Editing Pioneer 11

{{Short description|First spacecraft to visit Saturn (1973–1995)}}
{{Use mdy dates|date=May 2020}}
{{italic title}}
{{Infobox spaceflight
| name               = ''Pioneer 11''
| image              = An artist's impression of a Pioneer spacecraft on its way to interstellar space.jpg
| image_size         = 300px
| image_caption      = An artist's impression of a Pioneer spacecraft on its way to interstellar space.
| mission_type       = Planetary / Heliosphere exploration
| operator           = [[NASA]] / [[Ames Research Center|Ames]]
| website            = [https://science.nasa.gov/mission/pioneer-11/ science.nasa.gov]
| COSPAR_ID          = 1973-019A
| SATCAT             = 6421
| mission_duration   = {{time interval| 5 Apr 1973|24 Nov 1995}}
| spacecraft         = Pioneer G
| manufacturer       = [[TRW Inc.|TRW]]
| launch_mass        = {{cvt|258.5|kg|lb}}{{r|nasa1}}
| power              = 155&nbsp;watts (at launch)
| launch_date        = {{start-date|April 6, 1973, 02:11:00|timezone=yes}}&nbsp;UTC{{r|nasa1}}
| launch_rocket      = {{nowrap|[[Atlas-Centaur|Atlas SLV-3D Centaur-D1A]] [[Star 37|Star-37E]]}}
| launch_site        = [[Cape Canaveral Air Force Station|Cape Canaveral]] [[Spaceport Florida Launch Complex 36|LC-36B]]
| launch_contractor  = 
| disposal_type      = Decommissioned
| last_contact       = {{end-date|November 24, 1995}}
| interplanetary     = {{Infobox spaceflight/IP
  |type         = flyby
  |object       = [[Jupiter]]
  |distance     = {{cvt|43000|km|mi}}
  |arrival_date = December 3, 1974
 }}
 {{Infobox spaceflight/IP
  |type         = flyby
  |object       = [[Saturn]]
  |distance     = {{cvt|21000|km|mi}}
  |arrival_date = September 1, 1979
 }}

<!--mission insignia or patch-->| insignia           = Pioneer 10 - Pioneer 11 - mission patch - Pioneer patch.png
| insignia_size      = 150px
| programme          = '''[[Pioneer program]]'''
| previous_mission   = [[Pioneer 10]]
| next_mission       = [[Pioneer Venus Orbiter|Pioneer 12]]
}}

'''''Pioneer 11''''' (also known as '''''Pioneer G''''') is a [[NASA]] robotic [[space probe]] launched on April 5, 1973, to study the [[asteroid belt]], the environment around [[Jupiter]] and [[Saturn]], the [[solar wind]], and [[cosmic ray]]s.{{sfn|Fimmel|Swindell|Burgess|1974|p=19}} It was the first probe to [[Exploration of Saturn|encounter Saturn]], the second to fly through the [[Asteroid belt#Exploration|asteroid belt]], and the second to fly by [[Jupiter]]. Later, ''Pioneer 11'' became the [[List of artificial objects leaving the Solar System|second of five artificial objects]] to achieve an [[escape velocity]] allowing it to [[Solar System#Farthest regions|leave the Solar System]]. Due to power constraints and the vast distance to the probe, the last routine contact with the spacecraft was on September 30, 1995, and the last good engineering data was received on November 24, 1995.{{r|Status}}

==Mission background==
===History===
Approved in February 1969, ''Pioneer 11'' and its twin probe, ''[[Pioneer 10]]'', were the first to be designed for exploring the [[outer Solar System]]. Yielding to multiple proposals throughout the 1960s, early mission objectives were defined as:
* Explore the [[interplanetary medium]] beyond the orbit of Mars
* Investigate the nature of the asteroid belt from the scientific standpoint and assess the belt's possible hazard to missions to the outer planets.
* Explore the [[Atmosphere of Jupiter|environment of Jupiter]].

Subsequent planning for an encounter with Saturn added many more goals:
* Map the [[magnetic field]] of Saturn and determine its intensity, direction, and structure.
* Determine how many electrons and protons of various energies are distributed along the trajectory of the spacecraft through the Saturn system.
* Map the interaction of the Saturn system with the [[solar wind]].
* Measure the temperature of Saturn's atmosphere and that of Titan, the largest satellite of Saturn.
* Determine the structure of the upper atmosphere of Saturn where molecules are expected to be electrically charged and form an ionosphere.
* Map the thermal structure of [[Atmosphere of Saturn|Saturn's atmosphere]] by infrared observations coupled with [[radio occultation]] data.
* Obtain spin-scan images of the [[Saturnian system]] in two colors during the encounter sequence and polarimetry measurements of the planet.
* Probe the ring system and the atmosphere of Saturn with S-band radio occultation.
* Determine more precisely the masses of Saturn and its larger satellites by accurate observations of the effects of their gravitational fields on the motion of the spacecraft.
* As a precursor to the [[Voyager Program|Mariner Jupiter/Saturn mission]], verify the environment of the ring plane to find out where it may be safely crossed by the Mariner spacecraft without serious damage.{{sfn|Fimmel|Swindell|Burgess|1974|p=19}}

''Pioneer 11'' was built by [[TRW Inc.|TRW]] and managed as part of the [[Pioneer program]] by [[NASA Ames Research Center]].{{r|Status}} A backup unit, [[Pioneer H]], is currently on display in the "Milestones of Flight" exhibit at the [[National Air and Space Museum]] in [[Washington, D.C.]]{{r|smithsonian1}} Many elements of the mission proved to be critical in the planning of the [[Voyager program|''Voyager'' program]].{{sfn|Burrows|1990|pp=266–268}}

<gallery mode=packed heights=180px>
File:Pioneer_10_systems_diagram.svg|''Pioneer 10'' and ''Pioneer 11'' spacecraft diagram
File:NASM-NASM2016-00083.jpg|Reconstructed full-scale mock-up Pioneer 10 / 11 spacecraft at the [[National Air and Space Museum]]
File:NASM-NASM2016-00089.jpg|Side view of the spacecraft
File:CAPE KENNEDY, Fla (KSC-73P-0116).jpg|''Pioneer 11'' during the installation of its protective shroud
</gallery>

===Spacecraft design===
The ''Pioneer 11'' bus measures {{convert|36|cm|in|sp=us}} deep and with six {{convert|76|cm|in|sp=us|adj=mid|-long}} panels forming the hexagonal structure. The bus houses propellant to control the orientation of the probe and eight of the twelve scientific instruments. The spacecraft has a mass of 259&nbsp;kilograms.{{sfn|Fimmel|Swindell|Burgess|1974|p=42}}

====Attitude control and propulsion====
:Orientation of the spacecraft was maintained with six 4.5-[[Newton (unit)|N]],{{r|Astronautix}} [[hydrazine]] [[monopropellant rocket|monopropellant]] thrusters: pair one maintains a constant spin-rate of 4.8 [[Revolutions per minute|rpm]], pair two controls the forward thrust, pair three controls attitude. Information for the orientation is provided by performing [[conical scanning]] maneuvers to track Earth in its orbit,{{r|weebau1}} a [[Star tracker#Star tracker|star sensor]] able to reference [[Canopus]], and two [[Sun sensor]]s.{{sfn|Fimmel|Swindell|Burgess|1974|pp=42–43}}

====Communications====
:The space probe includes a redundant system [[transceiver]]s, one attached to the [[Directional antenna|high-gain antenna]], the other to an omni-antenna and medium-gain antenna. Each transceiver is 8 watts and transmits data across the [[S band|S-band]] using 2110 MHz for the uplink from Earth and 2292 MHz for the downlink to Earth with the [[Deep Space Network]] tracking the signal. Prior to transmitting data, the probe uses a [[convolutional code|convolutional encoder]] to allow [[error correction|correction of errors]] in the received data on Earth.{{sfn|Fimmel|Swindell|Burgess|1974|p=43}}

====Power====
[[File:NASM-NASM2016-00091.jpg|thumb|SNAP-19 RTG on a ''Pioneer 10/11'' replica]]
:''Pioneer 11'' uses four SNAP-19 [[radioisotope thermoelectric generator]]s (RTGs) ('''''[[:File:Cutdrawing of an SNAP 19 RTG.jpg|see diagram]]'''''). They are positioned on two three-rod trusses, each {{cvt|3|m|ftin}} in length and 120 degrees apart. This was expected to be a safe distance from the sensitive scientific experiments carried on board. Combined, the RTGs provided 155 watts at launch, and decayed to 140 W in transit to Jupiter. The spacecraft requires 100 W to power all systems.{{sfn|Fimmel|Swindell|Burgess|1974|pp=44–45}}

====Computer====
:Much of the computation for the mission was performed on Earth and transmitted to the probe, where it is able to retain in memory, up to five commands of the 222 possible entries by ground controllers. The spacecraft includes two command decoders and a command distribution unit, a very limited form of a processor, to direct operations on the spacecraft. This system requires that mission operators prepare commands long in advance of transmitting them to the probe. A data storage unit is included to record up to 6,144 [[bytes]] of information gathered by the instruments. The digital telemetry unit is then used to prepare the collected data in one of the thirteen possible formats before transmitting it back to Earth.{{sfn|Fimmel|Swindell|Burgess|1974|p=38}}

====Scientific instruments====
''Pioneer 11'' has one additional instrument more than ''Pioneer 10'', a flux-gate magnetometer.{{r|solarviews1}}
{| class="wikitable"
|-
! colspan="2" style="text-align: left"  | Helium Vector [[Magnetometer]] ('''HVM''')
|-
| [[File:Pioneer 10-11 - P50 - fx.jpg|150px]]
|Measures the fine structure of the interplanetary magnetic field, mapped the Jovian magnetic field, and provides magnetic field measurements to evaluate solar wind interaction with Jupiter.<ref name=nssdc2/>
* {{small|'''Principal investigator:''' Edward Smith / JPL}}
* {{small|1='''Data:''' [http://pds-ppi.igpp.ucla.edu/search/?filter=PN_5001,PN_6001&title=Pioneer_11_Helium_Vector_Magnetometer PDS/PPI data catalog], [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/pioneer/pioneer11/mag/ NSSDC data archive]}}
|-
! colspan="2" style="text-align: left"  | Quadrispherical [[Plasma (physics)|Plasma]] Analyzer
|-
| [[File:Pioneer 10-11 - P51b - fx.jpg|150px]]
|Peer through a hole in the large dish-shaped antenna to detect particles of the solar wind originating from the Sun.<ref name=nssdc3/>
* {{small|'''Principal investigator:''' Aaron Barnes / NASA Ames Research Center ([https://web.archive.org/web/20000520044455/http://arwen.arc.nasa.gov/ archived website])}}{{sfn|Simpson|2001|p=146}}
* {{small|1='''Data:''' [http://pds-ppi.igpp.ucla.edu/search/?filter=PN_5001,PN_6001&title=Pioneer_11_Quadrispherical_Plasma_Analyser PDS/PPI data catalog], [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/pioneer/pioneer11/plasma/ NSSDC data archive]}}
|-
! colspan="2" style="text-align: left"  | [[Charged particle|Charged Particle]] Instrument ('''CPI''')
|-
| [[File:Pioneer 10-11 - P52a - fx.jpg|150px]]
|Detects cosmic rays in the Solar System.<ref name=nssdc4/>
* {{small|'''Principal investigator:''' [[John Alexander Simpson|John Simpson]] / University of Chicago}}{{sfn|Simpson|2001|p=146}}
* {{small|'''Data:''' [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/pioneer/pioneer11/particle/cpi/ NSSDC data archive]}}
|-
! colspan="2" style="text-align: left"  | [[Cosmic Ray]] Telescope ('''CRT''')
|-
| [[File:Pioneer 10-11 - P52b - fx.jpg|150px]]
|Collects data on the composition of the cosmic ray particles and their energy ranges.{{r|nssdc5}}
* {{small|'''Principal investigator:''' [[Frank B. McDonald]] / NASA Goddard Space Flight Center}}{{sfn|Simpson|2001|p=146}}
* {{small|1='''Data:''' [http://pds-ppi.igpp.ucla.edu/search/?filter=PN_5001,PN_6001&title=Pioneer_11_Cosmic_Ray_Telescope PDS/PPI data catalog], [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/pioneer/pioneer11/particle/crt/ NSSDC data archive]}}
|-
! colspan="2" style="text-align: left"  | [[Geiger tube telescope|Geiger Tube Telescope]] ('''GTT''')
|-
| {{center|[[File:Pioneer 10-11 - p53 - fx.jpg|x100px]]}}
|Surveys the intensities, energy spectra, and angular distributions of electrons and protons along the spacecraft's path through the radiation belts of Jupiter and Saturn.{{r|nssdc6}}
* {{small|'''Principal investigator:''' [[James A. Van Allen]] / University of Iowa ([http://www-pw.physics.uiowa.edu/pioneer/home.html website])}}{{sfn|Simpson|2001|p=146}}
* {{small|1='''Data:''' [http://pds-ppi.igpp.ucla.edu/search/?filter=PN_5001,PN_6001&title=Pioneer_11_Gieger_Tube_Telescope PDS/PPI data catalog], [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/pioneer/pioneer11/particle/gtt/ NSSDC data archive], [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/pioneer/pioneer11/geiger_tube_telescope_%28gtt%29/jupiter_encounter_data/ NSSDC Jupiter data archive]}}
|-
! colspan="2" style="text-align: left"  | Trapped [[Radiation]] Detector ('''TRD''')
|-
| [[File:Pioneer 10-11 - P54 - fx.jpg|150px]]
|
Includes an ''unfocused [[Cherenkov detector|Cerenkov counter]]'' that detects the light emitted in a particular direction as particles passed through it recording electrons of energy, 0.5 to 12 [[electronvolt|MeV]], an ''electron scatter detector'' for electrons of energy, 100 to 400 keV, and a ''minimum ionizing detector'' consisting of a solid-state diode that measured minimum ionizing particles (<3 MeV)  and protons in the range of 50 to 350 MeV.{{r|nssdc7}}
* {{small|'''Principal investigator:''' R. Fillius / University of California San Diego}}{{sfn|Simpson|2001|p=146}}
* {{small|'''Data:''' [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/pioneer/pioneer11/particle/trd/ NSSDC hourly data archive], [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/pioneer/pioneer11/jovian_trapped_radiation/saturn_enctr_binary_reduction_dat/ NSSDC Saturn data archive]}}
|-
! colspan="2" style="text-align: left"  | [[Meteoroid]] Detectors
|-
| [[File:Pioneer 10-11 - P56 - fx.jpg|150px]]
|Twelve panels of pressurized cell detectors mounted on the back of the main dish antenna record penetrating impacts of small meteoroids.{{r|nssdc8}}
* {{small|'''Principal investigator:''' William Kinard / NASA Langley Research Center}}{{sfn|Simpson|2001|p=146}}
* {{small|1='''Data:''' [http://nssdc.gsfc.nasa.gov/nmc/datasetSearch.do?spacecraft=Pioneer%2011&experiment=Meteoroid%20Detectors NSSDC data archive list]}}
|-
! colspan="2" style="text-align: left"  | Asteroid/Meteoroid Detector ('''AMD''')
|-
| [[File:Pioneer 10-11 - P55b - fx.jpg|150px]]
|Meteoroid-asteroid detector looks into space with four non-imaging telescopes to track particles ranging from close by bits of dust to distant large asteroids.{{r|nssdc9}}
* {{small|'''Principal investigator:''' Robert Soberman / General Electric Company}}{{sfn|Simpson|2001|p=146}}
* {{small|1='''Data:''' [http://nssdc.gsfc.nasa.gov/nmc/datasetSearch.do?spacecraft=Pioneer%2011&experiment=Asteroid/Meteoroid%20Astronomy NSSDC data archive list]}}
|-
! colspan="2" style="text-align: left"  | Ultraviolet [[Photometer]]
|-
| [[File:Pioneer 10-11 - P57a - fx.jpg|150px]]
|Ultraviolet light (200 to 800 [[Angstrom|Å]]) is sensed to determine the quantities of hydrogen and helium in space and on Jupiter and Saturn.{{r|nssdc10}}
* {{small|'''Principal investigator:''' [[Darrell Lynn Judge|Darrell Judge]] / University of Southern California}}{{sfn|Simpson|2001|p=146}}
* {{small|1='''Data:''' [http://ppi.pds.nasa.gov/search?filter=PN_5001,PN_6001&title=Pioneer_11_Ultraviolet_Photometer PDS/PPI data catalog], [ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/pioneer/pioneer11/uv/ NSSDC data archive]}}
|-
! colspan="2" style="text-align: left"  | Imaging [[Polarimeter|Photopolarimeter]] ('''IPP''')
|-
| [[File:Pioneer 10-11 - P60 - fx.jpg|150px]]
|The imaging experiment relies upon the spin of the spacecraft to sweep a small telescope across the planet in narrow strips only 0.03 degrees wide, looking at the planet in red (5800 to 7000 [[Angstrom|Å]]) and blue (3900 to 4900 Å) light. These strips are then processed to build up a visual image of the planet.{{r|nssdc11}}
* {{small|'''Principal investigator:''' [[Tom Gehrels]] / University of Arizona}}{{sfn|Simpson|2001|p=146}}
* {{small|1='''Data:''' [http://nssdc.gsfc.nasa.gov/nmc/datasetSearch.do?spacecraft=Pioneer%2011&experiment=Imaging%20Photopolarimeter%20%28IPP%29 NSSDC data archive list]}}
|-
! colspan="2" style="text-align: left"  | Infrared [[Radiometer]]
|-
| [[File:P58 - fx.jpg|150px]]
|Provides information on cloud temperature and the output of heat from Jupiter and Saturn.{{r|nssdc12}}
* {{small|'''Principal investigator:''' [[Andrew Ingersoll]] / California Institute of Technology}}{{sfn|Simpson|2001|p=146}}
|-
! colspan="2" style="text-align: left"  | Triaxial Fluxgate [[Magnetometer]]
|-
| [[File:Triaxial Fluxgate Mars Global Surveyor Magnetometer.gif|150px]]
|Measures the magnetic fields of both Jupiter and Saturn. This instrument is not carried on ''Pioneer 10''.{{r|nssdc13}}
* {{small|'''Principal investigator:''' [[Mario Acuna]] / NASA Goddard Space Flight Center}}
* {{small|1='''Data:''' [http://nssdc.gsfc.nasa.gov/nmc/datasetSearch.do?spacecraft=Pioneer%2011&experiment=Jovian%20Magnetic%20Field NSSDC data archive list]}}
|}

==Mission profile==

[[File:Pioneer G (Pioneer 11) launch.jpg|thumb|alt=''Pioneer 11'' launching from Space Launch Complex 36A |''Pioneer 11'' launching from [[Cape Canaveral Air Force Station Space Launch Complex 36|Launch Complex 36A]].]]

===Launch and trajectory===
The ''Pioneer 11'' probe was launched on April 6, 1973, at 02:11:00&nbsp;UTC, by the [[National Aeronautics and Space Administration]] from [[Cape Canaveral Air Force Station Space Launch Complex 36|Space Launch Complex 36A]] at [[Cape Canaveral Air Force Station|Cape Canaveral]], Florida aboard an [[Atlas-Centaur]] launch vehicle, with a [[Star-37E]] propulsion module. Its twin probe, ''[[Pioneer 10]]'', had been launched on March 3, 1972.

''Pioneer&nbsp;11'' was launched on a trajectory directly aimed at Jupiter without any prior gravitational assists.{{r|pioneer-40th}} In May 1974, Pioneer was retargeted to fly past Jupiter on a north–south trajectory, enabling a Saturn flyby in 1979. The maneuver used {{cvt|17|lb|kg}} of propellant, lasted 42 minutes and 36 seconds, and increased ''Pioneer&nbsp;11''<nowiki/>'s speed by 230&nbsp;km/h.{{r|newsci-1974}} It also made two mid-course corrections, on April 11, 1973 and November 7, 1974.{{r|nasa1}}
{{-}}

<gallery mode="packed" heights="180">
File:72413main ACD97-0036-3.jpg|alt=Official NASA map of the Pioneer 10, Pioneer 11, Voyager 1, and Voyager 2 spacecraft's trajectories through the Solar System.|NASA map showing trajectories of the ''[[Pioneer 10]]'', ''Pioneer 11'', ''[[Voyager 1]]'', and ''Voyager 2'' spacecraft.
File:Animation of Pioneer 11 trajectory.gif|Animation of ''Pioneer 11''{{'s}} trajectory from April 6, 1973 to December 31, 1980<br />{{legend2|magenta| ''Pioneer 11'' }}{{·}}{{legend2|Royalblue|[[Earth]]}} {{·}}{{legend2| Cyan |[[Jupiter]]}}{{·}}{{legend2| Lime |[[Saturn]]}}
File:Animation of Pioneer 11 trajectory around Jupiter.gif|Animation of ''Pioneer 11''{{'s}} trajectory around Jupiter from November 30, 1974 to December 5, 1974<br />{{legend2|magenta| ''Pioneer 11''}}{{·}}{{legend2|Lime  |[[Jupiter]]}}{{·}}{{legend2|Royalblue|[[Io (moon)|Io]]}}{{·}}{{legend2| Cyan |[[Europa (moon)|Europa]]}} {{·}}{{legend2| Gold  |[[Ganymede (moon)|Ganymede]]}} {{·}}{{legend2| OrangeRed  |[[Callisto (moon)|Callisto]]}}
File:Animation of Pioneer 11 around Saturn.gif|Animation of Pioneer 11 around Saturn<br>{{legend2| Magenta| Pioneer 11}}{{·}}{{legend2| Yellow|Saturn}}{{·}}{{legend2| Lime|Epimetheus}}{{·}}{{legend2| Gold|Janus}}{{·}}{{legend2| cyan|Mimas}}{{·}}{{legend2| OrangeRed|Enceladus}}
</gallery>

===Encounter with Jupiter===
{{main|Exploration of Jupiter}}
''Pioneer 11'' flew past Jupiter in November and December 1974. During its closest approach, on December 2, it passed {{cvt|42828|km|mi}} above the cloud tops. The probe obtained detailed images of the [[Great Red Spot]], transmitted the first images of the immense polar regions, and determined the mass of Jupiter's moon [[Callisto (moon)|Callisto]]. Using the gravitational pull of Jupiter, a [[gravity assist]] was used to alter the trajectory of the probe towards Saturn and gain velocity. On April 16, 1975, following the Jupiter encounter, the micrometeoroid detector was turned off.{{r|nasa1}}

<gallery class="center">
File:P11C06.jpg|alt=Pioneer 11 Jupiter encounter |''Pioneer 11'' Jupiter encounter
File:Pioneer f12.gif|alt=Approach on Jupiter |Approach on Jupiter
File:Pioneer f18.gif|alt=The Great Red Spot imaged by Pioneer 11 |The [[Great Red Spot]] imaged by ''Pioneer 11''
File:P11C03.jpg|alt=The Great Red Spot prior to closest approach |The Great Red Spot prior to closest approach
File:Pioneer f08.gif|alt=Cloud bands along the edge of Jupiter |Cloud bands along the edge of Jupiter
File:Pioneer f15.gif|alt=Beginning polar gravity assist |Beginning polar [[gravity assist]]
File:Pioneer 11 - Jupiter - p176.jpg|alt=Jupiter polar region from 1,079,000 km |[[Jupiter]] polar region from 1,079,000&nbsp;km
File:Pioneer11 Io.gif|alt=Io imaged from 756,000 km |[[Io (moon)|Io]] imaged from 756,000&nbsp;km
</gallery>
{{center|{{commons-inline|bullet=none|Category:Photos of Jupiter by Pioneer 11|''Pioneer 11'' Jupiter encounter}}}}

===Encounter with Saturn===
{{Main|Exploration of Saturn}}
{{More citations needed section|date=October 2024}}
''Pioneer 11'' passed by Saturn on September 1, 1979, at a distance of {{cvt|21000|km|mi}} from Saturn's cloud tops.{{r|pioneer-40th}}

By this time, ''[[Voyager 1]]'' and ''[[Voyager 2]]'' had already passed Jupiter and were en route to Saturn, so it was decided ''Pioneer 11'' would pass through the Saturn ring plane at the same position Voyager 2 would later have to fly through in order to reach [[Uranus]] and [[Neptune]]. If there were faint ring particles capable of damaging a probe in that area, mission planners felt it was better to learn about it via Pioneer.{{r|pioneer-40th}} Thus, ''Pioneer 11'' was acting as a "''pioneer''" in a true sense of the word; if danger were detected, then Voyager 2 could be redirected further away from the rings but miss the opportunity to visit the [[Ice giant|ice giants]] in the process.

''Pioneer 11'' imaged—and nearly collided with—one of Saturn's small moons, passing at a distance of no more than {{cvt|4000|km|mi}}. The object was tentatively identified as [[Epimetheus (moon)|Epimetheus]], a moon discovered the previous day from ''Pioneer''{{'}}s imaging, and suspected from earlier observations by Earth-based telescopes. After the [[Voyager program|Voyager]] flybys, it became known that there are two similarly sized moons (Epimetheus and [[Janus (moon)|Janus]]) in the same orbit, so there is some uncertainty about which one was the object of Pioneer's near-miss. ''Pioneer 11'' encountered Janus on September 1, 1979, at 14:52&nbsp;[[UTC]], at a distance of {{cvt|2500|km|mi}}. At 16:20&nbsp;UTC the same day, ''Pioneer&nbsp;11'' encountered [[Mimas (moon)|Mimas]] at a distance of {{cvt|103000|km|mi}}.

Besides Epimetheus, instruments located another previously undiscovered small moon and an additional ring, charted Saturn's magnetosphere and magnetic field, and found its planet-sized moon, [[Titan (moon)|Titan]], to be too cold for life. Hurtling underneath the ring plane, the probe sent back pictures of Saturn's rings. The rings, which normally seem bright when observed from Earth, appeared dark in the Pioneer pictures, and the dark gaps in the rings seen from Earth appeared as bright rings.

<gallery class="center">
File:P11F81.jpg|alt=Pioneer 11 image of Saturn (image F81). Taken on 1979/08/26, showing the satellite Rhea |''Pioneer 11'' image of Saturn taken on 1979/08/26
File:P11saturn.jpg|''Pioneer 11'' image of Saturn taken on 1979/09/01
File:P11saturnb.jpg|''Pioneer 11'' image of Saturn taken on 1979/09/01
File:P11g21.jpg|Outgoing ''Pioneer 11'' image of Saturn taken on 1979/09/03
File:Pntitan.jpg|alt=Pioneer 11 image of Titan|''Pioneer 11'' image of Saturn's moon Titan
</gallery>
{{center|{{commons-inline|bullet=none|Category:Photos of Saturn by Pioneer 11|''Pioneer 11'' Saturn encounter}}}}

===Interstellar mission===
On February 25, 1990, ''Pioneer 11'' became the fourth human-made object to pass beyond the orbit of the planets.{{r|NYT-19900225}}

By 1995, ''Pioneer 11'' could no longer power any of its detectors, so the decision was made to shut it down.{{r|Farewell}} On September 29, 1995, NASA's [[Ames Research Center]], responsible for managing the project, issued a press release that began, "After nearly 22 years of exploration out to the farthest reaches of the Solar System, one of the most durable and productive space missions in history will come to a close." It indicated NASA would use its [[Deep Space Network]] antennas to listen "once or twice a month" for the spacecraft's signal, until "some time in late 1996" when "its transmitter will fall silent altogether." NASA Administrator [[Daniel Goldin]] characterized ''Pioneer 11'' as "the little spacecraft that could, a venerable explorer that has taught us a great deal about the Solar System and, in the end, about our own innate drive to learn. ''Pioneer 11'' is what NASA is all about – exploration beyond the frontier."{{r|nssdc1}} Besides announcing the end of operations, the dispatch provided a historical list of ''Pioneer 11'' mission achievements.

NASA terminated routine contact with the spacecraft on September 30, 1995, but continued to make contact for about two hours every two to four weeks.<ref name=Farewell/> Scientists received a few minutes of good engineering data on November 24, 1995, but then lost final contact once Earth moved out of view of the spacecraft's antenna.{{r|nasa1|space.com2}}

=== Timeline ===
[[File:Pioneer speed and distance from Sun.svg|thumb|right|Pioneer 10 and 11 speed and distance from the Sun]]
{{interstellar_probes_trajectory.svg}}

{|
|-
! colspan="2" | Timeline of travel
|-
|
{| class="wikitable"
|-
! scope="col" style="width:100px;"| Date
! Event
|-
| {{center|1973-04-06}}
| Spacecraft launched at 02:11:00.
|-
| {{center|1974-04-19}}
| Passage through the [[asteroid belt]].
|-
| {{center|1974-11-03}}
| Start Jupiter observation phase.
{| class="wikitable collapsible"
|-
! scope="col" style="width:100px;"| Time
! scope="col" style="width:230px;"| Event
|-
| {{center|'''1974-12-02'''}}
| '''Encounter with [[Jovian system]].'''
|-
| {{center|08:21:00}}
| [[Callisto (moon)|Callisto]] flyby at 786,500&nbsp;km.
|-
| {{center|22:09:00}}
| [[Ganymede (moon)|Ganymede]] flyby at 692,300&nbsp;km.
|-
| {{center|'''1974-12-03'''}}
|
|-
| {{center|03:11:00}}
| [[Io (moon)|Io]] flyby at 314,000&nbsp;km.
|-
| {{center|04:15:00}}
| [[Europa (moon)|Europa]] flyby at 586,700&nbsp;km.
|-
| {{center|05:00:21}}
| Jupiter shadow entry.
|-
| {{center|05:01:01}}
| Jupiter [[occultation]] entry.
|-
| {{center|05:21:19}}
| [[Jupiter]] closest approach at 42,828&nbsp;km.
|-
| {{center|05:33:52}}
| Jupiter shadow exit.
|-
| {{center|05:43:03}}
| Jupiter occultation exit.
|-
| {{center|22:29:00}}
| [[Amalthea (moon)|Amalthea]] flyby at 127,500&nbsp;km.
|-
| {{center|'''1975-01-01'''}}
| '''Phase stop.'''
|}
|-
| {{center|1979-07-31}}
| Start Saturn observation phase.
{| class="wikitable collapsible"
|-
! scope="col" style="width:100px;"| Time
! scope="col" style="width:230px;"| Event
|-
| {{center|'''1979-08-29'''}}
| '''Encounter with [[Saturnian system]].'''
|-
| {{center|06:06:10}}
| [[Iapetus (moon)|Iapetus]] flyby at 1,032,535&nbsp;km.
|-
| {{center|11:53:33}}
| [[Phoebe (moon)|Phoebe]] flyby at 13,713,574&nbsp;km.
|-
| {{center|'''1979-08-31'''}}
|
|-
| {{center|12:32:33}}
| [[Hyperion (moon)|Hyperion]] flyby at 666,153&nbsp;km.
|-
| {{center|'''1979-09-01'''}}
|
|-
| {{center|14:26:56}}
| Descending ring plane crossing.
|-
| {{center|14:50:55}}
| [[Epimetheus (moon)|Epimetheus]] flyby at 6,676&nbsp;km.
|-
| {{center|15:06:32}}
| [[Atlas (moon)|Atlas]] flyby at 45,960&nbsp;km.
|-
| {{center|15:59:30}}
| [[Dione (moon)|Dione]] flyby at 291,556&nbsp;km.
|-
| {{center|16:26:28}}
| [[Mimas (moon)|Mimas]] flyby at 104,263&nbsp;km.
|-
| {{center|16:29:34}}
| [[Saturn]] closest approach at 20,591&nbsp;km.
|-
| {{center|16:35:00}}
| Saturn [[occultation]] entry.
|-
| {{center|16:35:57}}
| Saturn shadow entry.
|-
| {{center|16:51:11}}
| [[Janus (moon)|Janus]] flyby at 228,988&nbsp;km.
|-
| {{center|17:53:32}}
| Saturn occultation exit.
|-
| {{center|17:54:47}}
| Saturn shadow exit.
|-
| {{center|18:21:59}}
| Ascending ring plane crossing.
|-
| {{center|18:25:34}}
| [[Tethys (moon)|Tethys]] flyby at 329,197&nbsp;km.
|-
| {{center|18:30:14}}
| [[Enceladus]] flyby at 222,027&nbsp;km.
|-
| {{center|20:04:13}}
| [[Calypso (moon)|Calypso]] flyby at 109,916&nbsp;km.
|-
| {{center|22:15:27}}
| [[Rhea (moon)|Rhea]] flyby at 345,303&nbsp;km.
|-
| {{center|'''1979-09-02'''}}
|
|-
| {{center|18:00:33}}
| [[Titan (moon)|Titan]] flyby at 362,962&nbsp;km.
|-
| {{center|'''1979-10-05'''}}
| '''Phase stop.'''
|}
|-
| {{center|1979-10-05}}
| Begin Pioneer Interstellar Mission.
|-
| {{center|1990-}}
| Passed the orbit of [[Pluto]].
|-
| {{center|1995-09-30}}
| Routine daily mission operations stopped. ''Pioneer 11'' is 6.5 billion km from Earth.
|-
| {{center|1995-11-24}}
| Last signal received.
|}{{sfn|Fimmel|Swindell|Burgess|1974|pp=61–94}}{{r|nasa1|DMuller}}
|}

==Current status==
Due to power constraints and the vast distance to the probe, the last routine contact with the spacecraft was on September 30, 1995, and the last good engineering data was received on November 24, 1995.{{r|Status|nasa1}}

As of June 24, 2024, ''Pioneer 11'' is estimated to be {{cvt|113.121|AU|e9km e9mi}} from the Earth and {{convert|114.089|AU|e9km e9mi|abbr=unit}} from the Sun. It was traveling at {{cvt|11.155|km/s|kph mph}} relative to the Sun and traveling outward at about 2.35&nbsp;AU per year.{{r|heavens1|skylive1}} The spacecraft is heading in the direction of the constellation [[Scutum (constellation)|Scutum]] near the current position (June 2024) [[Right ascension|RA]] 18h 54m [[Declination|dec]] -8° 46' ([[Epoch (astronomy)#Julian years and J2000|J2000.0]]), close to [[Messier 26]]. In 928,000 years, it will pass within {{Convert|0.25|pc|ly|lk=on|abbr=off}} of the K dwarf TYC 992-192-1{{r|Bailer-Jones_2019}} and will pass near the star [[Lambda Aquilae]] in about four million years.{{r|dk_space1}}

''Pioneer 11'' has been overtaken by the two Voyager probes launched in 1977. ''[[Voyager 1]]'' has become the most distant object built by humans and will remain so for the foreseeable future, as no probe launched since Voyager has the speed to overtake it.{{r|voyager1}}

==Pioneer anomaly==
{{Main|Pioneer anomaly}}
Analysis of the radio tracking data from the ''Pioneer 10'' and ''11'' spacecraft at distances between 20 and 70&nbsp;AU from the Sun had consistently indicated the presence of a small but anomalous [[Doppler effect|Doppler]] frequency drift. The drift can be interpreted as due to a constant acceleration of {{nowrap|(8.74 ± 1.33) × 10<sup>−10</sup> m/s<sup>2</sup>}} directed towards the Sun. Although it was suspected that there was a [[Systematic bias|systematic origin]] to the effect, none was found. As a result, there has been sustained interest in the nature of this so-called "[[Pioneer anomaly]]".{{r|space.com1}} Extended analysis of mission data by [[Slava Turyshev]] and colleagues determined the source of the anomaly to be asymmetric thermal radiation and the resulting thermal recoil force acting on the face of the ''Pioneer''s away from the Sun.{{r|ps00003459|physrev1}}

==Pioneer plaque==
{{Main|Pioneer plaque}}
[[File:Pioneer10-plaque.jpg|thumb|Pioneer plaque]]
''Pioneer 10'' and ''11'' both carry a gold-anodized aluminum [[Commemorative plaque|plaque]] in the event that either spacecraft is ever found by intelligent lifeforms from other planetary systems. The plaques feature the nude figures of a human male and female along with several symbols that are designed to provide information about the origin of the spacecraft.{{r|Sagan1972}}

==Commemoration==
In 1991, ''Pioneer 11'' was honored on one of 10 United States Postage Service stamps commemorating uncrewed spacecraft exploring each of the then nine planets and the Moon. ''Pioneer 11'' was the spacecraft featured with Jupiter. Pluto was listed as "Not yet explored".{{r|index_1991}}

==Gallery==
<gallery mode=packed heights=150px>
Pioneer 11 Saturn Rings.png |''Pioneer 11'' and Saturn rings on September 1, 1979 (artist concept)
An artist's impression of the encounter between Pioneer 11 and Saturn.jpg |''Pioneer 11''{{'}}s flyby of [[Saturn]] (artist concept)
</gallery>

==See also==
{{Portal|Astronomy|Spaceflight}}
* [[Exploration of Jupiter]]
** ''[[Pioneer 10]]'', Jupiter fly-by
** ''[[Voyager 1]]'' and ''[[Voyager 2]]'', Jupiter fly-by en route to other outer Solar System fly-bys
** ''[[Galileo (spacecraft)|Galileo]]'', Jupiter orbiter
** ''[[New Horizons]]'', Jupiter flyby en route to Pluto fly-by
** ''[[Juno (spacecraft)|Juno]]'', Jupiter polar orbiter
* [[Exploration of Saturn]]
** ''[[Cassini–Huygens]]'', Saturn orbiter and Titan lander, respectively
* [[List of artificial objects leaving the Solar System]]
* [[List of missions to the outer planets]]
* [[Pioneer anomaly]]
* [[Robotic spacecraft]]
* [[Timeline of artificial satellites and space probes]]
{{clear right}}

==References==
{{reflist|refs=

<ref name="Astronautix">{{cite encyclopedia
| author1= M. Wade
| encyclopedia= Encyclopedia Astronautica
| title= Pioneer 10-11
| url= http://astronautix.com/p/pioneer10-11.html
| access-date= 8 February 2011 }}
</ref>

<ref name="Bailer-Jones_2019">{{cite journal
| author1= C. A. L. Bailer-Jones
| author2= D. Farnocchia
| title= Future Stellar Flybys of the Voyager and Pioneer spacecraft 
| journal= Research Notes of the AAS
| volume= 3
| issue= 4
| pages= 59
| date= 3 April 2019
| doi= 10.3847/2515-5172/ab158e
| arxiv= 1912.03503
| bibcode= 2019RNAAS...3...59B
| s2cid= 134524048
| doi-access= free }}
</ref>

<ref name="dk_space1">{{cite encyclopedia 
| encyclopedia= DK Eyewitness - Encyclopedia of Space and the Universe
| title= Hardware, Leaving the Solar System: Where are they now?
| year= 2001
| isbn= 978-0-789-40881-5 }}
</ref>

<ref name="DMuller">{{cite web 
| author1= D. Muller 
| url= https://www.dmuller.net/spaceflight/mission.php?mission=pioneer11
| title= Pioneer 11 Full Mission Timeline
| work= Spaceflight Realtime Simulations and Information
| access-date= 9 January 2011
| archive-date= 4 March 2016
| archive-url= https://web.archive.org/web/20160304175744/https://www.dmuller.net/spaceflight/mission.php?mission=pioneer11
| url-status= dead }}
</ref>

<ref name="Farewell">{{cite magazine
| title= Farewell to a Pioneer
| magazine= [[Science News]]
| publisher= [[Society for Science]]
| date= 14 October 1995
| page= 250 
| volume= 148
| issue= 16
| jstor= 4018121 }}
</ref>

<ref name="heavens1">{{Cite web
| url= https://www.heavens-above.com/SolarEscape.aspx
| title= Spacecraft escaping the Solar System
| work= Heavens Above
| access-date= 24 August 2022 }}
</ref>

<ref name="index_1991">{{cite news
| author1= S. Kronish
| title= Space Launches are Featured
| url= https://www.newspapers.com/image/69797194
| newspaper= The Index Journal
| page= 21
| location= South Carolina, USA
| via= Newspapers.com
| access-date= 5 December 2017
| date= 27 October 1991
| url-access= registration }}
</ref>

<ref name="nasa1">{{cite web
| url= https://science.nasa.gov/mission/pioneer-11/
| title= Pioneer 11 - NASA Science
| website= science.nasa.gov
| publisher= [[NASA]]
| access-date= 1 December 2022 }}
</ref>

<ref name="newsci-1974">{{cite magazine
| date= 9 May 1974
| title= Pioneer 11 Successfully Retargeted for Saturn 
| url= https://books.google.com/books?id=fDMeAQAAMAAJ&q=Pioneer+11+retargeted+Saturn
| magazine= [[New Scientist]]
| volume= 62
| page= 294
| access-date= 5 December 2017 }}
</ref>

<ref name="nssdc1">{{cite web
| author1= D. Savage
| author2= Ann Hutchison
| url= http://nssdc.gsfc.nasa.gov/planetary/text/pioneer-11_endops.txt
| title= Pioneer 11 to End Operations after Epic Career
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]] / [[Ames Research Center|Ames]]
| date= 28 September 1995
| access-date= 7 August 2011
| format= TXT }}
</ref>

<ref name="nssdc2">{{cite web
| author1= E. J. Smith
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-01
| title= Pioneer 11: Magnetic Fields
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc3">{{cite web
| author1= A. Barnes
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-13
| title= Pioneer 11: Quadrispherical Plasma Analyzer
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc4">{{cite web
| author1= J. A. Simpson
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-02
| title= Pioneer 11: Charged Particle Instrument (CPI)
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc5">{{cite web
| author1= F. B. MacDonald
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-12
| title= Pioneer 11: Cosmic-Ray Spectra
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc6">{{cite web
| author1= J. A. Van Allen
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-11
| title= Pioneer 11: Geiger Tube Telescope (GTT)
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc7">{{cite web
| author1= R. W. Fillius
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-05
| title= Pioneer 11: Jovian Trapped Radiation
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc8">{{cite web
| author1= W. H. Kinard
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-04
| title= Pioneer 11: Meteoroid Detectors
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc9">{{cite web
| author1= R. K. Soberman
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-03
| title= Pioneer 11: Asteroid/Meteoroid Astronomy
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc10">{{cite web
| author1= D. L. Judge
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-06
| title= Pioneer 11: Ultraviolet Photometry
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc11">{{cite web
| author1= T. Gehrels
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-07
| title= Pioneer 11: Imaging Photopolarimeter (IPP)
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc12">{{cite web
| author1= A. P. Ingersoll
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-08
| title= Pioneer 11: Infrared Radiometers
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 19 February 2011 }}
</ref>

<ref name="nssdc13">{{cite web
| author1= M. H. Acuña
| url= https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1973-019A-14
| title= Pioneer 11: Jovian Magnetic Field
| website= nssdc.gsfc.nasa.gov
| publisher= [[NASA]]
| access-date= 24 September 2013 }}
</ref>

<ref name="NYT-19900225">{{cite news
| title= Pioneer 11 Is Reported to Leave Solar System
| url= https://www.nytimes.com/1990/02/25/us/pioneer-11-is-reported-to-leave-solar-system.html
| newspaper= [[The New York Times]]
| access-date= 3 December 2017
| date= 25 February 1990
| page= 24
| url-access= registration }}
</ref>

<ref name="physrev1">{{cite journal
| author1= S. G. Turyshev
| author2= V. T. Toth
| author3= G. Kinsella
| author4= S. C. Lee
| author5= S. M. Lok
| author6= J. Ellis
| display-authors= 3
| title= Support for the Thermal Origin of the Pioneer Anomaly
| journal= [[Physical Review Letters]]
| volume= 108
| issue= 24
| date= 12 June 2012
| page= 241101
| doi= 10.1103/PhysRevLett.108.241101
| pmid= 23004253
| arxiv= 1204.2507 | bibcode= 2012PhRvL.108x1101T
}}
</ref>

<ref name="pioneer-40th">{{cite web
| author1= J. Uri
| title= 40 Years Ago: Pioneer 11 First to Explore Saturn
| url= https://www.nasa.gov/solar-system/planets/saturn/40-years-ago-pioneer-11-first-to-explore-saturn/
| date= 3 September 2019
| website= nasa.gov
| publisher= [[NASA]]
| access-date= 25 July 2024 }}
</ref>

<ref name="ps00003459">{{cite web
| url= http://www.planetary.org/blog/article/00003459/
| access-date= 20 April 2012
| title= Pioneer Anomaly Solved!
| website= [[The Planetary Society]]
| archive-date= 22 April 2012
| archive-url=https://web.archive.org/web/20120422065322/http://www.planetary.org/blog/article/00003459/
| url-status= dead }}
</ref>

<ref name="Sagan1972">{{cite journal
| doi=10.1126/science.175.4024.881
| title= A Message from Earth
| author1= C. Sagan
| author2= L. S. Sagan
| author3= F. Drake
| journal= [[Science (journal)|Science]]
| volume= 175
| issue= 4024
| pages= 881–884
| date= 25 February 1972
| pmid= 17781060
| bibcode= 1972Sci...175..881S }}
</ref>

<ref name="skylive1">{{cite web
| url= https://theskylive.com/pioneer11-tracker
| title= Pioneer 11 - Live Position
| access-date= 19 July 2015
| website= www.theskylive.com }}
</ref>

<ref name="smithsonian1">{{cite web
| url= http://www.nasm.si.edu/exhibitions/gal100/index.cfm#pioneer10
| title= Milestones of Flight
| publisher= [[Smithsonian National Air and Space Museum]]
| access-date= 8 February 2011
| archive-date= 15 April 2012
| archive-url= https://web.archive.org/web/20120415154411/http://www.nasm.si.edu/exhibitions/gal100/index.cfm#pioneer10
| url-status= dead }}
</ref>

<ref name="solarviews1">{{Cite web
| url= https://solarviews.com/eng/pn10-11.htm
| title= Pioneer 10 & 11
| work= Views of the Solar System
| access-date= 20 December 2018 }}
</ref>

<ref name="space.com1">{{cite web
| url= https://www.space.com/448-problem-gravity-mission-probe-strange-puzzle.html
| access-date= 7 June 2011
| title= The Problem with Gravity: New Mission Would Probe Strange Puzzle
| author1= R. R. Britt
| date= 18 October 2004
| website= Space.com }}
</ref>

<ref name="space.com2">{{cite web
| author1= E. Howell 
| title= Pioneer 11: Up Close with Jupiter & Saturn
| url= https://www.space.com/17785-pioneer-11.html
| website= Space.com
| date= 26 September 2012
| access-date= 10 December 2017 }}
</ref>

<ref name="Status">{{Cite web
| url= http://www.nasa.gov/centers/ames/missions/archive/pioneer.html
| title= The Pioneer Missions
| website= nasa.gov
| publisher= [[NASA]] / [[Ames Research Center|Ames]]
| date= 27 March 2007
| access-date= 3 March 2015
| archive-date= 19 October 2021
| archive-url= https://web.archive.org/web/20211019013857/https://www.nasa.gov/centers/ames/missions/archive/pioneer.html
| url-status= dead }}
</ref>

<ref name="voyager1">{{Cite web
| url= https://voyager.jpl.nasa.gov/mission/status/
| title= Voyager - Mission Status
| website= voyager.jpl.nasa.gov
| publisher= [[NASA]] / [[Jet Propulsion Laboratory|JPL]]
| access-date= 15 December 2021 }}
</ref>

<ref name="weebau1">{{cite encyclopedia
| title= Pioneer 11
| encyclopedia= Weebau Space Encyclopedia
| date= 9 November 2010
| url= https://weebau.com/satplan/pioneer%2011.htm
| access-date= 12 January 2012 }}
</ref>

}}

=== Bibliography ===

*{{cite book
| last1= Burrows | first1= W. E. | title= Exploring Space: Voyages in the Solar System and Beyond | url= https://books.google.com/books?id=9okgAQAAIAAJ | year= 1990 | edition= first | location= New York | publisher= Random House | isbn= 978-0-394-56983-3 }}

*{{cite book
| last1= Fimmel | first1= R. O. | last2= Swindell | first2= W. 
| last3= Burgess | first3= E. | url= https://ntrs.nasa.gov/citations/20190002224 | title= Pioneer Odyssey: Encounter with a Giant | id= NASA-SP-349/396 | location= Washington, D.C. | publisher= [[NASA]] / [[Ames Research Center|Ames]] | year= 1974 | oclc= 3211441 | isbn= 978-1-493-71200-7 }}

*{{cite journal
| last1= Fimmel | first1= R. O. | last2= van Allen | first2= J. A.
| last3= Burgess | first3= E. | url= https://atmos.nmsu.edu/data_and_services/atmospheres_data/SATURN/logs/nasa-sp-446-Pioneer-First-to-Jupiter-Saturn-and-Beyond.pdf | title= Pioneer: First to Jupiter, Saturn, and Beyond | journal= NASA Special Publication | id= NASA-SP-446 | location= Washington, D.C. | publisher= [[NASA]] / [[Ames Research Center|Ames]] | year= 1980 | volume= 446 | asin= B000IRXYN0 | bibcode= 1980NASSP.446.....F }}

*{{cite book
| last=Simpson | first=J. A. | date=2001 | page=146 | chapter=The Cosmic Radiation | title= The Century of Space Science | editor=Johan A. M. Bleeker | editor2=Johannes Geiss | editor3=Martin C. E. Huber | volume=1 | publisher=Springer | isbn=978-0-7923-7196-0 | url= https://books.google.com/books?id=NMk3adgqfawC | chapter-url= https://books.google.com/books?id=NMk3adgqfawC&pg=PA146 }}

==External links==
{{commons category|Pioneer 11}}
* [https://web.archive.org/web/20070802052346/http://solarsystem.nasa.gov/missions/profile.cfm?MCode=Pioneer_11 ''Pioneer 11'' Profile] by [http://solarsystem.nasa.gov NASA's Solar System Exploration]
* [https://web.archive.org/web/20071004222059/http://www.strykfoto.org/pioneersaturn.htm Ted Stryk's ''Pioneer 11'' at Saturn page]

{{Pioneer program | before=[[Pioneer 10]] | after=[[Pioneer H]]}}
{{Jupiter spacecraft}}
{{Saturn spacecraft}}
{{NASA navbox}}
{{TRW}}
{{Orbital launches in 1973}}
{{Navboxes
|title = Visited planets and their moons
|list1 =
{{Jupiter}}
{{Saturn}}
{{Ganymede}}
{{Callisto}}
{{Io}}
{{Europa}}
{{Titan}}
{{Rhea}}
{{Iapetus}}
{{Tethys}}
{{Enceladus}}
}}
{{Authority control}}

[[Category:1973 in spaceflight]]
[[Category:Derelict space probes]]
[[Category:Missions to Jupiter]]
[[Category:Missions to Saturn]]
[[Category:Pioneer program]]
[[Category:Spacecraft escaping the Solar System]]
[[Category:Spacecraft launched by Atlas-Centaur rockets]]
[[Category:Spacecraft launched in 1973]]