The 2004 Las Campanas/Lowell Observatory campaign II. Surface properties of Hayabusa target Asteroid 25143 Itokawa inferred from Hapke modeling

Abstract

We present an analysis of Hapke photometric modeling applied to uniform ground-based UBVRIJHK broadband data of asteroid 25143 Itokawa collected over a wide range of solar phase angles (4• -130• ) during the 2004 apparition (Thomas-Osip et al., this issue, hereafter Paper I). Our photometric analyses indicate that Itokawa has a blocky surface with properties different from other, albeit larger, S-class asteroids studied using similar Hapke modeling analyses. Images from the Hayabusa spacecraft affirm the Hapke modeling results, demonstrating the ability of Hapke photometric modeling to predict a rocky asteroid surface correctly; this is the first time that a predicted rocky surface has been observed by a spacecraft. The single particle scattering functions are dominantly forward scattering, suggesting the surface material is composed primarily of clear particles whose scattering is dictated by the particle's surface as opposed to internal scatterers (more typical of S-class asteroids), while the opposition parameters indicate that the regolith may be more compact than most of the limited number of asteroids visited by spacecraft to date. The roughness properties, single particle scattering properties, and opposition surge characteristics are all indicative of a surface where multiple scattering does not play a major role in defining the photometric properties of the regolith.

Opposition effect on S-type asteroid (25143) Itokawa

“…4. Relationship between the incidence angle and I/F, which is computed based on the Hapke model with the parameters given in Lederer et al (2008). The horizontal axis can be regarded as the emission angle due to the small phase angle (assuming zero azimuth angle).…”

Retrieval of Sediment Filling Factor in a Salt Panne from Multi-View Hyperspectral Imagery

“…In most past studies, inversion of the large set of free parameters in the Hapke IMSA model used either laboratory observations and validation data [6,[51][52][53], astronomical observational data from ground-based systems, or probes [15,16,18,19,21] for which direct corroborating ground truth is difficult to obtain, or combinations of these two types of data [2,54,55]. Even when the input data have been Earth remote sensing imagery, typically the Hapke model has been fit to the remote sensing imagery data, and it is an error in the reconstruction of the original spectral reflectance of the remote sensing imagery from the optimized Hapke parameters that has served as validation rather than direct comparison to physical measurements on the ground [7].…”

“…The IMSA model also has been used widely in astronomy, particularly for planetary studies [15][16][17] as well in studies of asteroids and comets [18][19][20][21] associated with recent and future NASA and JAXA probes [16,19,21]. Protopapa et al [15], for example, applied the Hapke IMSA model to the inversion of Linear Etalon Imaging Spectral Array (LEISA) spectral imagery of Pluto from the Ralph instrument onboard the New Horizons probe [22] to retrieve abundances of H 2 O ice, tholin, and mixtures of CH 4 ice and N 2 ice.…”

“…They likewise combined their model with an equivalent slab model and a mixture model; however, they considered three different types of mixtures: areal, intimate, and intraparticle, with best results obtained using the latter. Lederer et al [18] used the Hapke model to analyze disk-integrated reflectance of the asteroid Itokawa from ground-based multi-spectral observations. Their model similarly focused on the phase function, opposition effect, and surface roughness parameters.…”

Application of multiple photometric models to disk-resolved measurements of Mercury’s surface: Insights into Mercury’s regolith characteristics

“…Hapke's model has been used to model a photometric correction to images of many Solar System objects, including the Moon (Sato et al, 2014), Mercury (Domingue et al, 2011(Domingue et al, , 2015, asteroids (Domingue and Hapke, 1989;Helfenstein et al, 1994Helfenstein et al, , 1996Murchie et al, 2002;Lederer et al, 2005Lederer et al, , 2008Hillier et al, 2011;Li et al, 2013;Spjuth et al, 2012;Maoumzadeh et al, 2015), and many planetary satellites (Simonelli and Veverka, 1986;Helfenstein et al, 1988Helfenstein et al, , 1991Domingue et al, 1991Domingue et al, , 1995Skypeck et al, 1991;Domingue and Hapke, 1992;Veverka, 1992, 1994;Hillier et al, 1994;Domingue and Verbiscer, 1997;Simonelli et al, 1998;Hendrix et al, 2005;Verbiscer et al, 2005;Ciarniello et al, 2011;Fraeman et al, 2012). The form of the model used has depended on the state of the development of the model at the time of application, image coverage of the range of plausible i, e, and a values, and coverage of the opposition surge.…”