Japan Geoscience Union Meeting 2015

Presentation information


Symbol P (Space and Planetary Sciences) » P-CG Complex & General

[P-CG30] New Progress toward the Understanding of Small Solar System Bodies

Tue. May 26, 2015 6:15 PM - 7:30 PM Convention Hall (2F)

Convener:*Masahiko Arakawa(Graduate School of Science, Kobe University), Taishi Nakamoto(Tokyo Institute of Technology), Sei-ichiro WATANABE(Division of Earth and Planetary Sciences, Graduate School of Science, Nagoya University), Masanao Abe(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), MASATERU ISHIGURO(Department of Physics and Astronomy, Seoul National University)

6:15 PM - 7:30 PM

[PCG30-P03] Results of the development for NIRS3: the Near Infrared Spectrometer on Hayabusa-2

*Takahiro IWATA1, Kohei KITAZATO2, Masanao ABE1, Takehiko ARAI1, Yusuke NAKAUCHI3, Tomoki NAKAMURA4, Takahiro HIROI5, Takahito OSAWA6, Moe MATSUOKA4, Shuji MATSUURA1 (1.Institute of Space and Astronautical Science, JAXA, 2.University of Aizu, 3.Graduate University for Advanced Studies, 4.Tohoku University, 5.Brown University, 6.JAEA)

Keywords:Hayabusa-2, asteroid, 1999JU3, NIRS3, near infrared, spectrometer

NIRS3: the Near Infrared Spectrometer is one of the candidate scientific instruments which will be equipped on Hayabusa-2 mission. It aims to observe near infrared spectroscopy at the wave length band of 1.8-3.2 micrometer to detect specific molecular absorption lines, including the absorption by hydrated minerals at 3 micrometer, on the target C-type asteroid. We implemented ground performance tests using the flight mode of the Spectrometric Unit (NIRS3-S) and the Analogue Electric Unit (NIRS3-AE). Infrared rays from the black body source are reflected by the sample and two gold mirrors in a vacuum desiccator, and then injected into NIRS3-S which is refrigerated at -60 to -90oC in a vacuum cryostat. The black body source emission is directly injected into NIRS3-S during amplitude-calibration tests. Lights from a halogen lamp are injected into NIRS3-S through a monochromator during frequency-calibration tests. NIRS3-AE controls the inner calibration lamps, the chopper, and data acquisition by the sensor in NIRS3-S.
Results of flight-model tests implied that the dark current at the InAs sensor is much lower than that of the engineering model, which improves the signals-to-noise ratio (SNR). The projected on-board SNR was confirmed to be sufficient during the one-year observation period of Asteroid 1999JU3 assuming the surface temperature estimated from the heliocentric range and solar phase angle. The SNR exceeds 300 after 2.5 ms integration and 1024-stacking at the home position observations. It exceeds 60 after 1 ms integration and 64-stacking for the observations of artificial crater made by the Small Carry-on Impactor (SCI) on Hayabusa-2. The data obtained after the vibration tests and thermal-vacuum tests indicate that NIRS3 is sufficiently durable for the launching and on-orbit environments. The observed spectra for samples of serpentine, olivine, and CM-chondrites such as Murchison, Murray, and Jbilet Winselwan demonstrated that the derived reflectances are almost the same as those obtained by Fourier-transform infrared (FTIR) spectroscopy. These results show that NIRS3 has sufficient performance for scientific objectives. We will also report the first results on Hayabusa-2 after the launch.