| What's Going on Here? |
| Loading below is a close-up photograph of the door to the HST instrument bay taken during the February 1997 repair mission. Next to the door is an informative plaque with instructions for opening the doors. The plaque says: |
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1. RETRACT SEALS BEFORE OPENING DOORS (TURN ADJ. SCREWS CW) 2. EXTEND SEALS BEFORE CLOSING DOORS (TURN ADJ. SCREWS CCW) |
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| The acronym "EVA" (Extra Vehiclular Activity) indicates the instructions were meant to be read in space, not by ground personnel. "CW" and "CCW" mean ClockWise and Counter-ClockWise respectively. Thus, the adjusting screws work in reverse of standard earth-bound (right-hand) screw threads. |
| The background on this page is a Hubble deep field image from 276 exposures taken over 10 days. |
I hope we can rest assured that any astronauts sent by NASA to open the door would know which way to turn the adjusting screws before they left the ground. It's not (excuse me), rocket science. |
| Dare we presume that the plaque was placed next to the door to assist other-earthly astronauts? If so, will their clocks "wise" as our clocks "wise"? Do they even need clocks? Will the agony of an alien cross-threading be the demise of the Hubble Space Telescope? |
| To NASA's credit, they did not use the term "left hand" thread which may have been incomprehensible to beings with no left, much less hands. |
| Perhaps, dear reader, you are knowledgeable about this folly, and can shed some light. If so, please |
| email me. |
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A visitor writes:
CW or CCW aside, the first step says to retract the seals before opening. The second step says to extend the seals before closing. Shouldn't it say extend seals AFTER closing???? I believe when they went back to the telescope to make repairs, they could not get this door to close properly. Maybe these instructions were the problem! |