suitabilities of the onboard sensors. The name of the Marine 
Observation Satellite MOS-1 is related to this reason. 
Design features 
At present, the MOS-1 is in a conception design phase and 
its onboard sensors are now under preliminary development. 
Table 1 shows a general conception of this MOS-1, indicating the 
orbit parameters, the characteristics of the sensors and the com- 
munication equipment. 
The planned orbit is a non-sun- synchronous one which is 
about 540 km high and about 70 degrees in orbit inclination. 
This orbit was selected taking into account many factors such as 
the mission objectives, the launching rocket capability, the launch- 
ing range safety, etc.. However, an higher altitude orbit may 
have the preference if the resolution of the onboard sensors could 
be improved. 
Three sensors are selected : a Visible and near-infrared 
scanning radiometer ( VNIR ), a Visible and thermal-infrared 
scanning radiometer ( VTIR ) and a Microwave scanning radiometer 
(MSR ). The VNIR observes sea surface colors which relate to 
the content of vegetal plankton. The VTIR measures sea surface 
temperature. The MSR measures sea-surface temperature and 
water vapour distribution. 
For the communication equipment which transmits the above- 
mentioned sensor data to the earth station, 21 GHz band is selected 
taking into consideration the present international frequency allo- 
cation as wellas the frequency bandwidth required. However, a 
15 GHz band is an alternate candidate, considering a new interna- 
tional allocation in future. 
The estimated weight of the satellite is about 500 kg. The 
electric power required is about 300 W. The satellite attitude 
control system is of 3-axis type, whose accuracies are * 0.5? for 
pitch and roll and Y0.7° for yaw. This satellite is scheduled to 
be launched arround 1983, and its design life will be about 2 years. 
Ground System for Receiving Landsat Data 
General 
The objectives of the establishment of the ground system for 
receiving Landsat data are to develop advanced use of Landsat data 
as well as to promote the development of Japanese Earth observation 
satellites. 
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