This note details the preparation of the MDI instrument before the
Leonids meteor storm on 17 November 1998, and the instrument recovery
afterwards. The MDI activities will be performed by shared NRT
commanding. It is requested that the MDI safing take place as late as
practical, and it is desirable to perform the MDI safing immediately
after the spacecraft roll.

There are no new requirements for MDI procedures for the momentum
management and station keeping maneuver on 13 November except for the
standard ISS loop management by the FOT. The MDI ISS loop should be
opened via the TSTOL procedure m_fl_issopen.prc before transition to
CSP pointing mode for both the momentum management and maneuver, and
closed via the TSTOL procedure m_fl_issclos.prc after the spacecraft is
back in RMW mode.

It is not anticipated that any of the MDI parameters monitored by the
FOT or the spacecraft will be outside of the acceptable range.

Procedures for Safing of the MDI Instrument

The MDI safing will power off the CCD camera, the Image Stabilization
System, and all mechanisms including the shutter, MTM motors, and the
PA/CAL wheels. After these subsystems are confirmed to be powered off,
the MDI controlled Optics Package heater will be turned on and adjusted
to compensate for the decreased thermal input to the Optics Package
because of the camera electronics being powered down.

As a final step, the MDI front door will be closed after verifying that
the redundant mechanism functions properly.

The three MDI control file procedures that will be run are summarized
below.  It is estimated that the MDI safing will take less than an hour
to perform.

	fl_safe.src

	fl_htr_config.src

	fl_fd_close.src 


Procedures for Recovery of the MDI Instrument

The MDI recovery procedures are similar to the final steps of the recent
MDI power up, except that they will all be performed via NRT commanding.
The following sequence of MDI control file procedures will power up the
CCD camera, Optics Package mechanisms and the Image Stabilization System.

	fl_cmon.src

	fl_mchson.src 

	fl_lton.src

After the MDI subsystems are verified to be in an acceptable state, the
standard observing sequence will be started while the front door is still
closed. A focus test sequence will be run while the front door is opening
and the front window temperature is changing. The procedure to open the
front door is:

	fl_fd_open.src 

It is expected that the instrument recovery activities will take less
than two hours.  We will need VC2 telemetry for a four hour period to
perform the front window focus tests.