View source for Astronomy:Mars Pathfinder

{{Short description|Mission including first robotic rover to operate on Mars (1997)}}
{{DISPLAYTITLE:''Mars Pathfinder''}}
{{Infobox spaceflight
| name                  = ''Mars Pathfinder''
| image                 = Mars Pathfinder Lander preparations.jpg
| image_caption         = ''Pathfinder'' and ''[[Engineering:Sojourner (rover)|Sojourner]]'' at JPL in October 1996, being 'folded' into its launch position.<ref name="NASA-Sojourner">{{cite web |last=Nelson |first=Jon |title=Mars Pathfinder / Sojourner Rover |url=http://www.jpl.nasa.gov/missions/details.php?id=5913 |work=[[Organization:NASA|NASA]] |access-date=February 2, 2014 |archive-url=https://web.archive.org/web/20140219235613/http://www.jpl.nasa.gov/missions/details.php?id=5913 |archive-date=February 19, 2014 |url-status=live }}</ref>
| image_alt             = A group of scientists, all wearing white protective clothing, gather around a spacecraft as it is being folded into its launch position; a triangular pyramid shape.

| mission_type          = Lander{{dot}}Rover
| operator              = [[Organization:NASA|NASA]]{{dot}}[[Organization:Jet Propulsion Laboratory|Jet Propulsion Laboratory]]
| COSPAR_ID             = 1996-068A
| SATCAT                = 24667
| website               = {{url|http://mars.nasa.gov/MPF/}}
| mission_duration      = 85 days<br />''Launch to last contact'': 9 months, 23 days
| manufacturer          = 
| launch_mass           = 890 kg (includes propellant)<ref name=fact-sheet />
| dimensions            = 
| power                 = ''Pathfinder'': 35 W<br />''Sojourner'': 13 W
| launch_date           = {{start date|1996|12|04}} 06:58:07 [[Physics:Coordinated Universal Time|UTC]]
| launch_rocket         = [[Engineering:Delta II|Delta II]] 7925 (#D240)
| launch_site           = {{wipe|Cape Canaveral Air Force Station}} SLC-17
| launch_contractor     = None<ref>{{cite web|first=Erik|last=Conway|url=http://www.jpl.nasa.gov/jplhistory/the90/pathfinder-t.php|title=The Discovery Program: Mars Pathfinder|work=[[Organization:Jet Propulsion Laboratory|Jet Propulsion Laboratory]]|year=2015|access-date=June 10, 2015|archive-url=https://web.archive.org/web/20150117184051/http://www.jpl.nasa.gov/jplhistory/the90/pathfinder-t.php|archive-date=January 17, 2015|url-status=live}}</ref>

| last_contact          = {{start date|1997|09|27}} 10:23 [[Physics:Coordinated Universal Time|UTC]]

|interplanetary         = 
  {{Infobox spaceflight/IP
   |type                = lander
   |object              = [[Astronomy:Mars|Mars]]
   |arrival_date        = {{start date and age|1997|07|04}} 16:56:55 [[Physics:Coordinated Universal Time|UTC]] <br/> MSD 43905 04:41 AMT
   |location            = Ares Vallis, [[Astronomy:Chryse Planitia|Chryse Planitia]], [[Astronomy:Mars|Mars]]<br />{{Coord|19|7|48|N|33|13|12|W|globe:mars|name=Sojourner rover (Mars Pathfinder)}}
   |distance            = 
  }}
| trans_band            = X-Band with high-gain antenna
| trans_bandwidth       = 6 kb/s to 70 m Deep Space Network, 250 b/s to surface command<ref name=fact-sheet>{{cite web|url=http://mars.jpl.nasa.gov/MPF/mpf/fact_sheet.html|title=Mars Pathfinder Fact Sheet|publisher=NASA/JPL|date=March 19, 2005|access-date=February 21, 2014|archive-url=https://web.archive.org/web/20140919015757/http://mars.jpl.nasa.gov/MPF/mpf/fact_sheet.html|archive-date=September 19, 2014|url-status=live}}</ref>

| insignia              = Mars Pathfinder Insignia.png
| insignia_caption      = Official insignia of the ''Mars Pathfinder'' mission.
| insignia_alt          = An image inside an oval, depicting two spacecraft, one a lander, and one a rover, on the surface of Mars. The words "Mars Pathfinder" are written on the top and the words "NASA{{dot}}JPL" are written on the bottom.

| programme             = '''Discovery program'''
| previous_mission      = ''[[Astronomy:NEAR Shoemaker|NEAR Shoemaker]]''
| next_mission          = ''[[Astronomy:Lunar Prospector|Lunar Prospector]]''
}}

'''''Mars Pathfinder''''' ('''''MESUR Pathfinder''''')<ref name="NASA-Sojourner" /><ref>{{cite news |last=Sawyer |first=Kathy |newspaper=Washington Post |title=One Way or Another, Space Agency Will Hitch a Ride to Mars |date=November 13, 1993 |url=https://www.washingtonpost.com/archive/politics/1993/11/13/one-way-or-another-space-agency-will-hitch-a-ride-to-mars/c3c354a0-59d1-4373-aa88-15d8b5a3f602/ |access-date=March 6, 2023 }}</ref> is an American [[Engineering:Robotic spacecraft|robotic spacecraft]] that landed a base station with a [[Astronomy:Rover (space exploration)|roving probe]] on [[Astronomy:Mars|Mars]] in 1997. It consisted of a [[Engineering:Lander (spacecraft)|lander]], renamed the '''[[Biography:Carl Sagan|Carl Sagan]] Memorial Station''', and a lightweight, {{cvt|10.6|kg|lb|adj=on}} wheeled [[Engineering:Robot|robot]]ic [[Astronomy:Mars rover|Mars rover]] named ''[[Engineering:Sojourner (rover)|Sojourner]]'',<ref>{{cite web |url=http://mpfwww.jpl.nasa.gov/missions/past/pathfinder.html |title=Mars Pathfinder |work=NASA |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20111112062226/http://mpfwww.jpl.nasa.gov/missions/past/pathfinder.html |archive-date=November 12, 2011 |url-status=dead }}</ref> the first rover to operate outside the Earth–Moon system.

Launched on December 4, 1996, by [[Organization:NASA|NASA]] aboard a [[Engineering:Delta II|Delta II]] booster a month after the ''[[Astronomy:Mars Global Surveyor|Mars Global Surveyor]]'', it landed on July 4, 1997, on [[Astronomy:Mars|Mars]]'s Ares Vallis, in a region called [[Astronomy:Chryse Planitia|Chryse Planitia]] in the [[Astronomy:Oxia Palus quadrangle|Oxia Palus quadrangle]]. The [[Engineering:Lander (spacecraft)|lander]] then opened, exposing the rover which conducted many experiments on the Martian surface. The mission carried a series of scientific instruments to analyze the Martian atmosphere, [[Earth:Climate|climate]], and geology and the composition of its [[Earth:Rock (geology)|rocks]] and soil. It was the second project from NASA's [[Astronomy:Discovery Program|Discovery Program]], which promotes the use of low-cost spacecraft and frequent launches under the motto "cheaper, faster and better" promoted by then-administrator Daniel Goldin. The mission was directed by the [[Organization:Jet Propulsion Laboratory|Jet Propulsion Laboratory]] (JPL), a division of the [[Organization:California Institute of Technology|California Institute of Technology]], responsible for NASA's [[Astronomy:Mars Exploration Program|Mars Exploration Program]]. The project manager was JPL's Tony Spear.

This mission was the first of a series of missions to Mars that included rovers, and was the first successful lander since the two ''[[Engineering:Viking program|Vikings]]'' landed on Mars in 1976. Although the [[Place:Soviet Union|Soviet Union]] successfully sent rovers to the Moon as part of the Lunokhod program in the 1970s, its attempts to use rovers in its [[Astronomy:Mars program|Mars program]] failed.

In addition to scientific objectives, the ''Mars Pathfinder'' mission was also a "proof-of-concept" for various technologies, such as [[Engineering:Airbag|airbag]]-mediated touchdown and automated obstacle avoidance, both later exploited by the [[Astronomy:Mars Exploration Rover|Mars Exploration Rover]] mission. The ''Mars Pathfinder'' was also remarkable for its extremely low cost relative to other robotic space missions to Mars. Originally, the mission was conceived as the first of the Mars Environmental Survey (MESUR) program.

==Mission objectives==
* To prove that the development of "faster, better and cheaper" spacecraft was possible (with three years for development and a cost under $150&nbsp;million for the lander, and $25 million for the rover<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=MESURPR |title=Mars Pathfinder Rover |publisher=National Aeronautics and Space Administration |access-date=2020-09-30 }}</ref>).
* To show that it was possible to send a load of scientific instruments to another planet with a simple system and at one-fifteenth the cost of a [[Engineering:Viking program|Viking]] mission. (For comparison, the Viking missions cost $935&nbsp;million in 1974<ref>{{cite book |chapter-url=http://solarviews.com/history/SP-4212/ch8-6.html |chapter=Viking Lander: Building A Complex Spacecraft - Reorganizations and Additional Cutbacks |url=http://solarviews.com/history/SP-4212/contents.html |title=On Mars: Exploration of the Red Planet 1958-1978 |first1=Edward Clinton |last1=Ezell |first2=Linda Neuman |last2=Ezell |pages=268–270 |publisher=National Aeronautics and Space Administration |location=Washington, D.C. |year=1984 |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20160408053821/http://solarviews.com/history/SP-4212/contents.html |archive-date=April 8, 2016 |url-status=live }}</ref> or $3.5&nbsp;billion in 1997 dollars.)
* To demonstrate NASA's commitment to low-cost planetary exploration by finishing the mission with a total expenditure of $280&nbsp;million, including the launch vehicle and mission operations.

==Science experiments==
[[File:Sojourner on Mars PIA01122.jpg|thumb|left|200px|''Sojourner'' rover on Mars on sol 22]]
The ''Mars Pathfinder'' conducted different investigations on the Martian soil using three scientific instruments. The lander contained a [[Stereo camera|stereoscopic camera]] with spatial filters on an expandable pole called Imager for Mars Pathfinder (IMP),<ref>{{Cite journal|title= The imager for Mars Pathfinder experiment|author1=Smith, P. H. |author2=Tomasko, M. G. |author3=Britt, D. |author4=Crowe, D. G. |author5=Reid, R. |author6=Keller, H. U. |author7=Thomas, N. |author8=Gliem, F. |author9=Rueffer, P. |author10=Sullivan, R. |author11=Greeley, R. |author12=Knudsen, J. M. |author13=Madsen, M. B. |author14=Gunnlaugsson, H. P. |author15=Hviid, S. F. |author16=Goetz, W. |author17=Soderblom, L. A. |author18=Gaddis, L. |author19=Kirk, R. |journal=[[Earth:Journal of Geophysical Research|Journal of Geophysical Research]] |volume= 102 |issue=E2 |pages=4003–4026 |date=1997 |doi=10.1029/96JE03568 |bibcode=1997JGR...102.4003S|doi-access=free }}</ref><ref>{{Cite journal |title=Results from the Mars Pathfinder camera |author1=Smith P. H. |author2=Bell J. F. |author3=Bridges N. T. |journal=Science |volume= 278|issue=5344 |pages=1758–1765|date=1997| doi=10.1126/science.278.5344.1758|pmid=9388170|bibcode = 1997Sci...278.1758S |doi-access=free }}</ref> and the Atmospheric Structure Instrument/Meteorology Package (ASI/MET)<ref>{{Cite journal| title= The Mars Pathfinder atmospheric structure investigation meteorology (ASI/MET) experiment|author1=Schofield J. T. |author2=Barnes J. R. |author3=Crisp D. |author4=Haberle R. M. |author5=Larsen S. |author6=Magalhaes J. A. |author7=Murphy J. R. |author8=Seiff A. |author9=Wilson G. |journal= Science|volume= 278|issue=5344|pages= 1752–1758|date= 1997| doi= 10.1126/science.278.5344.1752| pmid= 9388169|bibcode = 1997Sci...278.1752S |doi-access=free }}</ref> which acts as a Mars meteorological station, collecting data about pressure, temperature, and winds. The MET structure included three [[Engineering:Windsock|windsock]]s mounted at three heights on a pole, the topmost at about {{convert|1|m|ft|spell=in|sp=us}} and generally registered winds from the West.<ref>{{cite web |url=http://mars.jpl.nasa.gov/MPF/science/windsocks.html |title=Windsocks on Mars |work=JPL/NASA Mars Pathfinder |year=2005 |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20160305011341/http://mars.jpl.nasa.gov/MPF/science/windsocks.html |archive-date=March 5, 2016 |url-status=live }}</ref>

The ''[[Engineering:Sojourner (rover)|Sojourner]]'' rover had an Alpha Proton X-ray Spectrometer (APXS),<ref>{{Cite journal |title=Determination of the chemical composition of Martian soil and rocks: The alpha proton X ray spectrometer |author1=R. Rieder |author2=H. Wänke |author3=T. Economou |author4=A. Turkevich |journal=  Journal of Geophysical Research |date= 1997 |volume= 102 |issue=E2 |pages=4027–4044 |doi=10.1029/96JE03918 |bibcode=1997JGR...102.4027R|doi-access=free }}</ref> which was used to analyze the components of the rocks and soil. The rover also had two black-and-white cameras and a color one. These instruments could investigate the geology of the Martian surface from just a few millimeters to many hundreds of meters, the [[Chemistry:Geochemistry|geochemistry]] and evolutionary history of the rocks and surface, the [[Physics:Magnetic|magnetic]] and [[Physics:Mechanics|mechanical]] properties of the land, as well as the magnetic properties of the dust, atmosphere and the [[Physics:Rotation|rotation]]al and [[Physics:Orbit|orbit]]al dynamics of the planet.
[[File:h rover-comp wheels 02.jpg|thumb|right|200px|Wheel size comparison: ''Sojourner'', Mars Exploration Rover, Mars Science Laboratory]]
The rover was equipped with three [[Engineering:Charge-coupled device|CCD]] cameras, all manufactured by [[Company:Kodak|Eastman Kodak Company]] and controlled by the rover's CPU. The two front-facing monochrome cameras served navigation purposes and were coupled with five laser stripe projectors for [[Stereoscopy|stereoscopic]] hazard detection. These front cameras had a resolution of 484 vertical by 768 horizontal pixels, and an [[Physics:Optical resolution|optical resolution]] capable of discerning details as small as {{cvt|0.6|cm|in}} across a range of {{cvt|0.65|m|in}}. Images from these cameras could be compressed using the [[Block Truncation Coding|block truncation coding]] (BTC) algorithm.

The third camera, situated at the rear near the APXS, was used for color imaging. It shared the resolution of the front cameras but was rotated 90 degrees to capture images of both the APXS target area and the rover's tracks. This rear camera featured a 4x4 pixel block with specific color sensitivities: 12 pixels for green, two for red, and two for [[Physics:Infrared|infrared]]. All cameras employed lenses made of [[Chemistry:Zinc selenide|zinc selenide]], which blocks light wavelengths below 500 nm; as a result, the blue/infrared pixels effectively detected only infrared light. Each camera had auto-exposure and bad-pixel handling functions. Image parameters, such as exposure time and compression settings, were included in the transmitted image headers. If BTC compression was to be used on the rear camera, the color information would need to be discarded.<ref name="sojcam" />

===''Pathfinder'' lander===

==== Imager for ''Mars Pathfinder'' (IMP), (includes [[Physics:Magnetometer|magnetometer]] and [[Engineering:Anemometer|anemometer]])<ref>{{Cite web |title=IMP Camera Specifications |url=https://mars.nasa.gov/MPF/imp/science/specs.html |access-date=2023-03-29 |website=mars.nasa.gov}}</ref><ref name=":0">{{Cite journal |last1=Smith |first1=P. H. |last2=Tomasko |first2=M. G. |last3=Britt |first3=D. |last4=Crowe |first4=D. G. |last5=Reid |first5=R. |last6=Keller |first6=H. U. |last7=Thomas |first7=N. |last8=Gliem |first8=F. |last9=Rueffer |first9=P. |last10=Sullivan |first10=R. |last11=Greeley |first11=R. |last12=Knudsen |first12=J. M. |last13=Madsen |first13=M. B. |last14=Gunnlaugsson |first14=H. P. |last15=Hviid |first15=S. F. |date=1997-02-25 |title=The imager for Mars Pathfinder experiment |journal=Journal of Geophysical Research: Planets |language=en |volume=102 |issue=E2 |pages=4003–4025 |doi=10.1029/96JE03568|bibcode=1997JGR...102.4003S |doi-access=free }}</ref> ====
[[File:Mars Pathfinder IMP camera.gif|thumb|Mars Pathfinder IMP camera closeup]]
[[File:Diagram of Mars Pathfinder IMP camera.jpg|thumb|Diagram of Mars Pathfinder IMP camera]]
The IMP had a set of filters designed to record surface and atmospheric phenomena. There were two cameras, or eyes, allowing for [[Stereoscopy|stereoscopic imagery]], with the set of filters being slightly different between them. <ref name=":1">{{Cite web |title=Mars Pathfinder Instrument Descriptions |url=https://mars.nasa.gov/MPF/mpf/sci_desc.html |access-date=2023-03-29 |website=mars.nasa.gov}}</ref><ref name=":2">{{Cite web |title=How does the IMP work ? |url=https://mars.nasa.gov/MPF/imp/howdoes/how_does.html |access-date=2023-03-29 |website=mars.nasa.gov}}</ref><ref name=":3">{{Cite web |title=IMP Instrument Overview |url=https://atmos.nmsu.edu/data_and_services/atmospheres_data/MARS/pathfinder/logs/Instrument%20Overview.pdf |website=atmos.nmsu.edu}}</ref>
{| class="wikitable sortable"
|+IMP filter characteristics<ref name=":0" /><ref name=":2" /><ref name=":3" />
!Eye and Filter
!Center Wavelength (nm)
!Bandwidth (nm)
!Category
|-
|L0
|443
|26
|Stereo, Geology
|-
|L5
|671
|20
|Stereo, Geology
|-
|L6
|802
|21
|Geology
|-
|L7
|858
|34
|Geology
|-
|L8
|898
|41
|Geology
|-
|L9
|931
|27
|Stereo, Ranging, Geology
|-
|L10
|1003
|29
|Geology
|-
|L11
|968
|31
|Stereo, Ranging, Geology
|-
|R0
|443
|26
|Stereo, Geology
|-
|R5
|671
|20
|Stereo, Geology
|-
|R6
|752
|19
|Geology
|-
|R8
|600
|21
|Geology
|-
|R9
|531
|30
|Stereo, Ranging, Geology
|-
|R10
|480
|27
|Geology
|-
|R11
|967
|30
|Stereo, Ranging, Geology
|-
|L1
|450
|5
|Solar
|-
|L2
|883
|6
|Solar
|-
|L3
|925
|5
|Solar
|-
|L4
|935
|5
|Solar
|-
|R1
|670
|5
|Solar
|-
|R2
|946
|44
|Solar
|-
|R3
|936
|5
|Solar
|-
|R4
|989
|5
|Solar
|}

==== Atmospheric and [[Physics:Meteorology|meteorological]] sensors (ASI/MET) ====
[[File:Mars Pathfinder lander scheme.jpg|thumb|Mars Pathfinder lander scheme. ASI/MET pole is visible extending towards the top.]]
The ASI/MET records temperature, pressure and wind data, during entry and descent, and once on the surface.<ref name=":1" /> It also houses electronics for sensor operation and data recording.<ref name=":1" />

===''Sojourner'' rover===
{{Main |Engineering:Sojourner (rover)}}
# Imaging system (three cameras: front B&W stereo,<ref name="sojcam">{{cite web |url=http://pdsimg.jpl.nasa.gov/data/mpfr-m-rvrcam-2-edr-v1.0/mprv_0001/document/rcinst.htm |title=Rover Camera Instrument Description |work=NASA |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20160305001725/http://pdsimg.jpl.nasa.gov/data/mpfr-m-rvrcam-2-edr-v1.0/mprv_0001/document/rcinst.htm |archive-date=March 5, 2016 |url-status=dead }}</ref> 1 rear color)
# [[Physics:Laser|Laser]] striper hazard detection system<ref name=Stone1996>{{cite report 
 | title =  Mars Pathfinder Microrover: A Small, Low-Cost, Low-Power Spacecraft 
 | author =  Stone, H. W.
 | year = 1996  
 | hdl = 2014/25424
 | url = http://hdl.handle.net/2014/25424}}</ref>
# Alpha Proton [[Physics:X-ray|X-ray]] [[Physics:Spectrometer|Spectrometer]] (APXS)
# Wheel Abrasion Experiment
# [[Astronomy:Materials Adherence Experiment|Materials Adherence Experiment]]
# [[Physics:Accelerometer|Accelerometer]]s

==Landing site==
The landing site was an ancient flood plain in Mars's northern hemisphere called "Ares Vallis" ("the valley of Ares", the ancient Greek equivalent of the ancient Roman deity Mars) and is among the rockiest parts of Mars. Scientists chose it because they found it to be a relatively safe surface to land on and one that contained a wide variety of rocks deposited during a catastrophic flood. After the landing, at {{Coord|19.13|N|33.22|W|globe:Mars|display=inline,title}},<ref>{{cite web | url=http://mpfwww.jpl.nasa.gov/MPF/science/geology.html | title=Mars Pathfinder Science Results | work=NASA | access-date=June 9, 2008 | archive-url=https://web.archive.org/web/20080920093840/http://mpfwww.jpl.nasa.gov/MPF/science/geology.html | archive-date=September 20, 2008 | url-status=dead }}</ref> succeeded, the lander received the name ''The [[Biography:Carl Sagan|Carl Sagan]] Memorial Station'' in honor of the [[Astronomy:Astronomer|astronomer]].<ref>{{cite web|title=Mars lander renamed for Sagan|url=https://www.jpl.nasa.gov/releases/97/sagansta.html|publisher=NASA|access-date=September 5, 2017|archive-url=https://web.archive.org/web/20181211162346/https://www.jpl.nasa.gov/releases/97/sagansta.html|archive-date=December 11, 2018|url-status=live}}</ref> (See also [[Astronomy:List of extraterrestrial memorials|List of extraterrestrial memorials]])

{{Wide image|Mars pathfinder panorama large.jpg|1200px|''Mars Pathfinder'' panorama of landing site taken by IMP}}

==Entry, descent and landing==
[[File:Landing sequence.gif|thumb|Landing sequence]]
[[File:Mars Pathfinder.jpg|thumb|''Mars Pathfinder'' during final assembly showing the aeroshell, cruise ring and solid rocket motor]]

''Mars Pathfinder'' entered the Martian atmosphere and landed using an innovative system involving an entry capsule, a supersonic [[Engineering:Parachute|parachute]], followed by solid rockets and large airbags to cushion the impact.

''Mars Pathfinder'' directly entered Mars atmosphere in a retrograde direction from a hyperbolic trajectory at {{cvt|6.1|km/s|mph}} using an atmospheric entry aeroshell (capsule) that was derived from the original Viking Mars lander design. The aeroshell consisted of a back shell and a specially designed ablative heatshield to slow to {{cvt|370|m/s|mph}} where a supersonic disk-gap-band parachute was inflated to slow its descent through the thin Martian atmosphere to {{cvt|68|m/s|mph}}. The lander's on-board computer used redundant on-board accelerometers to determine the timing of the parachute inflation. Twenty seconds later the heatshield was pyrotechnically released. Another twenty seconds later the lander was separated and lowered from the backshell on a {{cvt|20|m|ft}} bridle. When the lander reached {{cvt|1.6|km|ft}} above the surface, a radar was used by the on-board computer to determine altitude and descent velocity. This information was used by the computer to determine the precise timing of the landing events that followed.<ref>{{Cite web|title=Mars Pathfinder - Entry Descent and Landing|url=https://mars.nasa.gov/MPF/mpf/edl/edl1.html|access-date=2021-02-16|website=mars.nasa.gov}}</ref>

[[File:Pathfinder Air Bags - GPN-2000-000484.jpg|thumb|right|200px|The ''Pathfinder'' air bags are tested in June 1995]]
Once the lander was {{cvt|355|m|ft}} above the ground, airbags were inflated in less than a second using three gas generators.<ref>{{Cite web|title=Mars Pathfinder Lander Description|url=https://pdsimage2.wr.usgs.gov/Missions/Mars_Pathfinder/mpim_0001/document/insthost.htm|access-date=31 March 2021|website=pdsimage.wr|publisher=USGS}}</ref> The airbags were made of four inter-connected multi-layer [[Chemistry:Vectran|vectran]] bags that surrounded the tetrahedron lander. They were designed and tested to accommodate grazing angle impacts as high as {{cvt|28|m/s|mph}}. However, as the airbags were designed for no more than about {{cvt|15|m/s|mph}} vertical impacts, three solid retrorockets were mounted above the lander in the backshell.<ref>{{Cite web|title=Rocket Assisted Descent – The RAD Rocket Motors|url=https://mars.nasa.gov/MPF/mpf/rad.html|access-date=2021-02-16|website=mars.nasa.gov}}</ref> These were fired at {{cvt|98|m|ft}} above the ground. The lander's on-board computer estimated the best time to fire the rockets and cut the bridle so that the lander velocity would be reduced to about zero between {{cvt|15|and|25|m|ft}} above the ground. After 2.3&nbsp;seconds, while the rockets were still firing, the lander cut the bridle loose about {{cvt|21.5|m|ft}} above the ground and fell to the ground. The rockets flew up and away with the backshell and parachute (they have since been sighted by orbital images). The lander impacted at {{cvt|14|m/s|mph}} and limited the impact to only 18&nbsp;G of deceleration. The first bounce was {{cvt|15.7|m|ft}} high and continued bouncing for at least 15 additional bounces (accelerometer data recording did not continue through all of the bounces).<ref>{{Cite journal|last1=Spencer|first1=David A.|last2=Blanchard|first2=Robert C.|last3=Braun|first3=Robert D.|last4=Kallemeyn|first4=Pieter H.|last5=Thurman|first5=Sam W.|date=March 1998|title=Mars Pathfinder Entry, Descent, and Landing Reconstruction|url=http://dx.doi.org/10.2514/2.3478|journal=Journal of Spacecraft and Rockets|volume=36|issue=3|pages=357–366|doi=10.2514/2.3478|issn=0022-4650}}</ref>

The entire entry, descent and landing process was completed in four minutes.

Once the lander stopped rolling, the airbags deflated and retracted toward the lander using four winches mounted on the lander "petals". Designed to right itself from any initial orientation, the lander happened to roll right side up onto its base petal. 87 minutes after landing, the petals were deployed with ''Sojourner'' rover and the solar panels attached on the inside.<ref name=nssdca/>

The lander arrived at night at 2:56:55 Mars local solar time (16:56:55 UTC) on July 4, 1997. The lander had to wait until sunrise to send its first digital signals and images to Earth. The landing site was located at 19.30° north latitude and 33.52° west longitude in Ares Vallis, only {{cvt|19|km|mi}} southwest of the center of the {{cvt|200|km|mi}} wide landing site ellipse. During [[Astronomy:Timekeeping on Mars#Sols|Sol]] 1, the first Martian solar day the lander spent on the planet, the lander took pictures and made some meteorological measurements. Once the data was received, the engineers realized that one of the airbags had not fully deflated and could be a problem for the forthcoming traverse of ''Sojourner''{{'}}s descent ramp. To solve the problem, they sent commands to the lander to raise one of its petals and perform additional retraction to flatten the airbag. The procedure was a success and on Sol 2, ''Sojourner'' was released, stood up and backed down one of two ramps.<ref name=nssdca>{{Cite web|title=NASA – NSSDCA – Spacecraft – Details|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1996-068A|access-date=2021-02-16|website=nssdc.gsfc.nasa.gov}}</ref>

==Rover operations==
{{further|Engineering:Sojourner (rover)}}

===''Sojourner'' deployment===
The ''Sojourner'' rover exit from the lander occurred on Sol 2, after its landing on July 4, 1997. As the next sols progressed it approached some rocks, which the scientists named "Barnacle Bill", "[[Astronomy:Yogi Rock|Yogi]]", and "Scooby-Doo", after famous [[Engineering:Cartoon|cartoon]] characters. The rover made measurements of the elements found in those rocks and in the martian soil, while the lander took pictures of the ''Sojourner'' and the surrounding terrain, in addition to making climate observations.

The ''Sojourner'' is a six-wheeled, {{cvt|65|cm|in|adj=on}} long vehicle, {{cvt|48|cm|in}} wide, {{cvt|30|cm|in}} tall and weighing {{cvt|10.5|kg|lb}}.<ref>{{Cite web |url=http://mepag.jpl.nasa.gov/meeting/mar-09/02_MEPAG_McCuistion_Mar_09.pdf |title=Mars – the search for life |date=March 4, 2009 |access-date=March 28, 2009 |publisher=NASA |archive-url=https://web.archive.org/web/20090327083233/http://mepag.jpl.nasa.gov/meeting/mar-09/02_MEPAG_McCuistion_Mar_09.pdf |archive-date=March 27, 2009 |url-status=dead }}</ref> Its maximum speed reached {{cvt|1|cm/s|in/s}}. ''Sojourner'' travelled approximately {{cvt|100|m|ft}} in total, never more than {{cvt|12|m|ft}} from the ''Pathfinder'' station. During its 83 [[Astronomy:Timekeeping on Mars#Sols|sols]] of operation, it sent 550 photographs to Earth and analyzed the [[Chemistry:Chemistry|chemical]] properties of 16 locations near the lander. (See also [[Astronomy:Rover (space exploration)|Space exploration rovers]])

===''Sojourner''{{'}}s rock analysis===
[[File:Sojourner and Barnacle Bill.jpg|thumb|''Sojourner'' next to the rock Barnacle Bill]]
The first analysis on a rock started on Sol 3 with Barnacle Bill. The Alpha Particle X-ray Spectrometer (APXS) was used to determine its composition, the spectrometer taking ten hours to make a full scan of the sample. It found all the elements except [[Chemistry:Hydrogen|hydrogen]], which constitutes just 0.1 percent of the rock's or soil's mass.

The APXS works by irradiating rocks and soil samples with [[Physics:Alpha particle|alpha particle]]s ([[Chemistry:Helium|helium]] [[Physics:Atomic nucleus|nuclei]], which consist of two [[Physics:Proton|proton]]s and two [[Physics:Neutron|neutron]]s). The results indicated that "Barnacle Bill" is much like Earth's [[Earth:Andesite|andesite]]s, confirming past [[Earth:Volcano|volcanic]] activity.  The discovery of andesites shows that some Martian rocks have been remelted and reprocessed.  On Earth, andesite forms when magma sits in pockets of rock while some of the iron and magnesium settle out.  Consequently, the final rock contains less iron and magnesiums and more silica.  Volcanic rocks are usually classified by comparing the relative amount of alkalis (Na<sub>2</sub>O and K<sub>2</sub>O) with the amount of silica (SiO<sub>2</sub>).  Andesite is different from the rocks found in meteorites that have come from Mars.<ref name="Golombek, M 1997"/><ref name="nssdc.gsfc.nasa.gov">{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/marspath/apxs.html |title=APXS Composition Results |work=NASA |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20160603120939/http://nssdc.gsfc.nasa.gov/planetary/marspath/apxs.html |archive-date=June 3, 2016 |url-status=live }}</ref><ref name="Bruckner, J. 2001">{{cite journal |last1=Bruckner |first1=J. |first2=G. |last2=Dreibus |first3=R. |last3=Rieder |first4=H. |last4=Wanke |year=2001 |title=Revised Data of the Mars Pathfinder Alpha Proton X-ray spectrometer: Geochemical Behavior of Major and Minor Elements |journal=Lunar and Planetary Science XXXII|page=1293 |bibcode=2001LPI....32.1293B }}</ref>

Analysis of the Yogi rock again using the APXS showed that it was a [[Earth:Basalt|basalt]]ic rock, more primitive than Barnacle Bill. Yogi's shape and texture show that it was probably deposited there by a [[Earth:Flood|flood]].

Another rock, named Moe, was found to have certain marks on its surface, demonstrating erosion caused by the wind. Most rocks analyzed showed a high content of [[Chemistry:Silicon|silicon]]. In another region known as Rock Garden, ''Sojourner'' encountered crescent moon-shaped dunes, which are similar to crescentic dunes on Earth.

By the time that final results of the mission were described in a series of articles in the journal ''Science'' (December 5, 1997), it was believed that the rock Yogi contained a coating of dust, but was similar to the rock Barnacle Bill.  Calculations suggest that the two rocks contain mostly the minerals orthopyroxene (magnesium-iron silicate), feldspars (aluminum silicates of potassium, sodium, and calcium), and quartz (silicon dioxide), with smaller amounts of magnetite, ilmenite, iron sulfide, and calcium phosphate.<ref name="Golombek, M 1997"/><ref name="nssdc.gsfc.nasa.gov"/><ref name="Bruckner, J. 2001"/>
{{Wide image|PIA01153.jpg|1200px|Annotated panorama of [[Earth:Rock (geology)|rocks]] near the [[Engineering:Sojourner (rover)|''Sojourner'' rover]] (December 5, 1997)}}

===On-board computer===

The [[Embedded system|embedded]] computer on board the ''Sojourner'' rover was based around the 2&nbsp;MHz<ref>{{cite web |url=http://mars.jpl.nasa.gov/MPF/rover/faqs_sojourner.html#cpu |title=Mars Pathfinder FAQs - Sojourner CPU |work=NASA |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20141229132636/http://mars.jpl.nasa.gov/MPF/rover/faqs_sojourner.html#cpu |archive-date=December 29, 2014 |url-status=live }}</ref> Intel 80C85 [[Central processing unit|CPU]] with 512&nbsp;[[Kilobyte|KB]] of RAM and 176&nbsp;KB of [[Flash memory|flash memory]] solid-state [[Engineering:Data storage device|storage]], running a [[Cyclic executive|cyclic executive]].<ref name="ieeecomputer">{{cite journal |first1=Max |last1=Bajracharya |first2=Mark W. |last2=Maimone |first3=Daniel |last3=Helmick |title=Autonomy for Mars rovers: past, present, and future |journal=Computer |publisher=[[Organization:IEEE Computer Society|IEEE Computer Society]] |date=December 2008 |volume=41 |number=12 |pages=44–50 |doi=10.1109/MC.2008.479 |s2cid=9666797 |issn=0018-9162 |url=http://users.etown.edu/w/wunderjt/ITALY_2009/PUBLICATION_MARS_SPIRIT_ALL_PATH_PLANNING_JPL.pdf |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20160304095252/http://users.etown.edu/w/wunderjt/ITALY_2009/PUBLICATION_MARS_SPIRIT_ALL_PATH_PLANNING_JPL.pdf |archive-date=March 4, 2016 |url-status=live }}</ref>

The computer of the ''Pathfinder'' lander was a [[Engineering:IBM RAD6000|Radiation Hardened IBM Risc 6000]] Single Chip (Rad6000 SC) [[Central processing unit|CPU]] with 128&nbsp;MB of RAM and 6&nbsp;MB of [[EEPROM]]<ref>{{cite web | url=http://quest.arc.nasa.gov/mars/ask/about-mars-path/pathfinder_computer.txt | title="QUESTION: What type of computer is the Pathfinder utilizing? ..." (NASA Quest Q&A) | date=1997 | access-date=July 21, 2015 | publisher=[[Organization:NASA|NASA]] | archive-url=https://web.archive.org/web/20160307043527/http://quest.arc.nasa.gov/mars/ask/about-mars-path/pathfinder_computer.txt | archive-date=March 7, 2016 | url-status=dead }}</ref><ref>{{cite web | url=http://quest.arc.nasa.gov/mars/ask/about-rover/Why_to_use_a_80C85_microprocessor_in_Rover_.txt | title="QUESTION: When it was designed, why was only a single 80C85 CPU used? ..." (NASA Quest Q&A) | date=1997 | access-date=July 21, 2015 | publisher=[[Organization:NASA|NASA]] | archive-url=https://web.archive.org/web/20150723003545/http://quest.arc.nasa.gov/mars/ask/about-rover/Why_to_use_a_80C85_microprocessor_in_Rover_.txt | archive-date=July 23, 2015 | url-status=dead }}</ref> and its [[Operating system|operating system]] was [[Software:VxWorks|VxWorks]].<ref name=Wind_River>{{cite web | url=http://www.windriver.com/news/press/pr.html?ID=314 | title=Wind River Powers Mars Exploration Rovers—Continues Legacy as Technology Provider for NASA's Space Exploration | date=June 6, 2003 | access-date=August 28, 2009 | publisher=[[Company:Wind River Systems|Wind River Systems]] | archive-url=https://web.archive.org/web/20100106090354/http://www.windriver.com/news/press/pr.html?ID=314 | archive-date=January 6, 2010 | url-status=live }}</ref>

The mission was jeopardised by a [[Concurrent computing|concurrent]] software bug in the lander,<ref>Parallel sparking: Many chips make light work, Douglas Heaven, ''New Scientist'' magazine, issue 2930, August 19, 2013, p44. [https://www.newscientist.com/article/mg21929301.000-parallel-sparking-many-chips-make-light-work.html?page=2 Online (by subscription)] {{Webarchive|url=https://web.archive.org/web/20141006101728/http://www.newscientist.com/article/mg21929301.000-parallel-sparking-many-chips-make-light-work.html?page=2 |date=October 6, 2014 }}</ref> which had been found in preflight testing but was deemed a glitch and therefore given a low priority as it only occurred in certain unanticipated heavy-load conditions, and the focus was on verifying the entry and landing code. The problem, which was reproduced and corrected from Earth using a laboratory duplicate thanks to the logging and debugging functionality enabled in the flight software, was due to [[Reset (computing)|computer resets]] caused by [[Priority inversion|priority inversion]]. No scientific or engineering data was lost after a computer reset, but all the following operations were interrupted until the next day.<ref>{{cite web |url=http://research.microsoft.com/en-us/um/people/mbj/Mars_Pathfinder/Authoritative_Account.html |title=What really happened on Mars? – Authoritative Account |first=Glenn E. |last=Reeves |work=Microsoft.com |date=December 15, 1997 |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20150611035733/http://research.microsoft.com/en-us/um/people/mbj/mars_pathfinder/authoritative_account.html |archive-date=June 11, 2015 |url-status=live }}</ref><ref>{{cite web |url=http://research.microsoft.com/en-us/um/people/mbj/Mars_Pathfinder/ |title=What really happened on Mars? |first=Michael B. |last=Jones |work=Microsoft.com |date=December 16, 1997 |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20150612010836/http://research.microsoft.com/en-us/um/people/mbj/mars_pathfinder/ |archive-date=June 12, 2015 |url-status=live }}</ref> Four resets occurred (on July 5, 10, 11 and 14) during the mission,<ref>{{cite web|url= http://www.oarval.org/missionsr2.htm|title= The Mars Pathfinder Mission Status Reports &mdash; Second Week|publisher= Office of the Flight Operations Manager &ndash; Mars Pathfinder Project|access-date= October 24, 2015|archive-url= https://web.archive.org/web/20160104210211/http://www.oarval.org/missionsr2.htm|archive-date= January 4, 2016|url-status= live}}</ref> before patching the software on July 21 to enable [[Priority inheritance|priority inheritance]].<ref>{{cite web|url= http://www.oarval.org/missionsr3.htm|title= The Mars Pathfinder Mission Status Reports &mdash; Third Week|publisher= Office of the Flight Operations Manager &ndash; Mars Pathfinder Project|access-date= October 24, 2015|archive-url= https://web.archive.org/web/20160410091935/http://www.oarval.org/missionsr3.htm|archive-date= April 10, 2016|url-status= live}}</ref>

==Results from ''Pathfinder''==
[[File:Mars sunset PIA00920.jpg|thumb|Close-up of Mars sky at sunset, by ''Mars Pathfinder'' (1997)]]
The lander sent more than 2.3 billion bits (287.5 megabytes) of information including 16,500 pictures and made 8.5 million measurements of the [[Physics:Atmospheric pressure|atmospheric pressure]], temperature and wind speed.<ref name=jplpathfinder>{{cite web|url=http://www.nasa.gov/mission_pages/mars-pathfinder/|title=Mars Pathfinder and Sojourner|work=NASA|access-date=June 10, 2015|archive-url=https://web.archive.org/web/20150623112234/http://www.nasa.gov/mission_pages/mars-pathfinder/|archive-date=June 23, 2015|url-status=live}}</ref>

By taking multiple images of the sky at different distances from the Sun, scientists were able to determine that the size of the particles in the pink haze was about one [[Micrometre|micrometre]] in radius.  The color of some soils was similar to that of an iron oxyhydroxide phase which would support the theory of a warmer and wetter climate in the past.<ref>Smith, P. et al.  1997.  "Results from the Mars Pathfinder Camera" ''Science'': 278.  1758–1765</ref> ''Pathfinder'' carried a series of magnets to examine the magnetic component of the dust. Eventually, all but one of the magnets developed a coating of dust.  Since the weakest magnet did not attract any soil, it was concluded that the airborne dust did not contain pure [[Chemistry:Magnetite|magnetite]] or just one type of [[Chemistry:Maghemite|maghemite]]. The dust probably was an aggregate possibly cemented with ferric oxide (Fe<sub>2</sub>O<sub>3</sub>).<ref>Hviid, S.  et al.  1997.  "Magnetic Properties Experiments on the Mars Pathfinder Lander:  Preliminary Results".  ''Science'':278.  1768–1770.</ref> Using much more sophisticated instruments, Mars ''Spirit'' rover found that magnetite could explain the magnetic nature of the dust and soil on Mars.  Magnetite was found in the soil and that the most magnetic part of the soil was dark.  Magnetite is very dark.<ref>Bertelsen, P. et al.  2004.  "Magnetic Properties Experiments on the Mars Exploration rover Spirit at Gusev Crater".  ''Science'': 305. 827–829.</ref>

Using [[Physics:Doppler tracking|Doppler tracking]] and two-way ranging, scientists added earlier measurements from the ''Viking'' landers to determine that the non-hydrostatic component of the polar [[Physics:Moment of inertia|moment of inertia]] is due to the Tharsis bulge and that the interior is not melted. The central metallic core is between {{cvt|1300|and|2000|km|mi}} in radius.<ref name="Golombek, M 1997">Golombek, M. et al. 1997.  "Overview of the Mars Pathfinder Mission and Assessment of Landing Site Predictions".  ''Science''. Science: 278.  pp. 1743–1748</ref>

==End of mission==<!-- This section is linked from [[Biography:Carl Sagan|Carl Sagan]] -->
[[File:MPT Hardware on the Surface MRO picture.jpg|thumb|left|''Mars Pathfinder'' seen from space by the [[Astronomy:Mars Reconnaissance Orbiter|MRO]] HiRISE]]
Although the mission was planned to last from a week to a month, the rover operated successfully for almost three months. Communication failed after October 7,<ref name=batteryfailure/> with a final data transmission received from Pathfinder at 10:23 UTC on September 27, 1997. Mission managers tried to restore full communications during the following five months, but the mission was terminated on March 10, 1998. During the extended operation a high-resolution stereo panorama of the surrounding terrain was being made, and the Sojourner rover was to visit a distant ridge, but the panorama was only about one-third completed and the ridge visit had not begun when communication failed.<ref name=batteryfailure/>

The on-board battery—designed to operate for one month—may have failed after repeated charging and discharging. The battery was used to heat the probe's electronics to slightly above the expected nighttime temperatures on Mars. With the failure of the battery, colder-than-normal temperatures may have caused vital parts to break, leading to loss of communications.<ref name=batteryfailure>{{cite web |url=http://news.sciencemag.org/sciencenow/1997/10/27-04.html |title=Mars Pathfinder Nearing Its End |work=sciencemag.org |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20130621151651/http://news.sciencemag.org/sciencenow/1997/10/27-04.html |archive-date=June 21, 2013 |url-status=dead }}</ref><ref name=nasafacts>{{Cite web |url=http://www.jpl.nasa.gov/news/fact_sheets/mpf.pdf |title=NASA facts - Mars Pathfinder |website=[[Organization:Jet Propulsion Laboratory|Jet Propulsion Laboratory]] |access-date=September 30, 2013 |archive-url=https://web.archive.org/web/20130513063945/http://www.jpl.nasa.gov/news/fact_sheets/mpf.pdf |archive-date=May 13, 2013 |url-status=live }}</ref>  The mission had exceeded its goals in the first month.

''[[Astronomy:Mars Reconnaissance Orbiter|Mars Reconnaissance Orbiter]]'' spotted the ''Pathfinder'' lander in January 2007 (left).<ref>{{cite news |url=https://www.newscientist.com/article/dn10945 |title=Mars probe may have spotted lost rover |date=January 12, 2007 |first=Maggie |last=McKee |work=New Scientist |access-date=September 4, 2017 |archive-url=https://web.archive.org/web/20150424095729/http://www.newscientist.com/article/dn10945 |archive-date=April 24, 2015 |url-status=live }}</ref><ref>{{cite web |url=http://www.nasa.gov/mission_pages/MRO/multimedia/pia09105.html |title=Mars Pathfinder Landing Site and Surroundings |work=NASA |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20150520190938/http://www.nasa.gov/mission_pages/MRO/multimedia/pia09105.html |archive-date=May 20, 2015 |url-status=live }}</ref>

==Naming the rover==
[[File:Pathfinder01.jpg|thumb|300px|''Sojourner'' takes its Alpha Particle X-ray Spectrometer measurement of the [[Astronomy:Yogi Rock|Yogi Rock]]]]
The name ''Sojourner'' was chosen for the ''Mars Pathfinder'' rover when 12-year old Valerie Ambroise, of Bridgeport, Connecticut, won a year-long, worldwide competition in which students up to 18 years old were invited to select a heroine and submit an essay about her historical accomplishments. The students were asked to address in their essays how a planetary rover named for their heroine would translate these accomplishments to the Martian environment.

Initiated in March 1994 by [[Organization:The Planetary Society|The Planetary Society]] of Pasadena, California, in cooperation with NASA's Jet Propulsion Laboratory (JPL), the contest got under way with an announcement in the January 1995 issue of the National Science Teachers Association's magazine ''Science and Children'', circulated to 20,000 teachers and schools across the nation.<ref>{{cite web|title=NASA Names First Rover to Explore the Surface of Mars|url=http://mars.jpl.nasa.gov/MPF/rover/name.html|publisher=NASA|access-date=November 29, 2010|archive-url=https://web.archive.org/web/20110607010535/http://mars.jpl.nasa.gov/MPF/rover/name.html|archive-date=June 7, 2011|url-status=live}}</ref>

Ambroise's winning essay, which suggested naming the rover for the 19th century women's rights activist Sojourner Truth, was selected from among 3,500 essays. First runner-up was Deepti Rohatgi, 18, of Rockville, Maryland, who suggested scientist [[Biography:Marie Curie|Marie Curie]]. Second runner-up was Adam Sheedy, 15, of Round Rock, Texas, who submitted the name of the late astronaut Judith Resnik, who perished in the 1986 [[Engineering:Space Shuttle Challenger|Space Shuttle ''Challenger'']] explosion. Other popular suggestions included explorer and guide Sacajewea and aviator Amelia Earhart.<ref>{{cite web |url=http://mars.jpl.nasa.gov/MPF/rover/name.html |title=Pathfinder Rover Gets Its Name |work=NASA |access-date=June 10, 2015 |archive-url=https://web.archive.org/web/20150527055515/http://mars.jpl.nasa.gov/MPF/rover/name.html |archive-date=May 27, 2015 |url-status=live }}</ref>

==Honors==
* In 1997, the Sojourner Team was awarded a JPL Award for Technical Excellence
* On October 21, 1997, at the Geological Society of America's annual meeting in Salt Lake City, Utah, ''Sojourner'' was awarded honorary membership in the Planetary Geology Division of the society<ref>{{Cite journal|title=Division Activity at Recent Meetings |journal=Planetary Geology Division Newsletter |volume=16 |issue=1 |pages=1 |date=1997 |url=https://www.unb.ca/passc/GSA/Newsletters.img/formatted%20newsletter%201998.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110608004417/http://www.unb.ca/passc/GSA/Newsletters.img/formatted%20newsletter%201998.pdf |archive-date=June 8, 2011 }}</ref>
* In 2003, ''Sojourner'' was inducted into the Robot Hall of Fame

== In popular culture ==
* The opening title sequence of the television series ''Star Trek: Enterprise'' features footage of ''Sojourner'' on the Martian surface, intermixed with various other images representative of humankind's evolution of air and space flight.
* In the 2000 film ''Red Planet'', astronauts stranded on Mars make a makeshift radio from parts of ''Pathfinder'', and use it to communicate with their spaceship.
* In the 2011 novel ''The Martian'' by Andy Weir, and its 2015 film adaptation, the protagonist, Mark Watney, who is stranded alone on Mars, travels to the long-dead ''Pathfinder'' site (noting the "Twin Peaks" as a landmark in the novel), and returns it to his base in an attempt to communicate with Earth.<ref>{{cite book|last=Weir|first=Andy|title=The Martian|year=2014|location={{wipe|New York City}}|publisher=Crown Publishers|isbn=978-0-8041-3902-1}}</ref>

==''Sojourner''{{'s}} location in context==
{{Features and artificial objects on Mars}}

==See also==
* {{annotated link|Astronomy:Exploration of Mars}}
* {{annotated link|Astronomy:Life on Mars}}
* [[Astronomy:List of missions to Mars|List of missions to Mars]]
* {{annotated link|Astronomy:Mars Exploration Rover}}
* {{annotated link|Organization:Mars Science Laboratory}}
* {{annotated link|Astronomy:Mars 2020}}
* Comparison of embedded computer systems on board the Mars rovers

==Notes==
{{Reflist|2}}

==References==
{{Refbegin|2}}
* [https://web.archive.org/web/20050413001059/http://mpfwww.jpl.nasa.gov/missions/past/pathfinder.html JPL ''Mars Pathfinder'' article]
* ''Mars Pathfinder Litograph Set'', NASA. (1997)
* Poster: ''Mars Pathfinder –Roving the Red Planet'', NASA. (1998)
* ''Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958–2000'', Asif A. Siddiqi. Monographs in Aerospace History, #24. June 2002, NASA History Office.
* "Return to Mars", article by William R. Newcott. ''National Geographic'', pp.&nbsp;2–29. Vol. 194, 2nd edition – August 1998.
* "La misión Pathfinder –rebautizada Carl Sagan Memorial Station, en memoria del célebre astrónomo-, paso a paso todo Marte", de J. Roberto Mallo. ''Conozca Más'', págs. 90–96. Edición número 106 – agosto de 1997.
* "Un espía que anda por Marte", de Julio Guerrieri. ''Descubrir'', págs. 80–83. Edición número 73 – agosto de 1997.
* "Mars Pathfinder: el inicio de la conquista de Marte" ''EL Universo, Enciclopedia de la Astronomía y el Espacio'', Editorial Planeta-De Agostini, págs. 58–60. Tomo 5. (1997)
* ''Sojourner: An Insider's View of the Mars Pathfinder Mission'', by Andrew Mishkin, Senior Systems Engineer, NASA Jet Propulsion Laboratory. {{ISBN|0-425-19199-0}}
* ''Experiences with operations and autonomy of the Mars Pathfinder microrover'', A. H. Mishkin, J. C. Morrison, T. T. Nguyen, H. W. Stone, B. K. Cooper and B. H. Wilcox. In Proceedings of the IEEE Aerospace Conference, Snowmass, CO 1998.
{{Refend}}

==External links==
* [https://web.archive.org/web/20090717155620/http://mpfwww.jpl.nasa.gov/MPF/index0.html ''Mars Pathfinder'' NASA/JPL Website]

{{Planetary Missions Program Office|Discovery=y}}
{{Mars spacecraft}}
{{Jet Propulsion Laboratory}}

[[Category:Derelict landers (spacecraft)]]
[[Category:Discovery Program]]
[[Category:Missions to Mars]]
[[Category:NASA space probes]]
[[Category:Oxia Palus quadrangle]]
[[Category:Six-wheeled robots]]
[[Category:Soft landings on Mars]]

{{Sourceattribution|Mars Pathfinder}}