heritage of LAS on Ohzora (EXOS-C). Objectives: Measurement of atmospheric trace gases and the pressure and temperature profiles by the solar occultation technique (vertical profiles of O3, NO2, aerosols, H2O, CFC11, CH4, N2O). ILAS has two grating spectrometers, one is used for the IR-band trace gases, the other measures aerosols, air temperature and pressure in the VIS-band. The ILAS occultation measurements are performed only at high latitudes in both hemispheres (due to orbit characteristics). ILAS keeps looking at the sun during sunrise and sunset, it measures the sequence of spectral intensity changes in the solar light which pass through the various tangent heights of the atmosphere. Since atmospheric trace gases have their own characteristic absorption spectra, the concentration of gases can be derived from these absorption measurements. 42), 43), 44) 45) 46) 47)
Table 7: ILAS instrument parameters
Figure 27: Illustration of the ILAS observation concept (image credit: NASDA)
Figure 28: Schematic overview of the ILAS instrument (image credit: NASDA)
RIS (Retroreflector in Space):
RIS is a JEA (Japan Environmental Agency) funded sensor. RIS is a large aperture single element corner-cube reflector for Earth-satellite-Earth laser long-path absorption measurements of atmospheric trace gases. The RIS experiment was the first implementation of the laser long-path absorption method between the ground and a satellite. 48) 49)
Objective: Used for laser long-path absorption measurements of atmospheric trace species and to support two color laser ranging experiments. Measurements of ozone (O3), CFC12, HNO3, methane (CH4), CO, and other gases by the laser beam absorption technique. Wavelength range: 0.4 - 14 µm.
In the RIS experiments a laser beam is transmitted from a SLR ground station, reflected by RIS, and received back at the ground station. The absorption of the intervening atmosphere is measured in the round-trip optical path (measurement of absorption spectra by the Doppler shift of the reflected beam). The column contents and vertical profiles of atmospheric trace gases are obtained from the measured spectra. The RIS experiments are performed when ADEOS passes over the ground stations in Japan. The ground stations use two single-longitudinal-mode TEA-CO2 lasers for the spectroscopic measurements. 50) 51) 52) 53)
RIS has a hollow reflector structure with an effective diameter of 0.5 m. A spherical mirror with a very small curvature is used for one of the three mirrors forming the corner cube, in order to optimize the ground pattern of the beam reflected by RIS. Instrument mass=43 kg.
Figure 29: Schematic configuration of the RIS corner retroreflector (image credit: NASDA)
ADEOS carries in addition TEDA (Technical Engineering Data Acquisition Equipment) to measure the space environment surrounding the S/C. TEDA monitors radiation absorption, memory malfunction, static charge voltage, and contamination, and analyzes heavy ions.
Figure 30: Overview of the RIS experiment configuration (image credit: NIES)
1) NASDA handout at the CEOS WGD-10 Meeting in Annapolis MD, April 16-19, 1991
4) “ADEOS,” NASDA brochure, 1993
5) “Special issue on ADEOS,” IEEE Transactions on Geoscience and Remote Sensing, Vol. 37, No 3, May 1999, Part II of two parts
9) Haruhisa Shimoda, “ADEOS Malfunction,” ADEOS Newsletter No 7, July 4, 1997, URL: http://suzaku.eorc.jaxa.jp/GLI2/adeos/NewsLetters/newsletter7/MALFUNCTION.html
10) Tasuku Tanaka, “JAXA starts providing data to ADEOS PIs,” ADEOS Newsletter No 5, Jan. 10, 1997, URL: http://suzaku.eorc.jaxa.jp/GLI2/adeos/NewsLetters/newsletter5/providing.html
11) Haruhisa Shimoda, “Report of ADEOS Initial Mission Checkout,” URL: http://suzaku.eorc.jaxa.jp/GLI2/adeos/NewsLetters/newsletter4/checkout.html
12) “Ocean Color and Temperature Scanner (OCTS),” http://suzaku.eorc.jaxa.jp/GLI2/adeos/Project/Octs.html
13) Jun Tanii, Tsuneo Machida, Haruki Ayada, Yoshihiko Katsuyama, Juro Ishida, Nobuo Iwasaki, Yoshio Tange, Yuji Miyachi, Ryouta Satoh, “Ocean color and temperature scanner for ADEOS,” Proceedings of