think that has some implications for what we do in technology development. So we, your program office technologists, are very inspired by these recommendations, as I suspect many of you in the audience are. And so we're excited to get going. Nick, Pin, and I are getting ourselves organized in supporting headquarters in responding. And hopefully you were able to hear our Paul Hertz yesterday at his town hall, where he gave a framework that APD has in mind for preparation for the future Great Observatories, including the technology development. And Hannah, just a few minutes ago, of course, presented a more exoplanet-focused look at NASA's plans to respond as well, so you can refer back to those talks. But just to reiterate a little bit, you know, the idea is to have three stages starting with precursor science and technology work. You heard Karl talk about some science questions would be good to address now. And on the technology side, in fact, if you take the dot product between our current activities and the direction we probably need to go in for this next Great Observatory, it would be pretty close to one, and that's largely thanks to the recommendations from the earlier decadal in 2010 and the decades of work that you all in this community have put in. Stage two, which would start in a few years, is when the maturation program, whatever that looks like, is meant to start. But we consider analyses of alternatives as well as science and technology and architecture trades. And then stage three would be moving towards a more traditional NASA project development, you know, the decision to start and transitioning to a pre-Phase A. So APD is defining now what technology development will look like in this framework and particularly in this maturation program. And I've listed some of the considerations here, things like how best to use SAT and other funding mechanisms to advance the technology, the best way to take advantage of the fabulous capabilities that industry has, understanding things like what future large launch vehicles will be available, possibilities for servicing future large missions, and exploring international collaborations. But as you can see, of course, this planning has not come close yet to crystallizing. But so, you know, hopefully we'll be able to share more about this the next time we meet. One step we know we need to carry out is in updating our technology gap list, which we are going ahead with now. So a technology gap in this context just refers to the difference between the capability needed to enable or enhance a future mission and the current state-of-the-art that we have now. And APD maintains a list of these technology gaps and prioritizes them. In collaboration with our counterparts in the PCOS, COR program office, every two years we're tasked with going through a technology selection and prioritization process. So this update will, you know, it helps us to be sure that NASA is aware of all the future of capabilities that we actually need and how the state-of-the-art is involved. This is where a lot of community input comes in. It allows us to prioritize these gaps for investment. And then it also, having this list enables us to reflect back to the community, the technology problems that NASA essentially needs to solve in order to enable these astrophysics missions. So the last time we went through this process was back in 2019 with our gap list published on the web, or it's shown here on the right. But of course, in light of this recent decadal, clearly it's time for an update. Just to remind you what the gap list actually looks like. This is our old list of the 48 gaps. These were the exoplanet related ones. You can see it's divided into these tiers of priority with one being the highest. So how are things going with this update? We're now in the midst of our process. Last week was the due date for inputs from the community. So thank you to those in the audience who participated. I was very pleased to see the level of engagement from the community. Clearly there's enthusiasm out there. We received 96 submissions, so that's a lot of collective work filling out all those forms and then taking the time. So again, I appreciate it. It just happens to be exactly double the number of gaps that we're currently listing. And, you know, as we go forward with our process, that 96 will almost certainly boil down to a smaller number. You know, there's a lot of overlap, some redundancy. We may determine that some of these submissions are really engineering challenges, so don't necessarily qualify as a technology gap. Our next steps are, you know, first deciding which of the program offices will handle each of these gaps. We then go off and disposition, you know, choose to accept the gaps. We review them, consolidate them if appropriate. Then we go through our prioritization process. All our work on the ExEP side is reviewed by our Exoplanet Technology Assessment Committee, the ExoTAC, which acts as a independent standing review board for many of our tasks, including this one. And we're anticipating being ready to deliver the completed product to the community in April. So one of the uses of this gap list is to help focus the scope of the Strategic Astrophysics Technology Program. So this competed grant program helps to fund technology development in all areas of astrophysics, including for exoplanets, and ExEP facilitates the awards in technology areas that are relevant to our science. And so we help with review, scheduling access to testbeds, things like that. Currently, we're tracking 10 active efforts around the country in four different areas. So SAT has been a very important driver for maturing coronagraph technology in the last decade, for at least the level we needed to target exo-Earths. So we have currently four coronagraph architectures being worked on, three of which will make use of our vacuum testbed. We also have work looking at new wavefront-control techniques, either to improve coronagraph performance in certain circumstances, or actually to enable new types of observations with coronagraphs. We have several detector investigations underway to look at more sensitive detectors in the visible band and very stable mid-infrared detectors. And then we have a single effort underway to mature a new type of calibration source for extreme precision radial velocity. So I'm gonna go through and hit on some highlights from some of these SAT-funded investigations, starting with the ones that are taking advantage of the high-contrast imaging testbed. So the work on PIAACMC has actually been wrapping up. So this is an important type of coronagraph technology for a number of reasons, including the promise of excellent inner working angle. The investigation was aiming at a 10 to the minus 9 contrast with a segmented pupil, I should add. And it was achieved close to 10 to the minus 8. So there's some error budgeting and a final report coming soon. A vortex coronagraph was the baseline for the LUVOIR-B and HabEx concepts. It has a number of unique advantages in being insensitive to certain types of wavefront error instabilities. And that actually has carried out in number of demonstrations in the vacuum chamber over the last few months, including new record contrasts achieved over 10% and 20% bandwidths, invisible band, which is pretty exciting. And then earlier in the summer, another interesting achievement was to use a drop in a static segmented pupil that kind of looks like a LUVOIR-B aperture and was able to achieve a quite good contrast. So as the models predicted, you know, certain types of segment boundaries, at least in the fully static case, don't ruin your contrast. The next in the queue is John Trauger's new variety of a hybrid Lyot coronagraph, which, you know, historically has demonstrated the deepest contrasts that we've seen to date. So that's actually set up in the testbed. And so actually in the next few weeks, results should be starting to come in, which is quite exciting. Another couple of recent highlights also set up in the vacuum testbed is Rus Belikov's experiments on a multi-star wavefront control, which is an exciting technique that will enable coronagraphs to observe planets in multi-star systems. So the demonstrations with that experiment will be commencing soon. But then also, in parallel, a contributed mask for the CGI instrument on Roman has been fabricated, and that's what you see in the image here. That's pretty cool. In another wavefront control experiment, Olivier Guyon's team has been investigating a technique known as Linear Dark-Field Control, which has a number of important features by using a brighter signal and your coronagraph field, either out of band or spatially outside the dark zone to drive your adaptive optics. It can speed up the rate at which the control can be updated, and maybe even someday act as a way to loosen stability requirements elsewhere in the system, which would be great. Since we last met, there's actually a milestone report from Olivier's team published on the ExEP website, and he's also reported demonstrations in the SCExAO testbed in air that have gone beyond what he demonstrated for his milestone, which is great. He's now organizing future work, which will include tests in vacuum at higher contrast, and then also using spectral information, as well as the spatial. Our program maintains testbed facilities, which are located at JPL, to support a lot of these SAT-funded demonstrations, as well as the CGI. And we're always looking to keep these up to date to make sure the testbeds themselves are not the limiting factor for coronagraph demonstrations. So one bit of news is that we're well underway in duplicating our ultrastable testbed, which we called the Decadal Survey Testbed. But DST two is gonna include an additional pupil plane, which opens up the possibilities for different flavors of coronagraphs. We've achieved first light a couple of months ago. It'll be coming online more fully over the next few months, and in fact, will be ready for future investigators starting with those who just submitted proposals a few months ago. And I'll just note that we probably need a new name for these benches. So the deformable mirror is such a critical component to high-contrast space coronagraphs that, you know, we've undertaken some work within the program to advance that technology in a few ways. So in particular, we're aiming to have multiple vendors and technologies available to NASA. You know, CGI has been pushing ahead with a technology that they're gonna fly based on electrorestrictive materials. And ExEP has been taking on some testing of MEMS deformable mirrors. So in the six months since we last met, I can say that we've gone through some environmental testing of some of these MEMS DMs, and it was successful. We were able to observe no change in the performance of the DMs in a coronagraph in air before and after the exposure to random vibe. And just this past week, a final report has been completed. The deformable mirror also needs control electronics. And at least for our team, the control electronics have been a kind of ongoing vexing issue. So currently we're working with a vendor to create a more compact design with 18-bit control resolution. And so that'll be another part of our testbeds that'll be available to folks going forward. All right, so now I'm gonna move on to another activity, and this is addressing what is arguably the number one challenge for a future direct imaging using a coronagraph. And that's to look at how well coronagraphs play with segmented telescopes. So the study started a few years ago, simply by looking at the basic feasibility of using chronographs on a segmented-mirror telescope. I don't think that's really in question anymore. So we've returned to looking at how the chronograph and telescope behave as a system, and in particular, the stability of that system. And to take this on, we have a multi-institutional study using end-to-end modeling of the telescope dynamics, the coronagraph, and now including a wavefront control and propagating that all the way to a science yield. And particular, we've made some really fruitful progress working with the Ball and Lockheed Martin teams that have been funded to look at, to study system level performance of segmented telescopes. So we've been using a model that they've been developing for LUVOIR-A. And so the team here has reproduced the requirement reported in the LUVOIR final report of, you know, 10 picometer wavefront error stability, but added an additional dimension by looking at ways to potentially provide relief through wavefront control. So I just wanna point you to kind of a interesting plot that I think many of you will appreciate. So what you see plotted here is the residual contrast of the coronagraph, the goal being, you know, the 10 to the minus 10 contrast. And this is as a function of a guide star, the guide star brightness that's being used to drive the adaptive optics. The three curves plotted here show the underlying stability of the telescope. There's a different color for each of the telescope stability levels considered, 3 picometer RMS, 10 picometer, and a 100 picometer. So you can see that if you're at 10 picometers or better, it almost doesn't really matter what you do for adaptive optics. This telescope is just so stable by itself, that it doesn't really matter. But then, if you loosen up your telescope requirements, it's, it's actually a little bit funny to call this an unstable telescope. 100 picometers is like, you know, smaller than an atom. But you can see that at this point, using a guide star helps you. But if you look at the magnitude of the stars you need to drive down that contrast, you can see that you're driven to some pretty bright stars, even towards some form of laser system to stabilize the system well enough. So that's a pretty cool result to come out of this collaboration. A lot more details will come soon in a JATIS publication. And I think it's in SPIE papers at the Montreal meeting this summer. So yeah, just to put a 10 picometers in perspective, I mean that, you know, our space telescopes, like Hubble and Webb, are two to three orders of magnitude less stable than that, Hubble, of course, being in low-Earth orbit. So the study will continue. There's lots of really interesting questions raised here. You know, we'll wanna pivot towards the types of architectures that are more discussed in the decadal survey. We'll wanna improve the fidelity of the telescope model. I mean, one, you know, we've been relying either on a very passively stable system, but in reality, there'll be a lot of, there are opportunities for a closed-loop control of the telescopes ability in other ways with different metrology and actuators and so on. And then the idea is to kind of make this a more open process with the team, enhance the access to the model to everyone, and continue to improve the fidelity of that. So we're excited to see how that proceeds. But actually, given the challenge that the coronagraph faces, I just wanna make the point that, you know, from our perspective, a starshade is still a very viable option for starlight suppression. You know, in addition to not needing a telescope with wavefront error stability beyond the state-of-the-art, it also has some throughput and bandwidth benefits. You know, of course, there's other challenges in technologically realizing a starshade. And then, you know, and also in designing a mission to give you the science yield you want. But it's still a quite viable option. And ExEP manages what we call the S5 activity to mature starshade technology. This activity is aiming to close three technology gaps in starlight suppression, formation sensing, and in deployment accuracy and shape stability. Formation settings is actually considered to have already reached a TRL5, and the gap is closed, at least for the design reference mission that was under consideration by the activity. Some recent updates. So model validation is ongoing. This is probably one of the more important parts of the activity, because, you know, we're really only able to test the actual starlight suppression performance of a starshade at sub-scale from the ground. And so building confidence in the model is really essential to extrapolate to the inflight performance. And the agreement is not bad. The team's been including vector diffraction, but it's not quite at the 25% levels that they've set for themselves. So, you know, they've set themselves to quite a high standard for agreement.

- Hey, Brendan?

- Yeah.

- [Knicole] About five and a half minutes left, total.

- Thank you for the warning. So I just told you that the formation sensing gap is closed, but there's been some extra credit work completed using the sub-scale testbed facility at Princeton to demonstrate both formation sensing simultaneous with high-contrast imaging. So you can read more about that in a report that's posted on our website. Another report on the milestone aiming to achieve petal shape stability in the on-orbit thermal environment was completed after chasing down a small anomaly, which seems now to be understood. So if you're interested, you can go to our technology website and find these reports. Okay, so moving on to a couple of new things before I wrap up. So ExEP this year kicked off a small study to look into ways we can make a difference in the search for technological life. So if you remember, Congress, in 2018, actually had language in a bill. It was never fully realized, but it requested that NASA advance this field to some extent. So we just wanted to do kind of a light study to see, you know, to be ready in case this ever comes up again. So the goal of this study is essentially to gather information, creating a database. And that will include, you know, the purchase to search for technosignatures, whether there's any technology needs or gaps, and then other needs to advance the searches, you know, if that includes access to existing facilities, new funding avenues, access to data archives or ideas, and machine learning, and that kind of thing. The studies plan to just wrap up this coming summer. The first step was completed last month, which was to kind of list all the data fields to be collected. And the study includes a external technosignatures assessment committee to review each of these bits of work as they're completed. Another study that we actually just wrapped up, involved looking at nulling interferometry. So actually, ahead of the decadal survey release, we wanted to gather information on the current state-of-the-art for nulling interferometry in space and take another look at where we are in terms of technology gaps. We were anticipating, based on the exoplanet science strategy, that this could be, this could come up in the decadal. So a team of experts at JPL and Goddard took this on, revisiting, dusting off the TPF-I study and then looking at at how things have proceeded since then. However, Nick actually lost a bet with Paul Hertz. There really wasn't a prioritization of this capability in the decadal. So we're wrapping this up for now, but this is an extremely useful exercise. We'll, see possibly some SPIE papers coming out on this topic. And, you know, we'll have this on the shelf in case this comes up again. Finally, my last slide. I just wanted to mention our Exoplanet Exploration Technology Colloquium Series continued. We actually only had one talk, but it was a really interesting debrief on the deformable mirror study by Eduardo Bendek. If you missed it, we have the recordings and slides available on our website. You can expect some more colloquia coming soon, including the art of using KT matrices, assessing TRLs, and then more on ultrastability of telescopes. Okay, so just to wrap up, I'll return to this slide. It's one I always find to be very inspiring, the arc of exoplanet missions past, present, and future, that we're building on. And thanks to the decadal recommendation, we're now starting to turn a path to what comes beyond this. So thank you so much.

- All right. Thank you so much. We have time for a couple questions, and a couple questions were already answered by Doug Hudgins in the Q and A tool, so we'll skip those. So we'll start with, "Are there roles for program analysis groups to provide input in this," this says the science gap list, but we could also add the technology gap list process beyond the initial proposal process.

- Yeah, thank you for bringing that up. So, actually I think this topic is gonna be discussed at the business meeting later. The answer is yes, we would love that. We would love the ExoPAG to play a bigger role in reviewing our work. So I think we can, let' see. Sorry, I'm trying to flip back to our steps. So I think there's some natural places where that help would be really welcome. And so I think we will probably discuss that in more detail later.

- Okay, so I think this is a related question of how the science gaps that Karl mentioned in his talk tie to the technology gap identification and prioritization process.

- Yeah, that's a great question. So in past versions of the science gaps and the technology gaps, we kind of, you know, took a more active approach and looked at at how they mapped to one another. And I think maybe after this next round of updates, we can do the same thing. I mean, the processes are somewhat independent, but of course we're, you know, we engage our program office scientists. Karl and Eric are looking over our shoulder at a number of points in the technology gap process. And so there's definitely some cross-fertilization there. But yeah, I think some more explicit mapping between the two would probably be a very handy thing for everyone.

- Awesome, so there are some more questions, but I think in the interest of time, we should thank Brendan and all our speakers for a great session this morning. Just a reminder, there is a Slack channel that you can use for discussion as well. And I think it's time for a break actually. Well, a quick break, I guess. Michael, if you're on, maybe you want to just confirm.

- [Michael] Yeah, we can take five minutes and come back at 31 past, or sorry, 34 past the hour.

- Okay. So five minute break, and then we'll come back with the test talk. Thank you, again, to our morning speakers.