Solar system

Abstract:

<jats:title>Abstract</jats:title> <jats:p>We present radiative transfer analyses of IRTF-TEXES and SOFIA-EXES mid-infrared spectra of Jupiter's mid- to high latitudes recorded between 2019 April 16 and 2023 July 20. The spectra were inverted across a photochemical model grid of varying eddy diffusion coefficient profiles, and the quality of fit of the synthetic spectra to the observed was used to constrain the CH<jats:sub>4</jats:sub> homopause level. For a subset of latitudes/dates, we find that the CH<jats:sub>4</jats:sub> homopause level is elevated in the region enclosed inside of, or magnetospherically poleward of, the northern ultraviolet main auroral emissions (MAEs) in comparison to the region outside or equatorward of the MAE. For example, using SOFIA-EXES results on 2021 June 10, we derived a CH<jats:sub>4</jats:sub> homopause level of log(<jats:italic>p</jats:italic> <jats:sub>H</jats:sub>(nbar)) = 1.54<jats:inline-formula> <jats:tex-math> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.69</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.51</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> </jats:inline-formula> or <jats:italic>z</jats:italic> <jats:sub>H</jats:sub> = 453<jats:inline-formula> <jats:tex-math> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow/> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>76</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>128</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> </jats:inline-formula> km above 1 bar poleward of the northern MAE at 68<jats:sup>∘</jats:sup>N compared to a lower limit of log(<jats:italic>p</jats:italic> <jats:sub>H</jats:sub>) &gt; 2.43 and upper limit of <jats:italic>z</jats:italic> <jats:sub>H</jats:sub> &lt; 322 km derived equatorward of the northern MAE. We therefore conclude that the region poleward of the northern MAE is, at times, subject to enhanced vertical transport resulting from auroral energy deposition. The exact mechanisms responsible for the enhanced vertical transport in Jupiter's auroral regions are uncertain: time-dependent circulation modeling of Jupiter's polar atmosphere is required to better understand this phenomenon. Poleward of the southern MAE, derived homopause levels agreed within uncertainty with those at equatorward locations. However, we consider this result a spatial sampling artifact rather than concluding that the southern auroral region is not subject to enhanced vertical transport.</jats:p>

Abstract:

The Peregrine Ion Trap Mass Spectrometer (PITMS) was a mass spectrometer designed to measure lunar gases. PITMS flew on the first flight of Astrobotic’s Peregrine lander via the Commercial Lunar Payload Services (CLPS) program in 2024 January. After launch, the lander suffered a propulsion system anomaly that prevented the mission from reaching the Moon, but PITMS collected 80 high-quality spectra while in cislunar space. PITMS observed abundant outgassing products from the Peregrine lander, including water, MON-25 oxidizer from the propulsion system leak, and traces of combustion products. PITMS data help constrain the nature of the propulsion system failure: oxidizer molecular ratios show that the leak released molecules rapidly enough for them to fully dissociate, and the high observed abundances imply that the oxidizer traveled within the lander surfaces rather than jetting into space. The amount of water offgassed by the spacecraft is substantially more than other planetary spacecraft, so the PITMS results suggest that instruments flying in the CLPS paradigm need to consider lander cleanliness. Though not successful in measuring the native lunar exosphere, the PITMS results showcase the capabilities of a mass spectrometer on board a lunar lander, along with lessons in pragmatism and flexibility that would enable such an instrument to ultimately be successful in the CLPS initiative.

Abstract:

The L’Ralph instrument is a key component of NASA’s Lucy mission, intended to provide spectral image data of multiple Jupiter Trojans. The instrument operates from ∼0.35 to 4 μm using two focal plane assemblies: a 350–950 nm multispectral imager, Multi-spectral Visible Imaging Camera (MVIC), and a 0.97–4 μm imaging spectrometer, Linear Etalon Imaging Spectral Array (LEISA). Instrument calibration was established through ground testing before launch and has been monitored during cruise utilizing internal calibration sources and stellar targets. In-flight data have shown that the instrument thermal performance is exceeding expectations, allowing for early updates to LEISA radiometric and pointing calibrations. MVIC radiometric performance remains stable more than 3 yr since launch. The serendipitous identification of a new flyby target, (152830) Dinkinesh, allowed testing of instrument performance and interleaved LEISA and MVIC acquisitions on an asteroid target. Both MVIC and LEISA obtained data of Dinkinesh and its moon, Selam, demonstrating that they show good spectral agreement with an S- or Sq-type asteroid, along with evidence of a 3 μm absorption feature.