Report of ADEOS Initial Mission Checkout

Report of ADEOS Initial Mission Checkout

Haruhisa Shimoda, Yoshifumi Yasuoka and Ryuji matsuoka
Earth Observation Research Center, National Space Development Agency of Japan
Reppongi First Building, 1-9-9, Reoppongi, Minato-ku, Tokyo 106, JAPAN
Phone : +81-3224-7040, Fax : +81-3-3224-7051

Abstract
The national Space Development Agency of Japna (NASDA) successfully launched the Advanced Earth Observing Satellite (ADEOS0S) at 10:53 a.m.(JST) / 01:53 a.m. (UT) on August 17, 1996 from Taneagashima Space Center. ADEOS was placed into the final proper orbit on September 8 and the function of the bus system and the mission instruments are now being checked out. The initial mission checkout of ADEOS will continue for 90 days until the middle of November. This paper report the status of ADESOS as of September 24, 1996.

1.Launch
The National Space Development Agency of Japan (NASDA) launced the forth H-II Launch Vehicle from Tanegashima space Center with the Advanced Earth Observing Satellite (ADEOS) and Japan Amateur Satellite-2 (JAS-2) on board at 10:53 a.m. (UT) on August 17, 1986. ADEOS was separated approximately 15 minutes 49 seconds after the launched and ADEOS was inserted into the orbit as planned.

Figure- 1 Lanuch of ADEOS

Figure-2 ADEOS

Table-1 Sensors onboard ADEOS

Sensor	Sensor Provider
OCTS	NASDA	Japan
AVNIR	NASDA	Japan
IMG	MITI	Japan
ILAS	EA	Japan
RIS	EA	Japan
NSCAT	NASA	USA
TOMS	NASA	USA
POLDER	CNES	France

ADEOS is the largest satellite Japan has ever developed having dimensions of 4m x 4m x 5m. When the NASSA Scattermeter (NSCAT) antenna and the solar array paddle are deployed, it has a span of 11 m in the flight direction and 29m in the directing to its perpendicular. ADEOS has a launch mass of approximately 3,500 kg. The main objective of ADEOS is to contribute to elucidation of phenomena of the earth through integrated observation of geophysical parameters using a number of sensors. There are eight sensors listed in Table 1- aboard ADEOS.

In the critical phase of the launch, ADESO completed the followings:

Deployment of the solar array paddle
Tracking the Sun
Deployment of the NASA Scattermeter (NSCAT) antennas
Dep of the Inter Orbital Communication Subsystem (IOCS) antenna
Establishment of three axis attitude
The critical phase of ADEOS finished after 22nd revolution on august 19, 1996. 19,1996 NASDA started verifying the function of ADEOS from August 19.

2.Status of Satellite

2.1 Initial Orbit Control
In the test injection of the thrusters on August 20, an anomaly was found in one of the four 20 Newton thrusters which were planned to be used for the initial orbit control. NASDA carried out a series of the initial orbit control of ADEOS using the 1-Newton thrusters from August 24 through September 8, 1996. As a result of the initial orbit control, ADEOS has been thrown into the orbit shown in Tabl2 for the purpose. of the Earth observation as planned.

Apogee Altitude	804.6 km
Perigee Altitude	789.0 km
Orbit Inclination	98.625 degree
Period	100.8 minute
Local Time at Descending Node	10:41 a.m.
Recurrent	41 days

NASDA plans to carry out orbit control approximately once a month in order to correct ADEOS' fall from present orbit by the air drag.

2.2 Bus Module
ADEOS consists of a bus module that carries bus subsystems and a mission module that carries mission instruments. There are installed the communications and Data Handling Subsystem (C&DH), the Inter Orbit Communication Subsystem (IOCS), the Mission Data Processing Subsystem (MDP), HE IRECT Transmission subsystem (DT), the Electric Power Subsystem (DPS), the Solar Array Paddle (PDL), the Attitude and Orbit Control Subsystem 9AOCS), THE reaction Control Subsystem ( RCS), and the Direct Transmission of Local User (DTL) in the in the bus module.

The initial checkouts of C&DH and DT were carried out from August 21 through September 1 and it was confirmed that C&DH and DT are functioning normally except an anomaly on one of the four 20-Newton thruster. The initial checkout of DTL was carried out at the same of the initial checkout of the Ocean Colour and checkout of DTL was carried out at the same time to the initial checkout of the Ocean Color and Temperature Scanner (OCTS) and it was confirmed that DTL is functioning nominally. There have been found no serious troubles in the bus module in the bus module until September 24,1996.

3.Status of Mission Instruments

3.1.Ocean Color and Temperature Scanner (OCTS)
The Ocean Color and Temperature Scanner (OCTS) developed by NASDA is an optical radiometer to achieve highly sensitive spectral measurement with 12 bands covering visible and thermal infrared regions. In the visible and near-infrared bands, the ocean conditions are observed by taking advantage of spectral reflectance of the dissolved substances in the water and phytoplankton. On the other hand, the sea surface temperature is accurately measured in four thermal infrared bands. As the swath width of OCTS is approximately 1,400 km with scanning mirror (west-eat) and OCTS also scans south and north, it can observe the entire Earth's resolution is approximately 700m.

Figure-3 First Image of OCTS VNIR (September 3, 1996)
NASDA carried out the initial checkout of the visible and near-infrared bands (VNIR) of OCTS from September 3 through 9. Figure 3 shows the first image of OCTS VNIR acquired on September 3, 1996. Japan and its surrounding waters can be seen in this image. the image is 2,500 km long in the direction of the satellite flight path and has a 1400 km swath width.

As a result of the initial checkout of OCTS VNIR, it was assumed that OCTS VNIR and DTL are functioning nominally. NASDA has been investigating data quality of acquired images and continues the checkouts regarding the ground segments as well as those in space.

On September 11 NASDA confirmed that the earth shield in the radiation cooler of OCTS had normally been deployed. The earth shield in the radiation cooler is used for cooling-off the infrared detector of the OCTS. NASDA plans to carry out the initial checkout of the infrared bands (TIR) of OCTS in the beginning of October.

3.2 Advanced Visible and Near-Infrared Radiometer (AVNIR)
THE Advanced Visible and Near-Infrared Radiometer (AVNIR) developed by NASDA is an optical sensor with four spectral bands used to observe land and coastal zones in the visible and near-infrared regions. There bands in the visible region correspond approximately to blue, green and red while the near-infrared band is suited to observing plant growth. In addition to these four bands. Called the multispectral bands (Mu) of 16 m ground resolution , AVNIR has a panchromatic band (Pa) whose ground resolution is 8 m. AVNIR scans the earth's surface in an 80km (ground distance) swath perpendicular to the satellite track. Due to the narrow swath width of 80 km AVNIR has a pointing function which can change the location of the observation field within +r0 degrees from the satellite track.

NASDA carried out the initial checkout of AVNIR from August 31 to September 7. The first image of the multispectral bands of AVNIR shown in figure 4 was acquired on September 1, 1996. This image s of Kagoshima Prefecture, a southern par to Japan, and the width of the image is approximately 80 km. ADEOS took it using the pointing function f AVNIR. Figure 5 shows the first image of the panchromatic band of AVNIR acquired on September 5, 1996. the image shows the city of Hiroshima, a bit city in the west Japan, and the area indicated on this image is approximately 10 km x 8 km. ADEOS took it also using the pointing faction.

As a result of the initial checkout of AVNIR, it was assumed that AVNIR is functioning nominally. NASDA has been investigating data quality of acquired images.

Figure-4 First Image of AVNIR Mu (September 1, 1996)

Figure-5 First Image of AVNIR Pa (September 5, 1996)
3.3 Interferometer Monitor of Greenhouse Gases (IMG)
THE INTERFEROMETRIC monitor for Grenhouse Gases (IMG) is developed by the Ministry of international Trade and Industries (MITI). IMG is a sensor to monitors the Earth]'s surface, and physical properties of clouds. IMG is a Michelson-type Fourier Transform Spectrometer(FTS) with two mirrors and a beam splitter to obtain detailed spectra of thermal infrared radiation from the Earth's surface and atmosphere. The measured infrared spectra will be used to infer atmospheric concentrations of water vapor and other greenhouse gases.

The initial checkout of IMG was planed from September 20 through 24. on September 20 there was found an anomaly in the scanning mirror of `MG. As of September 24 IMG doesn't seem to work; and both MITI and NASDA have been investigating the cause of the anomaly.

3.4 Improved Limb Atmospheric Spectrometer (1LAS)
The Improved Limb Atmospheric Spectrometer (ILAS) is developed by the Environmental Agency of Japan (EA). I1LAS is a sensor to monitor the polar stratospheric ozone. The object of ILAS is to monitor and study changes in the stratosphere which are triggered by emissions of Chloro Fluuoro Carbons (CFC), and to check the effectiveness of worldwide emission controls of CFCs. ILAS observed the atmospheric limb absorption spectrum from the upper troposphere to the stratosphere using sunlight (solar occultation technique). The cover the infrared region (850 to 1610cm-1) and the near visible region (753 to 781nm). From these spectral observation, ILAS to 1610 cm-1) and the near visible region (753 to 781nm). From these spectral observations, ILAS can measure the vertical profile of ozone hole related components: ozone (O₃), nitrogen dioxide (NO₂), aerosols, water vapor (H₂O), CFC11, methane (CH₄), nitrous oxide (N₂O), temperature, and pressure.

The initial checkout of ILAS was conducted on September 17 and 18. Characteristics of the ILAS data have been investigated by National Institute for Environmental Studies of Japan (NIES). The ILAS instrument looks to have worked wel. Data from the sun-edge sensor, which was designed to detect the IFOV angular position from the top edge of the sun, showed a little bit different pattern from the expectation of NIES. Due to this, altitude registration was not successful, at present, with the operational data processing software of the ILAS Data Handling Facility in NIES. Thus gas profiles have not yet been able to be retrieved

3.5 Retroreflector in Space (RIS)
The Retroeflector In Space (RIS) developed by EA is a retroeflector for an earth-satellite -earth laser used in long-path absorption experiments. RIS has a corner-cube structure with an effective diameter of 50 cm. Measurements ofozone, CFC12, CO2, CH4, etc. are carried out using infrared pulsed laser.

The initial checkout of RIS was scheduled too be conducted from August 28 to 31, but the checkout was not carried out because of the bad weather condition. The initial checkout of RIS will conducted in the end of September or in the beginning of October.

3.6 NASA Scattermeter (NSCAT)
The NASA Scattermeter (NSCAT) is developed by the National Aeronautics and Space Administration (NASA). NSCAT is an active microwave radar to measure winds over the oceans by transmitting Ku band microwave pulse (1.995 GHz) and receiving backscatter powers from the ocean surface. The backscatter powers are subject to change in direction of surface waves. Multidirectional measurements can used to solve wind speed and direction simultaneously by using algorithm derived from the previous studied.

The NSCAT antenna was deployed on August 17 and the initial checkout of NSCAT was carried out from September 13 through 15. Any bad information concerning NSCAT has not been received and it is assumed that NSCAT I functioning nominally. The first result of NSCAT observing the EARTH will be expected in the beginning of October.3.7 Total 3.7Ozone Mapping Spectrometer (TOMS)

The Total Ozone Mapping Spectrometer (TOMS) developed by NASA is an optical sensor to measure the Aledo of the Earth's atmosphere at six narrow spectral bands. The total ozone content is interrelated with changes of solar radiation in the near ultraviolet wavelengths so that the spatial distribution of the total ozone can be inferred by observing several near UV bands. In addition, the distribution of the total ozone can be inferred by observing several near UV bands. In addition, the distribution of the totl ozone can be inferred by observing several near UV bands. In addition, the TOMS observation data can be used to make quantitative estimates of sulfur dioxide gases in the near UV band. The FOV of TOMS is 3 degrees x 3 degrees (ground swath width: 42 km x .42 km) and its scanning angle is + 55.5 degrees (approximately 2,800 km of the ground surface) along the track. The is wide swathe width can cover the entire earth surface in day.

The initial checkout of TOMS was carried out from September 11 through September 12. Figure 6 and Figure 7 are the first global images of total atmospheric ozone obtained from TOMS on September 12. Daily global mapping of the Earth's ozone layer from space has resumed with the acquisition of the first image from TOMS on September 12.

Figure- 6 Total Atmospheric Ozone Map

Figure-7 Total Atomospheric Ozone Map
3.8.Polarization and Directionality of the Earth's Reflectance (POLDER)
The Polarization and Directionality of the Earth's Reflectance (POLDER) is developed by Centre National d'Edudes Spatiales (CNES). POLDER is an optical sensor for observing the Centre National d'Etudes Spatials (CNES). POLDER is an optical sensor for observing the surface reflectance in visible and near infrared bands, and can observe an area from various directions and the spectral characteristics of the reflected solar light. POLDER has a wide FOV lens with +43 degrees x +51 degrees (ground swath width: approximately 1,825 km x 2,470km), and adopts pushbroom technique and an area can be observed from the maximum 14 different directions. The observation helps understand angular characteristics of the earth's reflectance. In addition, POLDER can observe multipolarization in multibands by rotating 16 types of interferences filters and polarizers.

The initial checkout of POLDER is scheduled for September 16 and 26. Any bed information concerning POLDER has not been received and it is assumed that POLDER is functioning nominally. The first result of POLDER absolving the Earth will be expected in the beginning of October.

4.Adeos Information
NASDA provides the latest information concerning DEOS via Internet. The ADEOS information is available at the following NASDA WWW sites:

NASDA Earth Observation Research Center (EORC) Home Page
URL: http:/www.eorc.nasda.go.jp
NASDA Earth Observation Center (EOC) Home Page
URL: http:/www.eoc.nasda.go.jp
NASDA Home Page
URL: http:/www.nasda.go.jp