Editing Pioneer Venus Orbiter (section)

==Spacecraft==
[[File:Pioneer Venus 1 at KSC.jpg|thumb|left|upright|Pioneer Venus 1 at [[Kennedy Space Center|KSC]].]]
Manufactured by [[Hughes Aircraft Company]], the Pioneer Venus Orbiter was based on the HS-507 [[spacecraft bus|bus]].<ref name="GSP">{{cite web |last=Krebs |first=Gunter |title=Pioneer 12 (Pioneer Venus Orbiter, PVO) |url=http://space.skyrocket.de/doc_sdat/pioneer-12.htm |url-status=live |archive-url=https://web.archive.org/web/20050112064044/http://space.skyrocket.de/doc_sdat/pioneer-12.htm |archive-date=2005-01-12 |work=Gunter's Space Page}}</ref> The spacecraft was a flat cylinder, {{convert|2.5|m|ft|sp=us}} in diameter and {{convert|1.2|m|ft|sp=us}} long. All instruments and spacecraft subsystems were mounted on the forward end of the cylinder, except the [[magnetometer]], which was at the end of a {{convert|4.7|m|ft|sp=us}} boom. A [[Photovoltaic module|solar array]] extended around the circumference of the cylinder. A {{convert|1.09|m}} despun dish [[antenna (electronics)|antenna]] provided [[S band|S]] and [[X band]] communication with [[Earth]]. A [[Star (rocket stage)|Star 24]] [[solid rocket motor]] was integrated into the spacecraft to provide the thrust to enter orbit around Venus.<ref name="GSP" />

=== Instruments ===
[[File:Pioneer-Venus-Orbiter-Instruments.png|thumb|Pioneer Venus Orbiter Instruments]]The Pioneer Venus Orbiter carried 17 experiments with a total mass of {{convert|45|kg|lb}}:<ref name="Intro">{{cite web |url=https://nssdc.gsfc.nasa.gov/planetary/pioneer_venus.html |title=Pioneer Venus Project Information |work=NASA Goddard Space Flight Center |access-date=2016-08-17 }}</ref>

==== Orbiter Cloud Photopolarimeter (OCPP) ====
The Orbiter Cloud Photopolarimeter was used to measure the vertical distribution of [[cloud]]s on Venus. It was a photo-polarimeter built by the [[Goddard Institute for Space Studies|Goddard Institute for Space Studies (GISS)]], similar to [[Pioneer 10]] and [[Pioneer 11]] imaging photopolarimeter (IPP). The principal investigator was J. Hansen, later succeeded by L. Travis. The instrument had a mass of 5 kilograms and consumed 5.4 watts of power.

==== Orbiter Radar Mapper Instrument (ORAD) ====
The Orbiter Radar Mapper Instrument was designed to determine the topography and surface characteristics of Venus. It was a radar system developed by the [[Massachusetts Institute of Technology]] (MIT), with G. Pettengill serving as the principal investigator. Weighing 9 kilograms and consuming 18 watts, the instrument operated when the spacecraft was within {{convert|4700|km}} of the planet. It transmitted a 20-watt [[S-band]] signal at 1.757 [[Gigahertz]] and achieved a surface mapping resolution of {{convert|23|x|7|km}} at [[periapsis]].

==== Orbiter Infrared Radiometer (OIR) ====
The Orbiter Infrared Radiometer was used to measure [[infrared]] emissions from [[Venus' atmosphere]]. It was constructed by the [[Jet Propulsion Laboratory]] (JPL), and the principal investigator was F. Taylor. The instrument had a mass of 5.9 kilograms and required 5.2 watts of power.

==== Orbiter Ultraviolet Spectrometer (OUVS) ====
The Orbiter Ultraviolet Spectrometer measured scattered and emitted [[ultraviolet]] light from Venus. Built by the [[Laboratory for Atmospheric and Space Physics]] (LASP), its principal investigator was A.I.F. Stewart. The spectrometer weighed 3.1 kilograms and consumed 1.7 watts of power.

==== Orbiter Neutral Mass Spectrometer (ONMS) ====
[[File:Pioneer Venus Orbiter - Neutral Mass Spectrometer (ONMS).jpg|thumb|Orbiter Neutral Mass Spectrometer (ONMS)]]
The Orbiter Neutral [[mass spectrometer|Mass Spectrometer]]  was used to determine the composition of Venus's upper atmosphere. Manufactured by the [[Goddard Space Flight Center]] (GSFC), it was managed by principal investigator H. Neimann. The instrument had a mass of 3.8 kilograms and consumed 12 watts.

==== Orbiter Plasma Analyzer (OPA) ====
[[File:Pioneer Venus Orbiter - Solar Wind Plasma Analyzer (OPA).jpg|thumb|Orbiter Plasma Analyzer (OPA)]]
The Orbiter [[Plasma (physics)|Plasma]] Analyzer measured properties of the [[solar wind]]. Developed at the [[Ames Research Center]] (ARC), the instrument was led by principal investigator J. Wolfe, who was later succeeded by A. Barnes. It had a mass of 3.9 kilograms and required 5 watts of power.

==== Orbiter Magnetometer (OMAG) ====
The Orbiter Magnetometer was designed to characterize Venus’s [[magnetic field]]. It was built by the [[University of California, Los Angeles]] (UCLA), with C. Russell as the principal investigator. The 2-kilogram instrument consumed 2.2 watts of power and was mounted on a 4.7-meter boom to reduce spacecraft interference.

==== Orbiter Electric Field Detector (OEFD) ====
[[File:Pioneer Venus Orbiter - Electric Field Detector (OEFD).jpg|thumb|Orbiter Electric Field Detector (OEFD)]]
The Orbiter Electric Field Detector studied electric fields in the Venusian environment. Built by [[TRW Inc.|TRW]] and led by principal investigator F. Scarf, it had a mass of 0.8 kilograms and used only 0.7 watts of power.

==== Orbiter Electron Temperature Probe (OETP) ====
[[File:Pioneer Venus Orbiter - Electron Temperature Probe (OETP).jpg|thumb|Orbiter Electron Temperature Probe (OETP)]]
The Orbiter [[Electron]] Temperature Probe investigated the thermal properties of Venus’s [[ionosphere]]. It was developed by the [[Goddard Space Flight Center]] (GSFC) under the direction of principal investigator L. Brace. The probe had a mass of 2.2 kilograms and consumed 4.8 watts.

==== Orbiter Ion Mass Spectrometer (OIMS) ====
[[File:Pioneer Venus Orbiter - Ion Mass Spectrometer (OIMS).jpg|thumb|Orbiter Ion Mass Spectrometer (OIMS)]]
The Orbiter Ion Mass Spectrometer was used to characterize the ion population in the ionosphere of Venus. Built by the [[Goddard Space Flight Center]] (GSFC), it was managed by principal investigator H. Taylor. The instrument had a mass of 3 kilograms and required 1.5 watts of power.

==== Orbiter Retarding Potential Analyzer (ORPA) ====
The Orbiter Retarding Potential Analyzer studied ionospheric particles. It was developed at the Lockheed Palo Alto Research Laboratory (LPARL), with W. Knudsen as the principal investigator. This instrument weighed 2.8 kilograms and consumed 2.4 watts of power.

==== Orbiter Gamma-Ray Burst Detector (OGBD) ====
The Orbiter Gamma-Ray Burst Detector recorded [[gamma-ray burst]] events. It was constructed by the [[Los Alamos National Laboratory|Los Alamos Scientific Laboratory]] (LASL), and W. Evans served as the principal investigator. The instrument had a mass of 2.8 kilograms.

=== Experiments ===
The orbiter also performed in situ radio science experiments:<ref name="Intro" />

==== Orbiter Atmospheric Propagation Experiment (OGPE) ====
The OGPE utilized dual-frequency radio signals to investigate how Venus's atmosphere affects radio wave propagation. By analyzing signal attenuation and phase shifts, the experiment aimed to deduce atmospheric properties such as electron density and refractive index. This information is crucial for understanding the structure and composition of Venus's ionosphere.<ref>{{Cite journal |title=1977SSRv...20..283C Page 283 |url=https://adsabs.harvard.edu/full/1977SSRv...20..283C?utm_source=chatgpt.com |access-date=2025-05-03 |journal=Space Science Reviews| bibcode=1977SSRv...20..283C | last1=Colin | first1=L. | last2=Hall | first2=C. F. | date=1977 | volume=20 | issue=3 | page=283 | doi=10.1007/BF02186467 }}</ref><ref>{{Cite journal |title=1977SSRv...20..451. Page 451 |url=https://adsabs.harvard.edu/full/1977SSRv...20..451.?utm_source=chatgpt.com |access-date=2025-05-03 |journal=Space Science Reviews| date=1977 | volume=20 | page=451 | bibcode=1977SSRv...20..451. }}</ref> T. Croft from [[SRI International|SRI]] was the principal investigator.

==== Orbiter Atmospheric Drag Experiment (OAD) ====
The OAD measured the deceleration of the spacecraft due to atmospheric drag at the fringes of Venus's atmosphere. By tracking changes in the spacecraft's velocity, the experiment provided data on atmospheric density and its variations with altitude and solar activity. G. Keating from [[Langley Research Center|LRC]] was the principal investigator.

==== Differential Long Baseline Interferometry (DLBI) ====
DLBI, also known as delta-VLBI, involved simultaneous observations of the spacecraft's radio signals by widely separated Earth-based antennas. By measuring the time difference in signal arrival, the experiment achieved precise spacecraft positioning, enhancing orbit determination and navigation accuracy. 

==== Orbiter Atmospheric and Solar Wind Turbulence Experiment (OTUR) ====
OTUR focused on detecting and analyzing turbulence in Venus's upper atmosphere and the solar wind. By examining fluctuations in radio signal properties, the experiment aimed to understand the dynamic interactions between the solar wind and Venus's ionosphere.  T. Croft from SRI was the principal investigator.

==== Orbiter Dual-Frequency Occultation (ORO) ====
The ORO experiment employed radio occultation techniques, where the spacecraft's radio signals passed through Venus's atmosphere to Earth. By analyzing changes in signal frequency and amplitude, the experiment derived vertical profiles of atmospheric temperature, pressure, and electron density. A. Kliore from JPL was the principal investigator.

==== Orbiter Internal Density Distribution Experiment (OIDD) ====
OIDD aimed to map Venus's gravitational field by tracking the spacecraft's orbit perturbations. Variations in gravity indicated differences in mass distribution within the planet, providing insights into its internal structure and composition.<ref>{{Cite book |url=https://ia804506.us.archive.org/12/items/pioneeringvenusp00fimmrich/pioneeringvenusp00fimmrich.pdf?utm_source=chatgpt.com |title=Pioneering Venus : a planet unveiled |publisher=NASA |pages=100 |oclc=32467981}}</ref> R. Phillips from JPL was the principal investigator.

==== Orbiter Celestial Mechanics Experiment (OCM) ====
The OCM focused on precise measurements of the spacecraft's trajectory to study Venus's gravitational field and test aspects of celestial mechanics. Data from this experiment contributed to refining models of planetary motion and gravitational interactions.  I. Shapiro from MIT was the principal investigator

=== Table ===
{| class="wikitable sortable alternance"  
|+Instrument and experience details<ref name="Intro" /><ref name="PVO Mission">{{cite web |title=PVO Mission Document |url=https://pds-ppi.igpp.ucla.edu/data/PVO-V-OEFD-3--EFIELD-HIRES-V1.0/DOCUMENT/MISSION/MISSION.HTM |publisher=NASA}}</ref>
|-
! scope="col" | Name
! scope="col" | Complete
!Studied
! scope="col" | Instrument Type
! scope="col" | Manufacturer
! scope="col" | Responsible scientist
! scope="col" | Mass
! scope="col" | Electrical consumption
|-
|OCPP|| Orbiter Cloud Photopolarimeter  
|Clouds|| Photo polarimeter ||  [[Goddard Institute for Space Studies|GISS]]|| J. Hansen  (later L. Travis) || align="center" | {{convert|5|kg|lb|abbr=on}}  || align="center" | 5.4 W 
|-
|ORAD||   Orbiter Radar Mapper Instrument 
|Surface and interior|| Radar   ||  [[Massachusetts Institute of Technology|MIT]]||   G. Pettengill || align="center" | {{convert|9|kg|lb|abbr=on}}  || align="center" | 18 W 
|-
|OIR||  Orbiter Infrared Radiometer  
|Thermal balance|| Infrared radiometer || [[Jet Propulsion Laboratory|JPL]]|| F. Taylor  || align="center" | {{convert|5.9|kg|lb|abbr=on}}  || align="center" | 5.2 W 
|-
|OUVS||  Orbiter Ultraviolet Spectrometer  
|Composition and structure of the atmosphere|| Ultraviolet spectrometer   || [[Laboratory for Atmospheric and Space Physics|LASP]]||   A.I.F. Stewart|| align="center" | {{convert|3.1|kg|lb|abbr=on}}  || align="center" | 1.7 W 
|-
|ONMS||  Orbiter Neutral Mass Spectrometer  
|Composition and structure of the atmosphere|| Neutral mass spectrometer ||  [[Goddard Space Flight Center|GSFC]]||  H. Neimann || align="center" | {{convert|3.8|kg|lb|abbr=on}}  || align="center" | 12 W 
|-
|OPA||  Orbiter Plasma Analyzer  
|Solar wind and ionosphere|| Analzer plasma ||  [[Ames Research Center|ARC]]|| J. Wolfe (later A. Barnes)  || align="center" | {{convert|3.9|kg|lb|abbr=on}}  || align="center" | 5 W 
|-
|OMAG || Orbiter Magnetometer  
|Solar wind and ionosphere|| Magnetometer ||  [[University of California, Los Angeles|UCLA]]|| C. Russell || align="center" | {{convert|2|kg|lb|abbr=on}} || align="center" | 2.2 W 
|-
|OEFD||  Orbiter Electric Field Detector   
|Solar wind and ionosphere|| Measure the electric fields of Venus ||   [[TRW Inc.|TRW]]||  F. Scarf  || align="center" | {{convert|0.8|kg|lb|abbr=on}}  || align="center" | 0.7 W 
|-
|OETP|| Orbiter Electron Temperature Probe   
|Solar wind and ionosphere|| Electron temperature gauge || [[Goddard Space Flight Center|GSFC]]||  L. Brace || align="center" | {{convert|2.2|kg|lb|abbr=on}}  || align="center" |4.8 W 
|-
|OIMS|| Orbiter Ion Mass Spectrometer     
|Solar wind and ionosphere|| Ion mass spectrometer || GSFC   || H. Taylor  || align="center" | {{convert|3|kg|lb|abbr=on}}  || align="center" |1.5 W 
|-
|ORPA||   Orbiter Retarding Potential Analyzer 
|Solar wind and ionosphere|| Ion charge meter ||  LPARL  || W. Knudsen  || align="center" | {{convert|2.8|kg|lb|abbr=on}}  || align="center" |2.4 W 
|-
|OGBD||  Orbiter Gamma-Ray Burst Detector  
|High-energy astronomy|| Gamma-ray burst detector ||  [[Los Alamos National Laboratory|LASL]]||  W. Evans || align="center" | {{convert|2.8|kg|lb|abbr=on}}  || align="center" |1.3 W 
|-
| align="center" | ''ORO''|| S and X-Band Radio Occultation Studies of the Atmosphere Ionosphere o | Orbiter Dual-Frequency Occultation     
|Solar wind and ionosphere|| rowspan="6" |Radio science experiments || align="center" |-   || A. Kliore (JPL) || rowspan="6" align="center" | –  || rowspan="6" align="center" |-  
|-
|''OGPE''
|  Orbiter Dual-Frequency Experiments    
|Composition and structure of the atmosphere|| align="center" |-   || T. Croft ([[SRI International|SRI]])
|-
|''OTUR''
|  Atmospheric and Solar Wind Turbulence Experiment 
|Dynamics|| align="center" |-   || T. Croft (JPL)
|-
|''OAD''
|  Orbiter Atmospheric Drag Experiment     
|Composition and structure of the atmosphere|| align="center" |-   || G. Keating ([[Langley Research Center|LRC]])
|-
|''OIDD''
|  Orbiter Internal Density Distribution Experiment    
|Surface and interior|| align="center" |-  || R. Phillips (JPL)
|-
|''OCM''
|  Orbiter Celestial Mechanics Experiment    
|Surface and interior|| align="center" |-  || I. Shapiro (MIT)
|}
''Note: <small>LASP: [[Laboratory for Atmospheric and Space Physics]] ([[University of Colorado Boulder|University of Boulder]], [[Colorado]]); UCLA: [[University of California in Los Angeles]]; JPL: [[Jet Propulsion Laboratory]]; MIT: [[Massachusetts Institute of Technology]]; GSFC: [[Goddard Space Flight Center]]  GISS: [[Goddard Institute for Space Studies]]; LRC:  [[Langley Research Center]]; ARC: [[Ames Research Center]]; LASL: [[Los Alamos National Laboratory]]; SRI: [[Stanford Research Institute]]</small>''