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\newcommand{\axaf}{{\em AXAF}}
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\large
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\centerline {\bf 5.1\_V2.0 CLOSE SMALL VENT VALVE } 
\vspace{0.25in}

\normalsize
\noindent{\it Last Revised: June 29,1999}\\

\noindent {\bf BRIEF FUNCTIONAL DESCRIPTION:} \\
\normalsize
The ``small'' (previously known as little) vent valve is planned to 
be opened once 
on orbit and left open.  In the event of an aborted \axaf\/
deployment and a shuttle return to earth with \axaf\/, it would
be desirable but not necessary to close the small vent valve.
The procedure is in essence the reverse of opening the small vent
valve, with the pressure measurements and DPA power-up deleted.
The procedure contains no indefinite wait so that the commands can be
sent as quickly as possible (6 commands in 6~s)
  

\vspace{0.25in}
\noindent The sequence of actions will be: 
\be
\item enable and close the small valve mechanism A \& B
\vspace{-0.10in}
\item disable the small vent valve mechanism A \& B
\ee


\vspace{0.15in}
\normalsize
\noindent {\bf ASSUMED INSTRUMENT STATE:} \\
\normalsize
Assumes that the PSMC has power from the spacecraft. \\

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\normalsize
\noindent {\bf SPECIAL INITIAL CONDITIONS:} \\
\normalsize
Assumes that \axaf\/ deployment had failed and the shuttle is
returning to earth with \axaf\/.\\
%\indent {Assumes that \axaf\/ ISIM RCTU is powered on and in telemetry format 6.}
Assumes that the spacecraft has power and connections for commanding and telemetry. \\


%\newpage 

%\vspace{0.25in}
\normalsize
\noindent {\bf OPERATIONAL CONSTRAINTS/CAUTIONS:} \\
\normalsize
There is no telemetry verifier that the small vent valve
mechanism has closed. \\
This procedure will execute in 6~s so that it will impossible to
verify the valves were actually enabled.  The only way to verify that
the valve has closed is to observe a pressure stabilization, if there
is still enough gas inside the camera housing to be measured.\\
CARD ACIS-003 \\


\vspace{0.15in}
\normalsize
\noindent {\bf REFERENCES:} \\
\normalsize
ACIS Long Form Functional Test Procedure (36-01301.01)

\normalsize
\noindent {\bf CHANGE HISTORY:} \\
\normalsize

{\bf V1.2}
\begin{itemize}
\item changed filenames from ``close\_lvv'' to ``close\_svv''
\end{itemize}

{\bf V1.3}
\begin{itemize}
\item deleted steps 1 and 4 which power-up/power-down the DPA A
\item re-ordered the commands into Enable A/Enable B/Open A/Open B in
steps 1.1 -- 1.4
\end{itemize}

{\bf V2.0}
\begin{itemize}
\item ACIS Team signed-off version
\item changed expected values from 0's and 1's to ``ENB'' and ``DIS''
\item removed criticality values for each step since this procedure
will execute in 6~s and there will be not time for TLM verification
\item edited ``Operations Constraints and Cautions''
\end{itemize}

\newcommand{\tablecaptiontext}{Close Small Vent Valve Procedure}
\input{close_svv.tab}

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