Mission Status Report #5      Star Date: June 28, 1999

Photo: FUSE launch photo, courtesy of NASA. (Click photo to see larger version.)

FUSE CHECKOUT CONTINUES ON TRACK

Date: Mon, 28 Jun 1999 16:59:47 -0400 (EDT)
From: Bill Oegerle 
Subject: FUSE IOC, June 28

FUSE IOC (in-orbit checkout), day 4

IOC is still progressing very well, and we are approximately on
schedule -- but as much as 2 days ahead of schedule for some activities.

Over the weekend, we powered on the IPSDU (power system distribution
units) and began active thermal control of the instrument.  The   
temperatures have stabilized from the first table load, and a new control
table is being loaded this afternoon. The GMAs (grating mount
assemblies) were a couple of degrees cooler than expected, so they are
being warmed up in this subsequent control table load (we want the
optics several degrees warmer than the surroundings to prevent
condensation).

We have loaded about half of the "flight project" into the instrument
computer (the "project" is the set of script and rules used to carry out
instrument commands).  Later today we will be loading the rest and also 
perform a "polarity" test of the attitude control system, by commanding 
some pitch, yaw and roll commands from the instrument.

Tomorrow, we will be performing a BOS (Bright Object Sensor) calibration
test, where we slew to high beta angles (ie. toward the sun), with the
baffle doors closed, and measure the output of the BOS sensor.  This is
the only time in the mission when we can do this test, and we need to
calibrate the BOS before we ever attempt an observation of Venus (we
dont want to accidently trigger a door closure).   This will be followed
by a BOS calibration against bright earth (for the same reasons).

We have been experiencing some intermittant software problems in the control 
center with a particular kind of data telemetry format if that data gets
corrupted on downlink.  This has cost us about a half day of schedule.  
The problem now seems to be understood, however, and repairs are underway.   

We have discovered that we can communicate with FUSE via TDRSS at 32 kbps 
(downlink) very reliably.  We had not planned on using TDRSS very much in 
IOC beyond launch support.  This is good news, since TDRSS availability 
could in principle allow us to accelerate some instrument activities, such 
as the detector high-voltage turn-on.  This particular activity would 
normally take 1 day per detector using only Puerto Rico and Hawaii ground 
stations.  However, we have no priority for TDRSS use, so we take whatever 
we can get.

An orbit determination is now available.  Our mean altitude is comfortably 
below the Iridium satellite complex, and about 20 km higher than that of the 
"Copernicus" observatory when it was operational!

    --Bill Oegerle, Science Ops Lead

Date: Date: Mon, 28 Jun 1999 12:47:22 -0400
From: JB Joyce 
Subject: FUSE Status Report-June 28,1999

 Please be advised of the latest FUSE status:

    * All primary spacecraft subsystems continue to function nominally 
     - Spacecraft subsystem monitoring and trending are ongoing

    * The FUSE Satellite Control Center System experienced anomalistic
      behavior during several real time IDS data dumps (no data lost); 
      analysis is underway        

    * JHU/UPRM ground station required a reboot due to lack of of antenna
      motion ( no data loss); no recurrence

    * Thermal control of the optics was successfully initiated 

    * IDS-A activation and checkout continued
       - Loaded and dumped tables


 Planned Activities:

     * Continue IDS-A activation and checkout
       - Load project

     * Continue activation of thermal control


   ************************************
   *                                  *
   *  J.B.Joyce                       *
   *  FUSE Mission Operations Manager *
   *                                  *
   ************************************

Reported by: Bill Oegerle, Science Ops Lead, and J. B. Joyce, Mission Operations Manager