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About Kibo

Inter-orbit Communication System

Last Updated: August 29, 2008
ICS Pressurized Module (ICS-PM) (left) and ICS Exposed Facility (ICS-EF) (right)

ICS Pressurized Module (ICS-PM) (left) and ICS Exposed Facility (ICS-EF) (right)



Kibo's Inter-Orbit Communication System (ICS) provides an independent intercommunications network between Kibo and the Tsukuba Space Center (TKSC, JAXA). Commands and voice data are uplinked from the ground through JAXA's Data Relay Test Satellite (DRTS), known as Kodama, to Kibo, and experiment data, image data or voice data are downlinked from Kibo to the ground. The ICS consists of two subsystem components: the ICS-Pressurized Module (ICS-PM) and the ICS-Exposed Facility (ICS-EF). The ICS-PM, which is installed in the PM, will provide command and data handling functions. The ICS-EF is mainly composed of an antenna and pointing mechanism that will be used to communicate with the DRTS.

Item Specification
Size 2.0×1.0×0.9m 1.1×0.8×2.0m (antenna retracted)
2.2×0.8×2.0m (antenna deployed)
Mass (weight) 330kg 310kg
Data rate /
frequency /
modulation method
Downlink 50Mbps / About 26GHz
Uplink 3Mbps / About 23GHz
DRTS communication window* Total of 7.8 hours per day (DRTS currently consists of only one satellite)
Max. 40min. per orbit

*The actual amount of time available for the DRTS communication may be shorter than the data shown in the above table since the data is based on estimations. In addition, the DRTS communication time may occasionally be allocated for other satellites.


The following are details of the ICS subsystems, ICS-PM and ICS-EF components.

ICS Pressurized Module (ICS-PM)


The ICS Pressurized Module (ICS-PM) is installed in the ICS rack that was delivered to the International Space Station (ISS) on the STS-123 Mission (1J/A). The ICS-PM will multiplex the Kibo's systems and experiment data for downlink to the ground, and demultiplex the data uplinked from the ground. Also, the ICS-PM will modulate the data before sending, and will demodulate the data after receipt. The ICS-PM has an automatic operation scheduling function where commands are uplinked from the ground in advance while the DRTS is in a communication window. The ICS-PM also has a data recording function for later downloading to the ground, whenever real-time communication is not available.

ICS Exposed Facility (ICS-EF)


The ICS Exposed Facility (ICS-EF) is comprised of several components, including an anntenna, pointing mechanism, frequency converters, high-power amplifier, and various sensors including the Earth sensor, Sun sensor, and inertial reference unit. The ICS antenna can automatically track the DRTS.


Current Status

The ICS-PM was installed in the ICS Rack and delivered to the ISS on the STS-123 Mission. The ICS Rack was installed in the PM during the STS-124 Mission (1J).

The ICS-EF will be launched on the STS-127 Mission (2J/A).

STS-123 Mission (1J/A)
STS-124 Mission (1J)
STS-127 Mission (2J/A)
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