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April 11, 2003

National Space Development Agency of Japan

NASDA REPORT NO.129

Part 1 of 3

C O N T E N T S

* Ushering the Way of Advanced Information and Communication Network.
  R & D Underway for Wideband InterNetworking engineering test
  and Demonstration Satellite (WINDS)
* Front Line of Advanced and Common Technology Research 11
* Let Us Talk to Space Challengers

Ushering the Way of Advanced Information and Communication Network.
R & D Underway for Wideband InterNetworking engineering test and
Demonstration Satellite (WINDS) Development phase starts in 2003
toward a 2005 launch.
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Two Goals of Development
NASDA has been conducting research and development on an ultra
high-speed satellite communications technology that can supplement
the existing terrestrial communication infrastructure with the unique
advantages of satellite communication, such as wide coverage,
simulcast capability, disaster-immunity, and the flexibility of
connection.

The proposed ultra high speed internet satellite is called the
Wideband InterNetworking engineering test and Demonstration
Satellite (WINDS). It is aimed at achieving the following two goals.


Sidebar

* Ultra high-speed data rate

The WINDS satellite communication system is aimed to provide a
service to home users at a rate of up to 155 Mbps with the use of a
small satellite dish comparable to a CS antenna in size (about 45 cm
in diameter), while businesses and the like can benefit from ultra
high-speed interactive communications at a rate of up to 1.2 Gbps.

* Wider area coverage

The satellite system is aimed to provide ultra high-speed
international internet connectivity to meet the high speed domestic
internet service, especially with neighboring nations in the
Asia-Pacific region.


NASDA has been designing the satellite since the project inception in
2001. Especially, the designs of the mission critical components have
been carefully verified through ground prototype testing and
numerical simulations.

As a result of these efforts, the satellite configuration has come
close to the final design by today. NASDA has been working hard on
the satellite design to meet their goal toward launch in three
years.


Ground Test of the Multi-port Power Amplifier Using the BBM

High-power multi-beam antenna and a Ka-band multi-port amplifier are
two of the key mission components of the WINDS. The multi-port
amplifier can flexibly distribute needed electric power in response
to local traffic demands and the rain attenuation. This enables the
efficient use of the satellite's limited total transmission power.

Among the technical challenges in the development of the Ka-band
multi-port amplifier are,

* Enhancement of output power;

* Improvement of isolation between ports;

* Securing a better (lower signal loss, etc.,) and uniform signal
  level in a 1.1-GHz broad bandwidth;

* Development of a broadband and high power traveling wave tube
  amplifier (TWTA)

These issues are projected to be solved through BBM evaluation
testing.

With the results of the BBM test, we intend to develop and verify the
ground test model. Then the data and results obtained from the ground
test model will in fact be incorporated in the manufacturing of the
flight hardware. In addition to the multi-port amplifier, an active
phased array antenna is also a key technology. This antenna is
currently being designed, and we will report its progress in the
future.

Multi-Port Amplifier Main Spec.

Item                Specification       Remarks

Frequency           17.7-18.8 GHz       1.1 GHz bandwidth

Configuration       8 ports             10 TWTAs (including2
                                        backups) are equipped

Total output power  About 280 watts or more
(max.)

TWTA output         50 w per TWTA       Linear operation


The Research on Rendezvous Sensors

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NASDA is researching the orbital service technologies. They are the
technologies to enable the works such as refueling the satellite in
orbit; swapping the onboard component to the latest one; and
constructing large space structure like orbital solar power plant; to
be done robotically, without the help from astronaut. In this issue
of the Front Line of Advanced and Common Technology Research, we like
to introduce you the research in sensor technologies for rendezvous,
one of the key technologies to enable all this, through the
rendezvous and docking experiments of "Orihime/Hikoboshi (Engineering
Technology Satellite VII: ETS-VII)" 


Rendezvous Sensors on Orihime/Hikoboshi

Orihime and Hikoboshi (ETS-VII) were launched in 1997 to test the
technologies for rendezvous/docking and space robotics. It was
launched as one unit, and separated into two spacecraft on 500km
altitude orbit. It performed three automatic rendezvous and docking
experiments. In this experiment, Hikoboshi, the chaser satellite,
used three types of rendezvous sensors (GPS receiver, rendezvous
radar, proximity sensor) in accordance to the relative distance to
Orihime, the target satellite. The distance, direction, the relative
speed, the relative attitude and so on of Orihime seen from Hikoboshi
were measured and fed into the orbit control calculation done by
Hikoboshi's onboard computer. System Guydance Technology group is
researching the improvement of these sensors used for
Orihime/Hikoboshi.

- Continued -

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