Abstract The sample from the near-Earth carbonaceous asteroid (162173) Ryugu is analyzed in the context of carbonaceous meteorites soluble organic matter. The analysis of soluble molecules of samples collected by the Hayabusa2 spacecraft shines light on an extremely high molecular diversity on the C-type asteroid. Sequential solvent extracts of increasing polarity of Ryugu samples are analyzed using mass spectrometry with complementary ionization methods and structural information confirmed by nuclear magnetic resonance spectroscopy. Here we show a continuum in the molecular size and polarity, and no organomagnesium molecules are detected, reflecting a low temperature and water-rich environment on the parent body approving earlier mineralogical and chemical data. High abundance of sulfidic and nitrogen rich compounds as well as high abundance of ammonium ions confirm the water processing. Polycyclic aromatic hydrocarbons are also detected in a structural continuum of carbon saturations and oxidations, implying multiple origins of the observed organic complexity, thus involving generic processes such as earlier carbonization and serpentinization with successive low temperature aqueous alteration.
Spacecraft escape and capture trajectories from or to Halo orbits about the L1 or L2 points using impulsive maneuvers at periapsis of the manifolds for interplanetary transfers are analyzed in the restricted Hill three-body problem. This application is motivated by future proposals to place deep-space ports at the Earth andMars L1 or L2 points. First, the feasibility of interplanetary trajectories between Earth Halo orbits and Mars Halo orbits is investigated. In this study, unstable and stable manifolds associated with the Halo orbits are used to approach the vicinity of the planet’s surface, and use impulsive maneuvers at periapsis for escape and capture trajectories to and from Halo orbits. Interplanetary trajectories between Earth and Mars Halo orbits with reasonable V and flight time are found. Next, applying these dynamics to an Earth–Mars transportation system using spaceports on Earth and Mars Halo orbits, the system is evaluated in terms of the spacecraft mass of round-trip transfer. As a result, transfer between low Earth orbits and low Mars orbits via the planets’ Halo orbits can reduce spacecraft wet mass compared with a direct round-trip transfer, by leaving propellant for the return.
Abstract Volatile components are abundant in carbonaceous asteroids and can be important tracers for the evolution of asteroid surfaces interacting with the space environment, but their behavior on airless surfaces is poorly understood. Samples from the C-type carbonaceous asteroid Ryugu show dehydration of phyllosilicate, indicating ongoing surface modifications on the aqueously-altered asteroid. Here we report the analysis of Ryugu samples showing selective liberation of carbon, oxygen, and sulfur from iron-rich oxide, sulfide, and carbonate, which are major products of aqueous alteration. These mineral surfaces are decomposed to metallic iron, iron nitride, and magnesium-iron oxide. The modifications are most likely caused by solar wind implantation and micrometeorite impacts and are distinct indicators of surface space exposure over 10 3 years. Nitridation of metallic iron may require micrometeorites rich in solid nitrogen compounds, which implies that the amount of nitrogen available for planetary formation in the inner solar system is larger than previously recognized.
Laboratory analysis of samples returned from an asteroid establishes a direct link between asteroids and meteorites and provides clues to the complex history of the asteroid and its surface.
Abstract C-type asteroids 1 are considered to be primitive small Solar System bodies enriched in water and organics, providing clues to the origin and evolution of the Solar System and the building blocks of life. C-type asteroid 162173 Ryugu has been characterized by remote sensing 2–7 and on-asteroid measurements 8,9 with Hayabusa2 (ref. 10 ). However, the ground truth provided by laboratory analysis of returned samples is invaluable to determine the fine properties of asteroids and other planetary bodies. We report preliminary results of analyses on returned samples from Ryugu of the particle size distribution, density and porosity, spectral properties and textural properties, and the results of a search for Ca–Al-rich inclusions (CAIs) and chondrules. The bulk sample mainly consists of rugged and smooth particles of millimetre to submillimetre size, confirming that the physical and chemical properties were not altered during the return from the asteroid. The power index of its size distribution is shallower than that of the surface boulder observed on Ryugu 11 , indicating differences in the returned Ryugu samples. The average of the estimated bulk densities of Ryugu sample particles is 1,282 ± 231 kg m −3 , which is lower than that of meteorites 12 , suggesting a high microporosity down to the millimetre scale, extending centimetre-scale estimates from thermal measurements 5,9 . The extremely dark optical to near-infrared reflectance and spectral profile with weak absorptions at 2.7 and 3.4 μm imply a carbonaceous composition with indigenous aqueous alteration, matching the global average of Ryugu 3,4 and confirming that the sample is representative of the asteroid. Together with the absence of submillimetre CAIs and chondrules, these features indicate that Ryugu is most similar to CI chondrites but has lower albedo, higher porosity and more fragile characteristics.
Abstract– The Planetary Material Sample Curation Facility of JAXA (PMSCF/JAXA) was established in Sagamihara, Kanagawa, Japan, to curate planetary material samples returned from space in conditions of minimum terrestrial contaminants. The performances for the curation of Hayabusa‐returned samples had been checked with a series of comprehensive tests and rehearsals. After the Hayabusa spacecraft had accomplished a round‐trip flight to asteroid 25143 Itokawa and returned its reentry capsule to the Earth in June 2010, the reentry capsule was brought back to the PMSCF/JAXA and was put to a series of processes to extract recovered samples from Itokawa. The particles recovered from the sample catcher were analyzed by electron microscope, given their ID, grouped into four categories, and preserved in dimples on quartz slide glasses. Some fraction of them has been distributed for initial analyses at NASA, and will be distributed for international announcement of opportunity (AO), but a certain fraction of them will be preserved in vacuum for future analyses.
