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Uranus Magnetosphere and Moons Investigator (Umami)

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Uranus Magnetosphere and Moons Investigator (Umami) Uranus Magnetosphere and Moons Investigator (UMaMI) C. M. Elder1, T. A. Nordheim1, D. A. Patthoff2, E. Leonard1, R. J. Cartwright3, C. Cochrane1, C. Paranicas4, M. Tiscareno3, A. Masters5, D. Hemingway6, M. M. Sori7,8, H. Cao9, R. T. Pappalardo1, B. J. Buratti1, I. de Pater10, W. M. Grundy11, M. Showalter3, W. Kurth12, I. Jun1, J. I. Moses13, K. L. Aplin14, J. Casani1 1Jet Propulsion Laboratory, California Institute of Technology, 2Planetary Science Institute, 3SETI Institute, 4Applied Physics Laboratory, 5Imperial College, 6Carnegie Institution, 7University of Arizona, 8Purdue University, 9Harvard University, 10University of California, Berkeley, 11Lowell Observatory, 12University of Iowa, 13Space Science Institute, 14Bristol University. SynopsisUMaMI Synopsis SynopsisUMaMI Science Goals § New Frontiers mission concept. 1. Moons: Determine whether the Uranian satellites host subsurface oceans, search for signs of ongoing § Observe the magnetosphere, moons, and rings of Uranus. These three systems interact and require a similar payload. endogenic activity, and determine to what extent the surfaces are modified by exogenic processes (e.g. § We would optimize instruments and the orbital tour for the magnetosphere, moons, and rings but would observe Uranus when possible. charged particle bombardment and irregular satellite dust accumulation). 2. Rings: Understand the formation and evolution of the Uranian rings and their interactions with the satellites. 3. Magnetosphere: Characterize the structure and dynamics of the Uranian magnetosphere, including its interaction with the solar wind and the Uranian moons. Science Goal Science Objective Measurement Instrument 1. To what extent are the structure and Particles and fields measurements with radial mag/plasma/ene dynamics of the Uranian magnetosphere and lat/lon sampling in magnetosphere. rgetic particles driven by the solar wind vs internal process? 2. Are the major moons sources of Mag and plasma measurements in vicinity of mag/plasma magnetospheric plasma? moons. 3. To what extent are the major moons Particles and fields measurements in regions mag/plasma/ene weathered by magnetospheric particles? of magnetosphere associated with moons. rgetic particles Magnetic field draping, exospheric pick-up 4. Do any of the major moons have an mag/plasma ions. exosphere? If so, how do they interact with Magnetosphere Energetic particle absorptions due to energetic the magnetosphere? interaction with exosphere. particle Above: Voyager 2 image mosaics of (a) Enceladus (d=504 km), (b) Miranda (d=472 km), and (c) Ariel 5. Do the major moons have conducting (d=1158 km) including night-side illumination by Uranus shine [1]. Cratered regions (red arrows) and Magnetic field measurements near the mag/plasma/ene subsurface oceans? If so, how does this boundaries of isolated recent resurfacing (blue arrows) highlighted in each figure. Miranda and Ariel show moons. Search for induced fields. rgetic particles affect moon-magnetosphere interactions? evidence of partial resurfacing, similar to Enceladus. Image credit: NASA/JPL/Caltech/USGS. Determine whether NH -rich materials are Left: Voyager 2 images of the rings. The epsilon ring (brightest) is approximately 100 km wide. The image 3 VIR associated with geologic landforms. spectrometer on the left revealed Uranus’s dusty rings and is the only Voyager 2 occultation image. Surface changes compared to Voyager camera 6. Are any of the major moons currently images. geologically active? What are their geologic If actively venting material: search for Synopsis Synopsis Why New Frontiers? Payload histories? What are the relative ages among magnetic field draping, pick-up ions, mag the moons and among different units on energetic particle absorptions. § UMaMI would be complementary to a variety of outer § High-resolution camera with color filters each individual moon? camera solar system Flagship class missions. § Magnetometer Limb images to search for plumes. VIR § UMaMI could study a primordial ice giant satellite § Visible and Infrared (VIR) spectrometer spectrometer system at Uranus, while a Flagship class mission to § Plasma spectrometer Image moons at better than 500 m/pixel. camera Neptune addressed questions related to ice giants and § Energetic particle detector Measure the degree of flattening and tidal elongation in the shapes of the moons camera 7. What are the internal structures of the Triton (Triton’s capture from the Kuiper Belt destroyed through limb pofile analysis. much of Neptune’s native satellite system [e.g. 2]). Moons major moons? Measure the moons low order gravity Synopsis radio science § Alternatively, if a Flagship mission to an ice-giant were Science Background coefficients, where possible. not recommended for the next decade, UMaMI would Above: Voyager Map the distribution of CO 2 ice and address a focused subset of the science objectives of a § Moons determine whether it is spatially associated 2’s highest 8. What are the endogenic and exogenic camera and VIR Flagship class mission. § Fractures, ridges with geologic landforms or whether its resolution image process that modify the surfaces of the spectrometer § Relaxed craters distribution is consistent with magnetospheric moons? Is the low-albedo spectrally red of Titania. Image interactions. credit: NASA/JPL § Volatiles that should not be stable material on the moons similar to other known Map the distribution of spectrally red material § Regions with relatively few craters materials such as the organics-rich material in camera and VIR on the major moons and determine whether it Equator and orbital § Possible cryovolcanism the Saturnian system or prebiotic material spectrometer is spatially associated with geologic features. plane of moons § Could host subsurface oceans possibly brought to the Earth by comets and Determine the compositions of the irregular § Northern hemispheres of moons were dark asteroids? VIR satellites and the spectrally red material on during Voyager 2 flyby spectrometer Left: Uranus’s magnetic the major moons. § Magnetosphere Measure the size and albedo of Mab field during the Voyager 2 camera flyby. N and S are the § Relatively low plasma densities (embedded in center of µ ring). magnetic north and south § Voyager 2 sampled only the inner plasma sheet Determine the composition of Mab and the µ VIR § Interaction between magnetosphere and solar ring. spectrometer poles. 9. What is the origin of the µ ring? wind is highly variable over both diurnal and Image µ ring to search for gradients. occultations seasonal timescales due to the large obliquity of Determine whether µ ring material spirals Camera (color Uranus (97.9º) and the tilt (-59º) of the dipole inward and mantles Puck and/or spirals filters) and VIR magnetic field outward and mantles Miranda. spectrometer Rings 10. Do the rings have the same composition VIR § Voyager 2 was a single flyby (could not observe Composition of both. Synopsis as the nearby moons/moonlets? spectrometer Why decade 2023-2032? temporal variability) § Rings Structure within the rings (propellers) for ring 11. What are the ring dynamics governing dynamics and clumping (embedded masses), § Uranus’ large obliquity (97.9º) results in extreme variations in insolation § Dense and sharp edged unlike other ring camera conditions of the moons and in interactions between the magnetosphere and the the Uranian rings? within and outside the ring (scalloped edges), systems varying ring textures. solar wind over Uranus’ 85-year orbital period. Uranian equinox § Dusty rings must be continuously replenished, 12. What causes the structure of the narrow, Eccentricity gradients, azimuthal structure, § Arriving within ~10 years of equinox (2049) would enable comparisons to camera Favorable arrival time for illumination if old dense rings? Are they self-sustaining? occultations, normal modes on the edges. Voyager 2 measurements (~southern solstice)and comparison and illumination to Voyager 2 conditions ideal § Dusty rings may have moved since Voyager for observingJGA launch the geology of the moons. ~Uranus flyby § Jupiter gravitywindow assist available from 2030 to 2034,arrival would [3, result 4] in arrival at Table 1 – Science objectives for the UMaMI mission and the corresponding measurements and instruments. § µ ring is blue in color (small uniform grain “Major moons” refers to Miranda, Ariel, Umbriel, Titania, and Oberon; “mag”=magnetometer; “plasma”=plasma Uranus2030 in the mid-2040s [3, 4]. 2040 2050 size), with moon Mab embedded in the center. spectrometer; “energetic particles”=energetic particle detector. § Launching between 2030 and 2034 would provide an opportunity for a Jupiter Only known ring with similar characteristics is gravity assist (JGA) and would enable arrival at Uranus just before equinox [3]. the E ring at Saturn References: [1] Stryk, T. and Stooke, P.J. (2008) LPSC, 39, Abstract #1362. [2] Agnor, C.B. and Hamilton, D.P. (2006) Nature, 441, 192. [3] Hofstadter, M. et al. (2017) Ice giants pre- § Voyager did not measure ring composition decadal survey mission study report, JPL D-100520. [4] Jarmak, S. et al. (2020) Acta Astronautica. [5] Elder, C.M. et al. (2018) Acta Astronautica, 148, 1-11. The information presented about the UMaMI concept is pre-decisional and is provided for planning and discussion purposes only. Part of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. © 2020. All rights reserved..
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