Showing papers by "Mahesh Anand published in 2022"

Isotopic evidence for pallasite formation by impact mixing of olivine and metal during the first 10 million years of the Solar System

Abstract: Abstract Pallasites are mixtures of core and mantle material that may have originated from the core–mantle boundary of a differentiated body. However, recent studies have introduced the possibility that they record an impact mix, in which case an isotopic difference between metal and silicates in pallasites may be expected. We report a statistically significant oxygen isotope disequilibrium between olivine and chromite in main group pallasites that implies the silicate and metal portions of these meteorites stem from distinct isotopic reservoirs. This indicates that these meteorites were formed by impact mixing, during which a planetary core was injected into the mantle of another body. The impactor likely differentiated within ∼1–2 Myr of the start of the Solar System based on Hf–W chronology of pallasite metal, and we infer the age of the impact based on Mn–Cr systematics and cooling rates at between ∼1.5 and 9.5 Myr after Ca–Al-rich inclusions (CAIs). When combined with published slow subsolidus cooling rates for these meteorites and considering that several pallasite groups exist, our results indicate that such impacts may be an important stage in the evolution of planetary bodies.

Open Research Online Extra-terrestrial construction processes -advancements, opportunities and challenges

Abstract: Government space agencies, including NASA and ESA, are conducting preliminary studies on building alternative space-habitat systems for deep-space exploration. Such studies include development of advanced technologies for planetary surface exploration, including an in-depth understanding of the use of local resources. Currently, NASA plans to land humans on Mars in the 2030s. Similarly, other space agencies from Europe (ESA), Canada (CSA), Russia (Roscosmos), India (ISRO), Japan (JAXA) and China (CNSA) have already initiated or announced their plans for launching a series of lunar missions over the next decade, ranging from orbiters, landers and rovers for extended stays on the lunar surface. As the Space Odyssey is one of humanity’s oldest dreams, there has been a series of research works for establishing temporary or permanent settlement on other planetary bodies, including the Moon and Mars. This paper reviews current projects developing extra-terrestrial construction, broadly categorised as: (i) ISRU-based construction materials; (ii) fabrication methods; and (iii) construction processes. It also discusses four categories of challenges to developing an appropriate construction process: (i) lunar simulants; (ii) material fabrication and curing; (iii) microwave-sintering based fabrication; and (iv) fully autonomous and scaled-up construction processes.

Open Research Online H and Cl isotope characteristics of indigenous and late hydrothermal fluids on the differentiated asteroidal parent body of Grave Nunataks 06128

Abstract: The paired achondrites Graves Nunataks (GRA) 06128 and 06129 are samples of an asteroid that underwent partial melting within a few million years after the start of Solar System formation. In order to better constrain the origin and processing of volatiles in the early Solar System, we have investigated the abundance of H, F and Cl and the isotopic composition of H and Cl in phosphates in GRA 06128 using secondary ion mass spectrometry. Indigenous H in GRA 06128, as recorded in magmatic merrillite, is characterised by an average d D of ca . (cid:1) 152 ± 330 ‰ , which is broadly similar to estimates of the H isotope composition of indigenous H in other differentiated asteroidal and planetary bodies such as Mars, the Moon and the angrite and eucrite meteorite parent bodies. The merrillite data thus suggest that early accretion of locally-derived volatiles was widespread for the bodies currently populating the asteroid belt. Apatite formed at the expense of merrillite around 100 million years after the differentiation of the GRA 06128/9 parent body, during hydrothermal alteration, which was probably triggered by an impact event. Apatite in GRA 06128 contains 5.4–5.7 wt.% Cl, 0.6–0.8 wt.% F, and (cid:3) 20 to 60 ppm H 2 O, which is similar to the H 2 O abundance in merrillite from which apatite formed. The apatite d D values range between around +100 ‰ and +2000 ‰ and are inversely correlated with apatite H 2 O contents. The Cl isotope composition of apatite appears to be homogeneous across various grains, with an average d 37 Cl value of 3.2 ± 0.7 ‰ . A possible scenario to account for the apatite chemical and isotopic characteristics involves interaction of GRA 06128/9 with fumarole-like fluids derived from D- and HCl-rich ices delivered to the GRA 06128/9 parent-body by an ice-rich impactor. (cid:1)

Open Research Online i-Drill: Surface and Sub-Surface Profiling of Lunar Volatiles and Resources by an Instrumented Drill Conference

Abstract: i-Drill: Surface and Sub-Surface Profiling of Lunar Volatiles and Resources by an Instrumented Drill Conference or Workshop Item How to cite: Barber, Simeon; Sheridan, Simon; Morse, Andrew; Anand, Mahesh; Harkness, P.; Timoney, R.; Worrall, K.; Murray, N. J.; Trautner, R. and Howe, C. J. i-Drill: Surface and Sub-Surface Profiling of Lunar Volatiles and Resources by an Instrumented Drill. In: European Lunar Symposium (ELS) 2020, 12-14 May 2020, Virtual.

Towards phosphate UPb texture-age records of Solar System dynamical evolution

Abstract: 1Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK, 2Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 OHA, UK, 3Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 China, 4School of Physical Sciences, Open University, Walton Hall, Milton, Keynes, MK7 6AA, United Kingdom, 5State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029 China. 6Department of Earth Sciences, The Natural History Museum, London, SW7 5BD, UK.