Pioneer 10 Update 24 July 2000

Pioneer 10
 
(Launched 2 March 1972)
 
Distance from Sun (1 July 2000): 75.53 AU
Speed relative to the Sun: 12.24 km/sec (27,380 mph)
Distance from Earth: 11.44 billion kilometers (7.111 billion miles) Round-trip Light Time: 21 hours 11 minutes
 
Another pointing maneuver was performed on Saturday morning, 8 July, but we have as yet not been able to confirm the success of this maneuver. We remain optimistic that we will be collecting data again by August (our next good DSN track is not until August 3) and that once again the spacecraft came through.
 
This was the 8th such maneuver attempted in the blind since 26 January 1997. The procedure requires turning off the downlink spacecraft transmitter to have enough power to run the attitude and conscan subsystems. The procedure takes about 1 hour 29 minutes. The round trip light time for the latest maneuver was about 21 hours 12 minutes. The distance from the Sun and the time the transmitter is off result in a very unstable signal. In February, it took three days before the signal had stabilized enough for us to lock up on it.
 
 
From a recent tracking report:
 
Deep Space Station (DSS): 63 Madrid, Spain
 
Spacecraft: 23 [Pioneer 10]
 
Date of track: 3/21/00 Day of Year (DOY)=081
 
Beginning of Track (BOT) = 21:15 (Universal Coordinated Time)
 
End of Track (EOT) = 23:50
 
Spacecraft Health: Thermal, Power, RF, Science all nominal.
 
The Radioisotope Thermoelectric Generators (RTGs) continue to provide sufficient power to support the current spacecraft load of transmitter, receiver, command and data handling as well as the Geiger Tube Telescope (GTT) science instrument.
 
The RTGs are currently providing approximately 65 Watts of power (about 42% of the 155 Watts launch value).
 
The science and transmitter are turned off to provide enough power to fire the attitude control engines for the biannual spacecraft pointing maneuvers towards the Sun (the latest maneuver was executed on 2/11-12/00). The battery voltage is often discharged and charged. However, the battery does not support any of the load, being charged to only about 1 volt at its peak, down from its nominal value of 9 volts.
 
The Bus Voltage is at a steady 27 Volts with a Bus Current of
about 1.3 Amps.
 
The platform temperature is still within acceptable limits at
-41 degrees F (the nominal range is between -63 F to 180 F).
 
The Deep Space Network (DSN) continues to provide good data with the received signal strength of -178 dBm (only a few dBm from the receiver threshold of -180 dBm).
 
Although powerwise Pioneer 10 is operating OK with one science instrument on, the DSN may not be able to get good telemetry lock as the signal-to-noise ratio (SNR) continues to decrease. Even>though in a year the DSN may still be able to get good telemetry lock, being this close to the receiver threshold and losing about 0.3 dBm/yr due to range, maintaining contact will be a challenge.
 
(From update report by Ric Campo, Pioneer Operations Supervisor)
 
Larry Lasher, Pioneer Project Manager