Introduction of Multi-bus Tethered-SPS · 2017. 12. 1. · Fig.2 Integration of Tethered-SPS units...

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Fig.2 Integration of Tethered-SPS units by connecting panels. Power Generation (Upper Plane) Power Generation/Transmission (Lower Plane) 95 m 100 m Microwave Beam 5-10 km Bus System Tether Wire Fig.1 A unit of Tethered-SPS. Introduction of Multi-bus Tethered-SPS S.Sasaki The Institute of Space and Astronautical Science (ISAS) Japan Aerospace Exploration Agency (JAXA) 3-1-1 Yoshinodai, Kanagawa 229-8510, JAPAN The Tethered-SPS, consisting of a power generation/transmission panel suspended by tether wires, has been studied for 5 years under coordination with university researchers (Kyoto University, Hokkaido University, Kanazawa University, Shizuoka University, Tokyo Metropolitan University) and USEF (Institute for Unmanned Space Experiment Free Flyer). Since this system does not track the sun, the total power efficiency is 36 % lower than that for the sun-pointing type SPS even when the solar cells are attached to both sides of the panel. However, the simple, technically feasible, and practical configuration resolves almost all the technical problems in the past SPS models. Figure 1 shows a unit of Tethered-SPS, in which a power generation/transmission panel of 100 m x 95 m is suspended by four 5~10 km tether wires extended from a bus system. The weight is about 45 MT. The unit has a power transmission capability of 2 MW. The units are connected to form a larger SPS as shown in Fig.2, depending on user requirements. 1 GW-class SPS can be constructed by 25 x 25 unit assembly. This simple and flexible configuration has many advantages, as summarized below; (1) Since the attitude is stabilized automatically by the gravity gradient force, no active attitude control is required. (2) There is no moving structure, which makes the system highly robust and stable. Especially one-point failure mode peculiar to the rotary mechanism is excluded. (3) The system is composed of equivalent units, which enables the phased construction and leads to easy integration and maintenance. (4) The unit consists of equivalent power generation/transmission modules, which enables low cost mass production. (5) There is no wired signal/power interface between the modules, which leads to easy deployment of the unit. (6) Active thermal control is not required because of uniform distribution of the transmitting power. (7) A scale model of the unit of the Tethered-SPS can be used for the demonstration experiment on the ground and in orbit in the near future, which assures an evolutional scenario for the SPS development from the initial demonstration to the commercial SPS. Presented at the Eleventh SPS Symposium, 17-18 September 2008 21

Transcript of Introduction of Multi-bus Tethered-SPS · 2017. 12. 1. · Fig.2 Integration of Tethered-SPS units...

Page 1: Introduction of Multi-bus Tethered-SPS · 2017. 12. 1. · Fig.2 Integration of Tethered-SPS units by connecting panels. Power Generation (Upper Plane) Power Generation/Transmission

Fig.2 Integration of Tethered-SPS units by connecting panels.

Power Generation

(Upper Plane)

Power Generation/Transmission

(Lower Plane)

95 m

100 m

Microwave

Beam

5-10 km

Bus System

Tether Wire

Fig.1 A unit of Tethered-SPS.

Introduction of Multi-bus Tethered-SPS∗

S.Sasaki

The Institute of Space and Astronautical Science (ISAS)

Japan Aerospace Exploration Agency (JAXA)

3-1-1 Yoshinodai, Kanagawa 229-8510, JAPAN

The Tethered-SPS, consisting of a power generation/transmission panel suspended by tether wires, has

been studied for 5 years under coordination with university researchers (Kyoto University, Hokkaido

University, Kanazawa University, Shizuoka University, Tokyo Metropolitan University) and USEF

(Institute for Unmanned Space Experiment Free Flyer). Since this system does not track the sun, the total

power efficiency is 36 % lower than that for the sun-pointing type SPS even when the solar cells are

attached to both sides of the panel. However, the simple, technically feasible, and practical configuration

resolves almost all the technical problems in the past SPS models. Figure 1 shows a unit of Tethered-SPS,

in which a power generation/transmission panel of 100 m x 95 m is suspended by four 5~10 km tether

wires extended from a bus system. The weight is about 45 MT. The unit has a power transmission

capability of 2 MW. The units are connected to form a larger SPS as shown in Fig.2, depending on user

requirements. 1 GW-class SPS can be constructed by 25 x 25 unit assembly.

This simple and flexible configuration has many advantages, as summarized below;

(1) Since the attitude is stabilized automatically by the gravity gradient force, no active attitude control is

required.

(2) There is no moving structure, which makes the system highly robust and stable. Especially one-point

failure mode peculiar to the rotary mechanism is excluded.

(3) The system is composed of equivalent units, which enables the phased construction and leads to easy

integration and maintenance.

(4) The unit consists of equivalent power generation/transmission modules, which enables low cost mass

production.

(5) There is no wired signal/power interface between the modules, which leads to easy deployment of the

unit.

(6) Active thermal control is not required because of uniform distribution of the transmitting power.

(7) A scale model of the unit of the Tethered-SPS can be used for the demonstration experiment on the

ground and in orbit in the near future, which assures an evolutional scenario for the SPS development

from the initial demonstration to the commercial SPS.

∗ Presented at the Eleventh SPS Symposium, 17-18 September 2008

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Page 2: Introduction of Multi-bus Tethered-SPS · 2017. 12. 1. · Fig.2 Integration of Tethered-SPS units by connecting panels. Power Generation (Upper Plane) Power Generation/Transmission

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