Ultraviolet and visible reflectance spectra of Phobos and Deimos as measured by the ExoMars-TGO/Nomad-UVIS spectrometer

Journal of Geophysical Research: Planets Wiley 128:12 (2023) e2023JE008002

Authors:

Jp Mason, Mr Patel, M Pajola, Ed Cloutis, J Alday, Ks Olsen, C Marriner, Ja Holmes, G Sellers, N Thomas, M Almeida, M Read, H Nakagawa, Ir Thomas, B Ristic, Y Willame, C Depiesse, F Daerden, Ac Vandaele, Jj Lopez-Moreno, G Bellucci

Abstract:

Spectroscopic measurements are a powerful tool to investigate the surface composition of airless bodies and provide clues of their origin. The composition and origin of Phobos and Deimos are still unknown and are currently widely debated. We present spectroscopic measurements of Phobos and Deimos at ultraviolet and visible wavelengths (250–650 nm) made by the NOMAD-Ultraviolet and Visible Spectrometer (UVIS) on the ExoMars TGO mission. These new spectra cover multiple areas on Phobos and Deimos, and are of generally higher spectral resolution and signal-to-noise than previous spectra, and extend to lower wavelengths than most previous measurements. The UVIS spectra confirm a red-sloped spectrum lacking any strong absorption features; however, we confirm the presence of a previously identified absorption feature near 0.65 μm and tentative absorption near 0.45 μm. The observed Phobos and Deimos spectra are similar to D- and T-type asteroids, adding weight to the captured asteroid hypothesis for the moons' origins. We also find, however, that the UVIS Phobos reflectance spectra of Phobos' red unit is a relatively close match to the olivine-rich, highly shocked Mars meteorite NWA 2737, with a low overall reflectance, a red-sloped spectrum, and lack of olivine-associated absorption bands in the UVIS spectral range. This meteorite, however, exhibits spectral features at longer wavelengths that not observed in the Martian moon spectra, indicating a need for further investigation at longer wavelengths to interpret whether this material could inform our understanding of Phobos' origin.

L’Ralph: A Visible/Infrared Spectral Imager for the Lucy Mission to the Trojans

Space Science Reviews Springer Nature 219:8 (2023) 69

Authors:

DC Reuter, AA Simon, A Lunsford, H Kaplan, M Garrison, J Simpson, G Casto, Z Dolch, P Finneran, W Grundy, C Howett, P Kim, M Loose, T Null, F Parong, J Rodriguez-ruiz, P Roming, K Smith, P Thompson, B Tokarcik, T Veach, S Wall, J Ward, E Weigle, H Levison

Revised upper limits for abundances of NH3, HCN and HC3N in the Martian atmosphere

Icarus Elsevier 407 (2023) 115789

Authors:

A Trokhimovskiy, Aa Fedorova, F Lefèvre, O Korablev, Kevin S Olsen, J Alday, D Belyaev, F Montmessin, A Patrakeev, N Kokonkov

Abstract:

The Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO) spacecraft has been studying Mars' atmosphere since 2018. The sensitivity of the middle infrared channel (MIR) allows it to address many ardent topics and it is capable of improving and establishing upper limits for many trace species. In this work we present analysis of transmittance spectra in the 3332.5–3338.6 cm−1 range with 30,000 resolution (λ∕Δλ), covering absorptions lines of three nitrogen-bearing species: ammonia (NH3), hydrogen cyanide (HCN) and cyanoacetylene (HC3N). According to existing models, all of those are not expected to be present in a CO2-rich Martian atmosphere, but outgassing or unknown chemistry sources cannot be discounted. The upper limits of 14, 1.5 and 11 ppbv are obtained for NH3, HCN and HC3N from individual occultation measurements during the warm and dusty perihelion season of martian year 36. For the ammonia and hydrogen cyanide the upper limits are improved compared to previously published results. A search for cyanoacetylene on Mars is reported for the first time.

A Spectroscopic Thermometer: Individual Vibrational Band Spectroscopy with the Example of OH in the Atmosphere of WASP-33b

The Astronomical Journal American Astronomical Society 166:2 (2023) 41

Authors:

Sam OM Wright, Stevanus K Nugroho, Matteo Brogi, Neale P Gibson, Ernst JW de Mooij, Ingo Waldmann, Jonathan Tennyson, Hajime Kawahara, Masayuki Kuzuhara, Teruyuki Hirano, Takayuki Kotani, Yui Kawashima, Kento Masuda, Jayne L Birkby, Chris A Watson, Motohide Tamura, Konstanze Zwintz, Hiroki Harakawa, Tomoyuki Kudo, Klaus Hodapp, Shane Jacobson, Mihoko Konishi, Takashi Kurokawa, Jun Nishikawa, Masashi Omiya, Takuma Serizawa, Akitoshi Ueda, Sébastien Vievard, Sergei N Yurchenko

Cassini composite infrared spectrometer: correcting an offset error and refining the pointing parameters for the midinfrared detectors.

Applied optics 62:22 (2023) 5882-5888

Authors:

John C Pearl, Conor A Nixon, Donald E Jennings, Shahid Aslam, Simon Calcutt, Monte S Kaelberer, Nicolas Gorius, Richard K Achterberg, Paul N Romani, Gordon L Bjoraker, Michael Flasar

Abstract:

Based on preflight laboratory testing, an unexpectedly large positional offset between the two midinfrared (mid-IR) detector arrays in the Cassini composite infrared spectrometer (CIRS) instrument has been noted in the literature. A much smaller offset was measured in-flight. We investigate this discrepancy by estimating several spatial relationships among the detectors and comparing these results with three independent data sets. This enables us to infer the probable cause of this offset and to derive a new reduced value. We comment on the effect that this change could have on previously published results involving CIRS data. We also present a graphical display of the arrays projected on the sky as CIRS would see it.