Editing Voyager 1 (section)

== Mission background ==
=== History ===
{{Main|Mariner Jupiter-Saturn}}
A 1960s proposal for a [[Planetary Grand Tour|Grand Tour]] to study the outer planets led NASA to begin work on a mission during the early 1970s.<ref>{{Cite web |title=1960s |url=http://voyager.jpl.nasa.gov/mission/index.html |url-status=dead |archive-url=https://web.archive.org/web/20121208070306/http://voyager.jpl.nasa.gov/mission/index.html |archive-date=December 8, 2012 |access-date=August 18, 2013 |publisher=JPL}}</ref> Information gathered by the ''[[Pioneer 10]]'' spacecraft helped engineers design ''Voyager'' to better cope with the intense radiation around Jupiter.<ref>{{Cite web |date=2007 |title=The Pioneer missions |url=https://www.nasa.gov/centers/ames/missions/archive/pioneer.html |url-status=live |archive-url=https://web.archive.org/web/20210831073224/https://www.nasa.gov/centers/ames/missions/archive/pioneer.html |archive-date=August 31, 2021 |access-date=August 19, 2013 |publisher=NASA}}</ref> Still, shortly before launch, strips of kitchen-grade [[aluminum foil]] were applied to certain cables to improve radiation shielding.<ref>{{Cite web |last=<!--Not stated--> |date=August 2017 |title=Preview Screening: The Farthest – Voyager in Space |url=https://informal.jpl.nasa.gov/museum/content/preview-screening-farthest-voyager-space |url-status=live |archive-url=https://web.archive.org/web/20190701213014/https://informal.jpl.nasa.gov/museum/content/preview-screening-farthest-voyager-space |archive-date=July 1, 2019 |access-date=August 18, 2019 |website=informal.jpl.nasa.gov |publisher=NASA Museum Alliance |quote=supermarket aluminum foil added at the last minute to protect the craft from radiation}}</ref>

Initially, ''Voyager 1'' was planned as ''Mariner 11'' of the [[Mariner program]]. Due to budget cuts, the mission was reduced to a flyby of Jupiter and Saturn and renamed the Mariner Jupiter-Saturn probes. The name was changed to ''Voyager'' when the probe designs began to differ substantially from Mariner missions.<ref>{{Cite book |last=Mack |first=Pamela Etter |title=From Engineering Science to Big Science: The NACA and NASA Collier Trophy Research Project Winners |date=1998 |publisher=National Aeronautics and Space Administration, NASA Office of Policy and Plans, NASA History Office |isbn=978-0-16-049640-0 |page=251 |language=en |chapter=11 |chapter-url=https://books.google.com/books?id=0j-4d73jQFEC&pg=PA251}}</ref>

=== Spacecraft components ===
{{Main|Voyager program#Spacecraft design}}
[[File:Voyager Program - High-gain antenna diagram.png|thumb|left|upright=0.72|The {{convert|3.7|m|abbr=on}} diameter [[Directional antenna|high gain dish antenna]] used on the Voyager craft]]

''Voyager 1'' was built by the [[Jet Propulsion Laboratory]] (JPL). It has 16 [[hydrazine]] thrusters, [[three-axis stabilization]] [[gyroscopes]], and [[Spacecraft attitude control|referencing instruments]] to keep the probe's radio antenna pointed toward [[Earth]]. Collectively, these instruments are part of the Attitude and Articulation Control Subsystem (AACS), along with redundant units of most instruments and eight backup thrusters.<ref name="PDS-Host">{{cite web |url=https://starbrite.jpl.nasa.gov/ds-view/pds/viewHostProfile.jsp?INSTRUMENT_HOST_ID=VG2 |title=Voyager 2: Host Information |date=1989 |publisher=NASA |access-date=January 2, 2011 |archive-url=https://web.archive.org/web/20170220172046/https://starbrite.jpl.nasa.gov/ds-view/pds/viewHostProfile.jsp?INSTRUMENT_HOST_ID=VG2 |archive-date=February 20, 2017}}</ref> The spacecraft also included 11 scientific instruments to study celestial objects such as [[planets]] as it travels through space.<ref name="jpl-1989">{{Cite web |date=1989 |title=Voyager 1: Host Information |url=https://voyager.jpl.nasa.gov/spacecraft/ |url-status=live |archive-url=https://web.archive.org/web/20150416054228/http://voyager.jpl.nasa.gov/spacecraft/ |archive-date=April 16, 2015 |access-date=April 29, 2015 |publisher=JPL}}</ref>

==== Communication system ====
The radio [[communication system]] of ''Voyager 1'' was designed to be used up to and beyond the limits of the [[Solar System]]. It has a {{convert|3.7|m|adj=on|sp=us}} [[diameter]] [[Directional antenna|high-gain]] [[Cassegrain antenna]] to send and receive [[radio waves]] via the three [[NASA Deep Space Network|Deep Space Network]] stations on the Earth.<ref>{{Cite web |title=High Gain Antenna |url=https://voyager.jpl.nasa.gov/spacecraft/instruments_hga.html |url-status=live |archive-url=https://web.archive.org/web/20130921060751/http://voyager.jpl.nasa.gov/spacecraft/instruments_hga.html |archive-date=September 21, 2013 |access-date=August 18, 2013 |publisher=JPL}}</ref> The spacecraft normally transmits data to Earth over Deep Space Network Channel 18, using a frequency of either 2.3&nbsp;[[GHz]] or 8.4&nbsp;GHz, while signals from Earth to Voyager are transmitted at 2.1&nbsp;GHz.<ref>{{Cite web |last1=Ludwig |first1=Roger |last2=Taylor |first2=Jim |date=March 2002 |title=Voyager Telecommunications |url=https://descanso.jpl.nasa.gov/DPSummary/Descanso4--Voyager_new.pdf |url-status=live |archive-url=https://web.archive.org/web/20130215195832/http://descanso.jpl.nasa.gov/DPSummary/Descanso4--Voyager_new.pdf |archive-date=February 15, 2013 |access-date=September 16, 2013 |website=Descanso Design and Performance Summary Series |publisher=NASA/JPL}}</ref>

When ''Voyager 1'' is unable to communicate with the Earth, its digital [[Magnetic storage|tape]] recorder (DTR) can record about 67 kilobytes of data for later transmission.<ref>{{Cite web |title=NASA News Press Kit 77–136 |url=http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=9476.0;attach=591860 |url-status=live |archive-url=https://web.archive.org/web/20190529081627/https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=9476.0;attach=591860 |archive-date=May 29, 2019 |access-date=December 15, 2014 |publisher=JPL/NASA}}</ref> {{As of|2023}}, signals from ''Voyager 1'' take more than 22 hours to reach Earth.<ref name="jet propulsion laboratory-2" />

==== Power ====
''Voyager 1'' has three [[radioisotope thermoelectric generator]]s (RTGs) mounted on a boom. Each [[MHW-RTG]] contains 24 pressed [[plutonium-238]] oxide spheres.<ref name="furlong-1999" /> The RTGs generated about 470 [[Watt |W]] of [[electric power]] at the time of launch, with the remainder being dissipated as waste heat.<ref>{{Cite web |title=Spacecraft Lifetime |url=https://voyager.jpl.nasa.gov/spacecraft/spacecraftlife.html |url-status=live |archive-url=https://web.archive.org/web/20170301102317/http://voyager.jpl.nasa.gov/spacecraft/spacecraftlife.html |archive-date=March 1, 2017 |access-date=August 19, 2013 |publisher=JPL}}</ref> The power output of the RTGs declines over time due to the 87.7-year [[half-life]] of the fuel and degradation of the [[thermocouple]]s, but they will continue to support some of its operations until at least 2025.<ref name="jpl-1989" /><ref name="furlong-1999">{{Cite journal |last1=Furlong |first1=Richard R. |last2=Wahlquist |first2=Earl J. |date=1999 |title=U.S. space missions using radioisotope power systems |url=http://www2.ans.org/pubs/magazines/nn/pdfs/1999-4-2.pdf |url-status=dead |journal=Nuclear News |volume=42 |issue=4 |pages=26–34 |archive-url=https://web.archive.org/web/20181016011258/http://www3.ans.org/pubs/magazines/nn/pdfs/1999-4-2.pdf |archive-date=October 16, 2018 |access-date=January 2, 2011}}</ref>

<gallery class="center" widths="170px" heights="180px" mode="packed">
File:Voyager Program - RTG diagram 1.png|Diagram of RTG fuel container, showing the [[plutonium-238]] oxide spheres
File:Voyager Program - RTG diagram 2.png|Diagram of RTG shell, showing the power-producing [[silicon]]-[[germanium]] [[thermocouple]]s
File:Voyager Program - RTG upclose.png|Model of an RTG unit
</gallery>

==== Computers ====
Unlike ''Voyager's'' other instruments, the operation of the cameras for [[visible light]] is not autonomous, but is controlled by an imaging parameter table contained in one of the  [[digital computer]]s, the Flight Data Subsystem (FDS). Since the 1990s, most space probes have been equipped with completely autonomous cameras.<ref>{{Cite web |title=pds-rings |url=https://pds-rings.seti.org/voyager/iss/inst_cat_wa1.html |url-status=live |archive-url=https://web.archive.org/web/20211107025433/https://pds-rings.seti.org/voyager/iss/inst_cat_wa1.html |archive-date=November 7, 2021 |access-date=May 23, 2015}}</ref>

The computer command subsystem (CCS) controls the cameras. The CCS contains fixed computer programs, such as command decoding, fault-detection and fault-correction routines, antenna pointing routines, and spacecraft sequencing routines. This computer is an improved version of the one that was used in the 1970s [[Viking program|Viking orbiters]].<ref>{{cite book
 |first         = James E.
 |last          = Tomayko
 |editor-last1  = Kent
 |editor-first1 = Allen
 |editor-last2  = Williams
 |editor-first2 = James G.
 |chapter       = Distributed Computing On Board Voyager and Galileo (chapter 6)
 |url           = https://ntrs.nasa.gov/citations/19880069935
 |title         = Computers in Spaceflight: The NASA Experience
 |series        = Encyclopedia of Computer Science and Technology
 |chapter-url   = https://history.nasa.gov/computers/Ch6-2.html
 |publisher     = NASA
 |bibcode       = 1988csne.book.....T
 |year          = 1987
 |isbn          = 978-0-8247-2268-5
 |volume        = 18. Supplement&nbsp;3
 |via           = NASA History
 |access-date   = December 16, 2023
 |archive-date  = October 18, 2023
 |archive-url   = https://web.archive.org/web/20231018062947/https://ntrs.nasa.gov/citations/19880069935
 |url-status    = live
}}</ref>

The Attitude and Articulation Control Subsystem (AACS) controls the [[Spacecraft attitude control|spacecraft orientation]]. It keeps the [[high-gain antenna]] pointing towards Earth, controls attitude changes, and points the scan platform. The custom-built AACS systems on both Voyagers are the same.<ref>{{Cite web |title=au.af |url=http://www.au.af.mil/au/awc/awcgate/jplbasic/bsf11-2.htm |url-status=dead |archive-url=https://web.archive.org/web/20151016052108/http://www.au.af.mil/au/awc/awcgate/jplbasic/bsf11-2.htm |archive-date=October 16, 2015 |access-date=May 23, 2015}}</ref><ref>{{Cite web |title=airandspace |url=https://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19990066000 |archive-url=https://web.archive.org/web/20160406141000/http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19990066000 |archive-date=April 6, 2016 |access-date=May 23, 2015}}</ref>

==== Scientific instruments ====
{{Main|Voyager program}}

{| class="wikitable" style="text-align:center;"
|-
! scope="col" style="width:135px;" | Instrument name
! scope="col" style="width:50px;" | {{abbr|Abbr.|Abbreviation}}
! Description
|-
| {{partial|Imaging Science System<br />{{small|(disabled)}}}}
| (ISS)
| style="text-align:left;" | Used a two-camera system (narrow-angle/wide-angle) to provide images of Jupiter, Saturn and other objects along the trajectory. 

{| class="wikitable collapsible"
|-
! colspan="2" | Filters
|-
| style="vertical-align:top;" |
{| style="text-align:center; width:320px;"
! colspan="4" scope="col" | Narrow-angle camera<ref>{{Cite web |title=Voyager 1 Narrow Angle Camera Description |url=https://pds-rings.seti.org/voyager/iss/inst_cat_na1.html#filters |url-status=live |archive-url=https://web.archive.org/web/20110811232250/http://pds-rings.seti.org/voyager/iss/inst_cat_na1.html#filters |archive-date=August 11, 2011 |access-date=January 17, 2011 |publisher=NASA}}</ref>
|-
! scope="col" style="background:#e5e5e5; width:60px;"| Name
! scope="col" style="background:#e5e5e5;" | Wavelength
! scope="col" style="background:#e5e5e5;" | Spectrum
! scope="col" style="background:#e5e5e5;" | Sensitivity
|-
| <small>0 – Clear</small>
| <small>280–640&nbsp;nm</small>
| [[File:Voyager - Filters - Clear.png|50px|center]]
| style="background:#fff;" |
|-
| style="text-align:center; height:25px;" | <small>4 – Clear</small>
|<small>280–640&nbsp;nm</small>
|[[File:Voyager - Filters - Clear.png|50px|center]]
| style="background:#fff;" |
|-
| <small>7 – [[Ultraviolet|UV]]</small>
| <small>280–370&nbsp;nm</small>
| [[File:Voyager - Filters - UV.png|50px|center]]
| style="background:#1d0036;" |
|-
| <small>1 – Violet</small>
| <small>350–450&nbsp;nm</small>
| [[File:Voyager - Filters - Violet.png|50px|center]]
| style="background:#8300b5;" |
|-
| <small>2 – Blue</small>
| <small>430–530&nbsp;nm</small>
| [[File:Voyager - Filters - Blue.png|50px|center]]
| style="background:#00d5ff;" |
|-
| <small>5 – Green</small>
| <small>530–640&nbsp;nm</small>
| [[File:Voyager - Filters - Green.png|50px|center]]
| style="background:#ffef00;" |
|-
| style="text-align:center; height:25px;" | <small>6 – Green</small>
|<small>530–640&nbsp;nm</small>
|[[File:Voyager - Filters - Green.png|50px|center]]
| style="background:#ffef00;" |
|-
| <small>3 – Orange</small>
| <small>590–640&nbsp;nm</small>
| [[File:Voyager - Filters - Orange.png|50px|center]]
| style="background:#ff8900;" |
|}

| style="vertical-align:top;" |
{| style="text-align:center; width:320px;"
! colspan="4" scope="col" | Wide-angle camera<ref>{{Cite web |title=Voyager 1 Wide Angle Camera Description |url=https://pds-rings.seti.org/voyager/iss/inst_cat_wa1.html#filters |url-status=live |archive-url=https://web.archive.org/web/20211107025433/https://pds-rings.seti.org/voyager/iss/inst_cat_wa1.html#filters |archive-date=November 7, 2021 |access-date=January 17, 2011 |publisher=NASA}}</ref>
|-
! scope="col" style="background:#e5e5e5; width:60px;" | Name
! scope="col" style="background:#e5e5e5;"             | Wavelength
! scope="col" style="background:#e5e5e5;"             | Spectrum
! scope="col" style="background:#e5e5e5;"             | Sensitivity
|-
| <small>2 – Clear</small>
| <small>280–640&nbsp;nm</small>
| [[File:Voyager - Filters - Clear.png|50px|center]]
| style="background:#fff;" |
|-
| <small>3 – Violet</small>
| <small>350–450&nbsp;nm</small>
| [[File:Voyager - Filters - Violet.png|50px|center]]
| style="background:#8300b5;" |
|-
| <small>1 – Blue</small>
| <small>430–530&nbsp;nm</small>
| [[File:Voyager - Filters - Blue.png|50px|center]]
| style="background:#00d5ff;" |
|-
| <small>6 – [[Methane|CH<sub>4</sub>]]-U</small>
| <small>536–546&nbsp;nm</small>
| [[File:Voyager - Filters - CH4U.png|50px|center]]
| style="background:#81ff00;" |
|-
| <small>5 – Green</small>
| <small>530–640&nbsp;nm</small>
| [[File:Voyager - Filters - Green.png|50px|center]]
| style="background:#ffef00;" |
|-
| <small>4 – [[Sodium|Na]]-D</small>
| <small>588–590&nbsp;nm</small>
| [[File:Voyager - Filters - NaD.png|50px|center]]
| style="background:#ffe200;" |
|-
| <small>7 – Orange</small>
| <small>590–640&nbsp;nm</small>
| [[File:Voyager - Filters - Orange.png|50px|center]]
| style="background:#ff8900;" |
|-
| <small>0 – [[Methane|CH<sub>4</sub>]]-JST</small>
| <small>614–624&nbsp;nm</small>
| [[File:Voyager - Filters - CH4JST.png|50px|center]]
| style="background:#ff7b00;" |
|}

|}
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' Bradford Smith / University of Arizona (PDS/PRN website)
 | '''Data:''' PDS/PDI data catalog, PDS/PRN data catalog
}}

|-
| {{partial|Radio Science System<br />{{small|(disabled)}}}}
| (RSS)
| style="text-align:left;" | Used the telecommunications system of the Voyager spacecraft to determine the physical properties of planets and satellites (ionospheres, atmospheres, masses, gravity fields, densities) and the amount and size distribution of material in Saturn's rings and the ring dimensions. 
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' G. Tyler / Stanford University PDS/PRN overview
 | '''Data:''' PDS/PPI data catalog, PDS/PRN data catalog (VG_2803), NSSDC data archive
}}

|-
| {{partial|[[Infrared interferometer spectrometer and radiometer]]<br />{{small|(disabled)}}}}
| (IRIS)
| style="text-align:left;" | Investigates both global and local energy balance and atmospheric composition. Vertical temperature profiles are also obtained from the planets and satellites as well as the composition, thermal properties, and size of particles in [[Saturn's rings]]. 
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' Rudolf Hanel / NASA Goddard Space Flight Center (PDS/PRN website)
 | '''Data:''' PDS/PRN data catalog, PDS/PRN expanded data catalog (VGIRIS_0001, VGIRIS_002), NSSDC Jupiter data archive
}}

|-
| {{partial|Ultraviolet [[Spectrometer]]<br />{{small|(disabled)}}}}
| (UVS)
| style="text-align:left;" | Designed to measure atmospheric properties, and to measure radiation. 
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' A. Broadfoot / University of Southern California (PDS/PRN website)
 | '''Data:''' PDS/PRN data catalog
}}

|-
| {{yes|Triaxial Fluxgate [[Magnetometer]]<br />{{small|(active)}}}}
| (MAG)
| style="text-align:left;" | Designed to investigate the [[magnetic field]]s of Jupiter and Saturn, the interaction of the [[solar wind]] with the [[magnetosphere]]s of these planets, and the magnetic field of [[interplanetary space]] out to the boundary between the [[solar wind]] and the magnetic field of [[interstellar space]]. 
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' [[Norman F. Ness]] / NASA Goddard Space Flight Center (website)
 | '''Data:''' PDS/PPI data catalog, NSSDC data archive
}}

|-
| {{no|[[Plasma (physics)|Plasma]] [[Spectrometer]]<br />{{small|(defective)}}}}
| (PLS)
| style="text-align:left;" | Investigates the microscopic properties of the plasma ions and measures electrons in the energy range from 5 eV to 1 keV. 
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' John Richardson / [[Massachusetts Institute of Technology|MIT]] (website)
 | '''Data:''' PDS/PPI data catalog, NSSDC data archive
}}

|-
| {{yes|Low Energy [[Charged particle|Charged Particle]] Instrument<br />{{small|(active)}}}}
| (LECP)
| style="text-align:left;" | Measures the differential in energy fluxes and angular distributions of ions, electrons and the differential in energy ion composition. 
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' [[Stamatios Krimigis]] / [[Johns Hopkins University|JHU]] / APL / University of Maryland (JHU/APL website / UMD website / KU website)
 | '''Data:''' UMD data plotting, PDS/PPI data catalog, NSSDC data archive
}}

|-
| {{partial|[[Cosmic Ray System]]<br />{{small|(disabled)}}}}
| (CRS)
| style="text-align:left;" | Determines the origin and acceleration process, life history, and dynamic contribution of interstellar cosmic rays, the nucleosynthesis of elements in cosmic-ray sources, the behavior of [[cosmic rays]] in the [[interplanetary medium]], and the trapped planetary energetic-particle environment. 
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' [[Edward C. Stone|Edward Stone]] / Caltech / NASA Goddard Space Flight Center (website)
 | '''Data:''' PDS/PPI data catalog, NSSDC data archive
}}

|-
| {{partial|Planetary [[Radio Astronomy]] Investigation<br />{{small|(disabled)}}}}
| (PRA)
| style="text-align:left;" | Uses a sweep-frequency radio receiver to study the radio-emission signals from Jupiter and Saturn. 
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' James Warwick / University of Colorado
 | '''Data:''' PDS/PPI data catalog, NSSDC data archive
}}

|-
| {{no|[[Polarimeter|Photopolarimeter]] System<br />{{small|(defective)}}}}
| (PPS)
| style="text-align:left;" | Used a telescope with a [[polarizer]] to gather information on surface texture and composition of Jupiter and Saturn and information on atmospheric scattering properties and density for both planets. 
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' Arthur Lane / JPL (PDS/PRN website)
 | '''Data:''' PDS/PRN data catalog
}}

|-
| {{yes|[[Plasma Wave Subsystem]]<br />{{small|(active)}}}}
| (PWS)
| style="text-align:left;" | Provides continuous, sheath-independent measurements of the electron-density profiles at Jupiter and Saturn as well as basic information on local wave–particle interaction, useful in studying the magnetospheres. 
{{unordered list
 | style=font-size:85%;
 | '''Principal investigator:''' William Kurth / University of Iowa (website)
 | '''Data:''' PDS/PPI data catalog
}}
|}

{{Gallery
 | align = center
 | title = Images of the spacecraft
 | width = 175
 | mode = packed
 | File:Voyager1 Space simulator.gif
 | ''Voyager 1'' 'Proof Test Model' in a [[space simulator]] chamber at JPL 3/12/1976
 | File:Record is attached to Voyager 1.jpg
 | [[Voyager Golden Record|Gold-Plated Record]] is attached to ''Voyager 1''
 | alt2 = ''Voyager 1'' in the Space Simulator chamber
 | File:P39582 2 Ed Stone.jpg
 | [[Edward C. Stone]], director of [[NASA]] [[JPL]], standing in front of a Voyager spacecraft model
 | File:Voyager Instruments.jpg|The location of Voyager's scientific instruments, indicated in a diagram
 | alt3 = Gold-Plated Record is attached to ''Voyager 1''
 | footer = {{center|{{commons-inline|bullet=none|Category:Voyager spacecraft|the Voyager spacecraft}}}}
 }}