From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Subject: Ulysses Update - 09/07/92
Followup-To: sci.space
News-Software: VAX/VMS VNEWS 1.3-4   
Keywords:  Ulysses, JPL, ESA
Reply-To: baalke@kelvin.jpl.nasa.gov
Organization: Jet Propulsion Laboratory
Date: Fri, 11 Sep 1992 05:02:44 GMT

Forwarded from Peter Beech, Ulysses Mission Operations Manager

SUBJECT:  ULYSSES MISSION OPERATIONS REPORT No. 107

PERIOD: 1st to 7th September 1992

1. MISSION OPERATIONS

     Experiment reconfigurations have been carried out as required.

     On 2nd September a KEP (Energetic Particles and Interstellar
     Neutral Gas instrument) EPAC RAM dump was carried out.

     Routine  Earth pointing manoeuvres were  performed  on 1st, 4th
     and 7th September.

     Minimum  Sun-Earth-Probe angle (SEP) occurred  on  1st September.
     Since  the spacecraft is now in excess of 9 degrees south of the
     Ecliptic Plane sun avoidance manoeuvres were not necessary.

     However,  data recovery problems occurred during the period
     immediately following minimum SEP angle and it is suspected that
     the proximity of the propagation path to  the solar corona was a
     contributing factor to the data recovery problems.
     An average of 96.69 % data recovery was achieved during the
     reporting period.

     The  percentage of data acquired as a function of  bit rate is
     as follows:

       1024 bps 59.31 %
        512 bps 37.36 %

     A reduction in the number of ranging passes continued during the
     reporting period in order to improve  the poor signal to noise
     ratio encountered at the present large spacecraft-Earth distances.

2.   SPACECRAFT STATUS

     POWER

     Nominal.
     Estimated S/C power consumption 259 watts.

     AOCS

     Nominal.

     TTC

     The spacecraft is currently configured with receiver 2 as the prime
     unit fed via the high gain antenna and with receiver 1 as backup fed
     through the low gain antenna LGA-F. The downlink is provided through
     EPC2/TWTA2.

     The 34 meter ground stations are in use to support TTC operations, with
     at least one 70m station pass per week to support ranging.

     Received downlink level -148 dBm.(34 meter) X-band.

     (Variations of up to 10 db. can be expected as a result of station
     antenna in use, local weather conditions, and spacecraft antenna
     off-pointing).

     Received uplink level -127 dBm.

     DATA HANDLING

     The anomaly on CTU2 (Central Terminal Unit #2) reported in previous
     Operations Reports is still under investigation.  However, some
     conclusions have now been reached which point to an electrical
     connection between two adjacent data lines as a result of component
     failure.  The operational impact of this anomaly is being studied by
     both the Spacecraft Control Team and the instrument teams in the event
     that this CTU would have to be configured for operational use.

     THERMAL

     Nominal.

3.   FLIGHT DYNAMICS

     Solar Aspect   The angle increased from 1.40 on
     Angle (deg.)   1st September to 1.66 on 7th September.

     Sun-Probe-Earth    The angle increased from 1.48 on
       Angle  (deg.)    1st September to 1.69 on 7th September.

     Spin Rate               4.982 rpm.

4.   ORBITAL DATA

     Data taken at 13:00 PDT on 7th September.
     Distance from Earth                     935,780,184 km.
     Velocity relative to the Earth          117,113 km/hr.
     Velocity relative to the Sun              31,148 km/hr.
     Ecliptic latitude                         9.5 deg/south

5.   PLANNED OPERATIONS

     Routine   data  gathering  operations  will  continue together with
     experiment reconfigurations as required.

     Earth  pointing manoeuvres will be performed on 10th, 13th and
     16th September.

     A HUS (Solar X-Rays and Cosmic Ray Bursts instrument) end-to-end
     timing test will take place via the Canberra station on 15th September.

     Periods of 2048 bps at low antenna elevations will be avoided
     to improve the signal to noise ratio in the coming months.  This
     will slightly reduce the percentage of 1024 bps real-time data
     received.  During this period, 70m passes will also be scheduled
     to perform ranging at large spacecraft-Earth distances while
     maintaining the desired bit rates.

6.   GROUND SEGMENT

      The ground segment performed nominally during the reporting period.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Anything is impossible if
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | you don't attempt it.
|_____|/  |_|/       |_____|/                     | 

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