Identifying the source of Earth's water is central to understanding the origins of life-fostering environments and to assessing the prevalence of such environments in space. Water throughout the solar system exhibits deuterium-tohydrogen enrichments, a fossil relic of low-temperature, ion-derived chemistry within either (i) the parent molecular cloud or (ii) the solar nebula protoplanetary disk. Utilizing a comprehensive treatment of disk ionization, we find that ion-driven deuterium pathways are inefficient, curtailing the disk's deuterated water formation and its viability as the sole source for the solar system's water. This finding implies that if the solar system's formation was typical, abundant interstellar ices are available to all nascent planetary systems.Water is ubiquitous across the solar system, in cometary ices, terrestrial oceans, the icy 1 moons of the giant planets, and in the shadowed basins of Mercury (1, 2). Water has left its mark in hydrated minerals in meteorites, in lunar basalts (3) and in martian melt-inclusions (4).The presence of liquid water facilitated the emergence of life on Earth, and thus understanding the origin(s) of water throughout the solar system is a key goal of astrobiology. Comets and asteroids (traced by meteorites) remain the most primitive objects, providing a natural "time capsule" of the conditions present during the epoch of planet formation. Their compositions reflect those of the gas, dust, and -most importantly -ices encircling the Sun at its birth, i.e., the solar nebula protoplanetary disk. There remains an open question, however, as to when and where these ices formed, whether they i) originated in the dense interstellar medium (ISM) in the cold molecular cloud core prior to the Sun's formation, or ii) are products of reprocessing within the solar nebula (5-7). Scenario i) would imply that abundant interstellar ices, including water and presolar organic material, are incorporated into all planet-forming disks. By contrast, local formation within the solar nebula in scenario ii) would potentially result in large water abundance variations from stellar system to system, dependent upon the properties of the star and disk.In this work, we aim to constrain the formation environment of the solar system's water using deuterium fractionation as our chemical tracer. Water is enriched in deuterium relative to hydrogen (D/H) compared to the initial bulk solar composition across a wide range of solar system bodies, including comets, (8, 9), terrestrial and ancient Martian water (4), and hydrated minerals in meteorites (10). The amount of deuterium relative to hydrogen of a molecule depends on its formation environment, and thus the D/H fraction in water, [D/H] H 2 O , can be used to differentiate between the proposed source environments. Interstellar ices, as revealed by sublimation in close proximity to forming young stars, also exhibit high degrees of deuteriumenrichment, ∼ 2 − 30× that of terrestrial water (11)(12)(13)(14). It is unknown to what extent these extreme...

Although no known asteroid poses a threat to Earth for at least the next century, the catalogue of near-Earth asteroids is incomplete for objects whose impacts would produce regional devastation1,2. Several approaches have been proposed to potentially prevent an asteroid impact with Earth by deflecting or disrupting an asteroid1–3. A test of kinetic impact technology was identified as the highest-priority space mission related to asteroid mitigation1. NASA’s Double Asteroid Redirection Test (DART) mission is a full-scale test of kinetic impact technology. The mission’s target asteroid was Dimorphos, the secondary member of the S-type binary near-Earth asteroid (65803) Didymos. This binary asteroid system was chosen to enable ground-based telescopes to quantify the asteroid deflection caused by the impact of the DART spacecraft4. Although past missions have utilized impactors to investigate the properties of small bodies5,6, those earlier missions were not intended to deflect their targets and did not achieve measurable deflections. Here we report the DART spacecraft’s autonomous kinetic impact into Dimorphos and reconstruct the impact event, including the timeline leading to impact, the location and nature of the DART impact site, and the size and shape of Dimorphos. The successful impact of the DART spacecraft with Dimorphos and the resulting change in the orbit of Dimorphos7 demonstrates that kinetic impactor technology is a viable technique to potentially defend Earth if necessary.

HNC and HCN, typically used as dense gas tracers in molecular clouds, are a pair of isomers that have great potential as a temperature probe because of temperature dependent, isomer-specific formation and destruction pathways. Previous observations of the HNC/HCN abundance ratio show that the ratio decreases with increasing temperature, something that standard astrochemical models cannot reproduce. We have undertaken a detailed parameter study on which environmental characteristics and chemical reactions affect the HNC/HCN ratio and can thus contribute to the observed dependence. Using existing gas and gas-grain models updated with new reactions and reaction barriers, we find that in static models the H + HNC gas-phase reaction regulates the HNC/HCN ratio under all conditions, except for very early times. We quantitively constrain the combinations of H abundance and H + HNC reaction barrier that can explain the observed HNC/HCN temperature dependence and discuss the implications in light of new quantum chemical calculations. In warm-up models, gas-grain chemistry contributes significantly to the predicted HNC/HCN ratio and understanding the dynamics of star formation is therefore key to model the HNC/HCN system.

Complex organic molecules (COMs) have been observed towards several low-mass young stellar objects (LYSOs). Small and heterogeneous samples have so far precluded conclusions on typical COM abundances, as well as the origin(s) of abundance variations between sources. We present observations towards 16 deeply embedded (Class 0/I) low-mass protostars using the IRAM 30m telescope. We detect CH 2 CO, CH 3 CHO, CH 3 OCH 3 , CH 3 OCHO, CH 3 CN, HNCO, and HC 3 N towards 67%, 37%, 13%, 13%, 44%, 81%, and 75% of sources respectively. Median column densities derived using survival analysis range between 6.0x10 10 cm −2 (CH 3 CN) and 2.4x10 12 cm −2 (CH 3 OCH 3 ) and median abundances range between 0.48% (CH 3 CN) and 16% (HNCO) with respect to CH 3 OH. Column densities for each molecule vary by about one order of magnitude across the sample. Abundances with respect to CH 3 OH are more narrowly distributed, especially for oxygen-bearing species. We compare observed median abundances with a chemical model for low-mass protostars and find fair agreement, although some modeling work remains to bring abundances higher with respect to CH 3 OH. Median abundances with respect to CH 3 OH in LYSOs are also found to be generally comparable to observed abundances in hot cores, hot corinos, and massive young stellar objects. Compared with comets, our sample is comparable for all molecules except HC 3 N and CH 2 CO, which likely become depleted at later evolutionary stages.