The
Mars Pathfinder (
MESUR Pathfinder) later called
The Carl SaganCarl Edward Sagan was an American astronomer, astrochemist, author, and highly successful popularizer of astronomy, astrophysics and other natural sciences...
Memorial Station was launched on December 4, 1996 by
NASAThe National Aeronautics and Space Administration is an agency of the United States government, responsible for the nation's public space program. NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for...
aboard a
Delta IIDelta II is a space launch system originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and has been in service since 1989...
just a month after the
Mars Global SurveyorThe Mars Global Surveyor was a US spacecraft developed by NASA's Jet Propulsion Laboratory and launched November 1996. It began the United States's return to Mars after a 10-year absence. It completed its primary mission in January 2001 and was in its third extended mission phase when, on , the...
was launched. After a 7-month voyage it landed on
Ares VallisAres Vallis is a valley on Mars which appears to have been carved by fluids, perhaps water. The valley 'flows' northwest out of the hilly Margaritifer Terra, where the Iani Chaos depression is connected to the beginning of Ares Vallis by a 100 km wide transition zone centred around 342.5°...
, in a region called
Chryse PlanitiaChryse Planitia is a smooth circular plain in the northern equatorial region of Mars close to the Tharsis region to the west, centered at...
on
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
, in the
Oxia Palus quadrangle.The Oxia Palus quadrangle covers the region of 0° to 45° west longitude and 0° to 30° north latitude on Mars. Mars Pathfinder landed in the Oxia Palus quadrangle at 19.13° N and 33.22° W, on July 4, 1997. Crater names in Oxia Palus are a Who's Who for famous scientists...
, on 4 July 1997. During its voyage the spacecraft had to accomplish four flight adjustments on 10 January, 3 February, 6 May and 25 June. The
landerA lander is a spacecraft which descends toward and comes to rest on the surface of an astronomical body. For bodies with atmospheres, the landing is called atmospheric reentry and the lander descends as a re-entry vehicle...
opened, exposing the
roverThere are two main types of rovers.A rover is a space exploration vehicle designed to move across the surface of a planet or other astronomical body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots...
called
Sojourner that would go on to execute many experiments on the Martian surface.
The mission carried a series of scientific instruments to analyze the Martian atmosphere,
climateClimate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and numerous other meteorological elements in a given region over long periods of time...
,
geologyGeology is the science and study of the solid and liquid matter that constitutes the Earth. The field of geology encompasses the study of the composition, structure, physical properties, dynamics, and history of Earth materials, and the processes by which they are formed, moved, and changed...
and the composition of its
rocksIn geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
and soil. It was the second project from NASA's
Discovery ProgramNASA's Discovery Program is a series of lower-cost, highly focused scientific space missions. It was founded to implement NASA Administrator Daniel S. Goldin's vision of "faster, better, cheaper" planetary missions...
, which promotes the use of low-cost spacecraft and frequent launches under the motto "cheaper, faster and better" promoted by the then administrator,
Daniel GoldinDaniel Saul Goldin served as the 9th and longest-tenured Administrator of NASA from April 1, 1992, to November 17, 2001. He was appointed by President George H. W. Bush and served under three presidential administrations....
. The mission was directed by the
Jet Propulsion LaboratoryJet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is situated in the northern portion of Pasadena...
(JPL), a division of the
California Institute of TechnologyThe California Institute of Technology is a private research university located in Pasadena, California, United States. The Institute maintains a strong emphasis on the natural sciences and engineering, and operates and manages NASA's neighboring Jet Propulsion Laboratory...
, responsible for NASA's
Mars Exploration ProgramThe exploration of Mars has been an important part of the space exploration programs of the Soviet Union , the United States, Europe, and Japan. Dozens of robotic spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s...
.
This mission to Mars, besides being the first of a series of missions to
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
that included rovers (robotic exploration vehicles), was the most important since the
VikingsNASA's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. Each vehicle was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...
landed on the red planet in 1976, and also was the first successful mission to send a rover to a
planetA planet , is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
. The then still extant
Soviet UnionThe Union of Soviet Socialist Republics was a constitutionally socialist state that existed in Eurasia from 1922 to 1991. The name is a translation of the , tr. Soyuz Sovetskikh Sotsialisticheskikh Respublik, abbreviated СССР, SSSR. The common short name is Soviet Union, from , Sovetskiy Soyuz...
successfully sent rovers to the Moon as part of the
Lunokhod programmeLunokhod 1 and 2 were a pair of Soviet robotic lunar rovers landed on the Moon in 1970 and 1973, respectively. They were in operation concurrently with the Zond series of flyby missions. The Lunokhod missions were primarily designed to explore the surface and return pictures...
in the 1970s, but its two attempts to send rovers in the
Mars probe programThe Mars program was a series of Mars unmanned landers and orbiters launched or attempted to launch by the Soviet Union in the 1960s-1970s.- First generation - Marsnik design :...
failed.
In addition to scientific objectives, the Mars Pathfinder mission was also a "proof-of-concept" for various technologies, such as
airbagAn airbag is a vehicle safety device. It is an occupant restraint consisting of a flexible envelope designed to inflate rapidly in an automobile collision, to prevent vehicle occupants from striking interior objects such as the steering wheel or window....
-mediated touchdown and automated obstacle avoidance, both later exploited by the
Mars Exploration RoverNASA's Mars Exploration Rover Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of two rovers — MER-A Spirit and MER-B Opportunity — to explore the Martian surface and geology....
s. The Mars Pathfinder was also remarkable for its extremely low price relative to other unmanned space missions to mars. Originally, the mission was conceived as the first of the Mars Environmental Survey (MESUR) program.
Mission overview
The lander relayed transmissions to and from the robot, allowing it to operate independently of the probe body. The robot was remotely controlled, but had a basic camera-assisted autonomous control system allowing it to navigate and negotiate minor obstacles without operator intervention.
The robot's freedom of movement allowed the exploration team to closely analyze many more rocks and soil samples than with a traditional probe. From its landing in July 4, 1997 until the final data transmission on September 27, 1997, Mars Pathfinder returned 16,500 images from the lander and 550 images from the rover, as well as more than 15 chemical analyses of rocks and soil and extensive data on winds and other weather factors. Findings from the investigations carried out by scientific instruments on both the lander and the rover suggest that Mars was at one time in its past warm and wet, with water existing in its liquid state and a thicker atmosphere.
The lander and rover performed for much longer and better than expected, but eventually contact with the lander was lost on sol 83. The lander's silver-zinc
batteryAn electrical battery is a combination of one or more electrochemical cells, used to convert stored chemical energy into electrical energy. Since the invention of the first Voltaic pile in 1800 by Alessandro Volta, the battery has become a common power source for many household and industrial...
was only capable of being recharged about 40 times, as a consequence after about 40 sols, the battery was not able to keep the lander warm at night. The exact reason for the final failure of the lander is not certain, but it was probably due to an electronics failure due to the very cold night-time temperatures that were experienced in the final weeks of the mission. After sol 92, the automatic backup procedures should have instructed the rover to return to the lander and circle it while attempting to re-establish communications. This behavior would have continued until hardware failure. The lack of communication may mean that the rover's final location and state are unknown. NASA's efforts to recontact Pathfinder ended on March 10, 1998.
Mission objectives
- To prove that the development of "faster, better and cheaper" spacecraft is possible (with three years for development and a cost under $150 million).
- To show that it is possible to send a load of scientific instruments to another planet with a simple system and at one fifteenth the cost of a Viking
NASA's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. Each vehicle was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...
mission. (For comparison, the Viking missions cost $935 million in 1974 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.
The project manager was
Tony SpearAnthony 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...
.
The probe
The probe consisted of a
landerA lander is a spacecraft which descends toward and comes to rest on the surface of an astronomical body. For bodies with atmospheres, the landing is called atmospheric reentry and the lander descends as a re-entry vehicle...
and a lightweight (10.6 kilograms/23 pounds) wheeled
robotA robot is a virtual or mechanical artificial agent. In practice, it is usually an electro-mechanical machine which is guided by computer or electronic programming, and is thus able to do tasks on its own...
(Rover) called
Sojourner ("one in a break from journeying"), after the slave and abolitionist
Sojourner TruthSojourner Truth was the self-given name, from 1843, of Isabella Baumfree, an African-American abolitionist and women's rights activist. Truth was born into slavery in Swartekill, New York...
.
http://mpfwww.jpl.nasa.gov/missions/past/pathfinder.html (See below for the selection of the name.)
Mission equipment
The
Mars Pathfinder executed different investigations on the Martian soil using three scientific instruments. The lander contained a
stereoscopic cameraA stereo camera is a type of camera with two or more lenses. This allows the camera to simulate human binocular vision, and therefore gives it the ability to capture three-dimensional images, a process known as stereo photography. Stereo cameras may be used for making stereoviews and 3D pictures...
with spatial filters on an expandable pole called
Imager for Mars Pathfinder (IMP), and the
Atmospheric Structure Instrument/Meteorology Package (ASI /MET) which acts as a Mars meteorological station, collecting data about pressure, temperature, and winds. The MET structure included three
windsockA windsock or wind cone is a conical textile tube designed to indicate wind direction and relative wind speed. Windsocks typically are used at airports and at chemical plants where there is risk of gaseous leakage...
s mounted at three heights on a pole, the topmost at about one meter (yard) and generally registered winds from the West.
The
Sojourner rover had a
Alpha Proton X-ray Spectrometer (
APXSAn Alpha Particle X-Ray Spectrometer is a device that analyses the chemical element composition of a sample from the scattered alpha particles, emitted protons , and fluorescent X-rays after the sample is irradidated with alpha particles and X-rays from radioactive sources...
), 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 make investigations of the geology of the Martian surface from just a few millimeters to many hundreds of meters, the
geochemistryThe field of geochemistry involves study of the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks and soils, and the cycles of matter and energy that transport the Earth's chemical components in time and space, and their...
and evolutionary history of the rocks and surface, the magnetic and
mechanicalMechanics is the branch of physics concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effect of the bodies on their environment....
properties of the land, as well as the magnetic properties of the dust, atmosphere and the
rotationA rotation is a movement of an object in a circular motion. A two-dimensional object rotates around a center of rotation. A three-dimensional object rotates around a line called an axis. If the axis of rotation is within the body, the body is said to rotate upon itself, or spin—which implies...
al and
orbitIn physics, an orbit is the gravitationally curved path of one object around a point or another body, for example the gravitational orbit of a planet around a star....
al dynamics of the planet.
Mars Pathfinder
LanderA lander is a spacecraft which descends toward and comes to rest on the surface of an astronomical body. For bodies with atmospheres, the landing is called atmospheric reentry and the lander descends as a re-entry vehicle...
:
- Imager for Mars Pathfinder (IMP), (includes magnetometer
A magnetometer is a scientific instrument used to measure the strength and/or direction of the magnetic field in the vicinity of the instrument. Magnetism varies from place to place and differences in Earth's magnetic field can be caused by the differing nature of rocks and the interaction...
and anemometerAn anemometer is a device that is used for measuring wind speed, and is one instrument used in a weather station. The term is derived from the Greek word anemos, meaning wind...
)
- Atmospheric and meteorological
Meteorology is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting . Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the eighteenth century...
sensors (ASI/MET)
Mars Pathfinder
Sojourner Rover:
- Imaging system (three cameras: front B&W stereo, 1 rear color)
- Laser
A laser is a device that emits light through a process called stimulated emission. Laser light is usually spatially coherent, which means that the light either is emitted in a narrow, low-divergence beam, or can be converted into one with the help of optical components such as lenses...
striper hazard detection system
- Alpha Proton X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays...
SpectrometerA spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...
(APXS)
- Wheel Abrasion Experiment
- Material Adherence Experiment
- Accelerometer
An accelerometer measures the acceleration it experiences relative to freefall.Single- and multi-axis models are available to detect magnitude and direction of the acceleration as a vector quantity, and can be used to sense orientation, vibration and shock...
s
- Potentiometer
A potentiometer is a three-terminal resistor with a sliding contact that forms an adjustable voltage divider. If only two terminals are used , it acts as a variable resistor or rheostat. Potentiometers are commonly used to control electrical devices such as volume controls on audio equipment...
s
Scientific objectives
- Surface morphology and geology using scaled measurements.
- Petrology
Petrology is the branch of geology that studies rocks, and the conditions in which rocks form...
and geochemistry of surface materials.
- Magnetic and mechanical properties of the surface.
- Atmospheric structure, besides diurnal and nocturnal meteorological variations.
- Rotational and orbital dynamics of Mars.
Pathfinder found temperatures varied on a diurnal cycle with the coldest just before sunrise about -78 Celsius with the warmest just after Mars noon about -8 Celsius. These extremes occurred near the ground which both warmed up and cooled down fastest. Temperatures further from the ground at 1.4 m (4.3 feet) were about 10 degrees inside these ranges (-70 at night, to -18 at day). Pathfinder measured temperatures at three heights above the surface: 0.65, 0.9 and 1.4 meters. Weather observations suggest that cold morning air was warmed by the ground and rose in small eddies.
Surface pressures varied diurnally over a 0.2 millibar range, but showed 2 daily minimums and two daily maximums. The average daily pressure decreased from about 6.75 millibars to a low of just under 6.7 millbars, corresponding to when the maximum amount of carbon dioxide has condensed on the south pole. Winds were usually less than 10m/s. Dust devils were detected in the early afternoon.
The sky had a pink color. There was evidence of clouds and maybe fog.
The Mars Pathfinder found its landing site to contain a great deal of rocks. Analysis shows the area to have a greater density of rocks than 90% of the Mars. Some of the rocks leaned against each other in a manner geologists term imbricated. It is believed strong flood waters in the past pushed the rocks around to face away from the flow. Some pebbles were rounded, perhaps from being tumbled in a stream. Some rocks have holes on their surfaces that seem to have been fluted by wind action. Some small sand dunes are present. Parts of the ground are crusty, maybe due to cementing by a fluid containing minerals. In gereral the rocks show a dark gray color with patches of red dust and/or weathered appearance on their surfaces. Dust covers the lower 5–7 cm of some rocks, so they may have once been buried, but have now become exhumed. Three knobs, one large crater, and two small craters were visible on the horizon.
Other results from Pathfinder
By taking multiple images of the sky at different distances from the sun, scientists were able to determine that size of the particles in the pink haze was about 1 micrometer 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.
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 possible cemented with ferric oxide (Fe
2O
3). 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.
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.
Landing site
The landing site was an ancient flood plain in Mars's northern hemisphere called "
Ares VallisAres Vallis is a valley on Mars which appears to have been carved by fluids, perhaps water. The valley 'flows' northwest out of the hilly Margaritifer Terra, where the Iani Chaos depression is connected to the beginning of Ares Vallis by a 100 km wide transition zone centred around 342.5°...
" ("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 coordinates 19.13 degrees north, 33.22 degrees west, succeeded, the landing site received the name
The Carl SaganCarl Edward Sagan was an American astronomer, astrochemist, author, and highly successful popularizer of astronomy, astrophysics and other natural sciences...
Memorial Station in honor of the late
astronomerAn astronomer is a scientist who studies celestial bodies such as planets, stars, and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
and leader in the field of robotic spacecraft missions.
Landing process
Mars Pathfinder entered the Martian atmosphere and landed using an innovative system involving an entry capsule, a supersonic
parachuteA parachute is a device used to slow the motion of an object through an atmosphere by creating drag. Parachutes are made out of cloth, most commonly nylon....
, followed by solid rockets and large airbags to cushion the impact.
Pathfinder lands
Sojourner rover
The Sojourner
rover was the second space exploration roverThere are two main types of rovers.A rover is a space exploration vehicle designed to move across the surface of a planet or other astronomical body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots...
to successfully reach another planet, and the first to actually be deployed on another planet. Sojourner landed on
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
as part of the Mars Pathfinder mission on July 4 1997.
The on-board computer
The
embeddedAn embedded system is a computer system designed to perform one or a few dedicated functions , often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. In contrast, a general-purpose computer, such as a personal...
computerA computer is a machine that manipulates data according to a set of instructions.Although mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century . These were the size of a large room, consuming as...
on board the Sojourner rover was based around the 100 KHz Intel 80C85
CPUThe Central Processing Unit or processor is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. This term has been in use in the computer industry at least since the early 1960s...
with 512
KBThe kilobyte is a unit of digital information storage equal to either 1,000 bytes or 1,024 bytes , depending on context....
of RAM and 176 KB of
flash memoryFlash memory is a non-volatile computer storage that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products...
solid-state
storagethumb|200px|right|A reel-to-reel tape recorder .The magnetic tape is a data storage medium. The recorder is data storage equipment using a portable medium to store the data....
.
The Sojourner gets out
Sojourner's exit from the lander occurred on Sol 2, after its landing in July 4, 1997. As the next sols progressed it approached some rocks which were named (by the scientists) "
Barnacle BillBarnacle Bill is a 40 centimeter 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...
", "
YogiYogi 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...
", and "Scooby Doo", after the famous
cartoonThe word cartoon has various meanings, based on several very different forms of visual art and illustration. The term has evolved over time....
s. 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, besides making climate observations.
The Sojourner is a six-wheeled 65 cm long vehicle, 48 cm wide, 30 cm tall and weighs 10.5 kg. When operating, it could move about 500 meters from the lander and its maximum speed reached one centimeter per second. During its 83 sols of operation, it sent 550 photographs to Earth and analyzed the
chemicalChemistry is the science concerned with the composition, behavior, structure, and properties of matter, as well as the changes it undergoes during chemical reactions...
properties of sixteen locations near the lander.
Sojourner's rock analysis
The first analysis on a rock started on Sol 3 with "
Barnacle BillBarnacle Bill is a 40 centimeter 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
Alpha Proton X-ray SpectrometerAn Alpha Particle X-Ray Spectrometer is a device that analyses the chemical element composition of a sample from the scattered alpha particles, emitted protons , and fluorescent X-rays after the sample is irradidated with alpha particles and X-rays from radioactive sources...
(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
hydrogenHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H
2...
, which constitutes just 0.1% of the rock's or soil's
massIn physics, mass commonly refers to any of three properties of matter, which have been shown experimentally to be equivalent: inertial mass, active gravitational mass and passive gravitational mass...
.
The APXS works by irradiating rocks and soil samples with
alpha particleAlpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus; hence, it can be written as or . They have a net spin of zero, and normally a total energy of about 5 MeV...
s (
heliumHelium is the chemical element with atomic number 2, and is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert monatomic gas that heads the noble gas group in the periodic table...
nucleiThe nucleus is the very dense region consisting of nucleons at the center of an atom. Almost all of the mass in an atom is made up from the protons and neutrons in the nucleus, with a very small contribution from the orbiting electrons....
, which consist of two
protonThe proton is a subatomic particle with an electric charge of +1 elementary charge. It is found in the nucleus of each atom but is also stable by itself and has a second identity as the hydrogen ion, H
+...
s and two
neutronThe neutron is a subatomic particle with no net electric charge and a mass slightly larger than that of a proton.Neutron are usually found in atomic nuclei. The nuclei of most atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of protons in a...
s). The results indicated that "Barnacle Bill" is much like Earth's
andesiteAndesite is an igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite, zircon, apatite, ilmenite, biotite, and garnet are common accessory minerals. Alkali...
s, confirming past
volcanic3. Conduit
4. Base
5. Sill
6. Dike
7. Layers of ash emitted by the volcano
8. Flank| 9. Layers of lava emitted by the volcano
10. Throat
11. Parasitic cone
12. Lava flow
13. Vent
14. Crater
15...
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
2O and K
2O) with the amount of silica (SiO
2). Andesite is different than the rocks found in meteorites that have come from Mars.
Analysis of "
YogiYogi 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...
" rock again using the APXS showed that it was a
basaltBasalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey.On Earth, most...
ic rock, more primitive than "Barnacle Bill". Yogi's shape and texture show that it was probably deposited there by a
floodA flood is an overflow or accumulation of an expanse of water that submerges land. In the sense of "flowing water", the word may also be applied to the inflow of the tide....
.
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
siliconSilicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. A tetravalent metalloid, silicon is less reactive than its chemical analog carbon...
. In another region known as Rock Garden
the 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 9, 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.
The lander, on the other hand, sent more than 16,500 pictures and made 8.5 million measurements of the
atmospheric pressureAtmospheric pressure is defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above...
,
temperatureIn physics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the higher temperature. Temperature is one of the principal parameters of thermodynamics...
and wind speed.
End of the mission
Although the mission was programed to last a week to a month, it eventually lasted for almost three months. The final contact with the Pathfinder
was at 10:23 UTC on September 27, 1997. Although the mission planners tried to restore contact during the following five months, the successful mission was terminated on March 10, 1998. After the landing, the Mars Pathfinder
was renamed as the Sagan Memorial Station in honor of the famous
astronomerAstronomy is the scientific study of celestial objects and phenomena that originate outside the Earth's atmosphere...
and planetologist
Carl SaganCarl Edward Sagan was an American astronomer, astrochemist, author, and highly successful popularizer of astronomy, astrophysics and other natural sciences...
. The mission had exceeded its goals in the first month.
The Mars Pathfinder entry descent and landing system design was used (with some modification) on the
Mars Exploration RoverNASA's Mars Exploration Rover Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of two rovers — MER-A Spirit and MER-B Opportunity — to explore the Martian surface and geology....
mission. Likewise many design aspects of Sojourner rover (e.g. the
rocker-bogieThe Rocker-Bogie system is the suspension arrangement used in the Mars rovers for both the Mars Pathfinder and Mars Exploration Rover missions. It is currently NASA's favored design....
mobility architecture and the navigation algorithms) were also successfully used on the
Mars Exploration RoverNASA's Mars Exploration Rover Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of two rovers — MER-A Spirit and MER-B Opportunity — to explore the Martian surface and geology....
mission.
Mars Reconnaissance OrbiterNASA's Mars Reconnaissance Orbiter is a multipurpose spacecraft designed to conduct reconnaissance and exploration of Mars from orbit....
may have spotted Pathfinder, January 2007
Naming the rover
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, CA, 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," which is circulated to 20,000 teachers and schools across the nation.
Valerie Ambroise, 12, of Bridgeport, CT, submitted the winning essay about
Sojourner TruthSojourner Truth was the self-given name, from 1843, of Isabella Baumfree, an African-American abolitionist and women's rights activist. Truth was born into slavery in Swartekill, New York...
, an African-American reformist who lived during the Civil War era. An abolitionist and champion of women's rights, Sojourner Truth, whose legal name was Isabella Van Wagener, made it her mission to "travel up and down the land," advocating the rights of all people to be free and the rights of women to participate fully in society. The name Sojourner was selected because it means "traveler." JPL scientists and engineers working on the Mars Pathfinder project and Planetary Society staff members reviewed the 3,500 total entries received from all over the world, including essays from students living in Canada, India, Israel, Japan, Mexico, Poland and Russia. Nearly 1,700 of the essays were submitted by students aged 5 to 18 years old.
The selection of winners from this group by representatives from JPL and NASA Headquarters was based on several factors: the quality and creativity of the essay, taking into consideration the age of each contestant, the appropriateness of the name for a Mars rover, and the knowledge of the heroine, and the understanding of the Pathfinder rover's mission conveyed in the essay.
The second place prize winner was Deepti Rohatgi, 18, of Rockville, MD, who proposed naming the rover after
Marie CurieMarie Skłodowska Curie was a physicist and chemist of Polish upbringing and, subsequently, French citizenship...
, a Polish-born chemist who won the Nobel Prize in 1911 for her discovery of the elements radium and polonium. The test model identical to Sojourner used on earth was named Marie Curie. The third place prize went to Adam Sheedy, 16, of Round Rock, TX, who chose the late astronaut
Judith ResnikJudith Arlene Resnik was an American engineer and a NASA astronaut who died in the destruction of the Space Shuttle Challenger during the launch of mission STS-51-L.-Life:...
as his namesake for the new rover.
Honors
- On October 21, 1997, at the Geological Society of America
The is a nonprofit organization dedicated to the advancement of the geosciences. The society was founded in New York in 1888 by James Hall, James D. Dana, and Alexander Winchell, and has been headquartered at 3300 Penrose Place, Boulder, Colorado, USA, since 1968. As of 2007, the society has...
's annual meeting in Salt Lake City, UtahUtah is a western state of the United States. It was the 45th state admitted to the Union, on January 4, 1896. Approximately 80 percent of Utah's 2,736,424 people live along the Wasatch Front, centering around Salt Lake City. In contrast, vast expanses of the state are nearly uninhabited, making...
, Sojourner was awarded honorary membership in the Planetary Geology Division of the society.
- In 2003, Sojourner was inducted into the Robot Hall of Fame
The Robot Hall of Fame was established in 2003 by the School of Computer Science at Carnegie Mellon University in Pittsburgh, Pennsylvania, USA. It is designed to honor both achievements in robotics technology and robots from science fiction that have served as creative inspiration in robotics...
.
- Images of Sojouner approaching 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...
were used in the opening credits of the Star Trek: EnterpriseEnterprise is a science fiction television program created by Brannon Braga and Rick Berman and set in the fictional Star Trek universe created by Gene Roddenberry in the 1960s...
science fiction television program, the first historical use in a science fiction film or television program of video taken on the surface of another planet.
See also
- Exploration of Mars
The exploration of Mars has been an important part of the space exploration programs of the Soviet Union , the United States, Europe, and Japan. Dozens of robotic spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s...
- Mars Exploration Rover
NASA's Mars Exploration Rover Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of two rovers — MER-A Spirit and MER-B Opportunity — to explore the Martian surface and geology....
s (2003-present mission)
- Space exploration
Space exploration is the use of astronomy and space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft....
- Atmospheric reentry
Atmospheric reentry refers to the movement of human-made or natural objects as they enter the atmosphere of a planet from outer space, in the case of Earth from an altitude above the "edge of space." This article primarily addresses the process of controlled reentry of vehicles which are intended...
- Lunokhod programme
Lunokhod 1 and 2 were a pair of Soviet robotic lunar rovers landed on the Moon in 1970 and 1973, respectively. They were in operation concurrently with the Zond series of flyby missions. The Lunokhod missions were primarily designed to explore the surface and return pictures...
(Lunar rovers)
External links