KPL/PCK Asteroid (162173) Ryugu PCK SPICE kernel File =========================================================================== This text PCK file contains the orientation and the size/shape data for Asteroid (162173) Ryugu. Version and Date -------------------------------------------------------- Version 0.8 -- September 30, 2022 -- Shin-ya Murakami, ISAS/JAXA Created based on Version 1.0 to store values for the old version, Version 20181109, as a part of data for public release with the new file naming convention. References -------------------------------------------------------- [1] Ishiguro, et al (2014), Optical Properties of (162173) 1999 JU3: In Preparation for the JAXA Hayabusa 2 Sample Return Mission, ApJ, 792, 74. https://doi.org/10.1088/0004-637X/792/1/74 [2] Mueller, et al (2017), Hayabusa-2 mission target asteroid 162173 Ryugu (1999 JU3): Searching for the object's spin-axis orientation, A&A, 599, A103. https://doi.org/10.1051/0004-6361/201629134 [3] Hirata (2020), Ryugu Coordinate System Description, in document collection of Hayabusa2 mission bundle. urn:jaxa:darts:hyb2:document:ryugu_coord_desc [4] Sugita, et al (2019), The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes, Science, 364, 6437, eaaw0422. https://doi.org/10.1126/science.aaw0422 [5] Yamamoto, et al (2020), Dynamic precise orbit determination of Hayabusa2 using laser altimeter (LIDAR) and image tracking data sets, Earth, Planets and Space, 72, 85. https://doi.org/10.1186/s40623-020-01213-2 Contact Information -------------------------------------------------------- Naru Hirata, The University of Aizu, naru@u-aizu.ac.jp Parameter History -------------------------------------------------------- Date RA [deg] Dec. [deg] Period [h] Init.Rot.Angle(JD0) ---------- ----------- ---------- ---------- ------------------------- 2020-03-23 96.43112 -66.38741 7.632624787382541 2019-03-28 96.43112 -66.38741 7.632624787382541 2019-03-08 96.42997 -66.39277 7.6326238293793 2018-11-09 96.40503 -66.38442 7.632616576126643 2018-10-14 96.40101 -66.39948 7.632621866444357 2018-08-29 96.39792 -66.39867 7.632622910551389 2018-08-10 96.39069 -66.40321 7.632625803575571 2018-08-05 96.38837 -66.40425 7.632626749577289 2018-07-31 96.37915 -66.41831 7.632613738534321 2018-07-27 96.35333 -66.42016 7.632595559221877 2018-07-17 96.36813 -66.40245 7.63255 2018-07-10 96.34221 -66.42105 7.63253 2018-07-05 96.33551 -66.47482 7.63249 2018-06-30 96.17157 -66.53653 7.63253 2018-06-27 95.783988 -66.382491 7.63109 in J2000EQ Date Lambda[deg] Beta[deg] Period [h] Init.Rot.Angle(JD0) ---------- ----------- ---------- ---------- ------------------------- 2018-04-05 310.0-340.0 -40.0+-15 7.63109 2016-03-04 329.0+-10 -39.0+-20 7.6312 phi0=0 JD0=2454289.000000 2014-09-22 325.0+-10 -40.0+-15 7.6312 2014-09-19 326.478506 -36.065302 7.63121164 phi0=0 JD0=2454289.000000 As of September 22, 2014 From private communication with Thomas Mueller: Rotational period 7.6312 +- 0.0010 hr H0 in V-band 19.25 +- 0.03 G parameter (a<30 deg) 0.3 +- 0.02 Geometric albedo 0.047 +- 0.003 Effective diameter 875 +- 15 m Thermal inertia 50 +- 50 J(m^2*s^0.5*K) Pole orientation (l, b) = (325, -40) +- (10, 15) deg l ... lambda_ecl (Ecliptic longitude) b ... beta_ecl (Ecliptic latitude) As of March 4, 2016, From design reference: Rotational period 7.6312 hr G parameter (a<30 deg) 0.13 +- 0.02 Geometric albedo 0.047 +- 0.043-0.050 (V-band) Effective diameter 880 +- 15 m Thermal inertia 250 +- 150-500 J/(m^2*s^0.5*K) Pole orientation (l, b) = (329, -39) +- (10, 20) deg Surface slope 0.1 rms GM 32 m^3/s^2 Ellipsoidal shape a=446.5, b=439.7, c=433.9 m Axis ratios (a/b, b/c) = (1.0153, 1.0135) As of March 9, 2017, Rotational period 7.63109 hr [2] H0 in V-band 19.22 +- 0.02 [1] G parameter (a<30 deg) 0.13 +- 0.02 [1] Geometric albedo 0.047 +- 0.003 [1] Effective diameter 850 - 880 m [2] Thermal inertia 150 - 300 J/(m^2*s^0.5*K) [2] Pole orientation (l, b) = (340, -40) deg (Table 5, ID 2) [2] Heat conductivity 0.1 to 0.6 W/(K*m) [2] Grain size 1 - 10 mm [2] Axis ratios (a/b, b/c) = (1.025, 1.014) [2] Values in Version 0,6 and Version 20181109 The W0 term for the prime meridian (PM) is set to 265.94597. The W1 term is set to 1131.98402066 that corresponds to the period of hours. 360 [deg/rev] x 24 [hours/day] / ( 1131.98402066 [deg/day] ) = 7.632616576126643 [hours/rev] \begindata BODY2162173_POLE_RA = ( 96.40503 0.0 0.0 ) BODY2162173_POLE_DEC = ( -66.38442 0.0 0.0 ) BODY2162173_PM = ( 265.94597 1131.98402066 0.0 ) \begintext Radii for asteroid (162173) Ryugu -------------------------------------------------------- The radii provided in the keyword below are also from [3]. \begindata BODY2162173_RADII = ( 0.502 0.502 0.438 ) \begintext Albedo values for asteroid (162173) Ryugu -------------------------------------------------------- The albedo provided in the keywords below is taken from [4]. \begindata BODY2162173_ALBEDO_GEOMETRIC = 0.045 \begintext GM value for asteroid (162173) Ryugu -------------------------------------------------------- The GM value provided in the keywords below is GM = 29.8 +- 0.3 m^3/s^2, taken from [5]. UNITS: km^3/s^2 \begindata BODY2162173_GM = 2.98E-08 \begintext Asteroid (162173) Ryugu name-ID mappings -------------------------------------------------------- The keywords below implement the Ryugu name-ID mappings. \begindata NAIF_BODY_NAME += ( '1999JU3' ) NAIF_BODY_CODE += ( 2162173 ) NAIF_BODY_NAME += ( 'RYUGU' ) NAIF_BODY_CODE += ( 2162173 ) \begintext End of PCK file.