We analyze ∼40–200 keV energetic particle observations from the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) on board the New Horizons (NH) spacecraft from 2007 to 2024 and compare them with similar measurements from the Low Energy Charged Particle experiments on the Voyager 1 and Voyager 2 spacecraft when they were at comparable heliocentric distances (5–60 au). In both Voyager data sets, particle intensities generally decrease with increasing radial distance from the Sun, reaching a minimum in the outer heliosphere before rising again prior to their respective encounters with the heliospheric termination shock (TS). This radial behavior in the intensity-time profiles is described as a heliospheric valley. The NH/PEPSSI time series from 5 au (2007) to 60 au (2024) exhibits a similar decrease in particle fluxes with distance. Analysis of the radial dependence of energetic particle intensities from all three spacecraft normalized by observations at 1 au to account for the solar cycle effects reveals an approximate piece-wise composite power-law relationship, with a slope break (steeper decline) beyond ∼33 au. This break may reflect differences in the dominant transport and acceleration mechanisms operating in the two regions demarcated by this radial break. In addition, a radial scaling method is applied to Voyager observations to best match the NH data. This comparison provides an estimate for the NH TS crossing between 2027 (68 au) and 2034 (83 au).

The magnetospheric systems of ice giants, as the ideal and the unique template of a typical class of exoplanets, have not been sufficiently studied in the past decade. The complexity of these asymmetric and extremely dynamic magnetospheres provides us a great chance to systematically investigate the general mechanism of driving the magnetospheres of such common exoplanets in the Universe, and the key factors of influencing the global and local magnetospheric structures of this type of planets. In this paper, we discuss the science return of probing magnetospheric systems of ice giants for the future missions, throughout different magnetospheric regions, across from the interaction with upstream solar wind to the downstream region of the magnetotail. We emphasize the importance of detecting the magnetospheric systems of ice giants in the next decades, which enables us to deeply understand the space enviroNMent and habitability of not only the ice giants themselves but also the analogous exoplanets which are widely distributed in the Universe.

While the near-term Interstellar Probe mission will revolutionize our understanding of the astrosphere in which we live, it will provide only a snapshot of the history of the heliosphere.Trans-Neptunian objects (TNOs), with numerous options conveniently located along whichever Interstellar Probe trajectory would ultimately be chosen, provide an opportunity to examine the history of the heliosphere measurable in the colors, spectra, and geologies of their surfaces.Interstellar Probe with a planetary augmentation would enable a scientifically rich close flyby of a TNO along with "remote" observations.The spacecraft can function as an in situ observatory to study TNOs up to 2 -3 au away, an order of magnitude closer than they are to the Earth.

In the present decade and beyond, now 51 years after the last Apollo landing, the NASA Artemis human exploration program will offer abundant opportunities for heliophysics investigations from, by, and of the Moon from the vantage points of the lunar orbit and the surface. The Lunar Solar Occultation Explorer (LunaSOX) concept uses the lunar limb to occult the solar disk for high-resolution coronal observations at hourly, daily, to biweekly cadences from spacecraft either in the lunar orbit or at the surface. A 0.2 m diameter solar telescope in orbit with white light and narrow-band visible filters would provide arcsecond spectroscopic imaging of the low-to-high corona (1–10 R☉) with an upper limit of 10 –12 B☉ on the local scattered light background from lunar atmospheric dust, as compared to 10 –9 B☉ for Earth ground-based solar eclipse observations looking up through the atmosphere at totality. For eclipse observations from and by the Moon, there would be no significant atmospheric disturbances that otherwise limit seeing to arcsec resolution from Earth’s surface. The present eccentric orbits of the ARTEMIS P1 and P2 spacecraft are used as models for a 1 × 10 Rm orbit of LunaSOX to compute the times of solar eclipse intervals, up to 2 hours in duration between the east and west solar hemispheres at a daily cadence for coronal observations at 1–16 R☉ when the orbital aposelene is in anti-sunward directions. In a low-altitude circular orbit and from the surface, the observational cadences would, respectively, be hourly and biweekly. LunaSOX satellites also carrying in situ space environment instruments could integrate into a network of orbital platforms for space weather monitoring and communications relay to far-side surface lander and permanent base sites, e.g., for low-frequency radio cosmology and detection of exoplanet magnetospheres.

The interaction of our protective heliosphere and the Very Local Interstellar Medium (VLISM) is the least explored and most rewarding frontier of space physics.New evidence amplifies the central role of the heliosphere in the evolution of the solar system along its 4.6billion-year journey around the galaxy.In addition to the dense clouds of plasma, gas and dust seeding the early proto solar nebula, recent supernovae have left the entire solar system exposed to extreme fluxes of interstellar material and cosmic radiation with far-reaching implications.Our current knowledge lacks the direct measurements necessary to understand how our star upholds its vast heliosphere and its potentially game-changing role in the evolution of our galactic home.Interstellar Probe provides new, required measurements over more than a solar cycle to uncover the physical processes starting near the Sun responsible for creating our dynamic heliosphere.In April 2022, the pragmatic Interstellar Probe Mission Concept Study was completed after four years, detailing a Large Strategic heliophysics mission that would transect the heliosphere from 1 au to the VLISM.Its journey provides rich science for generations across heliophysics and presents an opportunity to push the frontier of space exploration farther than ever done before.Modest crossdivisional investments enable high-value planetary science and astrophysics, deepening our understanding of the emergence of our habitable planetary system.A trajectory through the forward hemisphere of the heliosphere would be accomplished by a launch in the 2036-2042 timeframe using conventional chemical propulsion and a heavy-lift launch vehicle, such as the Space Launch System (SLS).A Jupiter Gravity Assist could propel an 860-kg spacecraft with an 87-kg payload of ten instruments delivering a unified view of the global heliosphere, reaching the VLISM after 16 years.The spacecraft is designed to a 50-year nominal lifetime using modern-day technology based on successful missions like New Horizons.Two next-generation Radioisotope Thermal Generators (RTGs) would ensure 300 We at end of nominal mission at 375 au and could enable exploration even beyond 500 au.

The classical Kuiper Belt Object (KBO) Arrokoth was surveyed by the New Horizons spacecraft on 1st January 2019, revealing a small bilobed object with a red surface, whose spectral slope lies in the average of the whole KBOs population. This red color has been assigned to reddish organic materials, either inherited from the protosolar disk during accretion, or formed through radiolytic processes in the surface due to exposure to solar or interstellar photons, Solar Wind, Solar Energetic Particles or Galactic Cosmic Rays. We report here a study investigating the radiolytic scenario, based on numerical calculations and experimental simulations run with swift heavy ions (74.8 MeV136Xe19+ and 33.06 MeV58Ni9+), and low-energy 105 keV18O6+ ions on CH3OH ice, the only molecule identified at Arrokoth's surface. Calculations show that sputtering is essentially controlled by Solar Wind (H and He), and that the sputtering rate depends on the nature of the material: erosion thickness over 4.55 Gyr are a few micrometers for amorphous carbon (as an analog of red organics) and a similar to 240 mu m to around similar to 10 mm for H2O and CO ice, respectively. Chemistry within the subsurface is essentially controlled by Galactic Cosmic rays (H and He), which penetrate deep down to several tens of meters and deliver an electronic dose higher than 1 eV.atom-1 in the first meter. The electronic and elastic doses delivered by Solar Wind ions are limited to the first 10s nm of the top surface, but Solar Energetic Particles deliver high electronic doses in the first 100 mu m of the surface (up to 200 eV.atom-1). Experimental simulations show that irradiating methanol ice with a dose consistent with that in planetary conditions, results in the formation of reddish organic materials made of aliphatic, conjugated and unconjugated olefinic, acetylinic, carbonyl and hydroxyl groups. A similarity with irradiated simple polymers (e.g. polyethyleneglycol) and materials formed through cold plasma experiments (tholins) is observed. There is little dependence with the nature and energy of the ion. The residue recovered at room temperature was analyzed with High Resolution Mass Spectrometry (Orbitrap), revealing a complex composition with around 6596 chemical formulas and likely several tens of thousands of molecules. Altogether, these analyses support active polymerization mechanisms similar to those observed in irradiated polymers, as bond-breaking, cross-linking or formation of olefinic bonds through recombination of radicals in adjacent carbon atoms. Considering both sputtering and radiolysis, as well as material ablation due to dust bombardment reported in literature, a scenario is taking shape as the production of reddish organics deep in the subsurface, and the settling of an organic crust at the top surface through volatiles removal. The presence of methanol and absence of water, inconsistent with sputtering fractionation, remains unexplained.

Earth and Space Science Open Archive PosterOpen AccessYou are viewing the latest version by default [v1]Lunar Plasma Environment in Magnetotail Lobe Conditions. First Results from 3-D Hybrid Kinetic Modeling and Comparison with ARTEMIS ObservationAuthorsAlexanderLipatoviDJasperHalekasiDMenelaosSarantosJohnCooperSee all authors Alexander LipatoviDCorresponding Author• Submitting AuthorUniversity of Maryland Baltimore CountyiDhttps://orcid.org/0000-0001-5026-8214view email addressThe email was not providedcopy email addressJasper HalekasiDUniversity of IowaiDhttps://orcid.org/0000-0001-5258-6128view email addressThe email was not providedcopy email addressMenelaos SarantosNASA/GSFCview email addressThe email was not providedcopy email addressJohn CooperNASA Goddard Space Flight Center (Emeritus)view email addressThe email was not providedcopy email address

Saturn is permanently surrounded by 6 discrete proton radiation belts that are rigidly separated by the orbits of its inner moons and dense rings. These radiation belts are ideal environments to study the details of radial diffusion and the CRAND source process, yet progress has been hindered by the fact that the energy spectra are not known with certainty: Reanalysis of the response functions of the LEMMS instrument on-board the Cassini orbiter has shown that measurements of ≲10MeV protons may be easily contaminated by ≳10MeV protons and that many available measurements characterize a very broad energy range, so that the calculation of an energy-resolved spectrum is not as straightforward as previously assumed. Here we use forward modeling of the measurements based on the instrument response and combine this technique where useful with numerical modeling of the proton belt physics in order to determine Saturn's spectra with higher certainty. We find significant proton intensities up to ≈1 GeV. While earlier studies reported on proton spectra roughly following a power law with exponent ≈−2, our more advanced analysis shows harder spectra with exponent ≈−1. The observed spectra provide independent confirmation that Saturn's proton belts are sourced by CRAND and are consistent with the provided protons being subsequently cooled in the tenuous gas originating from Saturn or Enceladus. The intensities at Saturn are found to be lower than at Jupiter and Earth, which is also consistent with the source of Saturn being exclusively CRAND, while the other planets can draw from additional processes. Our new spectra can be used in the future to further our understanding of Saturn's proton belts and the respective physical processes that occur at other magnetized planets in general. Also, the spectra have applications for several topics of planetary science, such as space weathering of Saturn's moons and rings, and can be useful to constrain properties of the main rings through their production of secondary particles.

The Outer Planets Assessment Group (OPAG) formed the Roadmaps to Ocean Worlds (ROW) group to 1) assemble the scientific framework guiding the exploration of Ocean Worlds over the next several decades; 2) to design a roadmap(s) to explore these worlds to address science objectives, and 3) to recommend technology development to advance future OW mission capabilities.Many of the ROW results are summarized by Hendrix and Hurford et al. (2019).In this white paper we summarize the mission priorities for Ocean Worlds in the next ~decade.Because this is a community document, numerous authors have contributed including those listed below.

The Outer Planets Assessment Group (OPAG) formed the Roadmaps to Ocean Worlds (ROW) group to 1) assemble the scientific framework guiding the exploration of Ocean Worlds over the next several decades; 2) to design a roadmap(s) to explore these worlds to address science objectives, and 3) to recommend technology development to advance future OW mission capabilities.Many of the ROW results are summarized by Hendrix and Hurford et al. (2019).

The near-term Interstellar Probe mission concept would enable flyby geoscience investigations of a Kuiper belt dwarf planet and its space environment, advancing comparative planetology beyond Neptune. Box 1. Comparative Planetology Questions for KBO Planets by Interstellar Probe• What fraction are geologically active?Is there ongoing plume, cryovolcanic, and/or tectonic activity?How are some planets able to remain active billions of years after their formation, as is the case for Pluto?• What can the variability of landforms and compositions tell us about the various formation processes and evolutions of KBO planets?• What fraction likely have or once had liquid water?If they had water, how long did it remain liquid before freezing?Was there a widespread process that extended the life of subsurface oceans, such as antifreeze?How is this related to the planet's window for habitability?• How do their atmospheres interact with the solar wind/interstellar medium, and how does that interaction change based on the planet's changing solar distance?• Can dwarf planets be used as analogs to infer properties of dwarf exoplanets?

Earth and Space Science Open Archive PosterOpen AccessYou are viewing the latest version by default [v1]Lunar Plasma Environment in Cases with Extreme Solar Wind Conditions: First Results from 3-D Hybrid Kinetic Modeling and Comparison with ARTEMIS ObservationsAuthorsAlexanderLipatoviDMenelaosSarantosJohnCooperiDJasperHalekasiDSee all authors Alexander LipatoviDCorresponding Author• Submitting AuthorUniversity of Maryland Baltimore County, Baltimore MDiDhttps://orcid.org/0000-0001-5026-8214view email addressThe email was not providedcopy email addressMenelaos SarantosNASA GSFCview email addressThe email was not providedcopy email addressJohn CooperiDNASA GSFCiDhttps://orcid.org/0000-0003-4832-7320view email addressThe email was not providedcopy email addressJasper HalekasiDUniv. of IowaiDhttps://orcid.org/0000-0001-5258-6128view email addressThe email was not providedcopy email address

The detection of crystalline H2O-ice on multiple surfaces of Kuiper Belt Objects (KBOs) seems to contrast with what scientists understand about the surface environment of these objects, as previous estimates suggest that radiolysis should have easily amorphized these objects' surface over their lifetimes. Here, we use a detailed laboratory approach to show that crystalline H2O-ice can be amorphized by energetic electrons at temperatures as high as 70 K. However, the estimated time needed to completely amorphize the H2O-ice present on the surface of a KBO to the depth probed by near-infrared spectroscopy is only slightly less than the age of the solar system. Given the uncertainties involved in these types of extrapolations and the possibility of a resurfacing event occurring in these objects lifetime, the detection of crystalline or at least partially crystalline H2O-ice on KBOs should be expected.

Europa is the closest and probably the most promising target to search for extant life in the Solar System, based on complementary evidence that it may fulfil the key criteria for habitability: the Galileo discovery of a sub-surface ocean; the many indications that the ice shell is active and may be partly permeable to transfer of chemical species, biomolecules and elementary forms of life; the identification of candidate thermal and chemical energy sources necessary to drive a metabolic activity near the ocean floor. In this article we are proposing that ESA collaborates with NASA to design and fly jointly an ambitious and exciting planetary mission, which we call the Joint Europa Mission (JEM), to reach two objectives: perform a full characterization of Europa's habitability with the capabilities of a Europa orbiter, and search for bio-signatures in the environment of Europa (surface, subsurface and exosphere) by the combination of an orbiter and a lander. JEM can build on the advanced understanding of this system which the missions preceding JEM will provide: Juno, JUICE and Europa Clipper, and on the Europa lander concept currently designed by NASA (Maize, report to OPAG, 2019). We propose the following overarching goals for our Joint Europa Mission (JEM): Understand Europa as a complex system responding to Jupiter system forcing, characterize the habitability of its potential biosphere, and search for life at its surface and in its sub-surface and exosphere. We address these goals by a combination of five Priority Scientific Objectives, each with focused measurement objectives providing detailed constraints on the science payloads and on the platforms used by the mission. The JEM observation strategy will combine three types of scientific measurement sequences: measurements on a high-latitude, low-altitude Europan orbit; in-situ measurements to be performed at the surface, using a soft lander; and measurements during the final descent to Europa's surface. The implementation of these three observation sequences will rest on the combination of two science platforms: a soft lander to perform all scientific measurements at the surface and sub-surface at a selected landing site, and an orbiter to perform the orbital survey and descent sequences. We describe a science payload for the lander and orbiter that will meet our science objectives. We propose an innovative distribution of roles for NASA and ESA; while NASA would provide an SLS launcher, the lander stack and most of the mission operations, ESA would provide the carrier-orbiter-relay platform and a stand-alone astrobiology module for the characterization of life at Europa's surface: the Astrobiology We Laboratory (AWL). Following this approach, JEM will be a major exciting joint venture to the outer Solar System of NASA and ESA, working together toward one of the most exciting scientific endeavours of the 21st century: to search for life beyond our own planet.

We discuss the formation of aerosols within Titan's thermosphere-ionosphere and the different chemical pathways. Negative ion measurements by the Cassini Plasma Spectrometer (CAPS) Electron Spectrometer (ELS) give evidence for formation of unsaturated anion carbon chains, while positive ion measurements of the Cassini Ion Neutral Mass Spectrometer (INMS) indicate formation of more aromatic cation hydrocarbons. There is presently no direct observational evidence for large neutral molecule growth in Titan's thermosphere-ionosphere. The hydrocarbon cations are expected to form Polycyclic Aromatic Hydrocarbons (PAH), those with the addition of nitrogen being called PAHNs. We theorize anion carbon chains can eventually become long enough to fold into fullerene C60,70 carbon shells, of various charge states. Based on laboratory data the fullerenes can trap incoming O+ magnetospheric ions that have relatively high energy collisions with the fullerenes and, once trapped, protect the oxygen atom from Titan's reducing thermosphere-ionosphere. The fullerenes can form into larger onion fullerenes and condense into larger embryo aerosols (i.e., m/q > 10,000 amu/q anions as observed by CAPS/ELS) eventually falling onto Titan's surface and precipitating to the bottom of its hydrocarbon lakes. Molecule production composed of H, C, N is known to occur in Titan's atmosphere with energy input from the magnetosphere, solar UV, and deep-penetrating irradiation from galactic cosmic rays (GCR). Space radiation effects by GCR irradiation of Titan's surface and lakes can lead to the manufacture of exobiological molecules with oxygen as the new ingredient. We have developed a model of galactic cosmic ray irradiation of Titan's atmosphere, surface, subsurface and bottoms of Titan lakes. GCR would provide further energy for processing of the aerosols into more complex organic forms such as tholins and precursor molecules for amino acids. A second process called hydrolysis then converts the precursor molecules into amino acids. Hydrolysis is provided via meteor impacts with size >10 km and cryovolcanism both which can produce liquid water on Titan's surface for episodic periods > several 100 to 1000 years. Our model shows that GCR secondary particles can penetrate ~ 100 m below the ice surface (including the bottom of Titan's less dense hydrocarbon lakes ~ 150 m depths) and produce chemically significant dosages over very long timescales ~ 450 Myrs. The GCR model is combined with laboratory data from experiments in which dry methyl ices were irradiated to doses producing prebiotic amino acids such as glycine. The model calculations show glycine can form to ~ 2.5 ppb levels near the surface after ~ 450 Myrs of GCR proton irradiation and potentially to 5 ppb if heavy-ion GCRs up through Fe are included. If such molecules were detected, this would not only confirm this model but indicate that life forms different from ours may not be required.

Earth and Space Science Open Archive PosterOpen AccessYou are viewing the latest version by default [v1]Parker Solar Probe In-Situ Data at the SPDF ArchivesAuthors Robert Candey iD Dieter Bilitza iD Reine Chimiak John Cooper iD Leonard Garcia Codie Gladney Bernard Harris Lan Jian iD Rita Johnson iD Tamara Kovalick Nand Lal Howard Leckner Michael Liu Robert McGuire iD Natalia Papitashvili Uthra Rao D Aaron Roberts Ronald Yurow See all authors Robert CandeyiDCorresponding AuthorNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0002-4698-8769view email addressThe email was not providedcopy email addressDieter BilitzaiDNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0001-6551-2929view email addressThe email was not providedcopy email addressReine ChimiakNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressJohn CooperiDNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0003-4832-7320view email addressThe email was not providedcopy email addressLeonard GarciaSGT, Inc.view email addressThe email was not providedcopy email addressCodie GladneyADNET Systems Inc. Greenbeltview email addressThe email was not providedcopy email addressBernard HarrisNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressLan JianiDNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0002-6849-5527view email addressThe email was not providedcopy email addressRita JohnsoniDADNET Systems Inc. GreenbeltiDhttps://orcid.org/0000-0002-5828-1744view email addressThe email was not providedcopy email addressTamara KovalickADNET Systems Inc. Greenbeltview email addressThe email was not providedcopy email addressNand LalNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressHoward LecknerNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressMichael LiuADNET Systems Inc. Greenbeltview email addressThe email was not providedcopy email addressRobert McGuireiDNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0002-0857-918Xview email addressThe email was not providedcopy email addressNatalia PapitashviliADNET Systems Inc. Greenbeltview email addressThe email was not providedcopy email addressUthra RaoADNET Systems Inc. Greenbeltview email addressThe email was not providedcopy email addressD Aaron RobertsNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressRonald YurowADNET Systems Inc. Greenbeltview email addressThe email was not providedcopy email address

Earth and Space Science Open Archive PosterOpen AccessYou are viewing the latest version by default [v1]Update on Space Physics Data Facility (SPDF) Data Archives and ServicesAuthorsRobertCandeyiDDieterBilitzaiDReineChimiakJohnCooperiDLeonardGarciaBernardHarrisLanJianiDRitaJohnsoniDTamaraKovalickNandLalHowardLecknerMichaelLiuSonyaLyatskyiDRobertMcGuireiDNataliaPapitashviliUthraRaoD AaronRobertsRonaldYurowSee all authors Robert CandeyiDCorresponding Author• Submitting AuthorNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0002-4698-8769view email addressThe email was not providedcopy email addressDieter BilitzaiDNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0001-6551-2929view email addressThe email was not providedcopy email addressReine ChimiakNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressJohn CooperiDNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0003-4832-7320view email addressThe email was not providedcopy email addressLeonard GarciaNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressBernard HarrisNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressLan JianiDNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0002-6849-5527view email addressThe email was not providedcopy email addressRita JohnsoniDNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0002-5828-1744view email addressThe email was not providedcopy email addressTamara KovalickNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressNand LalNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressHoward LecknerNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressMichael LiuNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressSonya LyatskyiDNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0001-6586-6188view email addressThe email was not providedcopy email addressRobert McGuireiDNASA Goddard Space Flight CenteriDhttps://orcid.org/0000-0002-0857-918Xview email addressThe email was not providedcopy email addressNatalia PapitashviliNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressUthra RaoNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressD Aaron RobertsNASA Goddard Space Flight Centerview email addressThe email was not providedcopy email addressRonald YurowADNET Systems Inc.view email addressThe email was not providedcopy email address