The National Space Development Agency of Japan (NASDA) has made the following announcement: To our most sincere regret, NASDA had to stop further operation of the Advanced Earth Observing Satellite (ADEOS) ("Midori" in Japanese) on July 1, 1997, although it was supposed to be in operation for 3 years after launch (ADEOS was launched on August 17, 1996 from the Tanegashima Space Center). The ADEOS ceased to reply to any commands from the ground due to a power loss on June 30, although we sent emergency commands to reduce the electrical burden of the satellite. So far we have confirmed unusual vibrations on the solar paddle as early as May 15, unusual reduction of the paddle's temperature since June 23, and a decreasing tendency of electrical generation since June 27, 1997. We established a Task Team to investigate the cause of this significant accident and to examine future plans of the Earth Observation in cooperation with the Space Activities Commission, our supervising organization under the Science Technology Agency of Japan. As a result of the initial investigation, it appears that the sudden power loss of ADEOS may have been caused by malfunction of the solar paddle, which was recently designed and developed to be lighter and more flexible than previous ones. More detailed results are expected to be released within a month. We anticipated that the ADEOS would be the cornerstone of future global environmental monitoring with collaboration among the international and domestic partners, namely the National Aeronautics and Space Administration (NASA), Centre National d'Etudes Spatiales (CNES), the Ministry of International Trade and Industry of Japan (MITI), and the Environment Agency of Japan (EA). During its operational phase, the ADEOS measured a range of environmental data, using 8 different sensors as follows: The Advanced Visible and Near-Infrared Radiometer (AVNIR), which accumulated data during daylight hours for a period of 8 months, around Japan. The Ocean Color and Temperature Scanner (OCTS) acquired global data during daylight hours, for a period of 8 months (see February 1997 backscatter article for description of the sensor). The Interferometric Monitor for Greenhouse Gases (IMG), which was used to infer atmospheric concentrations of water vapour and other greenhouse gases, acquired data for a period of 8 months, although currently available data are limited to a 2 month period. The Improved Limb Atmospheric Spectrometer (ILAS), used to monitor changes in the stratospheric ozone which are triggered by emissions of chloro-fluro-carbons, acquired data over the polar regions for an 8 month period. The Retroreflector in Space (RIS) - period of operation still to be confirmed. The NASA Scatterometer (NSCAT) which measured wind speed and direction, acquired global data over a 24 hour period for a total of 9.5 months. The Total Ozone Mapping Spectrometer (TOMS) which mapped the spatial distribution of total ozone with a high resolution, acquired global data during daylight hours for a period of 9.5 months.

The Polarization and Directionality of the Earth's Reflectances (POLDER) sensor which measured polarization, directional and spectral characteristics of reflected solar light, acquired global data during daylight hours for a period of 8 months. Various science programs have been conducted based on the research announcements issued jointly in 1993 with MITI and EA, and also with CNES in 1994 (for calibration and validation of data and research of the global climate). We will continue these programs until March 2000, as planned, and invite the selected Principal Investigators to maintain an interest in the ADEOS data. We would like to continue our support based on their research plans, which we are reviewing to omit simultaneous ground experiments. To maximize the individual and multiple utilization of each sensor onboard ADEOS, we are planning to: further calibrate and validate through July to December 1997, improve algorithms through July to September 1997, reprocess the Standard Products using the above mentioned algorithms through October 1997 to March 1998, and develop algorithms for new Highly Enhanced Products and process them through December 1997 to March 1999. We are currently working to prioritize the processing and distribution of the ADEOS data obtained world-wide to contribute to global environment research. We are planning on holding an ADEOS seminar every month as well as an Arctic Symposium in December, 1997 to evaluate the lowest ozone values over the Arctic measured by TOMS. Furthermore, the Third ADEOS Workshop will be held in January, 1998. The participation and interest of many researchers in these conferences will be vital for us. For our future Earth observing missions, such as Tropical Rainfall Measuring Mission (TRMM) and Advanced Earth Observing Satellite (ADEOS-II), we determine to make our best efforts to minimize the impact of the severe accident of ADEOS. Regardless of this regrettable experience, we would like to continue our efforts on the Earth Observing missions and express our most sincere apology to all of those who were interested in the utilization of the ADEOS data. Point of Contact for science programs: Mr. Yasuhisa Nakamura ADEOS Program Co-ordinator, Earth Observation Research Centre, NASDA Roppongi First Bldg. 1-9-9, Roppongi, Minato-ku, Tokyo, 106, Japan Fax: 81-3-3224-7051 E-mail: nakamura@eorc.nasda.go.jp Point of Contact for general information Mr. Yasuyuki Fukumuro Manager, Public Relations Office, NASDA World Trade Centre Bldg. 2-4-1, Hamamatsu-cho, Minato-ku, Tokyo, 105-06, Japan Fax: 81-3-5402-6513 E-mail: fukumuro.yasuyuki@nasda.go.jp This article appeared in the August 1997 issue of the backscatter magazine, published by the Alliance of Marine Remote Sensing (AMRS).