Space instrumentation

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.

Abstract:

The Lucy Mission to the Trojan asteroids in Jupiter’s orbit carries an instrument named L’Ralph, a visible/near infrared multi-spectral imager and a short wavelength infrared hyperspectral imager. It is one of the core instruments on Lucy, NASA’s first mission to the Trojans. L’Ralph’s primary purpose is to map the surface geology and composition of these objects, but it will also be used to search for possible tenuous exospheres. It is compact, low mass (32.3 kg), power efficient (24.5 W), and robust with high sensitivity and excellent imaging. These characteristics, and its high degree of redundancy, make L’Ralph ideally suited to this long-duration multi-flyby reconnaissance mission.

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.

Abstract:

This publisher's note serves to correct Appl. Opt.62, 5882 (2023).APOPAI0003-693510.1364/AO.491970.

Abstract:

Heterogeneous electrochemistry induced by Martian dust activity is an important type of atmosphere-surface interaction that affects geochemical processes at the Martian surface and in the Martian atmosphere. We have experimentally demonstrated that heterogeneous electrochemistry stimulated by mid-strength dust events can decompose common chloride salts, which is accompanied by the release of chlorine atoms into the atmosphere and the generation of (per)chlorates (chlorates and perchlorates) and carbonates. In this study, we present quantitative analyses on the above products from 26 heterogeneous electrochemical experiments on chloride salts. Based on these quantifications, our calculation indicates that such atmosphere-surface interaction during a portion of Amazonian period could accumulate the observed abundance of (per)chlorates, carbonates, and HCl by landed and orbital missions, and thus can be considered as a major driving force of the global chlorine-cycle on Mars. This study emphasizes the importance of measuring the electrical properties of dust activity on Mars.