Mars Pathfinder

Mars Pathfinder (MESUR Pathfinder)[1][4] is an American robotic spacecraft that landed a base station with a roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight (10.6 kg/23 lb) wheeled robotic Mars rover named Sojourner,[5] which became the first rover to operate outside the Earth–Moon system.

Launched on December 4, 1996 by NASA aboard a Delta II booster a month after the Mars Global Surveyor was launched, it landed on July 4, 1997 on Mars's Ares Vallis, in a region called Chryse Planitia in the Oxia Palus quadrangle. The 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, climate, geology and the composition of its rocks and soil. It was the second project from NASA's Discovery Program, which promotes the use of low-cost spacecraft and frequent launches under the motto "cheaper, faster and better" promoted by the then administrator, Daniel Goldin. The mission was directed by the Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology, responsible for NASA's 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 Vikings landed on the red planet in 1976. Although the Soviet Union successfully sent rovers to the Moon as part of the Lunokhod program in the 1970s, its attempts to use rovers in its Mars program failed.

In addition to scientific objectives, the Mars Pathfinder mission was also a "proof-of-concept" for various technologies, such as airbag-mediated touchdown and automated obstacle avoidance, both later exploited by the 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.

Mars Pathfinder
A group of scientists, all wearing white protective clothing, gather around a spacecraft as it's being folded into its launch position; a triangular pyramid shape.
Pathfinder and Sojourner at JPL in October 1996, being 'folded' into its launch position.[1]
Mission typeLander · Rover (Mars)
OperatorNASA · Jet Propulsion Laboratory
COSPAR ID1996-068A
SATCAT no.24667
Mission durationPathfinder: 85 days
Sojourner: 7 days
Launch to last contact: 9 months, 23 days
Spacecraft properties
Launch mass"890 kg (Includes Propellant)"[2]
PowerPathfinder: 35 W
Sojourner: 13 W
Start of mission
Launch dateDecember 4, 1996 06:58:07 UTC
(22 years, 1 month and 7 days ago)
RocketDelta II 7925 (#D240)
Launch siteCape Canaveral SLC-17
End of mission
Last contactSeptember 27, 1997 10:23 UTC
(21 years, 3 months and 15 days ago)
Mars lander
Landing dateJuly 4, 1997 16:56:55 UTC
(21 years, 6 months and 7 days ago)
Landing siteAres Vallis, Chryse Planitia, Mars
19°7′48″N 33°13′12″W / 19.13000°N 33.22000°W
BandX-Band with high-gain antenna
Bandwidth6 kb/s to 70m Deep Space Network, 250 b/s to surface command[2]
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 · JPL" are written on the bottom.

Official insignia of the Mars Pathfinder mission.

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 million).
  • 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 Viking mission. (For comparison, the Viking missions cost $935 million in 1974[6] or $3.5 billion in 1997 dollars.)
  • To demonstrate NASA's commitment to low-cost planetary exploration by finishing the mission with a total expenditure of $280 million, including the launch vehicle and mission operations.

Science experiments

Sojourner on Mars PIA01122
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 stereoscopic camera with spatial filters on an expandable pole called Imager for Mars Pathfinder (IMP),[7][8] and the Atmospheric Structure Instrument/Meteorology Package (ASI/MET)[9] which acts as a Mars meteorological station, collecting data about pressure, temperature, and winds. The MET structure included three windsocks mounted at three heights on a pole, the topmost at about one meter (yard) and generally registered winds from the West.[10]

The Sojourner rover had an Alpha Proton X-ray Spectrometer (APXS),[11] 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 geochemistry and evolutionary history of the rocks and surface, the magnetic and mechanical properties of the land, as well as the magnetic properties of the dust, atmosphere and the rotational and orbital dynamics of the planet.

H rover-comp wheels 02
Wheel size comparison: Sojourner, Mars Exploration Rover, Mars Science Laboratory

Three navigation cameras were on board the rover: Two black and white 0.3-megapixel cameras were located on the front (768 horizontal pixels × 484 vertical pixels configured in 4×4+100 pixel blocks), coupled with five laser stripe projectors, which enabled stereoscopic images to be taken along with measurements for hazard detection on the rover's path. A third camera with the same resolution but taking color images was located on the back, near the APXS, and rotated by 90°. It provided images of the APXS's target area and the rover's tracks on the ground. The pixels of this colour camera were arranged in such a way, that out of the 16 pixel of a 4×4 pixel block, 12 pixel were sensitive to green, 2 pixel to red and 2 pixel were sensitive to infrared as well as blue. As all cameras had lenses made out of zinc selenide, which blocks light below a wavelength of 500 nm, no blue light actually reached these "blue/infrared" pixels, which therefore recorded only infrared.

All three cameras were CCDs manufactured by Eastman Kodak Company, and were controlled by the rover's CPU. They all had auto-exposure and capabilities for handling bad pixels, and the image parameters (exposure time, compression used, etc.) were included in the transmitted images as part of the image header. The rover could compress the front cameras' images using the block truncation coding (BTC) algorithm, but it could only do the same for the back camera's images if the colour information was discarded. The cameras' optical resolution was sufficient to resolve 0.6 cm details across a 0.65 m range.[12]

Pathfinder lander

  1. Imager for Mars Pathfinder (IMP), (includes magnetometer and anemometer)
  2. Atmospheric and meteorological sensors (ASI/MET)

Sojourner rover

  1. Imaging system (three cameras: front B&W stereo,[12] 1 rear color)
  2. Laser striper hazard detection system
  3. Alpha Proton X-ray Spectrometer (APXS)
  4. Wheel Abrasion Experiment
  5. Materials Adherence Experiment
  6. Accelerometers

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 19°08′N 33°13′W / 19.13°N 33.22°WCoordinates: 19°08′N 33°13′W / 19.13°N 33.22°W,[13] succeeded, the lander received the name The Carl Sagan Memorial Station in honor of the astronomer.[14] (See also List of extraterrestrial memorials)

Mars Pathfinder panorama of landing site taken by IMP
Mars Pathfinder panorama of landing site taken by IMP

Entry, descent and landing

Atmospheric entry
1990s illustration of Mars atmospheric entry

Mars Pathfinder entered the Martian atmosphere and landed using an innovative system involving an entry capsule, a supersonic 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 6.1 km/s 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 370 m/s (830 mph) where a supersonic disk-gap-band parachute was inflated to slow its descent through the thin Martian atmosphere to 68 m/s (about 160 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 20 m bridle (tether). When the lander reached 1.6 km 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.

Pathfinder Air Bags - GPN-2000-000484
The Pathfinder air bags are tested in June 1995

Once the lander was 355 m above the ground, airbags were inflated in less than a second using three catalytically cooled solid rocket motors that served as gas generators. The airbags were made of 4 inter-connected multi-layer vectran bags that surrounded the tetrahedron lander. They were designed and tested to accommodate grazing angle impacts as high as 28 m/s. However, as the airbags were designed for no more than about 15 m/s vertical impacts, three solid retrorockets were mounted above the lander in the backshell. These were fired at 98 m 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 0 m/s between 15 and 25 m above the ground. After 2.3 seconds, while the rockets were still firing, the lander cut the bridle loose about 21.5 m 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 14 m/s and limited the impact to only 18 G of deceleration. The first bounce was 15.7 m high and continued bouncing for at least 15 additional bounces (accelerometer data recording did not continue through all of the bounces).

The entire entry, descent and landing (EDL) process was completed in four minutes.[15]

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. 74 minutes after landing, the petals were deployed with Sojourner rover and the solar panels attached on the inside.

Pan segment1
IMP image of landing site in 1997

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 19 kilometres southwest of the center of the 200 km wide landing site ellipse. During Sol 1, the first Martian solar day the lander spent on the planet, the lander took pictures and made some meteorologic measurements. Once the data was received, the engineers realized that one of the airbags hadn't 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.

The Mars Pathfinder entry descent and landing system design was used (with some modification) on the Mars Exploration Rover mission. Likewise, many design aspects of the Sojourner rover (e.g. the rocker-bogie mobility architecture and the navigation algorithms) were also successfully used on the Mars Exploration Rover mission.

Rover operations

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", "Yogi", and "Scooby-Doo", after famous 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 65 cm long vehicle, 48 cm wide, 30 cm tall and weighing 10.5 kg.[16] Its maximum speed reached one centimeter per second. Sojourner travelled approximately 100 metres in total, never more than 12 m from the Pathfinder station. During its 83 sols of operation, it sent 550 photographs to Earth and analyzed the chemical properties of 16 locations near the lander. (See also Space exploration rovers)

Sojourner's rock analysis

Sojourner and Barnacle Bill
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 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 alpha particles (helium nuclei, which consist of two protons and two neutrons). The results indicated that "Barnacle Bill" is much like Earth's andesites, confirming past 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 (Na2O and K2O) with the amount of silica (SiO2). Andesite is different from the rocks found in meteorites that have come from Mars.[17][18][19]

Analysis of the Yogi rock again using the APXS showed that it was a basaltic rock, more primitive than Barnacle Bill. Yogi's shape and texture show that it was probably deposited there by a 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 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), quartz (silicon dioxide), with smaller amounts of magnetite, ilmenite, iron sulfide, and calcium phosphate.[17][18][19]

Annotated panorama of rocks near the Sojourner rover (December 5, 1997)
Annotated panorama of rocks near the Sojourner rover (December 5, 1997)

On-board computer

The embedded computer on board the Sojourner rover was based around the 2 MHz[20] Intel 80C85 CPU with 512 KB of RAM and 176 KB of flash memory solid-state storage, running a cyclic executive.[21]

The computer of the Pathfinder lander was a Radiation Hardened IBM Risc 6000 Single Chip (Rad6000 SC) CPU with 128 MB of RAM and 6 MB of EEPROM[22][23] and its operating system was VxWorks.[24]

The mission was jeopardised by a concurrent software bug in the lander,[25] 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 computer resets caused by priority inversion. No scientific or engineering data was lost after a computer reset, but all the following operations were interrupted until the next day.[26][27] Four resets occurred (on July 5, 10, 11 and 14) during the mission,[28] before patching the software on July 21 to enable priority inheritance.[29]

Results from Pathfinder

Mars sunset PIA00920
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 atmospheric pressure, temperature and wind speed.[30]

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 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.[31] 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 magnetite or just one type of maghemite. The dust probably was an aggregate possibly cemented with ferric oxide (Fe2O3).[32] 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.[33]

Using Doppler tracking and two-way ranging, scientists added earlier measurements from the Viking landers to determine that the non-hydrostatic component of the polar moment of inertia is due to the Tharsis bulge and that the interior is not melted. The central metallic core is between 1300 km and 2000 km in radius.[17]

End of mission

MPT Hardware on the Surface MRO picture
Mars Pathfinder seen from space by the 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 7 October,[34] 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.[34]

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.[34][35] The mission had exceeded its goals in the first month.

Mars Reconnaissance Orbiter spotted Pathfinder lander in January 2007 (left).[36][37]

Naming the rover

Sojourner takes its Alpha Particle X-ray Spectrometer measurement of the Yogi Rock

The name Sojourner was chosen for the Mars Pathfinder rover after 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 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.[38]

The winning essay, which suggested naming the rover for Sojourner Truth, was selected from among 3,500 essays and was submitted by 12-year-old Valerie Ambroise of Bridgeport, CT. First runner-up was Deepti Rohatgi, 18, of Rockville, MD, who suggested Marie Curie. Second runner-up was Adam Sheedy, 15, of Round Rock, TX, who submitted the name of the late astronaut Judith Resnik, who perished in the 1986 Challenger space shuttle explosion. Other popular suggestions included Sacajewea and Amelia Earhart.[39]


In popular culture

  • 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.[41]

See also


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  • This article draws heavily on the corresponding article in the Spanish-language Wikipedia, which was accessed in the version of March 28, 2005.
  • 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.
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  • "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.
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  • 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
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The image above contains clickable linksInteractive imagemap of the global topography of Mars, overlain with locations of Mars landers and rovers. Hover your mouse to see the names of over 25 prominent geographic features, and click to link to them. Coloring of the base map indicates relative elevations, based on data from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor. Whites and browns indicate the highest elevations (+12 to +8 km); followed by reds and pinks (+3 to +8 km); yellow is 0 km; greens and blues are lower elevation (down to −8 km). Axes are latitude and longitude; Poles are not shown.
(See also: Mars map, Mars Memorials, Mars Memorials map) (view • discuss)
(  Rover;   Lander;   Future)
Alpha particle X-ray spectrometer

APXS is also an abbreviation for APache eXtenSion tool, an extension for Apache web servers.An alpha particle X-ray spectrometer (APXS) is a spectrometer that analyses the chemical element composition of a sample from the scattered alpha particles, and fluorescent X-rays after the sample is irradiated with alpha particles and X-rays from radioactive sources. This method of analysing the elemental composition of a sample is most often used on space missions, which require low weight, small size, and minimal power consumption. Other methods (e.g. mass spectrometry) are faster, and do not require the use of radioactive materials, but require larger equipment with less modest power requirements. A variation is the alpha proton X-ray spectrometer, such as on the Pathfinder mission, which also detects protons.

Over the years several modified versions of this type of instrument such as APS (without X-ray spectrometer) or APXS have been flown: Surveyor 5-7, Mars Pathfinder, Mars 96, Mars Exploration Rover, Phobos, Mars Science Laboratory and the Philae comet lander. APS/APXS devices will be included on several upcoming missions including the Chandrayaan-2 lunar rover.

Amitabha Ghosh

Amitabh Ghosh is an Indian planetary geologist. Amitabh did his schooling from Don Bosco Park circus, Kolkata. An IITian from Kharagpur he was a key member of the team who identified the landing site for Curiosity, the Gale crater location. Ghosh has played prominent role in various other missions by NASA such as Mars Pathfinder Mission and MER (Mars Exploration Rover) mission. He was the only Asian in the Pathfinder mission by NASA.

He has been honoured with NASA Mars Pathfinder Achievement Award in the year 1997 and the NASA Mars Exploration Rover Achievement Award in 2004, for his marvelous contributions.

Ares Vallis

Ares Vallis is an outflow channel on Mars, named after the Greek name for Mars: Ares, the god of war; it appears to have been carved by fluids, perhaps water. The valley 'flows' northwest out of the hilly Margaritifer Terra, where the Iani Chaos depression (180 km long and 200 km wide) is connected to the beginning of Ares Vallis by a 100 km wide transition zone centered on 342.5° East (17.5 West) and 3° North. It then continues through the ancient Xanthe Terra highlands, and ends in a delta-like region of Chryse Planitia. Ares Vallis was the landing site of NASA's Mars Pathfinder spacecraft, which studied a region of the valley near the border with Chryse in 1997.

Ares Vallis is in the Oxia Palus quadrangle of Mars.

It has been argued that Uzboi, Ladon, Margaritifer and Ares valles, although now separated by large craters, once comprised a single outflow channel flowing north into Chryse Planitia. The source of this outflow has been suggested as overflow from the Argyre Crater, formerly filled to the brim as a lake by channels (Surius, Dzigai, and Palacopus Valles) draining down from the south pole. If real, the full length of this drainage system would be over 8000 km, the longest known drainage path in the solar system. Under this suggestion, the extant form of the outflow channel Ares Vallis would thus be a remolding of a pre-existing structure. This long path for water flow has been named the * Uzboi-Landon-Morava (ULM) system. Water from this system may have helped to form Ares Vallis.

Research, published in January 2010, suggests that Mars had lakes, each around 20 km wide, along parts of the equator. Although earlier research showed that Mars had a warm and wet early history that has long since dried up, these lakes existed in the Hesperian Epoch, a much earlier period. Using detailed images from NASA's Mars Reconnaissance Orbiter, the researchers speculate that there may have been increased volcanic activity, meteorite impacts or shifts in Mars' orbit during this period to warm Mars' atmosphere enough to melt the abundant ice present in the ground. Volcanoes would have released gases that thickened the atmosphere for a temporary period, trapping more sunlight and making it warm enough for liquid water to exist. In this new study, channels were discovered that connected lake basins near Ares Vallis. When one lake filled up, its waters overflowed the banks and carved the channels to a lower area where another lake would form. These lakes would be another place to look for evidence of present or past life.

Barnacle Bill (Martian rock)

Barnacle Bill is a 40-centimetre (16 in) rock on Mars in Ares Vallis. It was the first rock on Mars analyzed by the Sojourner rover using its Alpha Proton X-ray Spectrometer. The encounter occurred during Sol 3 of the Mars Pathfinder mission on the surface of Mars and took ten hours to complete.

Early analysis of data sent from Sojourner led scientists to speculate that the rock was andesite.

The name was inspired in mission scientists by barnacle-like structures on the rock that appeared in transmitted photos.


The HUSAR rover is part of the Hunveyor system. Like as Hunveyor (Hungarian UNiversity SURVEYOR) is an experimental university lander model, so the HUSAR is (Hungarian University Surface Analyser Rover) an experimental university rover model. This rover accompanies the Hunveyor as like Sojourner was accompanying the Mars Pathfinder lander. For the Hunveyor the Surveyor was the example, for the Husar-rover the Mars Pathfinder-Sojourner system was the example from the real space exploration world.

The Hunveyor-Husar system is an educational work at Hungarian Universities, Colleges and High Schools. There are smaller and larger model-cars supported by onboard computer, camera and some additional instrumentation. The building of the Husar-rover types is focusing on the basic planetary surface activities by moving vehicle. The rover has a solar panel on its board placed on a model-car chassis. In the Husar-b version the drive is on the back wheels by electric engines, movements are controlled by the camera view through a wireless connection to the computer. It can be used for roving among rocks and observing their surfaces. On a larger chassis Husar-2a version there are independent driving on all the four wheels. This fact allows directing a special movement. The rover can turn in a very narrow arc which is important to approach objects in side direction. The wheels in one axis are connected by a differential. The structural framework, the driving mechanism all have a left- and right-hand side symmetric structure. The movements are directed through servo engines, which were originally designed for analogous direction, however, even 8 of these servos can be directed by a microcontroller. This microcontroller gets the position of the servos through RS 232 port of the computer. The camera of Husar-2 transmits images with 30 frame/sec, and it has wireless connection with the computer (1200 MHz).

In a planetary simulation work we use testfields which are analog to a selected planetary surface. On the testfields (test table) the most important rock types from the Solar System are arranged around the Hunveyor and Husar. For example, desert sand morphology (according to the observations of Mars Pathfinder) can be modelled around lander and rover in order to give a real planetary environment for simulation studies. Complex studies of the main streams in the surface, wind system and rock interactions also can be modelled. (i.e. stream strength of the wind can be deciphered from the deposition of deflation style of the lee-forms). We show one of our test-fields around Hunveyor and Husar.

Husar rovers were built with Hunveyor-1, -2, and -4 landers, and they were independently built by the Husar-5 and Husar-6 groups at Budapest, Pécs, Székesfehérvár, Sopron and Dorog.

List of artificial objects on Mars

The following table is a partial list of artificial objects on the surface of Mars, consisting of spacecraft which were launched from Earth. Most are defunct after having served their purpose, but the Curiosity rover and the InSight lander are still operational as of 2018. InSight is the most recent artificial object to land safely on Mars. The table does not include smaller objects, such as springs, fragments, parachutes and heat shields. As of November 5, 2016, there are about 14 spacecraft missions on the surface of Mars: some of these missions have multiple spacecraft.

List of extraterrestrial memorials

List of extraterrestrial memorials is a list of different types of memorials that are not on Earth.


MESUR, the Mars Environmental SURvey was a NASA program designed to explore the planet Mars in preparation for human follow-up missions of the Space Exploration Initiative. The only mission of the program that was completed was MESUR Pathfinder.

Mars Surveyor 2001 Lander

The NASA Mars Surveyor 2001 Lander was a planned Mars probe which was canceled in May 2000 in the wake of the failures of the Mars Climate Orbiter and Mars Polar Lander missions in late 1999. The Lander was a component of the Mars Surveyor 2001 project, and its companion spacecraft Mars Surveyor 2001 Orbiter, renamed 2001 Mars Odyssey, was launched and went into orbit about Mars on October 24, 2001.

The 2001 Surveyor lander spacecraft was built under contract to NASA by the Lockheed Martin corporation. Except for the solar arrays, the basic lander design is identical to that of the Mars Polar Lander, which had been intended to be the first of a series of low-cost "Mars Surveyor" landers sent to Mars. Prior to mission cancellation, cost overruns and technical problems caused the Lander design to be rescoped, and the planned large Athena rover was replaced by a small rover duplicating the Sojourner which was a part of the Mars Pathfinder mission. (The Athena did later make it to Mars, however, with two such rovers making up the Mars Exploration Rover Mission of 2004. The second of these, MER-B Opportunity, landed at Mars Surveyor 2001 Lander's target site, Meridiani Planum.)

Mars atmospheric entry

Mars atmospheric entry is the entry into the atmosphere of Mars. High velocity entry into Martian air creates a CO2-N2 plasma, as opposed to O2-N2 for Earth air. Mars entry is affected by the radiative effects of hot CO2 gas and Martian dust suspended in the air. Flight regimes for entry, descent, and landing systems include aerocapture, hypersonic, supersonic, and subsonic.

Mars landing

A Mars landing is a landing of a spacecraft on the surface of Mars. Of multiple attempted Mars landings by robotic, unmanned spacecraft, eight have been successful. There have also been studies for a possible human mission to Mars, including a landing, but none have been attempted.

The most recent landing took place on November 26th, 2018 by the NASA probe InSight.

Mars rover

A Mars rover is a motor vehicle that propels itself across the surface of the planet Mars upon arrival. Rovers have several advantages over stationary landers: they examine more territory, and they can be directed to interesting features, they can place themselves in sunny positions to weather winter months, and they can advance the knowledge of how to perform very remote robotic vehicle control.

There have been four successful robotically operated Mars rovers. The Jet Propulsion Laboratory managed the Sojourner rover, the Opportunity rover, Spirit rover, and, now the Curiosity rover. On January 24, 2016 NASA reported that current studies on Mars by the Curiosity Opportunity rovers would be searching for evidence of ancient life, including a biosphere based on autotrophic, chemotrophic or chemolithoautotrophic microorganisms, as well as ancient water, including fluvio-lacustrine environments (plains related to ancient rivers or lakes) that may have been habitable. The search for evidence of habitability, taphonomy (related to fossils), and organic carbon on Mars is now a primary NASA objective. Since June 2018, the Opportunity rover has been out of contact after going into hibernation mode in a dust storm. NASA has stated they are unsure if they will ever be able to regain contact.

Mars 2, Mars 3 were physically tethered probes; Sojourner was dependent on the Mars Pathfinder base station for communication with Earth; MER-A & B and Curiosity were on their own. Of these Curiosity is still active, and Spirit, Opportunity and Sojourner completed their missions before losing contact.

Materials Adherence Experiment

The Materials Adherence Experiment (MAE) was a material science experiment conducted during NASA's Mars Pathfinder mission. It consisted of a small module mounted to Pathfinder's rover Sojourner that examined the effects of Martian surface dust on solar cells.


Navcam, short for navigational camera, is a type of camera found on certain robotic rovers or spacecraft used for navigation without interfering with scientific instruments. Navcams typically take wide angle photographs that are used to plan the next moves of the vehicle or object tracking.


The rocker-bogie system is the suspension arrangement used in the Mars rovers (mechanical robot) introduced for the Mars Pathfinder and also used on the Mars Exploration Rover (MER) and Mars Science Laboratory (MSL) missions. It is currently NASA's favored design.The term "rocker" comes from the rocking aspect of the larger links on each side of the suspension system. These rockers are connected to each other and the vehicle chassis through a differential. Relative to the chassis, when one rocker goes up, the other goes down. The chassis maintains the average pitch angle of both rockers. One end of a rocker is fitted with a drive wheel and the other end is pivoted to a bogie.

The term "bogie" refers to the links that have a drive wheel at each end. Bogies were commonly used as load wheels in the tracks of army tanks as idlers distributing the load over the terrain. Bogies were also quite commonly used on the trailers of semi-trailer trucks. Both applications now prefer trailing arm suspensions.


A sojourner is a person who resides temporarily in a place.

Sojourner may also refer to:

Sojourner Truth (1797-1883), abolitionist and women's rights activist

Mike Sojourner (born 1953), American retired National Basketball League player

Willie Sojourner (1943-2005), basketball player and brother of Mike Sojourner

Sojourner (rover), a robotic rover that was part of the Mars Pathfinder mission

Sojourner (album) a box set by the alternative country band Magnolia Electric Co.

Sojourners, a Christian monthly magazine

Sojourner, a member of the DC Comics superhero team Hellenders

Sojourner (rover)

Sojourner is the Mars Pathfinder robotic Mars rover that landed on July 4, 1997 in the Ares Vallis region, and explored Mars for around three months. It has front and rear cameras and hardware to conduct several scientific experiments. Designed for a mission lasting 7 sols, with possible extension to 30 sols, it was in fact active for 83 sols. The base station had its last communication session with Earth at 3:23 a.m. Pacific Daylight Time on September 27, 1997. The rover needed the base station to communicate with Earth, despite still functioning at the time communications ended.Sojourner traveled a distance of just over 100 meters (330 ft) by the time communication was lost. It was instructed to stay stationary until October 5, 1997 (sol 91) and then drive around the lander.

Tony Spear

Anthony Spear is an American space exploration project manager most notable for leading the Mars Pathfinder mission for JPL/NASA in 1996. He retired from JPL in 1998. He is now seeking the Google Lunar X Prize with Red Whittaker, Astrobotic, and Carnegie Mellon University, where he received a B.S. degree in electrical engineering in 1962.

Yogi Rock

Yogi Rock is a rock on Mars that was discovered during the Mars Pathfinder mission in 1997, and named by Geoffrey A. Landis. The rocks found on the mission were named after famous icons and figures, and Yogi Rock was thought to resemble the head of a bear looking away from the spacecraft. As a result, it was named for the famed cartoon character Yogi Bear.

The rock was the first on Mars found to be made of basalt, which suggests previous volcanic activity in the region as basalt is an igneous rock. The smoothness of the surface also suggested the past existence of water in the region. Yogi was also the first large rock reached by the Sojourner rover and was analyzed by an alpha proton X-ray spectrometer to determine its composition.

Images of Sojourner approaching Yogi used in the opening credits of Star Trek: Enterprise made that television program the first science fiction television or film production in history to use footage taken on another planet.

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