Program: GS-2012A-DD-8

The objective of our observation is to obtain definite evidence for an absorption band of hydrous minerals on the target asteroid 162173 (1999JU3) for the Hayabusa-2 mission. The main purpose of this mission is to bring back samples from a C-type asteroid, which is believed to contain abundant hydrous minerals and organics. The mission strategy for Hayabusa 2 is to select sampling sites based on the spatial distribution of the absorption band strength of hydrous minerals. There are two lines of observational evidence for 0.7 um absorption, but the depths of the possible absorptions are comparable to the noise level (Vilas, 2008). There is also an observation result that exhibits no 0.7 um absorption (Binzel et al. 2001). The observed variation may be due to natural variegation of the asteroid but could be observational error, there may be no significant 0.7um absorption. Because whether 0.7 um absorption band is present on 1999JU3 has a major impact on the strat egy of Hayabusa 2, we need to resolve this ambiguity before its launch by conducting high signal-to-noise ratio observation. Because an observation opportunity comes only every 4-5 years, the upcoming one will be the last one before the spacecraft launch.