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NASA NTRS2021

The Impact and Recovery of Asteroid 2018 LA

The June 2, 2018 impact of asteroid 2018 LA over Botswana is only the second asteroid detected in space prior to impacting over land. Here, we report on the successful recovery of meteorites. Additional astrometric data refine the approach orbit and define the spin period and shape of the asteroid. Video observations of the fireball constrain the asteroid’s position in its orbit and were used to triangulate the location of the fireball’s main flare over the Central Kalahari Game Reserve. Twenty-three meteorites were recovered. A consortium study of eight of these classifies Motopi Pan as an HED polymict breccia derived from howardite, cumulate and basaltic eucrite, and diogenite lithologies. Before impact, 2018 LA was a solid rock of ~156 cm diameter with high bulk density ~2.85 g cm(exp -3), a relatively low albedo p(sub v) ~0.25, no significant opposition effect on the asteroid brightness, and an impact kinetic energy of ~0.2 kt. The orbit of 2018 LA is consistent with an origin at Vesta (or its Vestoids) and delivery into an Earth-impacting orbit via the m6 resonance. The impact that ejected 2018 LA in an orbit toward Earth occurred 22.8 ± 3.8 Ma ago. Zircons record a concordant U-Pb age of 4563 ± 11 Ma and a consistent 207Pb/206Pb age of 4563 ± 6 Ma. A much younger Pb-Pb phosphate resetting age of 4234 ± 41 Ma was found. From this impact chronology, we discuss what is the possible source crater of Motopi Pan and the age of Vesta’s Veneneia impact basin.

Peter Jenniskens↗
NASA NTRS2021

Volatile Composition and Outgassing in C/2018 Y1 (Iwamoto): Extending Limits for High-Resolution Infrared Cometary Spectroscopy between 2.8 and 5.0 µm

We used the powerful high spectral resolution cross-dispersed facility spectrograph, iSHELL, at the NASAInfrared Telescope Facility(IRTF)to observe C/2018 Y1(Iwamoto), a long-period comet from the Oort cloud.We report production rates for water and eight other parent molecules(native ices),C2H6, CO, CH4,H2CO,CH3OH, HCN, NH3, and C2H2, on three preperihelion UT dates, 2019 January 13 and(near perihelion)February4–5. We present abundance ratios relative to both C2H6(a nonpolar molecule)and H2O(a polar molecule), thereby providing a more complete picture of the parent volatile composition of C/2018 Y1 and potential associations of ices in its nucleus. Overall, the measured spatial distributions for polar molecules(in particular, H2O and CH3OH)were broader, exhibiting more complex structure compared with nonpolar or weakly polar species(CH4,C2H6, andCO). Our January 13 results permitted quantitatively assessing the significant improvement in sensitivity delivered by iSHELL compared with previous capabilities at the IRTF. The efficient spectral coverage of iSHELL plus the favorable geocentric Doppler shift of C/2018 Y1 allowed for measuring>50% of CH4ν3-band emission intensity on both January 13 and February 5. Compositionally, compared to their respective mean abundances among comets from the Oort cloud, C2H6and CH3OH were enriched, CH4and HCN were near normal, and all other species were depleted. The abundance ratio CH3OH/C2H6was higher by 45%±8% on January 13 versusFebruary 5, whereas CH4/C2H6was unchanged within the uncertainty, suggesting nonhomogeneous composition among regions of the nucleus dominating activity on these dates

Michael A. Disanti↗
NASA NTRS2022

Volatile Abundances, Extended Coma Sources, and Nucleus Ice Associations in Comet C/2014 Q2 (Lovejoy)

High-resolution infrared spectra of comet C/2014 Q2 Lovejoy were acquired with NIRSPEC at the W. M. Keck Observatory on two post-perihelion dates(UT 2015 February 2 and 3).H2O was measured simultaneously with CO,CH3OH, H2CO, CH4, C2H6,C2H4, C2H2, HCN, and NH3 on both dates, and rotational temperatures, production rates, relative abundances, H2O ortho-to-para ratios, and spatial distributions in the coma were determined. The first detection of C2H4in a comet from ground-based observations is reported. Abundances relative to H2O for all species were found to be in the typical range compared with values for other comets in the overall population to date. There is evidence of variability in rotational temperatures and production rates on timescales that are small compared with the rotational period of the comet. Spatial distributions of volatiles in the coma suggest complex outgassing behavior.CH3OH, HCN, C2H6, and CH4 spatial distributions in the coma are consistent with direct release from associated ices in the nucleus and are peaked in a more sunward direction compared with co-measured dust. H2O spatial profiles are clearly distinct from these other four species, likely due to a sizable coma contribution from icy grain sublimation.Spatial distributions for C2H2,H2CO, and NH3suggest substantial contributions from extended coma sources, providing further evidence for distinct origins and associations for these species in comets. CO shows a different spatial distribution compared with other volatiles, consistent with jet activity from discrete nucleus ice sources.

Neil Dello Russo↗
NASA NTRS2022

Satellite Data Applications for Sustainable Energy Transitions

Transitioning to a sustainable energy system poses a massive challenge to communities, nations, and the global economy in the next decade and beyond. A growing portfolio of satellite data products is available to support this transition. Satellite data complement other information sources to provide a more complete picture of the global energy system, often with continuous spatial coverage over targeted areas or even the entire Earth. We find that satellite data are already being applied to a wide range of energy issues with varying information needs, from planning and operation of renewable energy projects, to tracking changing patterns in energy access and use, to monitoring environmental impacts and verifying the effectiveness of emissions reduction efforts. While satellite data could play a larger role throughout the policy and planning lifecycle, there are technical, social, and structural barriers to their increased use. We conclude with a discussion of opportunities for satellite data applications to energy and recommendations for research to maximize the value of satellite data for sustainable energy transitions.

energy↗
NASA NTRS2026

Surprisingly Enriched CO and CH4 in Halley-type Comet 13P/Olbers: Clues to Its Interstellar Heritage

The native ice composition of Halley-type Comet 13P/Olbers (hereafter 13P) was measured post-perihelion, on UT 2024 August 16 using iSHELL, the 1–5 μm cross-dispersed, high-resolution facility spectrograph at the NASA InfraRed Telescope Facility. At that time, the heliocentric distance (Rh) of 13P was 1.37 au and the geocentric distance (Δ) was 1.99 au. Using a slit that delivered spectral resolving power RP λ/Δλ 4.5 × 104, two instrument settings targeted rovibrational emissions of seven parent molecules released into the coma through sublimation of ices in the nucleus. These settings provided broad and contiguous or nearly contiguous spectral coverage, one simultaneously measuring H2O, CO, and OCS, and the other simultaneously measuring CH4, C2H6, CH3OH, and H2CO. Meaningful abundances were obtained for all seven species. Our study revealed substantial enrichments of CO and CH4, the two most volatile species systematically targeted at IR wavelengths in comets. Relative to their respective mean abundance ratios among measured comets from the Oort cloud reservoir, CO in 13P was enriched by a factor of about six and CH4 was enriched by a factor of about three. Together with near-average abundances measured for CH3OH and C2H6, this suggests large endowments of CO and CH4 on interstellar grains, yet it could indicate inhibited surface chemistry on the pre-cometary grains subsequently contained in the nucleus or 13P. Assuming that this represents the primordial composition of 13P, it could reflect very low temperatures in its natal environment (∼10 K or lower).

Michael A Disanti↗