¹Anicia Arredondo,¹Humberto Campins,²Noemi Pinilla-Alonso,^3,4Juliade León,^5,3Vania Lorenzi,^5,6DavidMorat
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114028]
¹Physics Department, University of Central Florida, P.O. Box 162385, Orlando, FL 32816, USA
²Florida Space Institute, University of Central Florida, Orlando, FL 32816, USA
³Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, 38205, La Laguna, Tenerife, Spain
⁴Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
⁵Fundación Galileo Galilei – INAF, La Palma (TF), Spain
⁶Observatório Nacional, Coordenação de Astronomia e Astrofísica, Rio de Janeiro 20921-400, Brazil
Copyright Elsevier

There are eight primitive asteroid families in the inner main belt. The PRIMitive Asteroid Spectroscopic Survey (PRIMASS) has characterized all eight families using visible spectroscopy, and two of the families at near infrared wavelengths. This work is part of our survey at near infrared wavelengths and adds a third family, Chaldaea, to it. We see a compositional trend with inclination in the lower inclination families, however, the higher inclination families show more complexity. So far, primitive inner belt families appear spectrally similar (but not identical) in the near infrared despite their diversity at visible wavelengths.

We observed 15 objects in the Chaldaea primitive inner belt family using the NASA InfraRed Telescope Facility (IRTF) and the Telescopio Nazionale Galileo (TNG) between January 2017 and February 2020. Our survey shows that the Chaldaea family is spectrally homogeneous in the NIR, similar to what was seen in the other primitive inner belt families in the near infrared. The Chaldaea family spectra have overwhelmingly concave shapes and have red slopes (average slope 0.85 ± 0.42%/1000 Å in the region between 0.95 and 2.3 μm). We compare these new spectra with spectra from the Klio family and find that they are similar at these wavelengths, which is consistent with these two families having originated from the same parent body.

¹Samuel H.Halim,¹Ian A.Crawford,²Gareth S.Collins,³Katherine H.Joy,²Thomas M.Davison
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114026]
¹Department of Earth and Planetary Sciences, Birkbeck, University of London, Malet St., London WC1E 7HX, UK
²Department of Earth Science & Engineering, Imperial College London, Kensington, London SW7 2AZ, UK
³Department of Earth and Environmental Sciences, University of Manchester, Oxford Rd., Manchester M13 9PL, UK
Copyright Elsevier

The history of organic and biological markers (biomarkers) on the Earth is effectively non-existent in the geological record >3.8 Ga ago. Here, we investigate the potential for terrestrial material (i.e., terrestrial meteorites) to be transferred to the Moon by a large impact on Earth and subsequently survive impact with the lunar surface, using the iSALE shock physics code. Three-dimensional impact simulations show that a typical basin-forming impact on Earth can eject solid fragments equivalent to ~10⁻³ of an impactor mass at speeds sufficient to transfer from Earth to the Moon. Previous modelling of meteorite survivability has relied heavily upon the assumption that peak-shock pressures can be used as a proxy for gauging survival of projectiles and their possible biomarker constituents. Here, we show the importance of considering both pressure and temperature within the projectile, and the inclusion of both shock and shear heating, in assessing biomarker survival. Assuming that they survive launch from Earth, we show that some biomarker molecules within terrestrial meteorites are likely to survive impact with the Moon, especially at the lower end of the range of typical impact velocities for terrestrial meteorites (2.5 km s⁻¹). The survival of larger biomarkers (e.g., microfossils) is also assessed, and we find limited, but significant, survival for low impact velocity and high target porosity scenarios. Thermal degradation of biomarkers shortly after impact depends heavily upon where the projectile material lands, whether it is buried or remains on the surface, and the related cooling timescales. Comparing sandstone and limestone projectiles shows similar temperature and pressure profiles for the same impact velocities, with limestone providing slightly more favourable conditions for biomarker survival.

¹Yuki Itoh,¹Mario Parente
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114024]
¹Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, United States of America
Copyright Elsevier

We propose a new method to perform atmospheric correction and de-noising on hyperspectral image cubes acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board NASA’s Mars Reconnaissance Orbiter (MRO). The CRISM imager has had an important role in advancing our understanding of many aspects of Martian mineralogy. Many mineral detections from CRISM data have been facilitated by significant efforts in the development of the CRISM data processing pipeline to retrieve surface reflectance. However, some residuals remain in CRISM spectra after atmospheric correction, causing difficulty in the interpretation of processed reflectance spectra. In addition, CRISM images are occasionally corrupted with high noise levels exhibiting heterogeneous statistical properties. This paper identifies the cause of such spectral distortions and describe a technique that simultaneously performs both atmospheric correction and de-noising for each image cube individually. In particular, our method focuses on the 1.0–2.6 μm wavelength region of CRISM images and is applicable to images of non-icy surfaces. Experimental results show that our technique is able to significantly mitigate noise and distortions from various sources like gaseous absorptions, detector temperature, and water ice aerosols, compared with the atmospheric correction method in the CRISM official processing pipeline called volcano scan correction, for a variety of scenes. Careful validations that include the qualitative examination of noise and artifacts both on ratioed and non-ratioed spectra and comparison using multiple overlapping images strengthen confidence in our approach.

¹Apostolos A.Christou,^1,2Galin Borisov,³Aldo Dell’Oro,⁴Alberto Cellino,⁵Maxime Devogèle
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.113994] 
¹Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, United Kingdom
²Institute of Astronomy and NAO, 72 Tsarigradsko Chaussée Blvd, Sofia BG-1784, Bulgaria
³INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, Firenze I-50125, Italy
⁴INAF – Osservatorio Astrofisico di Torino, via Osservatorio 20, Pino Torinese 10025, Italy
⁵Lowell Observatory, 1400 W Mars Hill RD, Flagstaff, AZ 86001, USA
Copyright Elsevier

We investigate the mineralogical makeup of L5 Martian Trojan asteroids via reflectance spectroscopy, paying special attention to (101429) 1998 VF₃₁, the only L5 Trojan that does not belong to the Eureka family (Christou, 2013). We find that this asteroid most likely belongs to the Bus-Demeo S-complex, in agreement with Rivkin et al. (2007). We compare it with a variety of solar system bodies and obtain good spectral matches with Sq- or S-type asteroids, with spectra of the lunar surface and of Martian and lunar meteorites. Mixture fitting to spectral endmembers suggests a surface abundance of Mg-rich orthopyroxene and iron metal or, alternatively, a combination of plagioclase and metal with a small amount of Mg-poor orthopyroxene. The metallic component may be part of the intrinsic mineral makeup of the asteroid or an indication of extreme space weathering.

In light of our findings, we discuss a number of origin scenarios for (101429). The asteroid could be genetically related to iron-rich primitive achondrite meteorites (Rivkin et al., 2016), may have originated as impact ejecta from Mars – a scenario proposed recently for the Eureka family asteroids (Polishook et al., 2017) – or could represent a relic fragment of the Moon’s original solid crust, a possibility raised by the asteroid’s close spectral similarity to areas of the lunar surface. If, on the other hand, (101429) is a relatively recent addition to the Martian Trojan clouds (Christou et al., 2020), its origin is probably traced to high-inclination asteroid families in the Inner Main Belt.

For the olivine-dominated Eureka family, we find that the two smaller asteroids in our sample are more spectrally similar to one another than to (5261) Eureka, the largest family member. Spectral profiles of these three asteroids are closely similar shortward of ∼0.7 μ m but diverge at longer wavelengths. For the two smaller asteroids in particular, we find the spectra are virtually identical in the visible region and up to 0.8 μ m. We attribute spectral differences in the near-IR region to differences in either: degree of space weathering, olivine chemical composition and/or regolith grain size.

¹Nan Liu,²Andrew Steele,¹Larry R. Nittler,³Rhonda M. Stroud,³Bradley T. De Gregorio,¹Conel M. O’D. Alexander,¹Jianhua Wang
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13555]
¹Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, District of Columbia, 20015 USA
²Geophysical Laboratory, Carnegie Institution for Science, Washington, District of Columbia, 20015 USA
³Materials Science and Technology Division, US Naval Research Laboratory, Washington, District of Columbia, 20375–5320 USA
Published by arrangement with John Wiley & Sons

We noticed a few minor errors in Table S2 in the supplement of the original manuscript, as summarized below. (1) The error for the 14N/15N ratio of grain M2‐A4‐G27 should be 0.2 instead of 0.3. (2) The δ30Si value of grain M1‐A5‐G1112 should be 16 instead of 19. (3) The names of grains M2‐A1‐G569 and M2‐A1‐G576 should be M2‐A2‐G569 and M2‐A1‐G576‐2, respectively. This erratum contains the correct data table (Table S2).

In addition, we would like to note that the isotope ratios for grains M1‐A4‐G557 and M2‐A1‐G303 reported in Table S2 are slightly different from those reported in Liu et al. (2017), due to small differences in the adopted regions of interest (ROIs) for data reduction. The use of different ROIs and slightly different normalization approaches also resulted in small differences between the silicon isotope ratios of X grains reported in Table S2 and in Liu et al. (2018). The two sets of data, however, generally overlap with each other within 1σ errors, and the small differences do not affect any of the discussions or conclusions in these papers.