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Flight System

Mars Operations Status

Reference Information

Assembly, Test and Launch

Mars Pathfinder

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Landing Air Bags Tested

June 14, 1995 - Engineers tested the huge, multi-lobed air bags that protected the Mars Pathfinder Lander before it impacted the Martian surface. As Pathfinder descended to the Martian surface on a parachute, an onboard altimeter inside the lander monitored its distance from the ground. - The computer signaled to inflate the large air bags about 330 ft (100 meters) above the surface of Mars. The air bags were composed of four large bags with six smaller, interconnected spheres within each bag. - The bags measured 17 ft (5 meters) tall and about 17 ft (5 meters) in diameter and were manufactured by ILC Dover of Frederica, DE. -- ILC Dover is the same company that manufactures the International Space Station spacesuits.

Credit: NASA/JPL

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Lander Prepared for Launch Credit: NASA/KSC

October 2, 1996 - Jet Propulsion Laboratory workers are folding the three solar panels of the Mars Pathfinder Lander into its launch position in the Spacecraft Assembly and Encapsulation Facility-2 at Kennedy Space Center (KSC), FL. The Sojourner rover is visible on one of the solar panels. The Imager for Pathfinder (IMP) camera is shown stowed above the Instrument Electronics

Assemblies.

IMP CameraInstrument Electronics Assemblies

Sojourner Rover

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Entry Vehicle Mated to Cruise Stage

October 22, 1996 - The Mars Pathfinder Entry Vehicle is mated with the Cruise Stage in the Spacecraft Assembly and Encapsulation Facility-2 at Kennedy Space Center (KSC), FL. The cone-shaped Entry Vehicle is shown being moved upward into the Cruise Stage.- Mechanical mating is completed first and then electrical connections between the two elements are established. The Cruise Stage will deliver the Entry Vehicle directly to Mars, and then it is jettisoned before the Entry Vehicle makes its final descent to the Martian surface. The Aeroshell, Lander and Sojourner rover comprise the Entry Vehicle. - Inside the protective Aeroshell is the Lander, and inside the Lander is the Sojourner rover that will explore the Martian terrain.

Credit: NASA/KSC

Cruise Stage

Entry Vehicle

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Mars Pathfinder LaunchMars Pathfinder was launched by the Delta II 7925 from Pad 17-B at Cape Canaveral, FL on December 4, 1996.

Mars Pathfinder was launched on a Delta 7925 (a Delta II Lite launch vehicle with nine strap-on solid-rocket boosters and a Star 48 (PAM-D) third stage) at 6:58:00 UT (1:58 a.m. EST) on

Credit: NASA/JPLDecember 4, 1996 - Mars Pathfinder was launched on a Delta II-7925 launch vehicle from Pad 17-B at Cape Canaveral, FL. The Delta II-7925 included: nine strap-on solid-rocket boosters, the second stage, a Star 48 Payload Assist Module-D (PAM-D) third stage, and payload fairing.

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Flight SystemThe Mars Pathfinder Flight System weighed about 1,973 lbs at launch and consisted of the Cruise Stage and Entry Vehicle. The Cruise Stage propelled the Flight System from Earth to Mars. - It included the structure, solar panels, propulsion, medium and high gain antennas, and 207 lbs of cruise propellant. - It was 8.5 ft in diameter and stood 5 ft tall. The Entry Vehicle entered the Martian atmosphere after separating from the Cruise Stage. - The Entry Vehicle included the Backshell, Lander and Heatshield, and weighed 1,256 lbs.- The Backshell was the upper half of the aeroshell enclosing the top of the Lander.-- Three braking rockets, a parachute and an electronics unit were mounted to the interior of the Backshell.- The Lander was the instrumented vehicle the Flight System delivered to the surface of Mars.-- Four airbags stowed on the Lander deployedand protected it during the landing.-- The Heatshield was the lower half of the aeroshell with a heat-resistant material that protected the Entry Vehicle from overheating.

Base

Credit: NASA/JPL

Cruise Stage

Backshell

Lander

Heatshield

Pyro Control Electronics Unit

Solid Rocket Motor (3x)

Parachute Packed in Canister

Entry VehicleCruise Stage/BackshellInterface Plate

Airbag in Stowed Configuration (4x)

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Lander

The Lander structure is a tetrahedron, a small pyramid standing about 3 ft tall with three triangular-shaped solar panels and a base. The Lander, shown in the deployed position, measures 9 ft across with the IMP camera standing about 5 ft above the surface and weighs about 793 lbs.

Atmospheric Structure Instrument and Meteorology Package (ASI/MET) Mast

Wind Sensor

Wind SocksThermocouples

Imager for Mars Pathfinder (IMP)

Low-Gain Antenna

High-Gain Antenna

Solar Panel (3x)

Sojourner Rover

Instrument Electronics Assemblies

BaseCredit: NASA/JPL

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Sojourner Rover

The Sojourner rover, named in honor of Sojourner Truth (c. 1797-1883), ex-slave and abolitionist, is the first to explore the Martian surface. Sojourner is shown at the end of assembly and before its integration into the Lander. The vehicle measured 2 ft long by 1.5 ft wide by 1 ft tall and weighed 23 lbs on the surface. Science instruments included: the alpha proton x-ray spectrometer, 3 cameras (also technology experiments), and a material adherence experiment. The rover power was 16 watts at peak with up to 100 watt-hours per day from a solar panel and batteries.

Credit: NASA/JPL-Caltech

Solar Panel

Alpha Proton X-ray Spectrometer (APXS)

Electronics AssembliesEnclosure

Rocker-Bogie Mobility System

Antenna

Camera/Lasers

Material Adherence Experiment

5 inch Diameter Wheels (6x)

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Imager for Mars Pathfinder

Credit: University of Arizona/Lockheed Martin

Camera Head

Deployable Mast (with Pyrotechnic Pin Puller)

Camera Head Launch Lock (with Paraffin Pin Puller)

Electronic Cabling

The Imager for Mars Pathfinder (IMP) is a stereo imaging system with color capability provided by a set of selectable filters for each of the two camera channels. IMP consists of a camera head with stereo optics, filter wheel, CCD and pre-amp, mechanisms, stepper motors, and launch lock; extendable mast with electronic cabling; and two plug-in electronics cards (CCD data card and power supply/motor drive card) that plug into slots in the Lander Instrument Electronics Assemblies.- Azimuth and elevation drives for the camera head are provided by stepper motors with gear heads, providing a field of regard of ±180 degrees in azimuth and +83 degrees to -72 degrees in elevation relative to Lander coordinates. - The camera head is mounted at the top of a one-time deployable, open-lattice mast with continuous longerons provided by AEC-Able Engineering Company, Inc. -- When deployed, the mast provides an elevation of 3.28 ft above the lander mounting surface.- IMP was developed by a team lead by the University of Arizona with contributions from Lockheed Martin, Max Planck Institute for Aeronomy, Germany, the Technical University of Braunschweig, Germany and the Niels Bohr Institute for Astronomy, Denmark.

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Entry, Descent and Landing

July 4, 1997 - The entry, descent and landing phase began 1-1/2 hours before Mars arrival and ended when the lander solar panels (petals) were fully deployed.

Deflation / Petal Latch Firing

Airbag Retraction / Lander Righting

Airbag Retraction / Lander Righting

Bridle Cut

Rocket Ignition

Airbag Inflation

Radar Ground Acquisition

Lander Separation /Bridle Deployment

Heatshield Separation

Parachute Deployment

Entry

Cruise Stage Separationfrom Entry Vehicle

Credit: NASA

Select Image for Mars Pathfinder Landing Video

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Landing Site

The Pathfinder landing site is shown with all of the successful NASA Mars landing sites including the site selected for Insight, scheduled to land in 2018. Pathfinder landed in an ancient flood plain in the northern hemisphere known as Ares Vallis, among the rockiest parts of Mars. - It was chosen because scientists believed it to be a relatively safe surface to land on and one which contained a wide variety of rocks deposited during a catastrophic flood. -- Scientists believe, early in Mars’ history, the flood plain was cut by a volume of water the size of North America’s Great Lakes in about two weeks.

Credit: NASA

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Airbag Obstructs Rover Deployment

July 4, 1997 (Sol 1) - The Sojourner rover and the Lander’s two undeployed ramps can be seen in this image, taken by the Imager for Mars Pathfinder (IMP). The Sojourner rover is latched to a solar panel, and has not been deployed. The ramps are a pair of deployable metal reels which will provide a track for the rover as it slowly rolls off the Lander, over the deflated airbags, and onto the Martian surface. - The flight team used this image to determine whether it was safe to deploy the ramps. -- The team decided to retract the airbag, deploy the ramps, and use the rear ramp for the rover’s descent to the surface. The IMP image has been corrected for the curvature created by parallax.

Credit: NASA/JPL Sojourner Rover

AirbagRetracted

RearRamp Reel

Solar Panel

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Sojourner Rover Begins its Mission

July 6, 1997 (Sol 3) - This view was taken by the Imager for Mars Pathfinder (IMP) showing the Sojourner rover on the Martian surface after descending the Lander’s rear ramp; a portion of a deflated airbag is at the lower right. The small rock to the left of the rover, nicknamed “Barnacle Bill,” was the first to be examined by Sojourner’s Alpha Proton X-Ray Spectrometer (APXS) instrument and the rover’s cameras. Barnacle Bill has the chemical composition of an andesitic volcanic rock, but may have been produced by sedimentation processes or meteorite impact. Select https://www.youtube.com/watch?v=OKme8XabVR0&feature=youtu.be to view rover operating on Mars.

Credit: NASA/JPL

Barnacle Bill

DeflatedAirbag

RearRamp

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First Landing Site Panorama

July 11 to 13, 1997 - This 360 degree full color panorama is the first taken by the Imager for Mars (IMP) during Sols 8, 9 and 10. At the left is a Lander solar panel and a portion of the low-gain antenna mast. On the horizon the double “Twin Peaks” are visible, about 0.6 to 1.2 miles away. The rock “Couch” is the dark, curved rock at the right of Twin Peaks. Another Lander solar panel is at left-center, showing the fully deployed forward ramp at the far left, and the rear ramp at the right that the Sojourner rover used to descend to the surface. Immediately to the left of the rear ramp is the rock “Barnacle Bill.” Just beyond Barnacle Bill, rover tracks lead to Sojourner using its Alpha Proton X-Ray Spectrometer (APXS) instrument to study the large rock “Yogi.” Yogi, low in quartz content, appears to be more primitive than Barnacle Bill, most likely a common basalt. The tracks and circular pattern in the soil leading up to Yogi were part of Sojourner’s soil mechanics experiments in which varying amounts of pressure were applied by the wheels to determine physical properties of the soil. During one of the turns to deploy Sojourner’s APXS, the wheels exposed white material; this material may underlie much of the site. Deflated airbags are visible at the perimeter of all three Lander solar panels.

Couch SojournerCredit: NASA/JPL

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Lander Site Self-Portrait This image is a composite self-portrait of the Lander on the surface with the Sojourner rover investigating “Yogi” rock. The image has been rotated so that the main points of interest, which are the Sojourner and the rock “Yogi,” are visible arching across the upper portion of the image. - The top of the image looks out towards a point a few degrees north of west. - Color has been enhanced to improve contrast in features. The image is a product of three data sets:- A color mosaic panorama image.- An image which indicates the distance to the nearest object at each pixel location, referred to as a range image.- A digital image of a full-scale museum model of the Lander.-- It shows the Imager for Mars Pathfinder stowed.

Credit: NASA/JPLYogi

Sojourner

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Partial Coordinate Map of Rocks

A partial coordinate map of the rocks counted at the landing site is shown superimposed on a panorama image taken by the Imager for Mars Pathfinder camera. Positions, apparent diameters, and heights were measured to the nearest centimeter.Results of the investigation of the rocks and soil at the landing site included: The high silica or quartz content of some rocks suggests they were formed as the crust of Mars was being recycled, or cooled and heated, by the underlying mantle. The rocks are distinct from the meteorites found on Earth thought to be of Martian origin. The identification of rounded pebbles and cobbles on the ground, and sockets and pebbles in some rocks, suggests conglomerates were formed in running water, during a warmer past in which liquid water was stable. Some rocks appear grooved and fluted, suggesting abrasion by sand-sized particles. Dune-shaped deposits were found in a trough behind the Rock Garden, indicating sand. The soil chemistry appears to be similar to Viking 1 and 2 landing sites, suggesting that the soil may be a globally deposited unit.

Credit: NASA/JPL/USGS

Rock Garden

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Sojourner takes Pictures of LanderThe image of the Lander (left) was taken by the Sojourner’s left front camera on sol 33.- The Imager for Mars Pathfinder (IMP) camera, on the lattice mast, is looking toward the rover. - Airbags are prominent, and the meteorology (met.) mast is shown to the right. - The lowermost rock is “Ender,” with “Hassock” behind it and “Yogi” on the other side of the Lander.

This image of the Lander was taken on Sol 27 from a different rover location with its right front camera. - The Lander is seen with the IMP camera also looking toward the rover. - The large rock at the right, nicknamed “Squash,” exhibits a diversity of textures. -- It looks very similar to a conglomerate, a type of rock found on Earth that forms from sedimentary processes.

Credit: NASA/JPL

Credit: NASA/JPL

IMP Camera

Yogi

Hassock Ender

Met. Mast

Squash

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Right Big Crater Panorama

This view was taken by the Imager for Mars Pathfinder (IMP) right eye and the next slide shows a similar view taken by the IMP left eye. A stereo anaglyph mosaic of the view was produced by combining the left and right eye mosaics, assigning the left eye view to the red color plane and the right eye view to the green and blue color planes. - This mosaic can be viewed in 3-D on a computer monitor or in color print form by wearing red-blue 3-D glasses. The larger features visible in this scene are “Big Crater,” “Far Knob,” and “Southeast Knob.” - They were discovered on the first panoramas taken by the IMP on Sol 1 after landing, and subsequently identified in Viking Orbiter images from about 1977. - Big Crater is actually a relatively small Martian crater to the southeast of the Mars Pathfinder landing site. -- It is 4,900 ft in diameter, or about the same size as Meteor Crater in Arizona. - Superimposed on the rim of Big Crater (the central part of the rim as seen here) is a smaller crater nicknamed “Rimshot Crater.” -- The distance to this smaller crater, and the nearest portion of the rim of Big Crater, is 7,200 ft.

Credit: NASA/JPL

Big Crater Far Knob

Southeast Knob

Rimshot Crater

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Left Big Crater Panorama

This left view was taken by the Imager for Mars Pathfinder (IMP) left eye and the previous slide shows a similar view taken by the IMP right eye. The view includes rocky ridges and swales or “hummocks” of flood debris that range from a few tens of yards away from the Lander to the distance of Twin Peaks which is about 0.6 mile. The largest rock in the nearfield, just left of center in the foreground, nicknamed “Otter,” is about 4.9 ft long and 33 ft from the Lander. To the right of Big Crater, south from the Lander, almost lost in the atmospheric dust “haze,” is the large streamlined mountain nicknamed “Far Knob.”- This mountain is over 1,480 ft tall, and is over 19 miles from the spacecraft. Another, smaller and closer knob, nicknamed “Southeast Knob” can be seen as a triangular peak to the left of the flanks of the Big Crater rim and it is 13 miles southeast from the Lander. The two views are one of the last transmitted; November 4, 1997 was their addition date.- The only objective left unfinished at the time communications were lost on September 27, 1997 was the completion of a high resolution 360-degree image of the landing site, nicknamed the “Super Pan,” of which 83% was received on Earth. -- Other complete panoramas had already been received.

Credit: NASA/JPL

Big Crater Far Knob

Southeast Knob

Otter

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Status

Portions of the HiRISE image are overlaid onto color-coded topographic maps constructed by the U.S. Geological Survey (USGS) from stereo images acquired by the Imager for Mars Pathfinder, developed by the University of Arizona (UA), on the Lander. - The white feature at the center is the Pathfinder Lander. - The scales on the x and y axes are in meters, with the Lander as the zero point. - The color code for elevation relative to the Lander is shown in meters.- The black contour lines joins points of equal elevations.

Mars Pathfinder landed on July 4, 1997, and continued operating until the final data transmission on September 27 of that year. The landing site is on an ancient flood plain of the Ares and Tiu outflow channels. The High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter took an image (left) on December 21, 2006 that provided detail of the topography of the region as well as the Pathfinder Lander on the surface. - The correspondence between the 2006 HiRISE overhead view and the 1997 positions of topographic features from the Imager for Mars Pathfinder’s landscape horizontal view is striking. - The location labeled “Sojourner?” has been tentatively identified as the position of the rover.-- The position of Sojourner was near “Chimp” rock at the time of the last transmission.

Credit: NASA/JPL/UA/ USGS

Yogi

Ramp

RampEnder

Sojourner?

Barnacle Bill

Airbag Glint

Chimp

Lander Center

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Reference Information - Page 1 of 2

Images:NASA, NASA/Jet Propulsion Laboratory - California Institute of Technology, NASA/Jet Propulsion Laboratory, NASA/Jet Propulsion Laboratory/University of Arizona/U.S. Geological Survey, NASA/Kennedy Space Center, University of Arizona/Lockheed Martin, NASA/Jet Propulsion Laboratory/U.S. Geological Survey

Text:https://en.wikipedia.org/http://www2.jpl.nasa.gov/http://images.ksc.nasa.gov/http://nssdc.gsfc.nasa.gov/http://www.spacelaunchreport.com/http://mars.nasa.gov/http://science.jrank.org/http://www-robotics.jpl.nasa.gov/https://www.youtube.com/watch?v=K64KoLV39KIhttp://www.jpl.nasa.gov/http://solarsystem.nasa.gov/http://photojournal.jpl.nasa.gov/http://mars.jpl.nasa.gov/http://www.nasa.gov/http://science.nasa.gov/

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Reference Information - Page 2 of 2 EndText (Continued):

http://pdsimage.wr.usgs.gov/http://history.nasa.gov/http://nssdc.gsfc.nasa.gov/

Videos: Mars Pathfinder Landinghttps://www.youtube.com/watch?v=K64KoLV39KISojourner Rover on Marshttps://www.youtube.com/watch?v=OKme8XabVR0&feature=youtu.be

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Mars at a Glance in July 1997- Page 1 of 2 General One of 5 planets known to the ancients; Mars was the Roman god of war, agriculture and

the state. Reddish color; at times the 3rd brightest object in the night sky after the Moon and Venus.Physical Characteristics Average diameter is 4,217 miles (6,780 kilometers); about half the size of Earth, but twice

the size of Earth’s Moon. Mass 1/10th of Earth; gravity is only 38 percent as strong as the Earth. Density is 3.9 times greater than water compared to 5.5 times greater than water on Earth. No magnetic field detected to date.Orbit Fourth planet from the Sun, the next beyond Earth. About 1.5 times farther from the Sun than Earth. Orbit is elliptical; the distance from the Sun varies from a minimum of 128.4 million miles

(206.7 million kilometers) to a maximum of 154.8 million miles (249.2 million kilometers); average distance from the Sun, 141.5 million miles (227.7 million kilometers). Revolves around the Sun once every 687 Earth days. Rotation period, called “sol,” (length of day in Earth days) 24 hours, 37 min, 23 sec (1.026

Earth days). Poles tilted 25 degrees, creating seasons similar to Earth.Environment Atmosphere composed chiefly of carbon dioxide (95.3%), nitrogen (2.7%) and argon (1.6%);

only a trace of oxygen. Surface atmospheric pressure is less than 1/100th of Earth’s average. Surface temperature averages -64 F (-53 C); varies from -199 F (-128 C) during polar night

to 63 F (17 C) at equator during midday at closest point in orbit of Sun.

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Mars at a Glance in July 1997- Page 2 of 2 Features Highest point is Olympus Mons, a huge shield volcano more than 16 miles (27 kilometers)

high and 370 miles (600 kilometers) across; covers about the same area as Arizona. Canyon system of Valles Marineris is largest and deepest known in the solar system;

extends more than 2,500 miles (4,000 kilometers) and has 3 to 6 miles (5 to 10 kilometers) relief from floors to tops of surrounding plateaus. “Canals,” first observed by Giovanni Schiaparelli and Percival Lowell about 100 years ago,

were a visual illusion in which dark areas appeared connected by lines. - The Viking missions of the 1970s, however, established that Mars has channels, probably

cut by ancient rivers.Moons Two irregularly shaped moons, each only a few kilometers wide. The larger moon named Phobos (“fear”); smaller is Deimos (“terror”), named for attributes

personified in Greek mythology as sons of the god of war.

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Flight System HistoryThe Mars Environmental SURvey (MESUR) program was a planned set of 16 surface missions on Mars that would also develop a planetary network across Mars and work in conjunction with Mars Observer. Mars Observer was based on an Earth-orbiting communications satellite and carried a payload of science instruments designed to study Martian geology, geophysics and climate. The original MESUR plan was proposed by NASA Ames, but it would eventually include ideas from the competing JPL proposal. - It was envisioned as a low-cost method of surveying Mars, with risk tolerance. -- Loss of a spacecraft was not fatal to the program, because of multiple relatively inexpensive space probes.- The multi-year MESUR would have 16 landers, landing in the projected period of 1999-2003, and last 10 years; launches would start in 1996. -- The landers and rovers would have instruments and cameras to examine surface rocks, search for water, perform seismography, and observe meteorology. --- Several of the landers would carry Sojourner-class rovers. --- The seismology experiments would help determine the internal Martian structure.-- The entire program was projected at a cost of $1 billion, with per annum spending restricted to $150 million, starting in Fiscal Year 1994. --- The missions were planned to minimize cost, instead of being multibillion-dollar missions.- MESUR Pathfinder would be the first mission of the program and would start landing in 1999. Three days before Mars Observer’s orbit insertion, contact was lost and, subsequently, the MESUR program was canceled and Mars Pathfinder became part of the NASA Discovery Program.- The NASA Discovery Program was a series of lower-cost, highly focused scientific space missions that explored the Solar System. -- It was founded in 1992 to implement NASA Administrator Daniel S. Goldin’s vision of “faster, better, cheaper” planetary missions.

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Lander- Page 1 of 3 Operations The NASA Deep Space Network of giant dish antennas provided the two-way communications link for command, tracking and telemetry operations with the Lander. The airbag-cushioned Lander hit Martian soil at 10:07 a.m. PDT on July 4, 1997 or “sol 1” (a Martian day, or sol, is 24 hours, 37 minutes on Earth) at a speed of 31 miles per hour. - It bounced about 15 times, as high as 50 ft, before coming to rest 2-1/2 minutes later about six-tenths of a mile from the point of initial impact. The Lander came to rest right side up on its base, thereby, eliminating the need for the spacecraft to right itself while deploying its three solar panels.- It came to rest about 12 miles southwest of its targeted landing spot and was resting on the surface at a very slight tilt of about 2.5 degrees. - The antenna, mounted on a solar panel, sent confirmation back to Earth that Pathfinder had landed.- Approximately 90 minutes after landing, engineering data received by the flight team indicated that Pathfinder had fully deployed its solar panels and was awaiting sunrise to begin its mission. The first transmission from the low-gain antenna was received on time on the same day. - It contained preliminary information about the health of the Lander and rover; the orientation of the Lander on the surface; data about its entry, descent and landing; and a first look at the density and temperatures of the Martian atmosphere. The first transmission from the high-gain antenna, began the same day.- It returned to Earth the first images taken by the deployed Imager for Mars Pathfinder camera, including a color mosaic of the boulder strewn Ares Vallis flood plain. - Some of the images revealed that one of the airbags had not fully retracted, and was obstructing opening of one of the rover ramps. -- After receiving hundreds of new images of the Ares Vallis outflow channel, the flight team spent the rest of sol 1 retracting the airbag obstructing the Sojourner rover ramp.

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Lander- Page 2 of 3 Operations (Continued) On the night of July 5, late in the second Martian day, or sol 2, Sojourner extended to its full height of 1 ft and rolled down the lander’s rear ramp. - The ramp was tilted at 20 degrees from the surface, well within the limits of safe deployment.

Science Instruments The science instruments carried aboard Lander included: the IMP camera, the atmospheric structure instrument/meteorology package and the rover’s alpha proton X-ray spectrometer.- The Atmospheric Structure Instrument and Meteorology Package (ASI/MET) was an engineering subsystem that acquired atmospheric information during the descent of the Lander through the Martian atmosphere and during the entire landed mission. -- Data acquired during the entry and descent of the lander permitted reconstruction of profiles of atmospheric density, temperature and pressure from altitudes in excess of 75 miles from the surface. -- The accelerometer portion of the atmospheric structure instrument was designed to measure accelerations over a wide variety of ranges from the micro-G accelerations experienced upon entering the atmosphere to the peak deceleration and landing events in the range of 30 to 50 G’s.-- The package also included several sensors on the lander to measure pressure, temperature and wind. --- They recorded weather at the landing site throughout the mission. -- The instrument definition team was from San Jose State University, CA, and the science team that used the data acquired by the instruments was from JPL. The rover’s Alpha Proton X-ray Spectrometer (APXS) was designed to determine the elements that make up the rocks and soil on Mars. - It was a derivative of instruments flown on the Soviet Vega and Phobos missions and identical to the unit that flew on the Russian Mars landers, which were lost shortly after launch.

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Lander- Page 3 of 3 Science Instruments (Continued)- Due to the mobility provided by the rover, the APXS not only took measurements of the Martian dust but, more importantly, permitted analysis of rocks in the landing area. - The APXS was able to measure the amounts of all elements present (except hydrogen and helium) which make up more than about 1/10th of 1 percent of the mass of the sample rock or soil. - The APXS worked by bombarding a rock or soil sample with alpha particles, charged particles equivalent to the nucleus of a helium atom, consisting of two protons and two neutrons. -- The sources of the particles were small pieces of the radioactive element curium-244 onboard the instrument. -- In some cases, the alpha particles interacted with the rock or a soil sample by bouncing back; in other cases, they caused X rays or protons to be generated. --- The “backscattered” alpha particles, X rays, and protons that made it back into the detectors of the instrument were counted, and their energies were measured. ---- The number of particles counted at each energy level was related to the abundance of various elements in the rock or soil sample, and the energies are related to the types of elements present in the sample. -- A high-quality analysis required about 10 hours of instrument operation while the rover was stationary and could be done at any time of day or night. - The APXS alpha and proton portions were provided by the Max Planck Institute for Chemistry, Germany, and the X-ray spectrometer portion was provided by the University of Chicago.

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Sojourner Rover- Page 1 of 2 Operations Sojourner with its mounting and deployment equipment weighed about 34.2 lbs at launch. During the launch and cruise to Mars, the rover was folded in its stowage space and measured 7 inches tall. All rover communications were via the Lander. Two front camera/laser systems provided stereo viewing and ranging, while a rear mounted camera produced color images.- A laser system worked in conjunction with the two forward cameras to detect and avoid obstacles. - The rover took close-up images of the terrain during its travels. The top speed the vehicle could travel was 13.12 ft per minute. The rover’s wheels and suspension used a rocker-bogie system that did not use springs. - Its joints rotated and conformed to the contour of the ground, providing the greatest degree of stability for traversing rocky, uneven surfaces. A six-wheel chassis was chosen over a four-wheel design because it provided greater stability and obstacle-crossing capability. - Six-wheeled vehicles could overcome obstacles three times larger than those crossable by four-wheeled vehicles.-- Sojourner was capable of scaling a boulder more than 8 inches high and keep on going.-- Sojourner could tilt as much as 45 degrees as it climbed over a rock without tipping over. --- Three motion sensors along Sojourner's frame could detect excessive tilt and stop the rover before it got dangerously close to tipping over. - Each wheel was independently actuated providing superior climbing capability in soft sand. -- The front and rear wheels were independently steerable, providing the capability for the vehicle to turn in place.

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Sojourner Rover- Page 2 of 2 Operations (Continued)- The wheels were 5 inches in diameter and made of aluminum. -- Stainless steel tread and cleats on the wheels provided traction. The rover’s control system required the human operator to choose targets and for the rover to autonomously control how it reached the targets and performed tasks.

Science and Technology Experiments The rover performed a number of technology experiments designed to provide information to improve future planetary rovers. - These experiments included: terrain geometry reconstruction from lander/rover imaging; basic soil mechanics by studying wheel sinkage; path reconstruction by “dead reckoning” and track images; and vision sensor performance.- Sojourner experiments also determined vehicle performance; rover thermal conditions; effectiveness of the radio link; and material abrasion by sensing the wear on different thicknesses of paint on a rover wheel. - Scientists studied the adherence of Martian airborne material by measuring dust accumulation on a reference solar cell that had a removable cover, and by directly measuring the mass of accumulated dust on a quartz crystal microbalance sensor. A basic understanding of soil mechanics was obtained by the rover and Lander imaging rover wheel tracks, holes dug by rover wheels and any surface disruptions that had been caused by airbag bouncing and/or retraction. The rover’s alpha proton X-ray spectrometer (APXS), along with the spectral filters of the Lander’s imaging system (Imager for Mars Pathfinder) and close-up images from the rover, measured the elemental composition of rocks and surface soil and inferred their mineralogy.

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NASA Successful Mars Landings - Page 1 of 2 Name Vehicles Landing Site

& (Weight)Mission Objective & (Duration)

Viking 1 Orbiter & Lander

Chryse Planitiawestern slopes (1,261 lbs)

Obtained high resolution images of the surface, characterized the atmosphere and surface, and searched for evidence of life. Viking 1 was the first to land on Mars. (July 20, 1976 to 13 Nov. 1982)

Viking 2 Orbiter & Lander

Utopia Planitia(1,261 lbs)

See Viking 1 for mission objective. Viking 2 lander was the second to land on Mars. (Sep. 3, 1976 to April 11, 1980)

Pathfinder Lander & Sojourner Rover

Ares Vallisancient flood plain (793 lbs)

Demonstrated the feasibility of low-cost landings on the surface. Sojourner was the first rover to explore Mars. (July 4, 1997 to Nov. 4, 1997)

Spirit (MER-A)

Lander & Spirit Rover

Gusev Crater (408 lbs)

The Mars Exploration Rover-A (MER-A), named “Spirit,” searched for and characterized a variety of rocks and soils that held clues to past water activity.(Jan. 3, 2004 to March 22, 2010)

Opportunity(MER-B)

Lander & Opportunity Rover

MeridianiPlanum(408 lbs)

MER-B, named “Opportunity,” landed in a crater rich in hematite, often associated with water. It exceeded expectations and continues to return exceptional data.(Jan. 24, 2004 to Present)

Credit: NASA

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NASA Successful Mars Landings - Page 2 of 2 Name Vehicles Landing Site

& (Weight)Mission Objective & (Duration)

Phoenix Lander Green Valley of VastitasBorealis(772 lbs)

Phoenix investigated the history of water and habitability potential in the ice-rich Martian arctic soil. It was the first vehicle to confirm the presence of water ice on a body in the Solar System. (May 25, 2008 to Nov. 10, 2008)

Curiosity Curiosity Rover

Gale Crater(1,982 lbs)

The Mars Science Laboratory, named “Curiosity,” continues to assess whether Mars ever had an environment able to support small microbial life forms. (Aug. 6, 2012 to Present)

InSight Lander Elysium Planitia(794 lbs)

InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is similar in design to Phoenix. It will take the first look into the Martian deep interior to see why Mars evolved differently from Earth. Expected to land on Nov. 26, 2018.

Credit: NASA