MUSES-C has undergone a series of comprehensive performance tests
toward its launch scheduled at the end of 2002. Unfortunately,
however, it had to be postponed to a backup window set in May 2003.
It all started with the detection of gas leak from a pressure-
regulating valve during an airtight test of the orbit-attitude
control propulsion system (RCS) conducted in late April 2002. Our
inspection showed that it was due to an incorrect size O-ring that
keeps the valve airtight.
The broken ring was promptly replaced by a
proper-sized ring and the problem seemed solved. However, when the
material of the ring was examined by way of precaution, it was found
that the material used was different from the one specified in the
spec. Many other O-rings of the same type are used for the pressure-
regulating valves of MUSES-C and if their material differs from the
one in the spec, they may cause problems in the vapor tolerance of
fuel and oxidizer.
Besides, the RCS is built by welding, which
prevents us from removing the valves for checking. Therefore, some
other verification measures such as a gas chromatographic non-
destructive test were conducted, which took several months before
reaching an OK level and as a result, delayed the launch of MUSES-C
schedule at the end of 2002.
With a strong support from the Space
Development and Utilization Division of Mext, an approval for the
launch in May was obtained from Japan Associated Fisheries, which was
reported to the Space Development Committee held on September 26.
Though the launch is delayed 6 months, there is no change in the
schedule of arrival at the asteroid and return to the Earth.
