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%\input dspace12.tex
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\large
%\vspace*{-0.5in}
\centerline {\bf 2.10\_V2.2 OPEN ACIS DOOR ON ORBIT } 
\centerline {\bf (in 4 shots, including full bakeout) } 
\vspace{0.25in}

\normalsize
\noindent{\it Last Revised: July 2,1999}\\
\noindent{\bf Filename: open\_door} \\

\noindent {\bf BRIEF FUNCTIONAL DESCRIPTION:} \\
\normalsize
The ACIS camera housing door is planned to opened once on orbit.
The door will not be opened until the spacecraft environment has
outgassed sufficiently so that only a small amount of contaminants
will build up on the ACIS filter.  The spacecraft outgassing and 
venting models are provided by Loraynne Ryan at TRW.  The acceptable
level of contamination is specified by the ACIS IPI team.
Both the small and big vent valves must be opened before the
door can be opened. The door mechanism uses the same paraffin 
actuators as the big vent valve mechanism.  Extreme caution
must be exercised with these actuators, from the ACIS Long Form
Functional Test Procedure document:

\begin{quote}
\em{Because the Optical Blocking Filters are fragile and cannot 
withstand much differential pressure, mechanism motions may only 
be initiated when the differential pressure is less than 1 torr.
Be safe; check both transducers.  The mechanisms are driven by 
Starsys hot wax actuators. Power is applied directly from the 
space craft bus to heat the wax and, therefore, the time for a 
given motion to complete is dependent upon the bus voltage. To 
avoid failure of an actuator due to overheating--which would occur 
if the completion-of-motion switches failed, for instance--we 
monitor the actuator temperature. If the actuator temperature 
exceeds 135C, a command to abort the motion should be sent. Recovery 
from such a condition is never routine; no further motions should
be attempted without thorough analysis of the procedural failure.
 It is also imperative that the commanded actuator be allowed to 
cool below 50C before the opposing actuator is commanded, lest the 
afore-mentioned egregious situation occur.  It is not an error to 
command a valve open which is already open, etc., since the PSMC 
logic will know from the motion switches that the mechanism is 
already in the commanded state and not (falsely) apply power to 
the actuator.
}
\end{quote}

The side A HW serial digitial TLM has an extra bit to monitor the status of the
actuator.  However, the logic which determines the value of this bit
is sufficiently obtuse, that it is typically easier to use side B.
The door typically took 3.5~minutes to open with a 28VDC bus
voltage during ground testing; it will go faster with 32VDC on the
bus.  The peak
temperature should be $100\pm10$~C; damage can occur if the temperature
exceeds 135~C. An on-board regulator disconnects the voltage if the
temperature reaches 130~C.  Therefore, ground intervention to abort
the actuator motion should not be necessary or even possible, but 
is maintained as a backup to this automatic cutoff.  As the 
actuator warms above 70~C, it begins to move and the door closed
bit should switch to zero.  Once the motion is complete and the actuator
starts to cool, the door open bit should switch to one.  While in 
transition, both bits should be zero.


The door open actuator will be cycled four times nominally before the
door is completely open.  A library of  SCSs will be pre-built 
by the FOT which will contain the necessary commands to operate the
actuator with heating cycle durations ranging from  50 -- 150~s 
in 5~s intervals and 150,200, 250, and 300s.
Each SCS will contain the actuator heater on command, the appropriate 
time delay, the actuator
heater off command, a 1~s delay, and another actuator off command .
The FOT will also have the actuator heater off command queued up and
ready to be sent as quickly as possible in case of an emergency.
Each suceeding cycle keeps the actuator
heater on for a longer time.  The first cycle is intended to be long
enough to just melt the wax and have the plunger of the actuator move
a small amount.  The second cycle is
intended to melt the wax, trip the ``closed'' 
limit switch and rotate the shaft by a few degrees without beginning
to open the door.  The third cycle is intended to melt the wax, trip
the limit switch, and rotate the shaft by enough that the door
cracks open by $\sim 28$~degrees.  The last cycle is intended to open 
the door fully,
rotating the shaft the entire way and tripping the ``open'' limit
switch.  In the last cycle, it is expected that the actuator will
automatically shut itself off after it has hit the ``open'' limit switch.
During the execution of the procedure, the SOT will decide on the
appropriate duration for the heating cycle and instruct the FOT to
uplink the appropriate SCS.

After each one of these cycles, the desired motion may not be
observed.  If this is the case, a contingency procedure may be called
for.  The contingency procedures which have been prepared are to 
repeat the heating cycle with a different duration
than one of the planned 4 heating
cycles (all times will be available in 5s increments) and simply to
turn off the heater (hopefully this is unnecessary).  If after the
third heating cycle, the door has not lifted off of the camera housing
it may be decided to abort this procedure and to thermally cycle the
camera housing.


\vspace{0.25in}
\noindent The sequence of actions will be: 
\be
%\item enable and turn on DPA PSs A \& B and DEA side A {\it if necessary}
%\vspace{-0.10in}
%\item heat the DA housing to -60C if necessary {\it if necessary}
%\vspace{-0.10in}
\item start a DEA HKP run if necessary
\vspace{-0.10in}
\item enable FP bakeout and start heating FP to +30 C
\vspace{-0.10in}
\item Enable and turn on the DA housing bakeout heater, heat DA housing to +25~C \\
\vspace{-0.00in}
-------- In orbit, wait 8 hours for FP and DA to heat up ------------- \\
\vspace{-0.25in}
\item switch spacecraft telemetry format to 4
\vspace{-0.10in}
\item enable the door mechanism side B and verify actuator temperatures
\vspace{-0.10in}
\item Execute first heating cycle
\vspace{-0.10in}
\item Verify expected behavior (the temperature and motion of the actuator)
%\vspace{-0.10in}
%\item verify the close and open bits change
\vspace{-0.10in}
\item Monitor actuator cooldow
\vspace{-0.10in}
\item Decide if next heating cycle time is correct, if yes proceed, if
no execute contingency
\vspace{-0.10in}
\item Execute second heating cycle
\vspace{-0.10in}
\item Verify expected behavior 
\vspace{-0.10in}
\item Monitor actuator cooldow
\vspace{-0.10in}
\item Decide if next heating cycle time is correct, if yes proceed, if
no execute contingency
\vspace{-0.10in}
\item Execute third heating cycle
\vspace{-0.10in}
\item Verify expected behavior 
\vspace{-0.10in}
\item Monitor actuator cooldow
\vspace{-0.10in}
\item Decide if next heating cycle time is correct, if yes proceed, if
no execute contingency
\vspace{-0.10in}
\item Execute fourth heating cycle
\vspace{-0.10in}
\item Verify expected behavior 
\vspace{-0.10in}
\item Monitor actuator cooldow
\vspace{-0.10in}
\item disable the door mechanism B
\vspace{-0.10in}
\item switch spacecraft telemetry format to 1 or 2
\vspace{-0.10in}
\item Turn off DA housing bakeout heater, cool DA to -60~C 
\vspace{-0.10in}
\item gradually lower FP temperature to -40~C, keeping it above the DH
temperature at all times \\
%\vspace{+0.05in}
-------- In orbit, wait 8 hours for FP and DA to cool down ------------- \\
\vspace{-0.25in}
\item disable FP bakeout and reboot, lower FP temperature to -120~C
\ee


%\vspace{0.25in}
\normalsize
\noindent {\bf ASSUMED INSTRUMENT STATE:} \\
\normalsize
Assumes the small and big vent valves have been open for 
many days. \\
Assumes that the instrument is in the canonical thermal standy state
(the video boards and FEPs must be off !!!!). \\
Assumes the DA  heater on side B is on.\\
Assumes that the RCTU starts in format 1 or 2, is swithced to format 4 for
the door opening and is then put back into format 1 or 2.

\vspace{0.25in}
\normalsize
\noindent {\bf SPECIAL INITIAL CONDITIONS:} \\
\normalsize
Assumes the spacecraft environment has outgassed sufficiently to allow
the door to be opened.\\


%\newpage 

\vspace{0.25in}
\normalsize
\noindent {\bf OPERATIONAL CONSTRAINTS/CAUTIONS:} \\
\normalsize
The small and  big vent valves must already be open. \\
The open and close mechanism must not be enabled at the same time.\\
{CARD ACIS-002} \\
{CARD ACIS-007} \\


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

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

{\bf V1.2}
\begin{itemize}
\item changed filenames from ``open\_door\_4shots'' to ``open\_door''
\end{itemize}

{\bf V1.3}
\begin{itemize}
\item deleted commands in step 1 which verified that the Big Valve was
indeed open
\item put commands into a new step 1 to start a DEA HKP run if
necessary
\item inserted a command to set the warm boot flag off before the
focal plane bakeout enable and inserted a dumpSysConfig command in
step 2
\item added the DA heater output voltage and current as verifiers in
step 3.2
\item added cold radiator temperature as verfifiers in step 3.3
\item changed expected values of the actuator temperatures in step 5.2
\item changed all of the 4 heating cycles to explictly state that the
SOT selects a heating duration by calling out the name of a pre-built
SCS and the FOT uplinks, enables and executes that SCS. This effects
steps 6, 10, 14, and 18.
\item deleted 1MAHOBT as verifier in steps 8, 12, 16, and 20
\item updated heating durations and expected max temperatures to be
consistent with Ed's preflight predictions
\item changed step 17 to require that the shaft rotation angle must be
large than 18 degrees to proceed
\item deleted previous step 23 which maintained an elevated focal
plane temperature for 2 hours after the door had opened
\item changed Time Req for all of the substeps in step 24 to be 60
minutes
\item changed the expected value of the HW serial digital verifiers
1MEOPBOP and 1MECLBCL to be ``NOPE,OPEN'' and ``CLOS,NCLO'' throughout
the procedure instead of 1 or 0
\item added value of commandEcho for all SW command packets
\item edited Brief Functional Description to be consistent with procedure
\end{itemize}

{\bf V1.4}
\begin{itemize}
\item changed HW TLM verifier in step 2.1 to 1DE28AVO
\item changed expected value of DA Htr Current in step 3.2 to
$\sim2$~A
\item changed criticality of 1MODRBOP in steps 6.4, 10.4, 14.4, and
18.4 to ``2''
\item changed titles of steps 25.1 and 25.2 to ``remove FP bakeout
enable'' and ``disable FP bakeout''
\end{itemize}

{\bf V2.0}
\begin{itemize}
\item ACIS Team signed-off version, identical to previous version 1.4
\end{itemize}

{\bf V2.1}
\begin{itemize}
\item changed expected value of ``1STAT7ST'' to ``0'' in step 25.7
\end{itemize}

{\bf V2.2}
\begin{itemize}
\item moved commands to turn off the Housing Bakeout heater to step 22
before the TLM FMT switch to FMT 1or2
\end{itemize}

\newcommand{\tablecaptiontext}{Open ACIS Door on Orbit }
\input{open_door.tab}

\end{document}
