We would like to inform you about the situation after the 3rd report (October 17, 2023) as follows. We sincerely apologize for the long period of inconvenience this has caused to those planning to observe. We will continue to update information on our website about once a month.
1. Status of response to "abnormal values of primary mirror support mechanism (fixed point)"
・While confirming that the supporting force of the primary mirror support mechanism, including the fixed point, does not impose any load on the primary mirror's damage, we performed analysis work such as comparative evaluation with the model calculation of the primary mirror shape, and confirmed that there is a high possibility of a problem with the fixed point force sensor.
・Next, we conducted a stress evaluation on the damaged part of the primary mirror assuming the replacement of the force sensor at the fixed point, and confirmed that even if we manipulated the supporting force of the primary mirror support mechanism, no load would be applied to the damage on the primary mirror.
・Currently, in order to replace the force sensors at the fixed points,
a maintenance contractor is starting to procure force sensors, and plan to formulate a plan by around the end of November regarding specific work contents and procedures to ensure safe work.
・If the abnormal value is resolved after the force sensor is replaced, the inspection will be carried out again to complete the restoration after the damage on the primary mirror is repaired. On the other hand, if the abnormal value is not resolved even after replacing the force sensor, there may be a problem other than the force sensor, so further investigation will be conducted to identify the cause and location.
2. Status of response to "primary mirror damage"
・We are monitoring and comparing the damage on the primary mirror with the damage situation in September and October, and have confirmed that there is no damage progress.
・We confirmed the followings:
The area of the damage was small (approximately 1/100,000th of the area of the primary mirror).
It would not affect observation after repair.
It is technically possible to repair the damage.
・Next, we conducted stress evaluations on the primary mirror damages assuming repair work, and confirmed that even if we manipulated the supporting force of the primary mirror support mechanism, no load would be placed on the damages on the primary mirror.
・We are planning to repair the damage on the primary mirror after replacing the force sensor.
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