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Satellite Systems

Small Solar Power Sail Demonstrator "IKAROS"

The Small Solar Power Sail Demonstrator IKAROS is the world's first spacecraft to deploy a sail in space and employ both unfueled photon propulsion (solar sailing) and thin film solar power generation (power sailing) during its interplanetary cruise.

Under the direction of JAXA, NEC is engaged in the total system development, manufacturing, and testing for IKAROS.

IKAROS's mission

Currently mainstream rockets, which consume the propellant, represent only a secondary solution to the problem of providing propulsive energy for space transportation systems.

A solar sail gathers sunlight as propulsion by means of a large membrane while a solar power sail gets electricity from thin film solar cells on the membrane in addition to acceleration by solar radiation. What's more, if an ion-propulsion engine with high specific impulse is driven by such solar cells, it can become a hybrid engine that is combined with photon acceleration to realize fuel-effective and flexible missions. Achieving this would be useful for various future missions, including that of the Jupiter probe currently being planned.

IKAROS's technology

NEC developed the following subsystems of the IKAROS spacecraft system. NEC also supervised the total management of these subsystems to build the IKAROS spacecraft.

Structue subsystem: This is the structure of the spacecraft. NEC used a special cylinder type of the structure for the spacecraft: a cylinder with a diameter of no more than 1.6 meters and a height of no more than 0.9 meters.

Temperature control subsystem: In space, the temperature reaches 150 to 200属C when in the sunlight and -50属C when in the shade. Therefore, the temperature control system keeps the temperature of all the on-board equipment within the required temperature range during all phases.

Communication subsystem: This subsystem makes it possible to receive signals sent from the ground station (by way of an X-band uplink) and perform carrier wave acquisition and tracking. Command signals sent by the ground station are received and demodulated, and then the demodulated signals (including the command data and command playback clock) are sent to the data processing unit. In addition, ranging signals sent by the ground station are received and demodulated, and then ranging signals for which the S/N ratio has been improved are returned to the ground station.

Power subsystem: Solar cell panels are attached to the top of the spacecraft as a bus unit, and these panels make it possible to generate the required power and supply this power to IKAROS during all mission phases.

Data processing subsystem: NEC used a data transfer method that complies with the CCSDS. This subsystem also has a data recorder (data recording area).

Attitude control subsystem: NEC used the single spin method as the attitude control system, and the spin rate is fast before sail deployment and slow after deployment. IKAROS has various attitude control functions, including spin rate control, spin axis maneuver control, sun angle control, sun search control, and active nutation control (ANC).

IKAROS

IKAROS's status

After IKAROS separated from the rocket, it became the world's first spacecraft to deploy a solar sail and demonstrate that thin-film solar cells can be used to generate power in deep space. A separate camera was also detached from the probe and successfully photographed the probe with its sail deployed (open).

IKAROS

IKAROS Photograph of IKAROS taken in space

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