From: baalke@kelvin.jpl.nasa.gov (Ron Baalke)
Subject: Pioneer Venus Update - 10/09/92 (End of Mission)
Followup-To: sci.space
News-Software: VAX/VMS VNEWS 1.3-4   
Keywords:  Pioneer Venus
Reply-To: baalke@kelvin.jpl.nasa.gov
Organization: Jet Propulsion Laboratory
Date: Sun, 11 Oct 1992 13:38:11 GMT

                       PIONEER VENUS STATUS REPORT
                            October 9, 1992
                            End of Mission

     On October 8, 1992 at 12:30 PM PDT, the 70 meter antenna in Goldstone,
California (DSS-14), failed to detect a signal from the Pioneer Venus
spacecraft after periapsis on orbit 5056.  It was assumed that the
either the drag of the atmosphere had knocked the spacecraft's High Gain
Antenna (HGA) off Earth point, or the spacecraft did not survive its last
trip through the upper atmosphere of Venus.  DSS-14 and DSS-43 (70 meter
antenna in Canberra, Australia) continued to search for a signal from the
spacecraft for several more hours, including attempts to acquire a signal
from the forward Omni antenna, but still no signal was detected.
Pioneer Venus end of mission was declared on October 8, 1992 at 17:55 PM PDT
by the Pioneer Project Controller.  The spaceraft's remains will continue
to orbit Venus for a short while, but no data can be collected without a radio
signal.

     Here's a recap of the spacecraft events from the past week:

     October 2 - The sixth altitude raising maneuver was successfully
                 performed and raised the periapsis from 132.9 km to
                 141.7 km.

     October 3 - In an attempt to reorient the spacecraft during apoapsis
                 between orbits 5050 and 5051, Pioneer Venus apparently
                 ran out of fuel. After firing 90 pulses, only a 1 degree of
                 precession was achieved.  The propellant tank pressure
                 dropped by two data numbers to 54.1 psi, indicating that
                 pressurant gas instead of fuel was expelled.

     October 5 - Pioneer Venus was spun up with full thruster response for
                 150 seconds on orbit 5053.  The resultant near-doubling of
                 spin rate will reduce reorientation suffered from drag at
                 periapsis and will facilitate use of the HGA through the
                 next several orbits if the spacecraft survives the deeper
                 penetrations of the atmosphere.  It was also suspected that
                 4 oz of propellant still remained and the spin up would aid
                 in moving the propellant towards the thrusters.

     October 6 - Pioneer Venus survived periapsis on orbit 5054, at an
                 altitude of 130.8 km and a drag of 0.91 m/s.

     October 7 - Pioneer Venus survived periapsis on orbit 5055,
                 at an altitude of 128.9 km and a drag of 1.9 m/s.  Attempts
                 to reorient the spacecraft with thrusters after periapsis
                 was 25% effective.  At 22:25 PM PDT, a pulsed apoapsis
                 manuever of 200 pulses resulted in a gain of 1 kilometer
                 in periapsis altitude.  The tank pressure held at 52.6 psi,
                 indicating that propellant probably still existed.

     October 8 - DSS-14 failed to detect any signal from the spacecraft
                 after periapsis on orbit 5056.  When the signal acquistion
                 continued to be unsuccessful for several more hours, the end
                 of the mission for the Pioneer Venus spacecraft was
                 declared.  The estimated periapsis altitude of the final
                 orbit was 128.0 km, and the final estimated drag was at
                 2.5 m/s.
     ___    _____     ___
    /_ /|  /____/ \  /_ /|     Ron Baalke         | baalke@kelvin.jpl.nasa.gov
    | | | |  __ \ /| | | |     Jet Propulsion Lab |
 ___| | | | |__) |/  | | |__   M/S 525-3684 Telos | Einstein's brain is stored
/___| | | |  ___/    | |/__ /| Pasadena, CA 91109 | in a mason jar in a lab
|_____|/  |_|/       |_____|/                     | in Wichita, Kansas.

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