🚀 go-pugleaf

In article <4JAN199317595383@kelvin.jpl.nasa.gov> baalke@kelvin.jpl.nasa.gov writes:

>In article <IfG6hqu00XsFRFwEc9@andrew.cmu.edu>, bluelobster+@CMU.EDU (David O
> Hunt) writes...
>>Is there anyway of telling that the hammering is making progress (aside
>>from rib release)?
>
>The sun sensor and wobble measurements are the two main indicators.  The
>shadow of the antenna falling across the sun sensor is used measure the extent
>the antenna is open.  Since the stuck ribs cause the antenna to be
>more open on one side than the other (asymmetrically deployed) and the
>spacecraft is spinning, a slight wobble exists which can be measured.
>Also, when the antenna is fully open, a couple of switches will be activated.
>After the first antenna hammering last week, the sun sensor and wobble
>measurments indicated a change in the antenna, the first change measured
>since the initial antenna deployment attempt in April 1991.  The recent 
>sun sensor data indicates that the antenna is "more open", and this is either 
>due to one of the three stuck ribs popping loose, 
>or increased tension on the antenna is causing it to bend out more.  Several 
>more hammering sessions are scheduled this month to keep applying more force 
>on the ballscrew to free the stuck ribs.
>     ___    _____     ___
>    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
>    | | | |  __ \ /| | | |     Jet Propulsion Lab |
> ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Choose a job you love, and
>/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you'll never have to work
>|_____|/  |_|/       |_____|/                     | a day in your life. 
>
>

Is the HGA of no use at all unless completely open?  Couldn't a partially
open antenna be used at all - or does the fact that it's not a parabola
(or whatever) make it totally useless?

Chris
-- 
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| Chris Marriott                           | chris@chrism.demon.co.uk    |
| Warrington, UK                           | BIX: cmarriott              |
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