Earth: Observing Earth as an Exoplanet (variations, phase angle)30EE-1IROUV (exoplanets)Using observations of Earth to advance our understanding of how biospheres affect observed properties of planetsDetermine the effectiveness of co-adding reflected light spectra at different illumination phases and seasons when characterizing habitable terrestrial exoplanetsNoneNoEstablishes optimal observing strategy, cadence, wavelength range, and spectral resolution; reduces mission riskE-Q1e, E-Q2c+d, E-Q3b-d, E-Q4a-cLaunch a spacecraft to observe Earth as an exoplanetYYYAperture, Wavelength range, Spectral resolution, Spectroscopic modes/methods, Operations concepts, Observing strategy. EEM: Interesting question is: What new observations of Earth - or analysis of archival data - in near future would be helpful in clarifying design of IROUV for exoEarth survey? Submission seems to ignore other efforts to characterize remove observations of Earth (e.g. see Chap 4 of Robinson & Reinhard 2018; e.g. DISCOVR/EPIC, earthshine obs, EPOXI, etc.). Earth important for testing models, retreivals, etc. SCI-01
Atmospheres: Key signatures of exoplanet atmosphere diversity6EAt-1IROUV-exoplanetsAssess key signatures of exoplanet atmosphere diversity.What IROUV spectral resolution and wavelength coverage is needed to optimize classification of planets into broad atmospheric classes?Lab facilities available to measure the spectral signature of molecules/ions/aerosols in atmospheres at low temperatures (e.g., Titan)Lab facilities to be developped to measure the spectral signature of molecules/ions/aerosols in atmospheres at high temperaturesWhat IROUV spectral resolution and wavelength coverage is needed to optimize classification of planets into broad atmospheric classes?E-Q2. WHAT ARE THE PROPERTIES OF INDIVIDUAL PLANETS AND WHICH PROCESSES LEAD TO PLANETARY DIVERSITY?YYYCan we identify "basis sets" of exoplanet atmospheres which would span a useful range of space (formation and evolution), and inform strategies for efficient characterization (e.g. wavelength range and resolution)? Cf. EEM: see 'comparitive planetology' section of LUVOIR Report (Chap 1.4 & 4 & Appx B5; Signature Science Case #4: Comparative Atmospheres). This is an active ongoing region of research, including at the interface of exoplanets and Solar System science and much still needs to be done. As currently posed though, this gap is too broad, and could use some work to focus on specific sub regions needed more exploration. Key atmospheres to explore include evolved atmospheres (modified by atmosphere or ocean loss) for planets around different spectral types and for different planetary compositions, for the HZ, a diveristy of habitable but uninhabited atmospheres, a diversity of inhabited planets with biosignatures, environmental context, false positive or negative discriminants. Understanding the range of plausible environments uninhabitable/habitable/inhabited then helps identify target molecular features, and suites of features needed to interpret detections, which impacts needed wavelength range, spectral resolution, spectral sensitivity, observing cadence. SCI-02
Habitability [SubNeptunes]: Are some sub-Nepunes water worlds?14EW-1IROUV-exoplanetsIf yes, some of these worlds may be habitable and they are likely more observable than Earth-sized planetsYYSCI-02, SCI-16?
Signal Extraction: Separate planet light from exozodi light falling in the same spatial resolution element. (dupl w/#13)27ES-2IROUV (exoplanets)Light from HZ dust will be co-spatial at a given resolution element with the light from a potential planet detection in the same location. Researching and developing methods to separate the planet signal from the dust signal is crucial for achieving the highest S/N on the planet, which may require specific instrument characteristics (e.g., angular or spectral resolution) or observing strategies (e.g., appropriate integration time).Researching and developing methods to separate planet and dust signals, comparison of methods and their implementation to find the most effective/suitable.Studies of detection and characterization strategies for planets and their effectiveness are under way, but need to include the specific question how to separate the signals.See previous point.This significantly affects the architecture from primary mirror size to specific instrument capabilities (e.g., spectral resolution) and observing strategies (e.g., integration, thus survey duration).E-Q2, E-Q3Study of various methods to separate the signal (modeling, simulations), laboratory testbed for instrumentation designed to achieve this goal. Possibly a precursor mission or ground-based observations to mature the methods.YYYYYYAperture, Wavelength range, Pointing stability, Spectral resolution, Spectroscopic modes/methods, Polarization, Operations concepts, ServiceabilitySCI-03 (also SCI-11?)
Signal Extraction: Separate planet light from exozodi light falling in the same spatial resolution element. (dupl w/#27)13ES-2IROUV-exoplanetsMay directly impact design parameters such as spectral R and may reduce science yield at a given telescope size and wavelength. E-Q2 & E-Q3YYthis sounds like a technical requirement for the instrument, will require simulations with realistic planets and clumpy exozodi dust and simulating the instrument (analogous to simulated coronagraphic exoplanet spectra tool in Appendix B.1.1. of LUVOIR report).SCI-03 (also SCI-11?)
Time-resolved exoplanet spectroscopy and imagingIROUV (exoplanets)Some of the most difficult exoplanet observations will be time-based direct imaging/spectroscopy. These images have tremendous potential to identify sufface types such as oceans and continents, and potentially to identify/confirm the presence of biology. However, this an under-studied area of work as much of the prior work has focused on atmospheric (not surface) characterization. We need studies of the impacts of these surfaces on IROUV observables and the requirements for obtaining those observations.Need to understand what is possible/feasible for various combinations of architecture choices (aperture primarily) and target characteristics (such as distance to target). Some studies of modern Earth exist in the literature and in the LUVOIR final report. Further studies are needed to assess pigment detection and detection of different continent/ocean configurations than are present on modern-day Earth.Primary mitigation is leaning on prior research efforts.This could be the most ambitious observation we attempt with IROUV, and it is poorly studied. Its a critical gap!E-Q3 and E-Q4YYYSCI-03, SCI-06
Signal Extraction: Exo-Earth Photobombers: Time and wavelength varying blends of additional planets/moons in the same spatial resolution element as a potential Exo-Earth17ES-1IROUV (exoplanets)At the flagship mirror size recommended by the decadal, a potential Earth twin would have a PSF which was approximately equal to or larger than the system's HZ at 1-2.5um at distances beginning from 8-25 pc. The Earth, if viewed face-on by an analogous telescope from 10 pc away, would have a combined PSF with Venus for ~10-20% of its orbit in the 0.94 micron water band - at 20 pc, the Earth would have either Mercury, Mars, or Venus in its PSF over half the time. Identifying and extracting accurate spectra foundational to the flagships' goal will require an understanding of how to identify such issues for each individual system (including system inclination properties) and how both analysis techniques and sampling strategies on a detector can help mitigate the issue.Understanding trades that explore potential to extricate such photobombing sampling versus mirror size and versus pixel sampling on detectors for certain standard systems at pre-determined distances to ensure a sufficient sample of systems where
photobombers can be identified. Initial exploration of systems where such issues may be more difficult to solve with post processing based upon system properties. Work exploring the general time and wavelength varying effects on spectra.
See recent study by Saxena, 2022, varying and wavelength-dependent blending of additional planets (including those below noise floor) with target planets may lead to false positives and negatives in both identification and characterization efforts. It may also confound accurate estimates of time needed to observe a target to ascertain true atmospheric properties. All of these increase risk of main objective of finding and observing habitable worlds that may be Earth-like.While this gap goes directly to efforts will explore "Are we alone?", it more specifically is relevant to "How can signs of habitable life be identified and interpreted in the context of their planetary environment?" and "What is the range of planetary system architectures, and is the configuration of the solar system common?".End to end simulations of how the effect is likely to impact identification and characterization of Exo-Earths and exploration of potential mitigation strategies though both design architecture and post-processing methods. Analogue studies using ground based telescopes and Roman may also be pathfinders.YYYYYAperture, Wavelength range, Spectral resolution, Spectroscopic modes/methods, Instantaneous field of regard, Field of viewSCI-03?
Demographics (generic for #2 and #3)20ED-1IROUV (exoplanets)Knowledge of exoplanet demographics as a function of planet semi-major axis and radius/massThe IROUV mission yield is very much tied to the assumed exoplanet demographics, e.g. eta_EarthDulz, S., Plavchan, P., et al. 2020, the exoplanet demographics that were a merger of RV information, SAG13 and dynamical stability considerations and used in the HabEx and LUVOIR yield simulations and in the Standards and Definitions report.ExoPAG SIG2The science yield is directly tied to our knowledge of exoplanet demographicsYes - Direct imaging of ExoEarthsSIG2, continually revisited and refined exoplanet demographics. Creating a standardized virtual population of exoplanets orbiting direct imaging targets for mission yield estimates.YYAperture, Wavelength range, Pointing agility, Operations conceptsSCI-04
Demographics: Understand connection between small temperate planets and outer gas giants.9ED-2IROUV-exoplanetsIs an outer gas giant required in order to have a "dry" temperate planet (habitable, like Earth)? This might help prioritize direct imaging targets to search for biomarkers.E-Q1YY?YComments: I'm a little worried about letting theory of how important long-period giant planets are bias our targets. We won't have many viable targets anyway, so we probabl will need to observe them all anyway. This seems to fall into E-Q1e. Where Are the Nearby Potentially Habitable Planets and What Are the Characteristics of Their Planetary Systems? (I mention this because it might make sense to merge them before "voting", depending on how voting is done.). EEM: interesting theory and observational work, however it isn't clear that it would affect architecture design, although existence of giant planets impacting probability of existence of small HZ planets could affect prioritization of lower quality targets (fainter, more distant?) - sounds preparatory. However, it takes many years to characterize planetary systems (given long periods of distant planets, and need for lots of observations to constrain orbits) - so while 'preparatory', there is urgency to start sooner than late (indeed many of the likely IROUV exo-Earth targets have been on PRV surveys for decades due to their brightness).SCI-04, SCI-05
Demographics: Exoplanet demographics and eta-Earth among binary stars2ED-1bIROUV-exoplanetsDemographics of exoplanets around binaries (could be combined with single-star demographics, or binary targets)question of whether technicial ability to do multi-star wavefront control on tight binaries is needed could depend on whether there are any HZ planets to be found. If eta-Earth(tight binary) is too low, then probably not worth it, if eta-Earth(tight binary) is sufficiently high, then probably worth doing. Although some important nearby targets are tight binaries (e.g. Alpha Cen). Occurrence rates influence yield; many stars are binaries, binary observations influence instrument design, affects instrument design & multi-star wave-front control. Number of detectable exo-Earths goes as eta-Earth^0.96 (Stark+2019), see Decadal panel report page I-14, and Sec 12.9.2 of HabEx report.E-Q1. WHAT IS THE RANGE OF PLANETARY SYSTEM ARCHITECTURES AND IS THE CONFIGURATION OF THE SOLAR SYSTEM COMMON?This be mix of e.g. improved analysis of Kepler data with stellar data, RV surveys with current and near-future RV capabilities, theory/simulations on limits of existence of Earth-like planets given detection of larger planets, etc. YYYResults on planet frequency (especially exo-Earths) for binaries as function of separation could be included in yield calculations, and could inform design requirements related to high contrast imaging capability for tight bright binary stars. HabEx report Sec 12.9.2 is recommendation on technology for enabling planet searches in stellar multiples, but increasing scientific knowledge for those binaries is probably also important to achieve same aims: "there are many promising technologies that can suppress the scattered light from nearby binary companions to target stars, thereby allowing high- contrast imaging and potentially the detection and characterization of planets orbiting these stars. Given that roughly half of all solar type stars are in binary systems, these technologies have the potential to significantly increase the viable target sample and thus the number of planets that can detected and characterized within a given total observing time or IWA limit. " Are the planets even there to begin with in these binary systems? For which targets is it even possible to search for planets (planets not dynamically excluded)SCI-05
Demographics: Occurrence rates of earth-like planets around sunlike stars ("eta-Earth") (generic for #2 and #3)23ED-1eIROUV (exoplanets)Currently, the occurrence rate of Earth-like (similar radius, similar period to that the Earth) planets is largely unknown. While the Kepler mission was able to constrain the number, the errors on that constraint is significant enough that it adds significant risk and uncertainty to any mission architecture for a large IROUV mission for the 2040's-2050's. Despite promises, it has not been shown that planned missions abroad (eg, PLATO) will be able to significantly help mitigate this risk. Filling this science gap is key to the success of a large mission like the one mentioned above.A Kepler successor, most likely.There are none with the sensitivity needed to solve the issue in a short (~5-10 yr) timescale. Not directly from the US. Stellar activity likely precludes doing something like this via RVs. TESS might have some answers for the brightest obejcts in the CVZ, but likely not with the sensitivity needed to solve it.Extra funding for a Kepler-level mission successor perhaps.MMYYYYYAperture, Wavelength range, Spectral resolution, Spectroscopic modes/methods, Operations concepts, ServiceabilitySCI-05
Demographics: exoplanet demographics and eta-Earth for single stars3ED-1sIROUV-exoplanetsImprove knowledge of eta-Earth for single stars (previous entry is just for binaries)Recent eta-Earth estimates have uncertainties of ~+-50% (e.g. Bryson+2021: "We find that η⊕ for the conservative HZ is between 0.37+0.48−0.21 (errors reflect 68% credible intervals) and 0.60+0.90−0.36 planets per star, while the optimistic HZ occurrence is between 0.58+0.73−0.33 and 0.88+1.28−0.51 planets per star.")Given Decadal goal of delivering 25 hab zone rocky planets to search for biosignatures, and limited sample stars of sufficient proximity and brightness, means yield will depend sensitivity on frequency of such planets (reduce risk on designing mission to deliver Decadal goal). If we can't discover actual target plnets in advance, then improving our knowledge of eta Earth could reduce risk for a given mision size or reduce size/cost of a mission that must acheive some minimum number of detections. If we can't discover actual target planet in advance, then improved knowledge of eta Earth affects target list size.E-Q1. WHAT IS THE RANGE OF PLANETARY SYSTEM ARCHITECTURES AND IS THE CONFIGURATION OF THE SOLAR SYSTEM COMMON?Further analysis of Kepler data and integration with TESS/RV/etc data to reduce eta Earth uncertainties. YYYSince we'll be working with such a small sample size, it's not clear that it's better to focus on measuring eta-Earth (for any sample, e.g. improving Kepler estimate) than detecting and characterizing the planets around the actual target stars. Surveys for outer gas giants are feasible as precursor science (e.g. Gaia, RV, and ground-based direct imaging. This seems to fall into E-Q1b. What Are the Typical Architectures of Planetary Systems? EEM: published eta-Earth estimates are based on Kepler survey (small number stats and more distant population of Sun-like stars than local <20pc population) - besides further refinement of Kepler eta-Earth results, can more be done to improve knowledge of Kepler survey sample and comparison to local sample? (e.g. biases in binarity, metallicity/brightness, photometric noise?).SCI-05
Tools/Trades: Theoretical and computational trade studies in key mission parameters and exoplanet yield impact19ET-1IROUV (exoplanets)Improve upon current computation and theoretical estimates of how Exo-Earth and other exoplanet yields depend on key mission parameter choices such as iwa, diameter, SNR, spectral resolution, flux contrast, assumed noise model, and precursor knowledge.Higher fidelity simulations, standardization of evaluation, exposure time calculators, noise models; theoretical analytic scaling relations for point model comparisons for optimizing mission science objectives - e.g. maximizing number of imaged ExoEarthsExoSIMS, Altruistic Yield Optimizier, precursor RV simulationsBerberian et al. to be submitted theory paper on key mission parameter trades impacting survey yieldThis is the billion dollar question - optimizing mission design for maximizing science yield through high fidelity computational end-to-end simulations backed by theoretical scaling relationsYes - Imaging ExoEarths with IROUVa theoretical investigation based upon Berberian et al. to be submitted.YYAperture, Wavelength range, Pointing agility, Pointing stability, Spectral resolution, Spectroscopic modes/methods, Instantaneous field of regard, Field of view, Polarization, Operations conceptsSCI-06
Stellar High Energy Emissions: [high energy stellar emission + atmosphere evolution?]11EH-2IROUV-exoplanetsWhich stellar high-energy environments (photon and particle) are most conducive to development and maintence of "Earth-analog" (or other habitability criteria) atmospheres and how do escape processes change targeted atmospheric signatures around different types of stars?X-ray/IROUV observations/archival analysis + stellar models for EUV and stellar particles + planetary models for long term atmospheric (physical and chemical) evolution. Different instrumental techniques are optimial for characterizing atmospheres around different types of stars. Understanding the expected spectral signatures of different types of planets around different types of stars (as a function of time) enables us to focus the wavelength coverage and instrument sensitivity requirements for FGOsE-Q2 & E-Q3YYY?YYhigh energy/short wavelength spectrum of star probably needed for modeling atmospheric photochemistry of any detected planets. What is needed before architecture decisions? probably nothing... however, urgency may come from losing capability (e.g. UV spectra with HST?). When analyzing spectra of potentially habitable worlds, it would be useful to have detailed spectrum of star and ability to models atmospheres and interiors (coupled). All sounds "preparatory" or even "follow up", although could be "urgent preparatory" if ability to take observations in certain bands may disappear - especially if IROUV can not provide. A grid of UV/X-ray spectra for various Teff and chromospheric/coronal activity levels may be useful to build grid of synthetic spectra of planet atmospheres (even if not observed for each target individually - their activity levels are already known). "Follow-up" if UV spectra blueward to ~100nm could be measured with 6m itself (e.g. LUVOIR/LUMOS, HabEx/UVS?). See Sec 1.4.3 LUVOIR report (section "Stellar Spectra", p.1-18): "The host stars are bright (V < 11 mag) and the times required for high quality spectra [w/LUVOIR/LUMOS] are short."SCI-07
Stellar Abundances: Understanding the chemical connection between stars and their planet (interiors)29EC-1IROUV (exoplanets)Planetary interior structure and composition is fundamental to the planet's habitability. However, right now we are barely able to categorize a small planet (i.e. as Earth-like, a super-Mercury, or as a mini-Neptune) let alone determine whether the planet has tectonics, volcanism, and key geochemical cycles. To do this, we need to have precise mass and radius measurements of the planet as well as host star abundances for elements important to planets: Fe, Mg, Si, O, Al, Ca, Ti, Na, P, K, C, N, Th, and U (or their proxies). These key element observations are fundamental to use in conjunction in planetary interior models, which enable the determination of planetary classification, likely planetary interior structure, the potential of important geochemical cycles. High resolution (> 50k for optical, >20k for IR) spectra with high S/N (> 70), also capability to measure precise planetary mass and radiusThere are some high-resolution ground-based spectrographs but they are predominantly optical. However, the IR and UV -- necessary for many of these elements -- are difficult to measure from the ground. The combined high resolution and S/N are difficult to accomplish simultaneously -- no current balloon, cubesat, or satellite is capable of achieving high resolution stellar abundances. The combination of the stellar abundance measurements and the planetary interior models enables a robust planetary classficiation, which impacts the determination of eta-Earth, i.e. those that are truly rocky and have Earth-like composition. The geochemical cycles directly impact the composition of the atmosphere and often give similar signals as biosignatures (such as O2), making it impossible to definitively use the atmospheric composition to determine life on other planets. Also impacts planetary mass and radius measurements.E-Q1, E-Q2aYYYYYYWavelength range, Spectral resolution, Spectroscopic modes/methods.
EEM: Abundance data for best ~100+ Sun-like IROUV targets will be quite heterogeneous and incomplete. But not clear that detailed abundances are needed for mission design soon (precursor), but would be useful for planet modeling/spectra interpretation when IROUV takes spectra of planets (preparatory). Obviously if an exoEarth is imaged with IROUV, more detailed abundance measurements would be warranted (follow-up). see SAG 22 report.
NRH comment: Many key elements need to be in the UV and/or IR, which often isn't possible on the ground. In addition, there are no current balloon, cubesat, or satellite missions that can achieve the high S/N and resolution -- meaning this capability directly impacts the STM. In the interest of planetary diversity, it also behooves us to understand FGKM-type stars and not just Sun-like stars.
SCI-07, SCI-10
High Energy Emission: Host star spectral grid: high-energy emission for prediction of key spectral signatures18EH-1IROUV (exoplanets)1) Characterize how the diversity of stellar spectra change the optimal atmospheric signatures for detection around different types of stars, and 2) Determine which stellar high-energy environments (photon and particle) are most conducive to development and maintenance of "Earth-analog" (or other habitability criteria) atmospheres.
X-ray/UV observations/archival analysis + stellar models for EUV and stellar particles + planetary models for long term atmospheric (physical and chemical) evolution and spectral signature prediction (see previous gap #6).
HST + X-ray facilities operational through ~2025. However, a grid of stellar spectra for potential IROUV targets could be created with dedicated analysis and stellar modeling program without major additional observational effort.
HST + X-ray stellar programs to support JWST in place before launch; no comparable programs initiated for nearby star survey to support IROUV
Different instrumental techniques are optimal for characterizing atmospheres around different types of stars. Understanding the expected spectral signatures of different types of planets around different types of stars (and as a function of age/activity) enables us to focus the wavelength coverage and instrument sensitivity requirements for FGOs

E-Q2 & E-Q3Archival analysis of HST, IUE, and X-ray observatory archive, combined with stellar model development of the escape-driving XUV flux, to create a grid of high-energy radiation conditions covering notional IROUV target list in most important stellar mass, age, and activity parameters
YYYYYWavelength range, Spectral resolution, Spectroscopic modes/methods. The IROUV observatory will be able to observe the UV (but not EUV or X-ray) spectra of its host stars, however, this gap is about assembling a grid of high energy conditions for the IROUV target list (covering stellar mass, age, and activity) to predict the best spectral tracers for planets around different types of stars. One cannot predict exoplanet spectral features without the UV spectrum, so this task goes hand in hand with identifying the spectral features that drive wavelength coverage and spectral resolution of the exoplanet characterization instruments in the IROUV definition phase.SCI-07?
EPRV [Capability]: Extreme Precision Radial Velocity capability to detect Earth analogs and precisely measure their masses (dupl w/#5)4ERV-1IROUV-exoplanetsPrior survey for planets (y/n) informs size of target list, aperture etc. Without masses cannot accurately interpret atmospheric spectra. Is 2030s survey with new capabilities to detect & measure masses of exoEarths feasible? Is astrometry (other option) necessary? Do current EPRV archictures address this need or do we need alternative technologies/format?by time of IROUV trade decisions, there should be a NASA/ community "mass strategy" roadmap for 2030s and beyond (either w/IROUV or in support of IROUV) to support the detection and measurement of masses for the small HZ exoplanets IROUV will image/spectrally characterize. What mix of EPRV capability (ground or space) or astrometry (space) will be needed? Will IROUV itself be required to be the astrometric instrument (see e.g. LUVOIR HDI case for <1 uas astrometry capability)? Or another option? To what degree can EPRV detect and measure masses for IROUV targets, and measure ~10 cm/s amplitudes reliably (EPRV Working Group report; Morgan et al. 2022 JATIS). smallest claimed RV amplitude is Tau Ceti f (0.35+0.10-0.12 m/s), however this has not been confirmed. Only about 20 claimed detections of planets with RV < 1 m/s, with smallest uncertainties ~10 cm/s. Time series PRV spectra of Sun has yet to yield detection of Venus or Earth at ~10 cm/s level. New spectrographs have recently come online pushing measurements to tens of cm/s level (e.g. ESPRESSO, NEID, EXPRES). KPF will be commissioned on Keck later in 2022. EPRV Working Group published report and recommendations to NASA and NSF in 2021. EPRV Research Coordination Network (RCN) started 2022. Accurately characterizing atmosphers requires knowledge of planet mass. Therefore, we need to mature the ability of EPRV to the point where it can provide those masses or to realize that we need to pursue another approach (e.g., astrometry presumably at great expense). If EPRV can be completed in time to provide specific targets (and times to observe), then it will dramatically improve the efficiency and therefore reduce the time needed and cost. If EPRV can be completed in time to provide specific targets (and times to observe), then it will dramatically improve the efficiency and therefore increases science return.E-Q1Given the long-lead time needed for EPRV to measure masses of exoEarths (~15 years), need to advance this as rapidly as possible to ensure that we can have enough of a precursor survey completed in time to inform survey strategy. E.g., if we need to build out a network of EPRV facilities to acheive EPRV goals, then it will take even longer. YYYYThis seems to fall into E-Q1e. Where Are the Nearby Potentially Habitable Planets and What Are the Characteristics of Their Planetary Systems? (I mention this because it might make sense to merge them before "voting", depending on how voting is done.). EEM: The entire field of advancing EPRV to reach the capability to detect Earths around sun-like stars (~9 cm/s amplitude) is so important that it had its own recommendation in the Exoplanet Science Strategy (2018), however it is important precursor science for IROUV as by the time the design is finalized, we'll want to know how the masses of the hab zone exo-Earths will be measured (whether IROUV itself needs astrometric capability, or whether ground- or space-based RV is needed). Advancing EPRV to detect exoEarths - endorsement of ESS 2018 recommendation - was made in Sec 12.9.1 of HabEx report. Planet surface gravities and masses are not reliably extracted from retrievals of planet spectra at realistic R, S/N (Feng+2018 . Lupu+2016 "Observing planets with known masses therefore removes an important source of uncertainty and allows much greater precision in the inference of atmospheric abundances." Exoplanet Science Strategy (2018): "Mass is the most fundamental property of a planet, and knowledge of a planet’s mass (along with a knowledge of its radius) is essential to understand its bulk composition and to interpret spectroscopic features in its atmosphere. If scientists seek to study Earth-like planets orbiting Sun-like stars, they need to push mass measurements to the sensitivity required for such worlds." Important enough topic it has its own ROSES element in 2020 (D.17 )SCI-08
TTVs for Transiting ExoEarths: Minimum requirements to characterizing an Earth analog with TTV.22EV-1IROUV (exoplanets)Given different possible configurations involving an Earth analog and an inner neighbor, what sort of photometric precisions and how many transits are required to constrain the mass of the Earth analog?

Accurately characterizing atmospheres requires a planetary mass measurement. Finding Earth analogs for transmission spectroscopy will require a photometry successor to Kepler, that is precise enough and observes long enough to yield useful TTV. Given the low transit likelihood of Earth analogs, the discoveries may have no overlap with Earth analog candidates for direct imaging. However, tight constraints on Eta Earth will be of direct benefit to planning concepts for direct imaging and the survey would provide Earth-analog targets for transmission spectroscopy.
This is motivated by the approach of Plato, to combine the light of multiple cameras to both widen the field and improve the photometric sensitivity on targets that have multiple cameras on them. A high impact successor to Kepler would spend ~10 years on nearby sun-like stars obtaining precise photometry. Instead of a short stare and move on like K2/TESS/Plato, it may be worth the extra cost of simply having more identical spacecraft spending 10 years on different parts of the sky or adding aperture width to the same field with more cameras. The cost may even be comparable to Plato: experience with TESS and Kepler may make some parts cheaper, making it bigger or adding more cameras would add to the launch cost but maybe not the development cost.ESA's Plato mission will combine photometry from multiple cameras on the same targets to increase photometric sensitivity. However, Plato will not exceed Kepler's sensitivity or photometric baseline. This mitigates the risk of not obtaining a mass if challenges in EPRV take longer than expected to overcome. Assuming the Plato model for combining the photometry from multiple cameras on the same stars is viable, extending TTV to lower masses and longer orbital periods than Kepler is fairly low risk. A precise measurement of Eta Earth is an expected outcome before there is sufficient transit timing data, so this outcome is even lower risk.E-Q1e. Where Are the Nearby Potentially Habitable Planets and What Are the Characteristics of Their Planetary Systems?

Measuring the mass will also fall under..
E-Q2a. Which Physical Processes Govern a Planet’s Interior Structure?

Identifying candidates for transmission spectroscopy will also fall under...
E-Q2b. How Does a Planet’s Interior Structure and Composition Connect to Its Surface and
?YYYN?Aperture, Wavelength range. EEM: submission seems to be recommendation of (1) feasibility calculations + (2) another Kepler-like mission. # of transiting Earth analogs around Sun-like stars (1 in ~200?, periods ~ 1 year). If recommendation is another Kepler, this is probably "probe" class, not recommended by Decadal this decade, obviously beyond scale of small ROSES proposals. Explorer? SCI-09
Surveys: Precursor RVs of Direct Imaging IROUV Targets - pre-mission target identification and characterization (see also #1)21EU-1IROUV (exoplanets)Knowledge of which planets possess HZ planets - either terrestrial or gaseous - to help IROUV achieve lower cost, increased yield and increased survey efficiency, by optimizing target selection (e.g. observing targets with a priori known Exo-Earths, or avoiding targets with a-priori known gas giants in the HZ that dynamically cannot support a HZ ExoEarth).Precursor RVs and astrometry of direct imaging targetsNEID, ESPRESSO, EXPRES, MAROON-X are state of the art at visible wavelengths; at NIR wavelengths more investment is neededEPRV Working Group ReportPrecursor target information aids in target optimization, yield optimization, and in particular survey efficiency. It also reduces risk in the robustness of the mission architecture to our knowledge of and uncertainty in exoplanet occurrence rates and in particular eta_Earth.Yes -IROUVSee EPRV Working group RecommendationsYYYYAperture, Pointing agility, Operations concepts. EEM: even if nearby bright star has giant planet(s) in/near HZ, it will likely still be an important target for exoplanet studies ('big and small'). E.g. spectra of temperate gas giants and Neptunes between solar system examples and "hot" transiting varieties are still scientifically interesting. However, what if we find that very few of the nearest brightest ~50-100 targets can be home to exo-Earths given dynamical constraints from detected larger planet companions? Still value in getting orbits and masses of larger planets as well (preparatory).SCI-10
Surveys: Surveys for Exoplanets Orbiting IROUV Targets (generic of #1)7EU-1IROUV-exoplanetsKnowing where and when to look would dramatically increase the efficiency of a FGO. Knowing what other planets are in those systems would provide context for choosing targets that address goals.Knowing the number and properties of targets will allow for accurate mission simulations and reduce risk and cost since we can use actual targets rather than probability distributions.YYN?YEEM: likely pointing mainly at PRV and astrometric (Gaia) surveys over next ~5-10 years, question is how much they could impact IROUV design. Unlikely to have even mostly complete census of exoEarth targets for IROUV by end of 2020s (for Decadal goal of 25 HZ exoEarths to spectrally characterize) with 2020s spectrographs, however significant headway could be made towards discovering larger planets and some of the small HZ planets. Gaia may detect some distant giant planets, but not small ones. SCI-10
Surveys: EPRV survey of likely target stars of IROUV direct imaging missions to probe system architectures1EU-1IROUV-exoplanetsIf a significant fraction of the ~100 stars on the UVOIR Earth-analog search list are found to host planets that preclude Earth analogs, then the mission target list would need to be expanded to reach the 25 Earth analogs goal, which may impact the necessary apertureDetermining whether the ~100 stars on the UVOIR Earth analog search target list host massive planets near the habitable zone will remove risk of prioritizing stars that cannot host exo-Earths. Understanding properties of other planets in the systems is important for interpreting dections of biosignatures. E.g., do we only find biosignatures in systems with giant planets in 2-10 AU range? do we find that potentially habitable planets rarely show biosignatures if they're in system with Neptune-mass planets in the inner planetary system.E-Q1Y?YThis could be seen to fall into E-Q1e. Where Are the Nearby Potentially Habitable Planets and What Are the Characteristics of Their Planetary Systems? (I mention this because it might make sense to merge them before "voting", depending on how voting is done.). EEM: interesting topic - there is already considerable uncertainty in eta-Earth and many of the nearby systems are in binaries (adding to uncertainty), it is probably worth finding out the degree to which the top ~100 targets already have (or don't have) exoplanets - even if it is the larger ones being detected with current generation instruments. if the Decadal goal of delivering ~25 HZ exo-Earths is the "must" and not surveying ~100 stars, then exhaustive observational efforts (e.g. EPRV surveys?) should be made to lower the risk of delivering the Decadal goal with the selected UV/O/IR architecture.SCI-10
Surveys: Surveys for Exoplanets Orbiting Binary IROUV Targets (subgap of #7)8EU-1bIROUV-exoplanetsDiscovering exoplanet targets for IR/O/UV flagship around binariesAffects DRM and requirements for instrument and missionYYN?YTom Ditto: Do instruments have capability to find exoEarths around binaries? If not, then not clear if we need targets for them. Karl Stapelfeldt: An IROUV mission coronagraph should be able to deal with wider binaries > 5" separation. There are technology approaches to direct exoplanet imaging in closer binaries but they are currently far from demonstrating the needed capabilities. EEM: HabEx report recommends (Sec 12.9.2) "Technology Development for High Contrast Imaging of Binary Stars", so it makes sense to advance scientific knowledge of those binaries - calculate/refine orbits and parameters, stellar characterization (e.g. HZs), and estimates of planet frequency for binaries - and discover target planets in these systems. Arguably, the statistical result about the affects of binarity on planet frequency is more important in short term than the discovery of exoplanets orbiting specific nearby IROUV targets (if targets of such a survey are IROUV targets, all the better, but stats for small planets may be better from e.g., transit studies of binaries).SCI-10
Surveys: Direct imaging search for rocky, HZ planets around the nearest, suitable stars in the mid-infrared28EU-2IROUV (exoplanets)Detecting the first rocky, HZ planets around a few closest, most suitable stars is already possible in the N band from the ground. VLT/NEAR has shown this for alpha Cen with a candidate detection, but this is unlikely to be confirmed in the next decade until ELTs enter the scene. Detecting the first such planet(s) and starting characterization immediately as capabilities become available (EPRV, ELTs, etc.) will guarantee that we know as much as we can about the kind of planets we're looking for through actual observation of specific examples. This will help test strategies for detection and characterization, inform what to look for, etc. It will also allow for performing some of the science of a future exo-Earth imaging mission already, thereby gaining a head start on the questions to answer and how to answer them. Thermal-infrared observations are also critically complementary to fully understand the properties of directly imaged planets (radius, temperature, albedo can only be determined through thermal-IR observations in combination with visible-light imaging). Maturing this capability is thus critical to maximize the science return of an exo-Earth imaging mission.Sensitive mid-infrared observations from the ground on large telescopes equipped with adaptive secondary mirrors (for adaptive optics correction and best sensitivity).VLT/NEAR has observed alpha Cen and detected a candidate companion, but the instrument is unlikely to be available to follow up and confirm this detection (though this could possibly be achieved with a major community push to ESO). LBTI is currently able to detect Saturn-mass planets in the HZs around a small number of most suitable stars and possibly down to Neptune mass with a very deep observation.Fizeau imaging interferometry at LBTI with a 23m effective aperture for angular resolution and 2x8.4m collecting area can reach super-Earth sensitivity and resolve the HZs around a small sample of Sun-like stars (tau Cet, eps Eri, 61 Cyg A&B) and mini-Neptune to super-Earth sensitivity in the HZs and slightly further in around some more early-type stars. This requires a detector upgrade for which funding needs to be secured. E-ELT and the METIS mid-infrared imager are under construction to become available in about a decade and will revolutionize our ability to detect these kind of planets around a small sample of nearby stars. TMT/PSI is another instrument that may have a major impact in the next decade or two.Better understanding of the planets we are trying to detect and direct studies of one or more examples can allow us to better understand what we are looking for and how to detect it. This will allow us to optimize the mission in terms of both architecture and strategy.E-Q1, E-Q2, E-Q3Upgrade LBTI to enable Fizeau interferometric detection of rocky, HZ planets around the few most suitable target stars, carry out these observations.YYN?Aperture, Wavelength range, Pointing stability, Spectral resolution, Spectroscopic modes/methods, Polarization, Operations concepts, Serviceability: EEM: Mid-IR detection sounds like an opportunity, but how would it impact design of IROUV? Q: Are mid-IR detections of potentially hab worlds (e.g. HZ, ~0.8-1.4 Re) be possible within next few years on existing or planned instruments? Before 2028? SCI-10
Surveys: Characterization of potential binary star targetsIROUV (exoplanets)Many binary stars were removed from the LUVOIR & HabEx target lists. Some may actually still be viable targets to search for potentially habitable planets, if the stray light from the secondary is not too bright in the HQ of the primary (or vice versa). To know if this is the case, we need more than just a binary flag ... we need the stellar orbits and delta mags to use with a stray light model for the telescope.Orbits and delta mags for nearby binary systems hosting one or more Sun-like stars.Patchy ground-based surveys, I thinkPatchy ground-based surveys, I thinkMight expand target list and increase yield of potentially habitable planets discoveredSystematic high-resolution optical survey of nearby binary stars hosting one or more Sun-like starsY?YSCI-10
Exozodi: Exozodi dust brightness for IROUV target stars (dupl w/#10)24EZ-1IROUV (exoplanets)The amount (thus brightness) of habitable zone dust around specific mission targets and generally the typical amount around stars needs to be better quantified. Direct brightness measurements at visible wavelengths and strategies to accurately predict the brightness at visible wavelengths from the typically more readily available mid-infrared measurements need to be developed.Visible-light observations of exozodiacal dust around at least a small number of targets with known mid-infrared excess. Better a small survey of nearby stars with and without known mid-infrared excess. More sensitive observations at mid-infrared wavelengths and a larger sample of stars observed, including in the Southern hemisphere to better constrain the typical amount of HZ dust and to significantly constrain the HZ dust levels around mission targets specifically.LBTI has successfully completed the HOSTS survey for exozodiacal dust in the N band (Ertel et al., 2020). Crucial constraints have been derived, but more sensitive observations by a factor 2 to 3 would be crucial. Only half the stars that could have been targeted in the Northern hemisphere were observed. The other half could be observed with the same instrument performance. Roman/CGI is in principle able to detect a sample of HZ dust disks at visible wavelengths (exact number depends on instrument performance, to be determined), but time needs to be allocated to these observations.The LBTI team is working on improved background subtraction of existing and future data that could provide a significant sensitivity improvement (factor ~2, to be determined). The team is also working on securing a new detector that was determined to be the critical step to improving the instrumental sensitivity by a factor ~2 to 3, but funding needs to be secured. Vibration mitigation is in progress for further sensitivity improvement. Altogether, the sensitivity improvement expected from these efforts is potentially transformational with precise measurements on individual systems in reach at a precision similar to what is currently only reached on the whole sample.
A new nulling interferometric instrument (Hi-5) is being developed for ESO's VLTI in the Southern hemisphere. While it will operate at L band and thus be more sensitive to warmer dust than the that in habitable zone, this wavelength range is still suitable to detect dust close to the HZ and this will thus enable the first sensitive survey for warn HZ dust in the South.
I am not familiar with the exact status of a potential Roman/CGI survey, somebody better informed should comment.
Compensating for higher exozodi levels requires adjustments to aperture size, spectral resolution, etc., that come with extra costs. Understanding exozodi levels better informs which design choices are necessary or not. Alternatively, either a more expensive mission needs to be designed to mitigate risk and be on the safe side, or the risk of a lower yield needs to be taken into account.Yes, broadly in E-Q1 and E-Q2, though this is more a programmatic than scientific question. Other gaps more directly addressing the science aspects of this will be submitted.- LBTI detector upgrade and new exozodi survey with improved sensitivity.
- VLTI/Hi-5 exozodi survey of Southern stars.
- Roman/CGI exozodi survey.
- Theoretical work connecting visible and mid-infrared brightness of exozodis.
More specifically and immediate for proposals in fall 2022 given limited funding:
- Continued efforts to improve LBTI background subtraction.
- Define target list, plan observing strategy, and optimize exozodi data reduction for Hi-5.
- Modeling work and review/study of literature and archival data to predict scattered-light brightness of HZ dust (dust properties, albedo, etc.).
- Develop target list for Roman/CGI exozodi survey, develop different strategies depending on final instrument performance and time allocated.
YYYYAperture, Wavelength range, Spectral resolution, Spectroscopic modes/methods, Polarization, Operations concepts, ServiceabilitySCI-10 & SCI-11
Exozodi: Exozodi dust brightness for IROUV target stars (dupl w/#24)10EZ-1IROUV-exoplanetsHZ exozodial dust brightness around target stars and median brightness around stars in generalimprove knowledge of mean zodi level and distribution for exoplanet yield simulations that vary architecturesLBTI/HOSTS survey (Ertel+2020 ExoPAG SAG 23 (The Impact of Exo-Zodiacal Dust on Exoplanet Direct Imaging Surveys) was recently organized to address this yield prediction of exoplanets, primary mirror size, integration times.E-Q2 & E-Q3See Sec 12.9.3 of HabEx report - recommendations for "Improved Characterization of Exozodi Levels around Nearby Sunlike Stars". Further LBTI IR zodi observations? Roman/CGI observations in visible? YYY?Y"Chris Stark: I'd suggest focus on exozodi observations in the VIS/NIR, as well as structured exozodi
Bertrand: Which would aslo help understand the hot dust below and in particular whether it is coming from the HZ or not. A solar zodi model applied to Tau Ceti MIR (11um) data is 124 zodis. A solar zodi model applied to Tau Ceti NIR data is 10,0000 zodis! Steve: VIS/NIR is important, but mid-IR is what is readily available right now and can make the most progress in the near future with a lot still to learn! So we should definitely continue this. Bertrand: Yes, we need panchromatic data to get a better picture, mIR and NIR as well, ideally." EEM: While LBTI HOSTS provide statistical result, relatively few likely IROUV targets were observed, and usually with very large uncertainties. Current sims use zodi distribution informed by HOSTS, but still considerable uncertainty. Exoplanet yields scaled only softly with median exozodi level (e.g. Stark+2019 - for 4m monolith off-axis yield goes as <n_zodi>^-0.23, and for 8m segmented off-axis <n_zodi>^-0.14, i.e. much weaker dependence than eta-Earth (~linear). But what if the systems with exoEarths are dustier on average? or the exozodi dust clumps? SE: LBTI could be a factor 3-5 more sensitive, then providing useful constraints for individual stars. $2.5M upgrade + implementation of new data reduction methods being developed. Plus observations+science on relevant stars. Not for this call, but certainly worth doung!
SCI-10, SCI-11
Architectures: Presence, distribution, and dynamics of minor bodies in HZs, implications for planets and planet habitability (combined with duplicate gap #16)26EAr-1IROUV (exoplanets)Part of planetary system architecture. Minor body impacts affect atmospheric evolution, properties, planet habitability, ..... Minor bodies (comets, asteroids) are an important component of planetary systems. Their presence, distribution, and dynamics can inform about the presence, location, and orbits of planets in the system. Impacts from minor bodies on a rocky planet can strongly affect its atmosphere and the development of life, depending on impactor composition (origin), impact frequency (origin, orbits), and impact energy (size, orbits). Better knowledge of the presence of minor bodies in the target systems can thus help inform target lists for a general exo-Earth search (what systems best to search for planets), identify and prioritize detections for time-consuming follow-up spectroscopy (planets in what systems are most likely to host life), and understand the outcome of these observations (why does a planet host life or not given the environment it exists in).Minor bodies cannot be observed directly. Common signatures of minor bodies are the presence of exozodiacal dust and transient circumstellar gas ("falling evaporating bodies"). In a few extreme cases, transiting cometary clouds can be detected photometrically. Sensitive, detailed observations of known exozodis and surveys to detect more exozodis are needed to better characterize them and better understand their connection to the minor bodies (e.g., comet evaporation vs. asteroid collision as the origin of the dust, Jupiter family vs. Oort cloud comets). Monitoring of known systems with transient gas and surveys for more systems are needed to better characterize those features and link them to planetary system architectures. Theoretical and modeling studies of the properties and origin of the dust/gas to better understand the observations, and of the effects of minor body impacts of various kinds on planet atmospheres.Hot and HZ dust are commonly observed using interferometry (optical long-baseline interferometry and nulling interferometry), but sensitivity is limited. Several surveys have provided critical information, but much more to learn if sensitivity can be boosted. Transient gas features are now observed with a number of spectrographs on smaller telescopes, so that observations are relatively inexpensive. Theoretical and observational studies of exozodiacal dust are ongoing but limited on scope due to limited resources. First studies of the effects of minor body impacts have been conducted, but the parameter space explored is so far limited and these studies need to be expanded.LBTI has the potential to be 3+ times more sensitive through a detector upgrade, but funding needs to be secured. VLTI/Hi-5 will be a new nulling interferometer in the Southern hemisphere with new, critical capabilities to better characterize and understand both HZ and hot exozodiacal dust. Limited theoretical studies are ongoing but need to be extended.The impact as far as it is related to precursor science is largely on target selection for survey and follow-up observations. This can significantly improve the mission yield or reduce the amount of photons that need to be collected to reach a given yield: e.g., reduce the number of targets that need to be observed/followed up, thus save on total survey time, or secure a high return from a smaller/less sensitive mission as more integration time can be spent on the best targets.E-Q1,E-Q1b. What Are the Typical Architectures of Planetary Systems?, E-Q2, E-Q3, E-Q4For 2022 proposals given limited funding:
- Theoretical and modeling studies of available exozodi observations.
- Modeling of the effects of minor body impacts on planet habitability for a wide range of parameters. (But does this affect IROUV design?)
- Preparation for Hi-5 observations (target lists, pipeline optimized for exozodi detection). (what is Hi5?)
- Spectroscopic monitoring of systems transient gas features. (But does this affect IROUV design?)
- Hi-5 survey for and characterization of exozodiacal dust.
- More LBTI observations (characterization, survey) of exozodiacal dust with upgraded system.
- Large, deep surveys for transient gas features. (But does this affect IROUV design?)
- development and application of a comprehensive exozodi data fitting tool to extract the most information from heterogeneous observations (e.g., near-IR and mid-IR interferometry from various facilities).
?YYYYYYOther ideas for precusor science activities are JWST spectroscopic monitoring of time-variable debris disks that, together with theoretical modeling, can help understand the production and evolution of dust in the inner planetary system. Also theoretical models that study the production of dust during terrestrial planet formation and the population of small bodies that are behind. EEM: If JWST (or previously Spitzer) can detect a thermal IR excess from a debris disk, isn't that system already too dusty? (i.e. >hundreds zodis?). "minor bodies" are inferred from dust. So is this really about studying dust, and what aspects? "influence" on habitability maybe a follow-up topic for interpreting spectrum of a planet. main indicator of "minor bodies" is exozodi dust - important as source of background (potentially prohibitive in dustiest systems), or does author mean dynamics/simulations? Roman/CGI can provide constraints on exozodi dust (preparatory). IROUV itself will detect exozodi structures along with the planets (followup). So there are "preparatory" and "followup" aspects of this gap, but it isn't clear there is a "precursor" aspect. SE: Well, we're looking for habitable planets, so knowing better in which systems rocky, HZ planets are likely habitable can help prioritize target lists.SCI-11
Exozodi: Better understand hot exozodiacal dust (dupl w/#25)12EZ-2IROUV-exoplanetswhat is the relation between the hot exozodiacal dust and HZ exozodiacal dust probed by LBTI/HOSTS (10um)?Possibly linked to HZ dust, system dynamics, etc., thus may affect mission yield, planet parameters, etc.E-Q2 & E-Q3YYY?EEM: hot zodi dust as risk? what is the relation between the hot exozodiacal dust and HZ exozodiacal dust probed by LBTI/HOSTS (10um)? topic of SAG 23. SCI-11
Exozodi: Better understand the impact of hot exozodiacal dust on exo-Earth imaging performance (dupl w/#12)25EZ-2IROUV (exoplanets)Hot exozodiacal dust is dust close to the star, further in than the habitable zone and possibly as close as the dust sublimation distance. The origin of this dust is unclear but must be linked to a reservoir of material in the outer system. Thus, material must be moving through the HZ and this likely deposits material there as well, which may be an issue for exo-Earth imaging. Moreover, the presence of significant amounts of dust at ~4-10 stellar radii (dust-to-star flux ratio in H/K bands ~1% unclear how much scattered-light to expect at visible wavelengths) may result in significant coronagraph leakage compared to purely photospheric emission from the star, even if the emission is behind the coronagraph. This may degrade the contrast reached by an exo-Earth imaging mission.Better understand the connection between hot dust and habitable zone dust, i.e., detection of both dust species around nearby stars. Hot exozodiacal dust is commonly detected using precise near-infrared interferometry, HZ dust using nulling interferometry. Better understanding of the location and properties of hot dust in systems where it has been detected, through detailed modeling of the data. Theoretical studies of the origin of the hot dust. Predictions of coronagraph performance in the presence of extended emission from hot dust.VLTI/PIONIER is currently the only instrument capable of detecting hot exozodis, but the instrument has not been used for this in ~5 years and efforts need to be re-started. VLTI/MATISSE has been shown to be able to make some contributions. LBTI could be used to study hot dust, but implementing this capability requires funding and effort. LBTI is the only instrument capable of detecting HZ dust, Roman/CGI may provide this capability in the future for a sample of stars. No clear correlation between hot and warm dust has been identified so far. Individual efforts to model hot dust have been made, but no comprehensive modeling approach has been developed. Theoretical studies of the origin of the hot dust have so far only been able to identify processes that do not work and unlikely candidates, while the only known process to deliver the dust that could potentially work (star-grazing comets) needs further investigation. No analysis of the performance of coronagraphs in the presence of extended emission has been performed, though tools that could be adopted for this are available.Modeling and theory efforts are ongoing, but limited. VLTI/Hi-5 will be able to detect hot exozodis at unprecedented sensitivity in the near future and better make the connection between warm and hot dust as it operates in the L band (vs. H band for PIONIER and K band for past instruments). A small effort to characterize hot exozodis with MATISSE is in progress, but limited in scope due to resource limitations and limited success of securing telescope time. JWST/NIRISS aperture masking may be able to detect hot exozodis and critically inform the dust distribution and spectral shape of the emission, and thus the dust origin and properties.Coronagraph leakage is a risk that needs to be understood and mitigated. Habitable zone dust levels require adjustments to aperture size, spectral resolution, etc., that come with extra costs. Understanding exozodi levels better informs which design choices are necessary or not. Alternatively, either a more expensive mission needs to be designed to mitigate risk and be on the safe side, or the risk of a lower yield needs to be taken into account.Yes, broadly in E-Q1, E-Q2, and E-Q3, though this is more a programmatic than scientific question. Other gaps more directly addressing the science aspects of this will be submitted.Immediately for the 2022 call given limited funding:
- More theoretical studies of the origin of the hot dust and implications for HZ dust.
- JWST/NIRISS NRM observations to determine if they are able to detect and characterize the hot dust.
- Develop a comprehensive and unified modeling approach and tool to extract the most information from available and future observations of hot dust.
- Study of the impact of extended emission on coronagraph leakage and exo-Earth imaging contrast.
More long-term (more expensive, longer lead time, but some effort could/should be started with 2022 proposals):
- Survey observations with LBTI/Hi-5 to better understand the hot dust distribution, origin, and connection to HZ dust.
- Deep observations of the HZ dust (LBTI) in systems that have hot dust to understand the connection.
YYYYAperture, Wavelength range, Pointing stability, Spectral resolution, Spectroscopic modes/methods, Polarization, Operations concepts, ServiceabilitySCI-11
Exoplanet radii uncertainty15ER-1IROUV-exoplanetsConstrain and propagate the uncertainty of planet radius for exoplanets to be discovered by direct imagingDirect-imaging detections do not measure the planetary radius directly; rather, it would be determined together with the albedo. Will need to figure out how to constrain this uncertaintiy or incorporate this uncertainty in mission designE-Q2YYNYEEM: Acknowledged limitation of direct imaging that exoplanet radius isn't directly measured. already carrying considerable uncertainty on planet albedos, let alone radii. Yield simulators take into account a distribution of planet sizes informed by Kepler stats (e.g. SAG 13, e.g., LUVOIR report Sec 3.4.1, HabEx report Sec. 3.3.2). SCI-12
Theory: Connecting "Standards of Evidence" to ObservablesIROUV (exoplanets)The recent "Standards of Evidence for Biosignature Detection" workshop gives us a framework for biosignature detection and vertification/validation. This post-dated the mission concept studies and was done in parallel to the decadal survey. Thus, there has not yet been an opportunity to map thoes standards to specific observables, or those obesrvables to eventual drivers for the future observatory.Need to develop observables associated with various "steps" in the biosignature detection framework published in the workshop report.The foundational theory is there, as much of it led to the workshop's report. Now we need to fund people to go "in the other direction" from the standards to the observations.Active community or people have been thinking abou this.These may end up on the far-left side of the STM. Figuring out how those updates to that column map to the right side will be critical. Most likely impacts will be on direct imaging spectroscopy requirements such as wavelength range, noise characteristics, and spectral resolution.E-Q4Funding of simulations of observations that would "check" various levels of the framework. Consideration of impacts on wavelength range and spectral resolution for direct imaging.YYSCI-16
Simulations of Biosignature Characterization YieldsIROUV (exoplanets)We need to understand the time it will take to fully characterize potetnially habitable exoplanets, and understand the yields that result from those obsering times. This will be a critical piece of information for assessing the quality of information we get from various architectures.We need biosignature characterization yields.We have yields for planet detection but not for full characterization.None.This could be huge - heavilty impacted by many top-level archiecture decisions/trades.E-Q3 and E-Q4YSCI-16, SCI-06
EPRV [Capability]: Develop and validate the capability to measure precise and accurate EPRVs for likely IROUV targets in the presense of stellar variability. (dupl w/#4)5ERV-1IROUV-exoplanetsAbility to measure masses of exo-Earths and to characterize their atmospheres is dependent on ability to separate true RV signals from stellar variability. Validating complex data analysis tools and developing community trust in such methods (through combination of open-source tools and data challenges (e.g., testing based on solar data, synthetic data generated from solar data or simulations) will be essential to making science reliable. DuplicateMass measurements are critical, so we need to know whether EPRVs can deliver those. Knowing orbits in advance could enable a starshade design to be competative with designs with less slew time costs. Knowing orbits in advance would improve efficiency of observations and therefore allow for a smaller/shorter lifetime mision. Knowing orbits in advance would improve efficiency and allow characterizing more planets within a given mision's specsE-Q1YYYDuplicate with #2.SCI-8, SCI-10
Mapping Planet Diversity Theory to Yield Targets and Specific ObservablesIROUV (exoplanets)We have quantification of the yields of various planet types, but except for the habitable zone, these are disconnected from theories on planet formation and evolution.We need specific hypotheses related to planet formation and evolution, translated to yield targets and spectral observations.This will have an impact on multiple architecture and instrument properties, including aperture size, wavelngth range for direct imaging spectroscopy, IWA, OWA, and spectral resolutionE-Q1 and E-Q2simulations on how various yields would impact our ability to assess different models for planet formation or different theories on planet diversityYY
Absorption cross section determinationIROUV (exoplanets)We need continued advancement and expansion of laboratory assessments of absorption features for molecules that may appear in terrestrial but "not-Earth-like" worlds. Examples include features that appear at higher pressures, such as collision-induced absorption, and features of gases not present at high abundances in Earth's modern atmosphere.expanded line lists and absorption cross section listscould impact spectroscopy requirements such as wavelength range and resolutionE-Q1, E-Q2, E-Q3, and E-Q4continued funding of lab astro investigations of line lists - should be tied to potential observables on exoplanetsYY
Alternative BiosignaturesIROUV (exoplanets)There is a continued need to "think outside the box" when it comes to biosignatures. In the LUVOIR and HabEx reports, we advanced from "modern Earth" to "the Earth through time." But we need multiple expansions of this to biosignatures that would exist for other kinds of planets. This need to map to specific observables and parameters such as wavelength coverage.Need to know the biosignatures so we can fold them into mission designCould impact spectroscopy requirements such as wavelength range and resolutionE-Q4Photochemical simulations with sustainable fluxes of proposed biosignature gas, and predictions of the resulting spetra.YY
Agnostic and Quantitative BiosignaturesIROUV (exoplanets)Planetary science life detection has been advancing the idea of "agnostic" biosignatures that do not presume the kind of life present on the world. This would potentially expand our family of biosignatures and make the search for life more theoretically robust. Additionally, many of the agnostic biosignatures are quantiative in nature, which would bring additional rigor to the biosignature search and provide the future project team with additional metrics for assessing the quality of data returned by different architectures.We need these frameworks to be developed and applied to IROUV architectures.Could impact many, many architecture choices.E-Q4For starters, need demonstration of effectiveness of proposed biosignature. Then need to show how it can be assessed in the context of potential IROUV data. Eventually need to do this as a function of architecture properties.YY