This white paper presents an analysis of Astro2020 science priorities and NASA's future astrophysics mission architecture, advocating for a coordinated fleet of $1–2B missions, smaller than typical Flagship observatories, but strategically designed to complement them, i.e. a “Next Generation Great Observatories" program. The study addresses opportunities in current mission planning, design, and implementation and proposes a strategic approach to maximize scientific return on investment while strengthening partnerships across NASA divisions, other government organizations, universities, and industry.

High-resolution imaging is widely used to constrain false-positive scenarios in exoplanet validation, but it is a finite follow-up resource that reaches only a subset of candidates, and its population-level impact on validation outcomes has not been quantified through controlled removal experiments. Using an automated pipeline built on TRICERATOPS, we compute the false-positive probability (FPP) of 443 TESS planet candidates. For the 264 planet candidates with high-resolution imaging observations, we compute FPP with and without the corresponding contrast curves, allowing us to quantify the impact of the additional data. We find that 72

JWST defines a new era for the data-driven approach of retrieval modelling, which has become a cornerstone tool for the statistical inference of exoplanetary and brown dwarf properties. The Early Release Science program #1386 observations of VHS 1256 b represent a huge jump in data quality, data quantity and spectral coverage for such objects. VHS 1256 b is a young, planetary mass and extremely variable companion that populates the enigmatic L/T cohort of substellar atmospheres. In this first retrieval analysis of the full 1 - 18 micron dataset, we apply the Brewster retrieval framework to the NIRSpec and MIRI spectroscopic observations of VHS 1256 b, exploring a variety of cloud species and structures. Using Delta(BIC) we find that the data is best described by a forsterite (Mg_2SiO_4) and enstatite (MgSiO_3) cloud combination. Our analysis shows a strong preference for patchy silicate cloud coverage, which aligns with VHS 1256 b's extensive and well documented spectral variability. Our retrieval is able to place constraints on the abundances of H_2O, CO, CO_2, CH_4 as well as NH_3. We also show that the retrieved parameters are sensitive to the data used and the relative signal-to-noise ratios between data from different instruments. We conclude with the next steps for the wider retrieval community to better understand young and cloudy exoplanetary atmospheres.

The Nancy Grace Roman Space Telescope's Wide Field Instrument (WFI) will observe hundreds of thousands of bright stars across its Core Community Surveys, particularly in the dense stellar fields of the Galactic Bulge Time Domain Survey (GBTDS). Sources brighter than 17th magnitude will saturate WFI detector pixels in typical survey exposures, with the brightest stars deeply saturating large pixel regions and potentially producing persistence signals that may impact subsequent observations. Prior detector characterization did not explore the regime of deep point source saturation. To address this gap, we conducted a bright star saturation test during WFI's second Thermal Vacuum test campaign (TVAC2) at BAE Space Mission Systems in Boulder, CO. Using the Stimulus of Ray Cones (SORC) telescope simulator, we projected nine in-focus point sources through the F146 filter onto two Sensor Chip Assemblies (SCAs), with fluxes tuned to approximate stellar magnitudes ranging from 4 to 18 in 170 s exposures. We present analyses of the saturation response and persistence properties of these detectors. We find that the saturated region of a 4 mag source grows to 150 pixels in diameter after 170 s of illumination, compared to 15 pixels for a 12 mag source. Pixels adjacent to the expanding saturation front exhibit pronounced non-linear behavior consistent with charge leakage from saturated neighbors. For persistence, we find that the median signal in the first post-illumination dark exposure is broadly consistent across source magnitudes spanning 4 to 17, and that persistence decays to detector background levels (≲0.05 e^- s^-1) within approximately 20 minutes, consistent with flat field persistence measurements from the same TVAC2 campaign. These pre-flight characterization results inform community understanding of WFI detector response to prepare for Roman science.

We present the first homogeneous catalog of Kepler, K2, and TESS host stars and the corresponding catalog of exoplanet properties, which contain 10022 stars and 10189 planets, respectively. We used isochrone fitting and Gaia DR3 photometry, parallaxes, and spectroscopic metallicities to compute precise, homogeneous Teff, logg , masses, radii, mean stellar densities, luminosities, ages, distances, and V-band extinctions for 3387, 618, 6017 Kepler, K2, and TESS host stars, respectively. We compared our stellar properties to studies using fundamental and precise constraints, such as interferometry and asteroseismology, and find residual scatters of 2.8%, 5.6%, 5.0%, and 31%, with offsets of 0.2%, 1.0%, 1.2%, and 0.7% between our Teff, radii, masses, and ages and those in the literature, respectively. In addition, we compute planet radii, semimajor axes, and incident fluxes for as many as 4285, 678, and 5226 Kepler, K2, and TESS planets, respectively, and find that the exoplanet radius gap is less prominent in the K2, TESS, and combined samples than in the Kepler sample alone. We suspect this difference is due to heterogeneous planet-to-star radius ratios, shorter time baselines of K2 and TESS, smaller sample sizes, and the different gap locations hinted at by the K2 (similar to 1.5 R circle plus) and TESS (similar to 1.8 R circle plus) planet radius distributions. Finally, we identify a clear radius inflation trend in thousands of hot Jupiters and find 151 hot sub-Neptunian desert planets, in addition to a population of 233 young (less than or similar to 1 Gyr) host stars as potential opportunities for testing theories of planet formation and evolution.

Stellar photospheric heterogeneity is a dominant astrophysical systematic impacting exoplanet transmission spectroscopy. NASA's Pandora SmallSat Mission is designed to address this challenge through contemporaneous visible-band photometry and near-infrared spectroscopy of exoplanet host stars. Here, we present an end-to-end simulation study quantifying Pandora's ability to infer stellar photospheric properties and correct stellar contamination using out-of-transit observations. We construct eight representative stellar activity scenarios and generate 160 simulated Pandora datasets, incorporating time-dependent stellar spectra, instrument response, and noise. Given accurate models, Bayesian retrievals of joint visible photometry (0.4-0.7 mu m) and near-infrared spectroscopy (0.9-1.6 mu m, R approximate to 120) recover photospheric temperatures with typical uncertainties of approximate to 30 K, with no significant bias. Models with two spectral components (i.e., a quiescent photosphere and spots) are strongly favored in 95% of cases; one-component models are preferred when true spot filling factors fall below a detection threshold of approximate to 0.3%. We propagate the true and inferred stellar parameters to compute true, inferred, and residual contamination signals under physically motivated spot geometries. For simple spot distributions, contamination signals of 102-103 ppm are reduced to less than or similar to 10 ppm-well below Pandora's expected transmission spectroscopy precision (30-100 ppm). For more complex spot distributions, geometric degeneracies limit deterministic corrections, leaving residual contamination at the 103 ppm level that must be mitigated using additional constraints, such as spot-crossing events and joint stellar-planetary retrievals of transmission spectra. These results define regimes in which stellar contamination can be corrected from stellar observations alone and show how Pandora stellar observations can identify cases where additional information is required.

We report the masses, sizes, and orbital properties of 86 planets orbiting 55 stars observed by NASA’s K2 Mission with follow-up Doppler measurements by the HIRES spectrometer at the W. M. Keck Observatory and the Automated Planet Finder at Lick Observatory. Eighty-one of the planets were discovered from their transits in the K2 photometry, while five were found based on subsequent Doppler measurements of transiting planet-host stars. The sizes of the transiting planets range from Earth-size to larger than Jupiter (1–3 R _⊕ is typical), while the orbital periods range from less than a day to a few months. For 32 of the planets, the Doppler signal was detected with significance greater than 5 σ (51 were detected with >3 σ significance). An important characteristic of this catalog is the use of uniform analysis procedures to determine stellar and planetary properties. This includes the transit search and fitting procedures applied to the K2 photometry, the Doppler fitting techniques applied to the radial velocities (RVs), and the spectral modeling to determine bulk stellar parameters. Such a uniform treatment will make the catalog useful for statistical studies of the masses, densities, and system architectures of exoplanetary systems. This work also serves as a data release for all previously unpublished RVs and associated stellar activity indicators obtained by our team for these systems, along with derived stellar and planet parameters.

We present observations of the 1.35 ± 0.07 Earth radius planet L 98-59 c, collected using Wide Field Camera 3 on the Hubble Space Telescope (HST). L 98-59 is a nearby (10.6 pc), bright ( H = 7.4 mag) M3V star that harbors three small, transiting planets. As one of the closest known transiting multi-planet systems, L 98-59 offers one of the best opportunities to probe and compare the atmospheres of rocky planets that formed in the same stellar environment. We measured the transmission spectrum of L 98-59 c, and the extracted spectrum showed marginal evidence (2.1 σ ) for wavelength-dependent transit depth variations that could indicate the presence of an atmosphere. We forward-modeled possible atmospheric compositions of the planet based on the transmission spectrum. Although L 98-59 was previously thought to be a fairly quiet star, we have seen evidence for stellar activity, and therefore we assessed a scenario where the source of the signal originates with inhomogeneities on the stellar surface. We also see a correlation between transits of L 98-59 c and L 98-59 b collected 12.5 hr apart, which is suggestive (but at <2 σ confidence) of a contaminating component from the star impacting the exoplanet spectrum. While intriguing, our results are inconclusive and additional data are needed to verify any atmospheric signal. Fortunately, additional data have been collected from both the HST and James Webb Space Telescope. Should this result be confirmed with additional data, L 98-59 c would be the first planet smaller than 2 Earth radii with a detected atmosphere.

The Roman Space Telescope Wide Field Instrument (WFI) will enable revolutionary advancements in astronomical survey science. Instrument sensitivity spans the 0.5 to 2.3 mu m spectral range with a significant increase in field of view, detector sensitivity, and angular resolution compared with existing observatories. The science of the observatory drove tight stability requirements and necessitated an array of different optical elements within WFI to switch between imaging at different wavelengths, using two slitless spectroscopic elements. The science also drove the need for an uncommonly high level of detector calibration, requiring an on-board calibration system supported by unique optics, as well as precise stray light mitigation. WFI has recently completed its year-long integration and test campaign as a full instrument, including multiple environmental tests, enabling its performance to be studied in operational temperature conditions. This publication summarizes several key optical performance aspects of the instrument, including bandpass filter wavefront error, stray light control, and optomechanical alignment. The results demonstrate that the WFI is ready to help transform astrophysics as part of the next NASA flagship observatory.

The population of giant planets on wide orbits around low-mass M dwarf stars is poorly understood, but the unprecedented sensitivity of JWST NIRCam coronagraphic imaging now provides direct access to planets significantly less massive than Jupiter beyond 10 au around the closest, youngest M dwarfs. We present the design, observations, and results of JWST Guaranteed Time Observation Program 1184, a Cycle 1 NIRCam coronagraphic imaging survey of nine very nearby and young low-mass stars at 3–5 μ m wavelengths. In the F356W and F444W filters, we achieve survey median 5 σ contrasts deeper than 10 ^−5 at a separation of 1″, corresponding to 0.20 M _Jup in F444W and 1.30 M _Jup in F356W at planet–star separations of 10 au. Our results include 3–5 μ m debris disk detections and the identification of many extended and point-like sources in the final postprocessed images. In particular, we have identified a marginal point-source candidate having flux and color limits consistent with model predictions for a young sub-Jupiter-mass exoplanet. Under the assumption that the candidate is not confirmed, we place the first direct-imaging occurrence constraints on M dwarf wide-orbit (semimajor axes of 10–100 au), sub-Jupiter-mass exoplanets (0.3–1 M _Jup ). We find frequency limits of <0.10 and <0.16 objects per star with 1 σ and 3 σ confidence, respectively. This survey showcases the unprecedented capabilities of JWST NIRCam coronagraphic imaging when targeting young, low-mass stars and acts as a precursor to broader surveys to place deep statistical constraints on wide-orbit, sub-Jupiter-mass planets around M dwarfs.

We report the confirmation of TOI-6324 b, an Earth-sized (1.059 ± 0.041 R _⊕ ) ultra-short-period (USP) planet orbiting a nearby (∼20 pc) M dwarf. Using the newly commissioned Keck Planet Finder spectrograph, we have measured the mass of TOI-6324 b 1.17 ± 0.22 M _⊕ . Because of its extremely short orbit of just ∼6.7 hr, TOI-6324 b is intensely irradiated by its M dwarf host and is expected to be stripped of any thick H/He envelope. We were able to constrain its interior composition and found an iron-core mass fraction (CMF = 27% ± 37%) consistent with that of Earth (∼33%) and other confirmed USPs. TOI-6324 b is the closest to an Earth-sized USP confirmed to date. TOI-6324 b is a promising target for JWST phase-curve and secondary eclipse observations (emission spectroscopy metric = 25), which may reveal its surface mineralogy, day–night temperature contrast, and possible tidal deformation. From seven sectors of TESS data, we report a tentative detection of the optical phase-curve variation with an amplitude of 42 ± 28 ppm.

We present the detection and characterisation of the TOI-1438 multi-planet system discovered by the Transiting Exoplanet Survey Satellite (TESS). To confirm the planetary nature of the candidates and determine their masses, we collected a series of followup observations including high-spectral resolution observations with HARPS-N and HIRES over a period of 5 years. Our combined modelling shows that the K0V star hosts two transiting sub-Neptunes with R-b = 3.04 +/- 0.19 R-circle plus, R-c = 2.75 +/- 0.14 R-circle plus, M-b = 9.4 +/- 1.8 M-circle plus, and M-c =10.6 +/- 2.1 M-circle plus. The orbital periods of planets b and c are 5.1 and 9.4 days, respectively, corresponding to instellations of 145 +/- 10 F-circle plus and 65 +/- 4 F-circle plus. The bulk densities are 1.8 +/- 0.5 g cm(-3) and 2.9 +/- 0.7 g cm(-3), respectively, suggesting a volatile-rich interior composition. By combining the planet and stellar parameters, we were able to compute a set of planet interior structure models. Planet b presents a high-metallicity envelope that can accommodate up to 2.5% in H/He in mass, while planet c cannot have more than 0.2% as H/He in mass. For any composition of the core considered (Fe-rock or ice-rock), both planets would require a volatile-rich envelope. In addition to the two planets, the radial velocity (RV) data clearly reveal a third signal, likely coming from a non-transiting planet, with an orbital period of 7.6(-2.4)(+1.6) years and an RV semi-amplitude of 35(-5)(+3) m s(-1). Our best-fit model finds a minimum mass of 2.1 +/- 0.3 M-J and an eccentricity of 0.25(-0.11)(+0.08). However, several RV activity indicators also show strong signals at similar periods, suggesting this signal might (partly) originate from stellar activity. More data over a longer period of time are needed to conclusively determine the nature of this signal. If it is confirmed as a triple-planet system, TOI-1438 would be one of the few detected systems to date characterised by an architecture with two small, short-period planets and one massive, long-period planet, where the inner and outer systems are separated by an orbital period ratio of the order of a few hundred.

The Roman Space Telescope (Roman) is a three-mirror anastigmat design with a 2.4-m primary mirror. It will be based in the L2 orbit optimized for observations of cosmic expansion using the Wide-Field Instrument (WFI) and exoplanet discovery using the coronagraph instrument (CGI). The WFI features a 300-megapixel near-infrared detector array providing a field of view >100 times larger than that of the Hubble Space Telescope. To enable a low-resolution spectroscopy functionality for Roman, a compact Prism Assembly was added and installed in a slot in WFI's element wheel. The Prism Assembly has a 0.76 to 1.8 mu m passband enabling a survey of Supernova Type 1a redshifts in the range of 0.2 to 1.7. It achieves a spectral resolving power of 170>R>70 across the field. The Prism Assembly had restrictions on size, mass, and geometry, and a challenging schedule due to being a late addition to Roman. Despite this, the Prism Assembly is a compact high-performance spectrographic element, implemented as a refractive, all-spherical surfaces, two-element optical design using S-TIH1 glass and CaF2. We describe the Prism Assembly from design and implementation through alignment, optical performance test, and calibration to delivery for installation in the WFI instrument. (c) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License.Distribution or reproduction of this work in whole or in part requires full attribution of the originalpublication, including its DOI.

We present aperture masking interferometry (AMI) observations of the star HIP 65426 at 3.8 μ m, as part of the JWST Direct Imaging Early Release Science program, obtained using the Near Infrared Imager and Slitless Spectrograph instrument. This mode provides access to very small inner working angles (even separations slightly below the Michelson limit of 0.5 λ / D for an interferometer), which are inaccessible with the classical inner working angles of the JWST coronagraphs. When combined with JWST’s unprecedented infrared sensitivity, this mode has the potential to probe a new portion of parameter space across a wide array of astronomical observations. Using this mode, we are able to achieve a 5 σ contrast of Δ m F380M ∼ 7.62 ± 0.13 mag relative to the host star at separations ​​​​​≳0 . ″ 07 , and the contrast deteriorates steeply at separations ≲0 . ″ 07. However, we detect no additional companions interior to the known companion HIP 65426b (at separation ∼0 . ″ 82 or 8 7 − 31 + 108 au ). Our observations thus rule out companions more massive than 10–12 M Jup at separations ∼10–20 au from HIP 65426, a region out of reach of ground- or space-based coronagraphic imaging. These observations confirm that the AMI mode on JWST is sensitive to planetary mass companions at close-in separations (≳0 . ″ 07), even for thousands of more distant stars at ∼100 pc, in addition to the stars in the nearby young moving groups and associations, as stated in previous works. This result will allow the planning and successful execution of future observations to probe the inner regions of nearby stellar systems, opening an essentially unexplored parameter space.

M dwarfs have become increasingly important in the detection of exoplanets and the study of Earth-sized planets and their habitability. However, 20%–30% of M dwarfs have companions that can impact the formation and evolution of planetary systems. We use high-resolution imaging and Gaia astrometry to detect stellar companions around M dwarf exoplanet hosts discovered by TESS and determine the projected separation and estimated stellar masses for each system. We find 47 companions around 216 M dwarfs and a multiplicity rate of 19.4% ± 2.7% that is consistent with field M dwarfs. The binary projected separation distribution is shifted to larger separations, confirming the lack of close binaries hosting transiting exoplanets seen in previous studies. We correct the radii of planets with nearby companions and examine the properties of planets in M dwarf multistar systems. We also note three multiplanet systems that occur in close binaries (≲50 au) where planet formation is expected to be suppressed.

The Pandora SmallSat is a NASA flight project aimed at studying the atmospheres of exoplanets-planets orbiting stars outside our Solar System. Pandora will provide the first dataset of simultaneous, multiband (visible and NIR), long-baseline observations of exoplanets and their host stars. Pan-dora is an ambitious project that will fly a 0.44 m telescope in a small form factor. To achieve the scientific goals, the mission requires a departure from the traditional cost-schedule paradigm of half-meter-class observatories. Pandora achieves this by leveraging existing capabilities that necessitate minimal engineering development, disruptive and agile management, trusted partnerships with vendors, and strong support from the lead institutions. The Pandora team has developed a suite of high-fidelity parameterized simulation and modeling tools to estimate the performance of both imaging channels. This has enabled a unique bottom-up approach to deriving trades and system requirements. Pandora is a partnership between NASA and Lawrence Livermore National Laboratory. The project completed its Critical Design Review in October 2023 and is slated for launch into Sun-synchronous, low-Earth orbit in Fall 2025.

The Nancy Grace Roman Space Telescope will study the dark matter content of the universe, the expansion history of the universe, and the diversity of exoplanets in the Galaxy using unprecedented wide-field infrared surveys. Roman will accomplish this using a focal plane of 18 newly developed HgCdTe detectors. Roman's detectors, the H4RG-10, are 4 Kx4 K format 10-micron pixel pitch devices manufactured by Teledyne Imaging Sensors. After acceptance testing at the Goddard Detector Characterization Lab, 18 flight detectors were selected for the flight focal plane. Histograms of the performance parameters of the flight detectors are provided and compared against the requirements, deriving yield statistics. The dominant yield loss was read noise (32%) rather than persistence (21%), which may be attributed to the development and use of the PV3 passivation for Roman's sensors. The 18 flight sensors were selected and positioned in the focal plane according to sensor performance in addition to other criteria such as crosshatch and the presence of high total noise and low correlated double sample noise pixels. System-level testing of the focal plane was completed at Goddard in 2023, after which the focal plane was integrated into the Wide Field Instrument (WFI) at BAE Systems (formerly Ball Aerospace). At the end of 2023, the WFI completed its first thermal vacuum test, providing the first instrument-level performance measurements of the focal plane. In the spring of 2024, the WFI completed environmental (vibration and acoustic) testing and finished its second thermal vacuum test before being shipped back to Goddard for integration into the spacecraft assembly. We review the performance of Roman's flight lot of detectors and early results from integration and testing. (c) 2025 Society of Photo-Optical Instrumentation Engineers (SPIE)