Space telescope for solar system science

Space telescope for solar system science

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  Space Telescope forSolar System Science Cindy L. Young - NASA Langley Research Center Kunio M. Sayanagi - Hampton University A presentation to the Small Bodies Decadal Panel November 18, 2020 Gap in UV Coverage 1990 – mid 2020’s mid 2020’s – mid 2030’s late 2030’s early 2020’s – late 2020’s HST JWST Roman LUVOIR
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  Summary • Urgent need:preserve UV observation capabilities • Science • Time-domain science (high frequency, long-duration) • New, wide-ranging small bodies surveys • Mission targets • Cross-disciplinary planetary observations • A focused science target is also viable • Telescope Architecture options; optimized for: • Spatial resolution • Photometric sensitivity • Balance of both • Concept study objectives • Survey of technology options • Point design to demonstrate viable options for the next decade • We advocate to add a solar system space telescope to the NF6 list The time for a solar system space telescope is NOW!
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  Recommendations by RecentNational Academies Reports Getting Ready for the Next Planetary Science Decadal Survey (2017): “Synoptic observations of solar system bodies are limited by two factors, the availability of telescope time and resolution. First, while current (e.g., Hubble Space Telescope and Spitzer Space Telescope) and future (e.g., James Webb Space Telescope and Wide-Field Infrared Space Telescope) space observatories are available to the planetary astronomy community and are not resolution constrained, such assets are in great demand for other astronomical studies. Therefore, the availability of telescope time for long-term monitoring of, for example, Titan, Europa, and Io or for surveys is highly limited. Second, the resolution of such observations is primarily dictated by telescope aperture (the larger the aperture the greater the cost of the mission). Hence, studies to determine the potential scientific return of a space telescope dedicated to the monitoring and studies of solar system bodies that can be achieved within the scope of either the Discovery or the New Frontiers programs would benefit the next planetary science decadal survey. Visions into Voyages for Planetary Sciences in the Decade 2013-2022: A Midterm Review (2018): NASA should conduct an assessment of the role and value of space-based astronomy, including newly emerging facilities, for planetary science. This assessment should be finished before the next decadal survey is significantly under way. NASA Response to the Midterm Review Recommendation: NASA agrees that it is important to continue to explore the role that space-based astronomy plays in planetary science and will seek community input for an assessment through a mechanism such as a community workshop or study, the planning for which will begin in 2019. Further, NASA recognizes that space-based astronomy has already proven its value for planetary science such as observing the Comet F2 D/1993 Shoemaker-Levy 9 impacts with Jupiter using the HST; discovering approximately fifty of the potentially hazardous asteroids with NEOWISE and characterizing many more with NEOWISE and Spitzer; discovering the New Horizons follow-on target 2014 MU69 in the Kuiper Belt with HST; and assessing the potential hazard to the Mars orbiters posed by Comet C/2013 A1 (Siding Spring) using HST, NEOWISE, Spitzer and Swift.
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  Science Needs Understand TemporallyDynamic Phenomena High-Frequency, Long-Duration Campaigns to understand: • Interaction of planetary magnetospheres with the solar wind • Venus and giant planet atmospheric dynamics • Icy satellite geologic activity (e.g., plume searches) and surface evolution • Evolving ring phenomena • Cometary evolution & outgassing asteroids Understand Origin and Evolution of Small Bodies Comprehensive Spectral Survey of Solar System Minor Bodies to: • Characterize Surface Properties and Composition • Understand the overall physical properties including: size, shape, mass, density, porosity, and spin rate.
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  Cometary Evolution, Morphology,and Processes 5 Priority Questions 1. How do the coma and nucleus evolve with heliocentric distance (Rh)? 2. What drives outbursts and their frequency and how often is water ice expelled? 3. What processes dominate in the coma? Left: atomic and molecular UV emission can distinguish coma processes such as electron impact (blue, green) and fluorescence (red) [1] Right: Transmission during stellar occultation can determine associations between species such as O2 and H2O, as shown in these examples from Rosetta/Alice data [2]. [1] Feldman et al., 2018 Astronomical Journal. [2] Keeney et al., 2019 Astronomical Journal.
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  Solar System MinorBody and Irregular Satellite Survey 6 Priority Questions 1. What do the compositions/colors of minor bodies/irregular satellites reveal about planetary migration early in solar system history? 2. What dynamical processes are shaping minor body populations today? 3. What do the compositions of minor bodies reveal about the radial variations in the solar nebula? Broadband color data [3] (for (a) Centaurs, (b) Scattered Disk Objects (SDOs), and (c) both overplotted) cannot conclusively validate the dynamically-based hypothesis that Centaurs originate from the SDOs, requiring a spectroscopic sample from each population. (d) The transition region from water-rich to water-poor surfaces is shown in grey, in a plot of water ice feature strength vs. absolute magnitude [4]. [3] Hainaut et al., 2012 Astronomy and Astrophysics. [4] Barucci et al., 2011 Icarus.
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  Main Belt andNear-Earth Asteroids 7 Priority Questions 1. What are the spectral characteristics of asteroids in the far UV? 2. Can we constrain surface exposure to space weathering by measuring its effects on asteroids’ UV reflectance spectra? 3. What is the composition and spatial extent of outgassing produced by active comet-like asteroids? Left: Comparison of the geometric albedos for Psyche with Rosetta Alice observations of (2867) Šteins (purple triangles) and (21) Lutetia (blue squares), HST observations of (21) Lutetia (blue diamonds), and HST STIS observations of (1) Ceres (orange stars). These are the only four asteroids studied at wavelengths <220 nm, and their spectra appear very different from one another at these wavelengths [5]. [5] Becker et al., 2020 Planetary Science Journal.
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  Science Questions ScienceObjectives M is s io n S iz e S m a ll M id . / L a r g e 1 . 2 m 2 m 1 0 m Are Venus and Titan volcanically active today? Search for new evidence of ongoing activity on Venus and Titan R R What drives variability in volcanic and cryovolcanic activity? Determine the statistics of plume activity R R R What is the composition of magma and cryomagma reservoirs? Determine composition of lava and surface deposits R R What do the compositions/colors of minor bodies/irregular satellites reveal about planetary migration early in solar system history? Determine the source population(s) of the Jupiter Trojans and irregular satellites of the giant planets. D , S R What dynamical processes shape minor body populations today? Determine the source population(s) of the Centaurs. D , S What do the compositions of minor bodies reveal about the radial variations in the solar nebula? Determine how formation distance influenced KBO surface composition. D , S How does energy/momentum transport vary temporally and spatially in dense atmospheres? Determine statistics, properties, and evolution of convective events, wave systems, vortices, and jets R R How is atmospheric energy transport modulated by chemical and thermodynamic processes? Determine the response of horizontal circulation, aerosol properties, and gas composition to internal and solar climate forcing D What is the current outer solar system impactor flux? Detect and characterize impact ejecta fields in giant planet atmospheres R , D What controls auroral processes on different scales of time and planetary size? Map auroral emission on terrestrial/gas giant/icy bodies, under varying solar wind and magnetospheric conditions R R R What is the balance between internal/ external control of magnetospheric variability? Measure the 3D structure and variability of the Io plasma torus at Jupiter and the E-ring at Saturn How do cometary coma and nucleus evolve seasonally or with heliocentric distance (Rh)? Determine coma activity and composition and nucleus reflectance over a range of heliocentric distances D , S What processes dominate in cometary coma? Determine spatial associations of various coma species, as coma activity and morphology evolves D , S What is the current and past environment of planetary rings across the solar system? Determine the ring particle size distributions and compositions R R How do ring structures evolve and interact with nearby and embedded moons? Measure structural profiles and temporal variation R R
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  Kuiper Space Telescope Discovery 2015 L2 orbit enablesrapid commencement of science observations (L + 30d), and is well above the UV background induced by the Earth’s geocorona
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  SMALL BODIES Determine whatconnections exist between composition and dynamics/physical location of small bodies and what interactions with the external environment tell us about the formation and evolution of the outer solar system. SATELLITE SYSTEMS OF THE GIANT PLANETS Determine the processes and interactions that drive observable spatial and temporal variability of surfaces, atmospheres, and magnetospheres in giant planet satellite systems. GIANT PLANETS ATMOSPHERES AND MAGNETOSPHERES Determine the energetics and dynamics of giant planet atmospheres and magnetospheres. To achieve these objectives, Kuiper acquires observations with cadences and sensitivities that current ground-based and space-based assets have not and cannot be allocated to do. Kuiper Space Telescope Discovery 2015
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  Optical Tube Assembly (OTA) DesignTrade Measurement Req. • Imaging Resolution • Sensitivity • Spectral Range • Solar Exclusion Zone Note: Spectral Resolution is an instrument parameter, not OTA Optical Design • Filled Aperture • Sparse Aperture • Interferometer • Diffractive Optics Assembly Approach • Assembled on Ground • Deployable Structure • In-Space Assembly • Any Combination of Above Orbit (Affects temporal cadence) • Low-Earth Orbit • High-Earth Orbit • Earth-Trailing • L2
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  Notional PDX Design:Mature Optical Design Approach Limiting Factor: Launch Fairing Concept Study Objective: - Determine the biggest filled aperture that can be assembled on ground to be launched within the New Frontiers-class constraints PDX Concept: Filled-Aperture Ground Assembled Sensitivity Diffraction Limit Instrument FoV Measurement Performance Imaging Limiting Mag = 31 Spec. Limiting Mag = 24 63 mas at 500 nm 110 arcsec 4.2 arcsec/mm Plate Scale Baseline Design 2-meter circular aperture 2-meter circular aperture 58 m Focal Length Parameters HST PDX Atlas V 400 Atlas V 500 Delta IV Medium Length 13.2 m 11.0 m 5.8 m (Extra Extended) 7.6 m (Medium) 6.5 m Diameter 4.2 m 3.5 m 3.8 m 4.6 m 3.8 m Mass 12,000 kg 6,900 kg ? 15,718 kg (LEO) 5,860 kg (GTO) 18,814 kg (LEO) 6,860 kg (GTO) 13,140 kg (LEO) 4,490 kg (GTO) Stahl et al. (2017) parametric cost model suggests HST’s OTA could be built for <$1B Optical Design Tested with Z-max
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  Filled-Aperture in-Space Assembled: iSATConcept Astro2020 iSAT study: - Examined feasibility of a 5, 10, 15 and 20-meter telescope assembled in space - Optimized for sensitivity: Filled Aperture design - Optical surfaces: actively controlled to maintain mirror shape Solar System Telescope Trade Study Objective: - Use iSAT design as a point of departure - Examine the cost impact of relaxing the mirror shape precision - Determine the Diameter, Imaging Quality vs. Cost On-going Relevant Project: - Precision Assembled Space Structures (PASS) Laboratory Demonstration to build a 20-meter parabolic aperture Robotic Autonomous Assembly - Effort is applicable to future Solar System Telescope - See whitepaper by J. Dorsey https://exoplanets.nasa.gov/exep/technology/in-space-assembly/iSAT_study/ LaRC RAMSES Lab Robotic Assembly of Modular Space Exploration Systems
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  CHARISMA: Caroline Herschelhigh-Angular Resolution Imaging & Spectroscopy Multi-Aperture Telescope 14 Notional Architecture - ~10-meter Effective Aperture - Equivalent of 2-meter circular aperture area - Sparse-Aperture Design - Assembled and/or Deployed in Space - 30-deg Solar Exclusion Zone - Create tech heritage for future astrophysics telescopes Designed to balance sensitivity and resolution Sayanagi et al., 2020 Mission Concept White Paper
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  LightBeam: Optical Interferometer Concept DAWNat Ceres: 27×27 pix  Optimized for Imaging Resolution  Flyby-like snapshot imaging at ~10×10 to 100×100 pixels  Outer planet moons  Larger (~500+ km) KBOs  Thousands of >10-100km bodies throughout solar system  Based on existing NASA STMD technology investments & capabilities  ~100m baseline visible interferometer with 6 x 300mm apertures  Large s/c structure enabled by in-space manufacturing  van Belle et al., 2020 Mission Concept White Paper
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  Diffraction Zone Plate Telescope UnderDevelopment at NASA Langley - SPECIES Concept / PI: J. Leckey - Light-weight Membrane Diffraction Zone Plate - 90% reduction in system mass compared to traditional optics - 40% Optical Throughput - Design optimized for sensitivity (not for image quality) - Currently TRL =2, TRL = 4 expected by 2023 Concept Study Objective - Examine Technology Benefit for Planetary Science - Recommend Development Roadmap Multi-layer Fresnel Zone Plate LIDAR Concept Diffraction Zone Plate Image Example (From Wikipedia)
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  Relevant Ongoing Activities
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  Summary • Urgent need:preserve UV observation capabilities • Science • Time-domain science (high frequency, long-duration) • New, wide-ranging small bodies surveys • Mission targets • Cross-disciplinary planetary observations • A focused science target is also viable • Telescope Architecture options; optimized for: • Spatial resolution • Photometric sensitivity • Balance of both • Concept study objectives • Survey of technology options • Point design to demonstrate viable options for the next decade • We advocate to add a solar system space telescope to the NF6 list The time for a solar system space telescope is NOW!