OPTICAL PROPERTIES OF (162173) 1999 JU3: IN PREPARATION FOR THE JAXAHAYABUSA 2SAMPLE RETURN MISSION

Abstract

We investigated the magnitude-phase relation of (162173) 1999 JU3, a target asteroid for the JAXA Hayabusa 2 sample return mission. We initially employed the international Astronomical Union's H-G formalism but found that it fits less well using a single set of parameters. To improve the inadequate fit, we employed two photometric functions, the Shevchenko and Hapke functions. With the Shevchenko function, we found that the magnitude-phase relation exhibits linear behavior in a wide phase angle range (α = 5-75 • ) and shows weak nonlinear opposition brightening at α < 5 • , providing a more reliable absolute magnitude of H V = 19.25 ± 0.03. The phase slope (0.039 ± 0.001 mag deg −1 ) and opposition effect amplitude (parameterized by the ratio of intensity at α=0.3 • to that at α=5 • , I(0.3 • )/I(5 • )=1.31±0.05) are consistent with those of typical Ctype asteroids. We also attempted to determine the parameters for the Hapke model, which are applicable for constructing the surface reflectance map with the Hayabusa 2 onboard cameras. Although we could not constrain the full set of Hapke parameters, we obtained possible values, w=0.041, g=-0.38, B 0 =1.43, and h=0.050, assuming a surface roughness parameterθ=20 • . By combining our photometric study with a thermal model of the asteroid (Müller et al. in preparation), we obtained a geometric albedo of p v = 0.047 ± 0.003, phase integral q = 0.32 ± 0.03, and Bond albedo A B = 0.014 ± 0.002, which are commensurate with the values for common C-type asteroids.

Hayabusa-2 mission target asteroid 162173 Ryugu (1999 JU3): Searching for the object’s spin-axis orientation

“…We use the H-G system (Bowell et al 1989) to describe the amount of reflected light. We used H V = 19.25 ± 0.03 mag and G = 0.13 ± 0.02 which was derived from calibrated V-band observations covering a very wide phase angle range (Ishiguro et al 2014). Table 7 summarises the general TPM settings for our radiometric analysis.…”

Thermophysical Modeling of NEOWISE Observations of DESTINY+ Targets Phaethon and 2005 UD

“…Jenniskens et al 2009), while the same proximity of NEAs that makes them a hazard also means they are convenient targets for spacecraft missions (e.g. Cheng 2002;Yoshikawa et al 2015;Ishiguro et al 2014;Lauretta et al 2017).…”

The CM carbonaceous chondrite regolith Diepenveen

“…) and is thought to be the type of material to be sampled in the ongoing Hayabusa2 mission to Cg‐type asteroid (162173) Ryugu (Ishiguro et al. ; Perna et al. ; Kitazato et al.…”

“…2), Diepenveen is a CM chondrite fall new for study, like Sutter's Mill (Jenniskens et al 2012) and the recent Mukundpura meteorite (Ray and Shukla 2018), but with the possibility of some contamination from handling since 1873. CM chondrites are important as probes of the planetesimals that delivered water to the early Earth (Gounelle et al 2005;Alexander et al 2018) and is thought to be the type of material to be sampled in the ongoing Hayabusa2 mission to Cg-type asteroid (162173) Ryugu (Ishiguro et al 2014;Perna et al 2017;Kitazato et al 2019), or even the OSIRIS-REx mission to B-type asteroid (101955) Bennu (Clark et al 2011;Lauretta 2015;Lantz et al 2018;Hamilton et al 2019).…”