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From: starrfie@hydro.la.asu.edu (Sumner Starrfield) Subject: HST Mission on Sunday Dec 5 Date: Sun, 5 Dec 93 14:10:45 MST >From wms@stsci.edu Sun Dec 5 11:27:05 1993 11:00 AM December 5 339:16:00 One of the two solar arrays properly retracted. The second, the one with the bad kink, was only retracted about half-way. After some deliberation about whether to try to force it more, the decision was made to leave it as is during the crew sleep period (which has now started). It is highly likely that this array will be jettisoned tommorrow during EVA 2. The estimates are that the need to jettison one array should not compromise the ability to get both new arrays installed during EVA 2. I should mention, however, that there is still a lot of discussion on the nets about this, so things may change before EVA 2 starts. >From wms@stsci.edu Sun Dec 5 12:05:39 1993 Servicing Mission Status JSC, 5 Dec. 1993, 6:30am(CST) Day 4 of the STS-61 Mission has been extremely successful to this point. The first EVA day saw the successful installation of 2 Rate Sensor Units (RSUs), 2 Electronic Contol Units (ECUs), and several fuse plug assemblies. Functional tests of the gyro systems show that all 6 gyros are now operational, thus completely restoring HST's redundancy in this area. Preparations were also made for the replacement of the solar arrays in the 2nd EVA day. Some additional comments are given below. . The replacement of the gyros and the Solar Array preparations appeared to go almost flawlessly. However, there was difficulty in closing the aft shroud door. There was about a 1/2" gap at the top, after attempting to close the door from the lower latches. The astronauts came back to the door after changing out the ECUs. In the end, it was found that the door needed to be squeezed together in the center with a payload retention device (PRD) and the latches gradually buttoned up top & bottom. Apparantly, there had been some difficulty in closing this particular door at LMSC (though not this much). While there is some concern that the same problem may be encountered in the COSTAR and GHRS replacements, those doors are symmetric and more rigid. Part of the difficulty is that there is a double-bubble rubber light seal which needs to be compressed when the door is closed. The changeout of the ECUs went well, although there was some difficulty in torquing down the new ECU bolts. By doubling the torque from 5 to 10 ft-lbs, the astronauts were able to snug down and connect both ECUs. The higher torque had been recommended by GSFC but had not been changed in the flight rules prior to launch. Another surprise was a fault indication of both HST power sides prior to fuse checkout. It turned out that the DIU had been turned off in preparation for the fuse replacement and this caused the faulty indication. No real problem. . Depending on the success of the SA (Solar Array) retractions near the end of the crew day, the plans for tomorrow will involve changing both arrays. If one of the old arrays fails to retract, it may be jettisoned.
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