51ÁÔÆæÈë¿Ú

Abstract:

Spectral observations of Neptune made in 2019 with the MUSE instrument at the Very Large Telescope in Chile have been analysed to determine the spatial variation of aerosol scattering properties and methane abundance in Neptune’s atmosphere. The darkening of the South Polar Wave (SPW) at ∼ 60◦S, and dark spots such as the Voyager 2 Great Dark Spot is concluded to be due to a spectrally-dependent darkening (λ < 650nm) of particles in a deep aerosol layer at ∼ 5 bar and presumed to be composed of a mixture of ~ 650 nm, with bright zones latitudinally separated by ∼ 25◦ . This feature, similar to the spectral characteristics of a discrete deep bright spot DBS-2019 found in our data, is found to be consistent with a brightening of the particles in the same ∼5-bar aerosol layer at λ > 650 nm. We find the properties of an overlying methane/haze aerosol layer at ∼ 2 bar are, to first-order, invariant with latitude, while variations in the opacity of an upper tropospheric haze layer reproduce the observed reflectivity at methane-absorbing wavelengths, with higher abundances found at the equator and also in a narrow ‘zone’ at 80◦S. Finally, we find the mean abundance of methane below its condensation level to be 6-7% at the equator reducing to ∼3% south of ∼25◦S, although the absolute abundances are model dependent.

Abstract:

In the original publication, there has been a discrepancy between values mentioned in the text of Sect. 4.3.3 and in Table 1. The corrected version is provided here: Wrong: The gravity field harmonic coefficients up to an average degree strength of 130 (∼145 km) are generated together with corrections to the spin rate and to the pole right ascension and declination. Correct: The gravity field harmonic coefficients up to an average degree strength of 200 (∼105 km, see Table 1) are generated together with corrections to the spin rate and to the pole right ascension and declination.

Abstract:

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.