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Common Berthing Mechanism Acceptance Test of the Japanese Experiment Module"Kibo"

The Common Berthing Mechanism Acceptance Test of the Japanese Experiment Module "Kibo" was conducted at Tobishima factory of Mitsubishi Heavy Industry from June 27 to July 2, 2000.

Common Berthing Mechanism
Common Berthing Mechanism
(Active CBM and Passive CBM being connected)
The Common Berthing Mechanism (CBM) is a functional structure that is used to connect the components of the International Space Station (except the Russian modules).

The Japanese Experiment Module "Kibo" will use two CBMs. One will be used to connect the Pressurized Module (PM) and the Experiment Logistics Module's Pressurized Section (ELM-PS); the other, to connect the PM and Node 2.

A CBM is composed of two parts, an active CBM that uses an electric motor to make connection, and a passive CBM. To connect these two parts, an astronaut first uses the robot arm to grapple the module on which the passive CBM is attached and move it close to the active CBM. A limit switch located on the active CBM senses when the passive CBM is close enough to the active CBM and generates a signal indicating that preparation for berthing is completed. Next, the active CBM extends four capture latches to catch the passive CBM (see the figures).

The 16 power bolts then extend from the active CBM and are inserted into the holes of the passive CBM, completing the connection. When the pressurized modules are connected, a big O-ring seal made of special rubber will seal the CBMs to maintain air-tightness inside the connected modules.
Kibo's CBM location image

How a Capture Latch works

Test Summary
Active CBM
During actual operation, Kibo's CBM will be powered by Kibo's power source, controlled by commands generated by the Destiny's (US Experiment Module) controller. However, since the Destiny's controller is not available for this test and bacause this is a Kibo standalone test, we borrowed test equipment from NASA to conduct this functional test.

The active CBM attached to the Pressurized Module (PM) was first powered up by the test equipment power source. A control command was then sent from that test equipment to confirm that the capture latches and the power bolts work as they are expected.

Next we supplied power from Kibo's supply to the active CBM in the same manner as in actual operation and sent commands from the test equipment to the active CBM, confirming the normal operation of the capture latches and the power bolts.
Functional test of Capture Latches

Future Schedule
"Kibo" will be transported to the US, and undergo a connectivity test using a simulated CBM ring called a CBM master tool at Kennedy Space Center. Since all ISS modules including Kibo were designed to be operated in microgravity, they cannot be connected to each other under gravitational conditions on Earth.

Also, during ISS assembly mission STS-92, in which astronaut Wakata will participate, CBMs will be used for the first time to connect the Z1 truss and PMA-3 to the ISS (Unity).

Comments from the key person
This was a cooperative test between Japan and the United States and required more preparation than for tests conducted only by Japan. The test itself was conducted within just a few days, however I am very much satisfied that I could finish all the procedures including negotiations with the US. When the test facility that we borrowed from the United States caused a problem, we questioned whether we could continue and finish the test. However, thanks to NASA's efforts; an alternate system was transported to Japan in two or three days. That enabled us to successfully complete the test without much delay, and I felt relief and gratitude for their effort. Through the preparation and the trouble recovery procedures, we could directly understand the differences between Japanese and US cultures, both good and bad points, which was a valuable experience for me.
Mr.Toru Yoshihara
JEM Project Team Office of Space Utilization Systems NASDA

Last Updated : August 24, 2000

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