From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Subject: Ulysses Update - 07/28/92
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: Thu, 30 Jul 1992 01:03:24 GMT

Forwarded from Peter Beech, Ulysses Mission Operations Manager

SUBJECT:  ULYSSES MISSION OPERATIONS REPORT No. 101

PERIOD: 21st July to 27th July 1992


1.   MISSION OPERATIONS

     Experiment reconfigurations have been carried out as required.

     Routine Earth pointing manoeuvres were performed on 24th,
     and 27th July.

     On 21st July the Goldstone 34 meter station was not
     available due to failure of the Maser amplifier on the
     downlink.  Support was switched to another antenna which was
     not able to provide an uplink and as a consequence the
     scheduled STO (Radio and Plasma Wave instrument) commands
     were not transmitted.

     In addition, an erroneous playback of data at 1024 bps
     scientific format instead of 2048 bps interleaved format led
     to a loss of just under 8 hours of playback data.
     Procedures are under review reduce the probability of a
     reoccurrence.

     On 22nd July the Goldstone 34 meter station was still
     unavailable and as a result just under 3 hours of data were
     lost.  The loss was minimised by the use where possible of
     other ground facilities.

     On 23rd July the Goldstone 70 meter station was restored to
     service after earthquake damage repairs had been completed.

     On 26th July a power failure occurred at Goldstone which
     gave rise to further losses of data.

     An average of 90.46 % data recovery was achieved during the
     reporting period.

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

     1024 bps 51.83 %
       512 bps 38.66 %

     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 260 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 -149 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 -125 dBm.

     DATA HANDLING

     The anomaly on CTU2 reported in previous Operations Reports
     is still under investigation.

     THERMAL

     Nominal.

3.   FLIGHT DYNAMICS

     Solar Aspect   The angle decreased from 6.19 on
     Angle (deg.)   21st July to 5.13 on 27th July.

     Sun-Probe-Earth  The angle decreased from 6.32 on
     Angle (deg.)     21st July to 5.55 on 27th July.

     Spin Rate               4.982 rpm.

4.   ORBITAL DATA

     Data taken at 13:00 PDT on 27th July.
     Distance from Earth                922,709,026 km.
     Velocity relative to the Earth         108,455 km/hr.
     Velocity relative to the Sun            30,500 km/hr.
     Ecliptic latitude                          7.5 deg/south

     Note:  The distance of the spacecraft from Jupiter will
     no longer be reported.

5.   PLANNED OPERATIONS

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

     An Earth pointing manoeuvre will be performed on 31st July.

     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 experienced several problems during this
     reporting period which have been addressed above.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Most of the things you 
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | worry about will never
|_____|/  |_|/       |_____|/                     | happen.

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