Martian Robots
Spirit and Opportunity, the twin robots launched in
June 2003 from Earth that landed on Martian soil in January 2004, were designed to travel over the surface of the Red Planet. Both vehicles are part of NASA's Mars Exploration Rovers mission. They have tools that allow them to drill into rock and take samples of the soil to analyze their chemical composition. The robots are located on opposite
sides of the planet to explore two uniquely different places. They each use nine cameras.
Water and Life on Mars
The main purpose of the mission conceived by NASA was to find indications whether there had eve been water on Mars. In Spirit's first mission, it was
thought that small quantities of water might have seeped into the eroded rock fragments. The rocky Martian soil, it is believed, could have been affected by the action of water. So far, there is no evidence of the existence of living microorganisms. Between ultraviolet radiation and the oxidative nature of the soil, life on Mars is not currently possible. The question that remains is whether life might have existed at some time in the past or even today deep inside the Martian subsoil, where conditions for life might be more favorable.
June 2003 from Earth that landed on Martian soil in January 2004, were designed to travel over the surface of the Red Planet. Both vehicles are part of NASA's Mars Exploration Rovers mission. They have tools that allow them to drill into rock and take samples of the soil to analyze their chemical composition. The robots are located on opposite
sides of the planet to explore two uniquely different places. They each use nine cameras.
Water and Life on Mars
The main purpose of the mission conceived by NASA was to find indications whether there had eve been water on Mars. In Spirit's first mission, it was
thought that small quantities of water might have seeped into the eroded rock fragments. The rocky Martian soil, it is believed, could have been affected by the action of water. So far, there is no evidence of the existence of living microorganisms. Between ultraviolet radiation and the oxidative nature of the soil, life on Mars is not currently possible. The question that remains is whether life might have existed at some time in the past or even today deep inside the Martian subsoil, where conditions for life might be more favorable.
THE SPIRIT OF EXPLORATION
In April 2004, two mobile robots named Spirit and Opportunity successfully completed their primary three-month missions on opposite sides of Mars and
went into bonus overtime work. These twin vehicles of NASA’s Mars Exploration Rover project continued their pursuit of geological clues about whether
parts of Mars formerly had environments wet enough to be hospitable to life. Opportunity hit the jackpot early. It landed close to a thin outcrop of rocks.
Within two months, its versatile science instruments found evidence in those rocks that a body of salty water deep enough to splash in once flowed gently over the area. Preliminary interpretations point to a past environment that could have been hospitable to life and also could have preserved fossil evidence of it, though these rovers are not equipped to detect life or to be fossil hunters. As Opportunity’s primary mission ran out and an extended mission began, the rover was headed for thicker layers of exposed bedrock that might bear evidence about how long or how often water covered the region.
Spirit, during its primary mission, explored a plain strewn with volcanic rocks and pocked with impact craters. It found indications that small amounts of water
may have gotten into cracks in the rocks and may also have affected some of the rocks’ surfaces. This did not indicate a particularly favorable past environment for life. Spirit’s extended mission began with the rover starting a long trek toward a range of hills on the horizon whose rocks might have come from an earlier and wetter era of the region’s past. Second Extension as Adventure Continues.
In late September 2004, NASA approved a second extension of the rovers’ missions. The solar-powered machines were still in good health, though beginning
to show signs of aging. They had come through the worst days of the martian year from a solar-energy standpoint. Also, they had resumed full operations
after about two weeks of not driving in mid- September while communications were unreliable because Mars was passing nearly behind the Sun.
Spirit had driven 3.6 kilometers (2.25 miles), six times the goal set in advance as a criterion for a successful mission. It was climbing hills where its examinations of exposed bedrock found more extensive alteration by water than what the rover had seen in rocks on the younger plain. During the long trek,
Spirit’s right front wheel developed excessive friction. Controllers found a way to press on with the exploration by sometimes driving the rover in reverse with
the balky wheel dragging.
Opportunity had driven about 1.6 kilometers (1 mile). It was studying rocks and soils inside a crater about 130 meters (142 yards) wide and 22 meters (24 yards) deep. The rover entered this crater in June after careful analysis of its ability to climb back out. Inside, Opportunity examined layer upon layer of bedrock with characteristics similar to those of the outcrop inside the smaller crater where it landed. This indicated a much longer duration for the watery portion of the region’s ancient past. The rover also found some features unlike any it had seen before, evidence of changes in the environment over time. Whether the rovers’ unpredictable life spans would extend only a few more days or several more months, they had already racked up successes beyond the high expectations set for them when the Mars Exploration Rover project began. Favorable Time to Build on Experience Mars came closer to Earth in August 2003 than it had in thousands of years. NASA decided in the summer of 2000 to take advantage of this favorable planetary geometry to send two rovers to Mars.
The design began with some basics from Sojourner, the rover on NASA’s 1997 Mars Pathfinder mission. Some of the carried-over design elements are six wheels and a rocker-bogie suspension for driving over rough terrain, a shell of airbags for cushioning the landing, solar panels and rechargeable batteries
for power, and radioisotope heater units for protecting batteries through extremely cold martian nights. However, at 174 kilograms (384 pounds), each Mars
Exploration Rover is more than 17 times as heavy as Pathfinder. It is also more than more than twice as long (at 1.6 meters or 5.2 feet) and tall (1.5 meters or
4.9 feet). Pathfinder’s lander, not the Sojourner rover, housed that mission’s main communications, camera and computer functions. The Mars Exploration
Rovers carry equipment for those functions on board. Their landers enfolded them in flight and performed crucial roles on arrival, but after Spirit and Opportunity rolled off their unfolded landers onto martian soil, the landers’ jobs was finished. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., designed and built the two new rovers plus the lander and the cruise stage for each. The cruise stage provided capabilities needed during the journey from Earth to Mars. In early 2003, the hardware arrived at NASA’s Kennedy Space Station in Florida for final assembly, testing and integration with Boeing Delta II launch vehicles.
While the twin spacecraft were being built, scientists and engineers winnowed a list of 155 candidate landing sites to a final pair best suited to the missions’
goals and safety. More than 100 Mars experts participated in evaluating the sites. They made heavy use of images and other data from NASA’s Mars
Global Surveyor and Mars Odyssey orbiters.The rover project’s science goal has been to assess the history of environmental conditions at sites that
may once have been wet and favorable to life. Each of the two selected landing sites showed evidence detectable from orbit that it may have once been wet.
For Spirit, NASA chose Gusev Crater, a Connect it cut size basin that appears to have once held a lake, judging from the shapes of the landscape. A wide channel, now dry, runs downhill for hundreds of kilometers or miles to the crater and appears to have been carved by water flowing into the crater. For Opportunity, NASA chose part of a broad plain named Meridiani Planum based on a different type of evidence for a possibly watery past. A mineral-mapping instrument on Mars Global Surveyor had identified there an Oklahoma size exposure of gray hematite, a mineral that usually forms in the presence of liquid water.
went into bonus overtime work. These twin vehicles of NASA’s Mars Exploration Rover project continued their pursuit of geological clues about whether
parts of Mars formerly had environments wet enough to be hospitable to life. Opportunity hit the jackpot early. It landed close to a thin outcrop of rocks.
Within two months, its versatile science instruments found evidence in those rocks that a body of salty water deep enough to splash in once flowed gently over the area. Preliminary interpretations point to a past environment that could have been hospitable to life and also could have preserved fossil evidence of it, though these rovers are not equipped to detect life or to be fossil hunters. As Opportunity’s primary mission ran out and an extended mission began, the rover was headed for thicker layers of exposed bedrock that might bear evidence about how long or how often water covered the region.
Spirit, during its primary mission, explored a plain strewn with volcanic rocks and pocked with impact craters. It found indications that small amounts of water
may have gotten into cracks in the rocks and may also have affected some of the rocks’ surfaces. This did not indicate a particularly favorable past environment for life. Spirit’s extended mission began with the rover starting a long trek toward a range of hills on the horizon whose rocks might have come from an earlier and wetter era of the region’s past. Second Extension as Adventure Continues.
In late September 2004, NASA approved a second extension of the rovers’ missions. The solar-powered machines were still in good health, though beginning
to show signs of aging. They had come through the worst days of the martian year from a solar-energy standpoint. Also, they had resumed full operations
after about two weeks of not driving in mid- September while communications were unreliable because Mars was passing nearly behind the Sun.
Spirit had driven 3.6 kilometers (2.25 miles), six times the goal set in advance as a criterion for a successful mission. It was climbing hills where its examinations of exposed bedrock found more extensive alteration by water than what the rover had seen in rocks on the younger plain. During the long trek,
Spirit’s right front wheel developed excessive friction. Controllers found a way to press on with the exploration by sometimes driving the rover in reverse with
the balky wheel dragging.
Opportunity had driven about 1.6 kilometers (1 mile). It was studying rocks and soils inside a crater about 130 meters (142 yards) wide and 22 meters (24 yards) deep. The rover entered this crater in June after careful analysis of its ability to climb back out. Inside, Opportunity examined layer upon layer of bedrock with characteristics similar to those of the outcrop inside the smaller crater where it landed. This indicated a much longer duration for the watery portion of the region’s ancient past. The rover also found some features unlike any it had seen before, evidence of changes in the environment over time. Whether the rovers’ unpredictable life spans would extend only a few more days or several more months, they had already racked up successes beyond the high expectations set for them when the Mars Exploration Rover project began. Favorable Time to Build on Experience Mars came closer to Earth in August 2003 than it had in thousands of years. NASA decided in the summer of 2000 to take advantage of this favorable planetary geometry to send two rovers to Mars.
The design began with some basics from Sojourner, the rover on NASA’s 1997 Mars Pathfinder mission. Some of the carried-over design elements are six wheels and a rocker-bogie suspension for driving over rough terrain, a shell of airbags for cushioning the landing, solar panels and rechargeable batteries
for power, and radioisotope heater units for protecting batteries through extremely cold martian nights. However, at 174 kilograms (384 pounds), each Mars
Exploration Rover is more than 17 times as heavy as Pathfinder. It is also more than more than twice as long (at 1.6 meters or 5.2 feet) and tall (1.5 meters or
4.9 feet). Pathfinder’s lander, not the Sojourner rover, housed that mission’s main communications, camera and computer functions. The Mars Exploration
Rovers carry equipment for those functions on board. Their landers enfolded them in flight and performed crucial roles on arrival, but after Spirit and Opportunity rolled off their unfolded landers onto martian soil, the landers’ jobs was finished. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., designed and built the two new rovers plus the lander and the cruise stage for each. The cruise stage provided capabilities needed during the journey from Earth to Mars. In early 2003, the hardware arrived at NASA’s Kennedy Space Station in Florida for final assembly, testing and integration with Boeing Delta II launch vehicles.
While the twin spacecraft were being built, scientists and engineers winnowed a list of 155 candidate landing sites to a final pair best suited to the missions’
goals and safety. More than 100 Mars experts participated in evaluating the sites. They made heavy use of images and other data from NASA’s Mars
Global Surveyor and Mars Odyssey orbiters.The rover project’s science goal has been to assess the history of environmental conditions at sites that
may once have been wet and favorable to life. Each of the two selected landing sites showed evidence detectable from orbit that it may have once been wet.
For Spirit, NASA chose Gusev Crater, a Connect it cut size basin that appears to have once held a lake, judging from the shapes of the landscape. A wide channel, now dry, runs downhill for hundreds of kilometers or miles to the crater and appears to have been carved by water flowing into the crater. For Opportunity, NASA chose part of a broad plain named Meridiani Planum based on a different type of evidence for a possibly watery past. A mineral-mapping instrument on Mars Global Surveyor had identified there an Oklahoma size exposure of gray hematite, a mineral that usually forms in the presence of liquid water.
Getting to Mars
Time line of the Mars rovers
Both rovers were launched from Cape Canaveral Air Force Station on central Florida’s Space Coast. Spirit ascended in daylight on June 10, 2003. Opportunity followed with a nighttime launch on July 7 after several days of delays for repairing cork insulation. During the cruise to Mars, Spirit made four trajectory correction maneuvers. Opportunity performed three. The two spacecraft survived blasts of high energy particles from some of the most intense solar flares on record.
To prevent possible problems from the flares’ effects on computer memory, mission controllers commanded rebooting of the rovers’ computers, a capability originally planned for use on Mars but not during the cruise.Each rover made the trip tightly tucked inside its folded-up lander, which was encased in a protective aero shell and attached to a disc-shaped cruise stage about 2.6 meters (8.5 feet) in diameter. The cruise stage was jettisoned about 15 minutes before the spacecraft reached the top of Mars’ atmosphere. With the heat-shield portion of the aero shell pointed forward, the spacecraft slammed into the atmosphere at about 5.4 kilometers per second (12,000 miles per hour). Atmospheric friction in the next four minutes cut that speed by 90 percent, then a parachute fastened to the back shell portion of the aero shell opened about two minutes before landing.About 20 seconds later, the spacecraft jettisoned the heat shield. The lander descended on a bridle that un spooled from the back shell.
A downward-pointing camera on the lander took three pictures during the final half-minute of the flight. An on board computer instantly analyzed the pictures to estimate horizontal motion. In the final eight seconds before impact, gas generators inflated the lander’s airbags, retro rockets on the back shell fired to halt descent speed, and transverse rockets fired (on Spirit’s lander) to reduce horizontal speed. The bridle was cut to release the lander from the back shell and parachute.
Then the airbag encased lander dropped in free fall. Spirit landed on Jan. 4, Universal Time (at 8:35 p.m. Jan. 3, Pacific Standard Time). It bounced about 8.4 meters (27.6 feet) high. After 27 more bounces and then rolling, it came to a stop about 250 to 300 meters (270 to 330 yards) from its first impact. Spirit had journeyed 487 million kilometers (303 million miles). JPL navigators and engineers successfully put it only about 10 kilometers (6 miles) from the center of its target area. Coordinates of Spirit’s landing site are 14.57 degrees south latitude and 175.47 degrees east longitude. Opportunity landed on Jan. 25, Universal Time (at 9:05 p.m. Jan. 24, Pacific Standard Time). It traveled about 200 meters (220 yards) while bouncing 26 times and rolling after the impact, with a 90-degree turn northward during that period. It came to rest inside a small crater. One scientist called the landing an “interplanetary hole in one.” Opportunity had flown 456 million kilometers (283 million miles) from Earth and landed only about 25 kilometers (16 miles) from the center of the target area. The landing site crater, later informally named “Eagle Crater,” is about 22 meters (72 feet) in diameter, 3 meters (10 feet) deep. Its coordinates are 1.95 degrees south, 354.47 degrees east.
To prevent possible problems from the flares’ effects on computer memory, mission controllers commanded rebooting of the rovers’ computers, a capability originally planned for use on Mars but not during the cruise.Each rover made the trip tightly tucked inside its folded-up lander, which was encased in a protective aero shell and attached to a disc-shaped cruise stage about 2.6 meters (8.5 feet) in diameter. The cruise stage was jettisoned about 15 minutes before the spacecraft reached the top of Mars’ atmosphere. With the heat-shield portion of the aero shell pointed forward, the spacecraft slammed into the atmosphere at about 5.4 kilometers per second (12,000 miles per hour). Atmospheric friction in the next four minutes cut that speed by 90 percent, then a parachute fastened to the back shell portion of the aero shell opened about two minutes before landing.About 20 seconds later, the spacecraft jettisoned the heat shield. The lander descended on a bridle that un spooled from the back shell.
A downward-pointing camera on the lander took three pictures during the final half-minute of the flight. An on board computer instantly analyzed the pictures to estimate horizontal motion. In the final eight seconds before impact, gas generators inflated the lander’s airbags, retro rockets on the back shell fired to halt descent speed, and transverse rockets fired (on Spirit’s lander) to reduce horizontal speed. The bridle was cut to release the lander from the back shell and parachute.
Then the airbag encased lander dropped in free fall. Spirit landed on Jan. 4, Universal Time (at 8:35 p.m. Jan. 3, Pacific Standard Time). It bounced about 8.4 meters (27.6 feet) high. After 27 more bounces and then rolling, it came to a stop about 250 to 300 meters (270 to 330 yards) from its first impact. Spirit had journeyed 487 million kilometers (303 million miles). JPL navigators and engineers successfully put it only about 10 kilometers (6 miles) from the center of its target area. Coordinates of Spirit’s landing site are 14.57 degrees south latitude and 175.47 degrees east longitude. Opportunity landed on Jan. 25, Universal Time (at 9:05 p.m. Jan. 24, Pacific Standard Time). It traveled about 200 meters (220 yards) while bouncing 26 times and rolling after the impact, with a 90-degree turn northward during that period. It came to rest inside a small crater. One scientist called the landing an “interplanetary hole in one.” Opportunity had flown 456 million kilometers (283 million miles) from Earth and landed only about 25 kilometers (16 miles) from the center of the target area. The landing site crater, later informally named “Eagle Crater,” is about 22 meters (72 feet) in diameter, 3 meters (10 feet) deep. Its coordinates are 1.95 degrees south, 354.47 degrees east.
Science Instruments: A Geology Toolkit
Like a human field geologist, each Mars Exploration Rover has the capabilities to scout its surroundings for interesting rocks and soils, to move to those targets and to examine their composition and structure. Spirit and Opportunity have identical suites of five scientific instruments: a panoramic camera provided by JPL; a miniature thermal emission spectrometer from Arizona State University, Tempe; a Moessbauer spectrometer from the Johannes Gutenberg University, Mainz, Germany; an alpha particle X-ray spectrometer from Max Planck Institute for Chemistry, also in Mainz, Germany; and a micro-scopic imager from JPL. These are augmented by a rock abrasion tool from Honeybee Robotics, New York, N.Y., for removing the weathered surfaces of
rocks to expose fresh interiors for examination. The payload also includes magnetic targets provided by
Niels Bohr Institute in Copenhagen, Denmark, to catch samples of martian dust for examination. The
spectrometers, microscopic imager and abrasion tool share a turret at the end of a robotic arm provided by
Alliance Space systems Inc., Pasadena, Calif.
Panoramic Camera — Providing the geologic context: This high-resolution stereo camera reveals the surrounding terrain at each new location
that the rover reaches. Its two eyes sit 30 centimeters (12 inches) apart, atop a mast about 1.5 meters (5 feet) above the ground. The instrument carries 14 different types of filters, allowing not only full-color images but also spectral analysis of minerals and the atmosphere. Its images are used to help select rock
and soil targets for more intensive study and to pick new regions for the rover to explore.
Miniature Thermal Emission Spectrometer — Identifying minerals at the site: This instrument views the surrounding scene in infrared wavelengths,
determining types and amounts of many different kinds of minerals. A particular goal is to search for distinctive minerals that are formed by the action of
water. The spectrometer scans to build up an image. Data from it and from the panoramic camera are used in choosing science targets and new areas to explore. Scientists also use it in studies of Mars’ atmosphere.
Moessbauer Spectrometer — Identifying iron-bearing minerals: Mounted on the rover arm, this instrument is placed against rock and soil targets.
It identifies minerals that contain iron, which helps scientists evaluate what role water played in the formation of the targets and discern the extent to which
rocks have been weathered. The instrument uses two cobalt-57 sources, each about the size of a pencil eraser, in calibrating its measurements. It is a miniaturized version of spectrometers used by geologists to study rocks and soils on Earth.
Alpha Particle X-Ray Spectrometer — Determining the composition of rocks: An improved version of an instrument used by the Sojourner rover, this spectrometer is also similar to instruments used in geology labs on Earth. It uses small amounts of curium-244 in measuring the concentrations
of most major elements in rocks and soil. Learning the elemental ingredients in rocks and soils helps scientists understand the samples’ origins and
how they have been altered over time.
Microscopic Imager — Looking at fine-scale features: The fine-scale appearance of rocks and soils can provide essential clues to how those rocks and
soils were formed. For instance, the size and angularity of grains in water-lain sediments can reveal how they were transported and deposited. This imager provides the close-up data needed for such studies.
Supplemental Instruments — Engineering tools aid science: Each rover also has other tools that, while primarily designed for engineering use in
the operation of the rover, can also provide geological information. The navigation camera is a wider-angle stereo instrument on the same mast as the panoramic camera. Hazard-avoidance cameras ride low on the front and rear of the rover in stereo pairs to produce three-dimensional information about the nearby terrain. The front pair provides information to aid positioning of the tools mounted on the rover’s arm. Rover wheels, in addition to allowing mobility, are
used to dig shallow trenches to evaluate soil properties.
rocks to expose fresh interiors for examination. The payload also includes magnetic targets provided by
Niels Bohr Institute in Copenhagen, Denmark, to catch samples of martian dust for examination. The
spectrometers, microscopic imager and abrasion tool share a turret at the end of a robotic arm provided by
Alliance Space systems Inc., Pasadena, Calif.
Panoramic Camera — Providing the geologic context: This high-resolution stereo camera reveals the surrounding terrain at each new location
that the rover reaches. Its two eyes sit 30 centimeters (12 inches) apart, atop a mast about 1.5 meters (5 feet) above the ground. The instrument carries 14 different types of filters, allowing not only full-color images but also spectral analysis of minerals and the atmosphere. Its images are used to help select rock
and soil targets for more intensive study and to pick new regions for the rover to explore.
Miniature Thermal Emission Spectrometer — Identifying minerals at the site: This instrument views the surrounding scene in infrared wavelengths,
determining types and amounts of many different kinds of minerals. A particular goal is to search for distinctive minerals that are formed by the action of
water. The spectrometer scans to build up an image. Data from it and from the panoramic camera are used in choosing science targets and new areas to explore. Scientists also use it in studies of Mars’ atmosphere.
Moessbauer Spectrometer — Identifying iron-bearing minerals: Mounted on the rover arm, this instrument is placed against rock and soil targets.
It identifies minerals that contain iron, which helps scientists evaluate what role water played in the formation of the targets and discern the extent to which
rocks have been weathered. The instrument uses two cobalt-57 sources, each about the size of a pencil eraser, in calibrating its measurements. It is a miniaturized version of spectrometers used by geologists to study rocks and soils on Earth.
Alpha Particle X-Ray Spectrometer — Determining the composition of rocks: An improved version of an instrument used by the Sojourner rover, this spectrometer is also similar to instruments used in geology labs on Earth. It uses small amounts of curium-244 in measuring the concentrations
of most major elements in rocks and soil. Learning the elemental ingredients in rocks and soils helps scientists understand the samples’ origins and
how they have been altered over time.
Microscopic Imager — Looking at fine-scale features: The fine-scale appearance of rocks and soils can provide essential clues to how those rocks and
soils were formed. For instance, the size and angularity of grains in water-lain sediments can reveal how they were transported and deposited. This imager provides the close-up data needed for such studies.
Supplemental Instruments — Engineering tools aid science: Each rover also has other tools that, while primarily designed for engineering use in
the operation of the rover, can also provide geological information. The navigation camera is a wider-angle stereo instrument on the same mast as the panoramic camera. Hazard-avoidance cameras ride low on the front and rear of the rover in stereo pairs to produce three-dimensional information about the nearby terrain. The front pair provides information to aid positioning of the tools mounted on the rover’s arm. Rover wheels, in addition to allowing mobility, are
used to dig shallow trenches to evaluate soil properties.
Mars Science Laboratory-curiosity
NASA’s Mars Science Laboratory mission is preparing to set down a large, mobile laboratory — the rover Curiosity — using precision landing technology that makes many of Mars’ most intriguing regions viable destinations for the first time. During the 23 months after landing, Curiosity will analyze dozens of samples drilled from rocks or scooped from the ground as it explores with greater range than any previous Mars rover.
Curiosity will carry the most advanced payload of scientific gear ever used on Mars’ surface, a payload more than 10 times as massive as those of earlier Mars rovers. Its assignment: Investigate whether conditions have been favorable for microbial life and for preserving clues in the rocks about possible past life. The Mars Science Laboratory spacecraft was launched from Cape Canaveral Air Force Station, Florida, on Nov. 26, 2011, and is headed for arrival at Mars on Aug. 6, 2012, Universal Time (evening of Aug. 5, Pacific Time). The spacecraft has been designed to steer itself during descent through Mars’ atmosphere with a series of S-curve maneuvers similar to those used by astronauts piloting NASA space shuttles. During the three minutes before touchdown, the spacecraft slows its descent with a parachute, then uses retro rockets mounted around the rim of an upper stage.
In the final seconds, the upper stage acts as a sky crane, lowering the upright rover on a tether to the surface. Curiosity is about twice as long (about 3 meters or 10 feet) and five times as heavy as NASA’s twin Mars Exploration Rovers, Spirit and Opportunity, launched in 2003. It inherited many design elements from them, including six-wheel drive, a rocker-bogie suspension system and cameras mounted on a mast to help the mission’s team on Earth select exploration targets and driving routes. Unlike earlier rovers, Curiosity carries equipment to gather samples of rocks and soil, process them and distribute them to onboard test chambers inside analytical instruments. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., builder of the Mars Science Laboratory, has engineered Curiosity to roll over obstacles up to 65 centimeters (25 inches) high and to travel up to about 200 meters (660 feet) per day on Martian terrain. The rover’s electrical power will be supplied by a U.S. Department of Energy radioisotope power generator. The multimission radioisotope thermoelectric generator produces electricity from the heat of plutonium-238’s radioactive decay.
This long-lived power supply gives the mission an operating lifespan on Mars’ surface of a full Mars year (687 Earth days) or more. At launch, the generator will provide about 110 watts of electrical power to operate the rover’s instruments, robotic arm, wheels, computers and radio. Warm fluids heated by the enerator’s excess heat are plumbed throughout the rover to keep electronics and other systems at acceptable operating temperatures. The mission has been designed to use radio relays via Mars orbiters as the principal means of communication between Curiosity and the Deep Space Network of antennas on Earth.
The overarching science goal of the mission is to assess whether the landing area has ever had or still has environmental onditions favorable to microbial life, both its habitability and its preservation. More than 100 scientists participating in a series of open workshops since 2006 have compared merits of more than 30 Martian locations as potential landing sites for the rover.
Evaluations of scientific appeal and safety factors led NASA to select four finalist candidate sites in 2008, with the final selection to be made in 2011. All four have exposures of minerals formed under wet conditions. Selection of a landing site of prime scientific interest has benefited from examining candidate sites with NASA’s Mars Reconnaissance Orbiter since 2006, from earlier orbiters’ observations, and from a capability of landing within a target area only about 20 kilometers (12 miles) long. That precision, about a five-fold improvement on earlier Mars landings, makes feasible sites that would otherwise be excluded for encompassing nearby unsuitable terrain. For example, the mission could go to the floor of a crater whose steep walls would make a less precise landing too risky. Advancing the technologies for precision landing of a heavy payload will yield research benefits beyond the returns from Mars Science Laboratory itself. Those same capabilities would be important for later missions both to pick up rocks on Mars and bring them back to Earth, and conduct extensive surface exploration for Martian life.
Curiosity will carry the most advanced payload of scientific gear ever used on Mars’ surface, a payload more than 10 times as massive as those of earlier Mars rovers. Its assignment: Investigate whether conditions have been favorable for microbial life and for preserving clues in the rocks about possible past life. The Mars Science Laboratory spacecraft was launched from Cape Canaveral Air Force Station, Florida, on Nov. 26, 2011, and is headed for arrival at Mars on Aug. 6, 2012, Universal Time (evening of Aug. 5, Pacific Time). The spacecraft has been designed to steer itself during descent through Mars’ atmosphere with a series of S-curve maneuvers similar to those used by astronauts piloting NASA space shuttles. During the three minutes before touchdown, the spacecraft slows its descent with a parachute, then uses retro rockets mounted around the rim of an upper stage.
In the final seconds, the upper stage acts as a sky crane, lowering the upright rover on a tether to the surface. Curiosity is about twice as long (about 3 meters or 10 feet) and five times as heavy as NASA’s twin Mars Exploration Rovers, Spirit and Opportunity, launched in 2003. It inherited many design elements from them, including six-wheel drive, a rocker-bogie suspension system and cameras mounted on a mast to help the mission’s team on Earth select exploration targets and driving routes. Unlike earlier rovers, Curiosity carries equipment to gather samples of rocks and soil, process them and distribute them to onboard test chambers inside analytical instruments. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., builder of the Mars Science Laboratory, has engineered Curiosity to roll over obstacles up to 65 centimeters (25 inches) high and to travel up to about 200 meters (660 feet) per day on Martian terrain. The rover’s electrical power will be supplied by a U.S. Department of Energy radioisotope power generator. The multimission radioisotope thermoelectric generator produces electricity from the heat of plutonium-238’s radioactive decay.
This long-lived power supply gives the mission an operating lifespan on Mars’ surface of a full Mars year (687 Earth days) or more. At launch, the generator will provide about 110 watts of electrical power to operate the rover’s instruments, robotic arm, wheels, computers and radio. Warm fluids heated by the enerator’s excess heat are plumbed throughout the rover to keep electronics and other systems at acceptable operating temperatures. The mission has been designed to use radio relays via Mars orbiters as the principal means of communication between Curiosity and the Deep Space Network of antennas on Earth.
The overarching science goal of the mission is to assess whether the landing area has ever had or still has environmental onditions favorable to microbial life, both its habitability and its preservation. More than 100 scientists participating in a series of open workshops since 2006 have compared merits of more than 30 Martian locations as potential landing sites for the rover.
Evaluations of scientific appeal and safety factors led NASA to select four finalist candidate sites in 2008, with the final selection to be made in 2011. All four have exposures of minerals formed under wet conditions. Selection of a landing site of prime scientific interest has benefited from examining candidate sites with NASA’s Mars Reconnaissance Orbiter since 2006, from earlier orbiters’ observations, and from a capability of landing within a target area only about 20 kilometers (12 miles) long. That precision, about a five-fold improvement on earlier Mars landings, makes feasible sites that would otherwise be excluded for encompassing nearby unsuitable terrain. For example, the mission could go to the floor of a crater whose steep walls would make a less precise landing too risky. Advancing the technologies for precision landing of a heavy payload will yield research benefits beyond the returns from Mars Science Laboratory itself. Those same capabilities would be important for later missions both to pick up rocks on Mars and bring them back to Earth, and conduct extensive surface exploration for Martian life.
Science Payload
Payloads of curiosity
In April 2004, NASA solicited proposals for specific instruments and investigations to be carried by Mars Science Laboratory. The agency selected eight of the proposals later that year and also reached agreements with Russia and Spain for carrying instruments those nations will provide. A suite of instruments named Sample Analysis at Mars will analyze samples of material collected and delivered by the rover’s arm. It includes a gas chromatograph, a mass spectrometer, and a tunable laser spectrometer with combined capabilities to identify a wide range of organic (carbon-containing) compounds and determine the ratios of different isotopes of key elements. Isotope ratios are clues to understanding the history of Mars’ atmosphere and water.
The principal investigator is Paul Mahaffy of NASA’s Goddard Space Flight Center, Greenbelt, Md. An X-ray diffraction and fluorescence instrument called CheMin will also examine samples gathered by the robotic arm. It is designed to identify and quantify the minerals in rocks and soils, and to measure bulk composition. The principal investigator is David Blake of NASA’s Ames Research Center, Moffett Field, Calif. Mounted on the arm, the Mars Hand Lens Imager will take extreme close-up pictures of rocks, soil and, if present, ice, revealing details smaller than the width of a human hair. It will also be able to focus on hard-to-reach objects more than an arm’s length away. The principal investigator is Kenneth Edgett of Malin Space Science Systems, San Diego. Also on the arm, the Alpha Particle X-ray Spectrometer for Mars Science Laboratory will determine the relative abundances of different elements in rocks and soils. Dr. Ralf Gellert of the University of Guelph, Ontario, Canada, is principal investigator for this instrument, which will be provided by the Canadian Space Agency. The Mars Science Laboratory Mast Camera, mounted at about human-eye height, will image the rover’s surroundings in high-resolution stereo and color, with the capability to take and store high-definition video sequences. It will also be used for viewing materials collected or treated by the arm. The principal investigator is Michael Malin of Malin Space Science Systems. An instrument named ChemCam will use laser pulses to vaporize thin layers of material from Martian rocks or soil targets up to 9 meters (30 feet) away. It will include both a spectrometer to identify the types of atoms excited by the beam, and a telescope to capture detailed images of the area illuminated by the beam.
The laser and telescope sit on the rover’s mast and share with the Mast Camera the role of informing researchers’ choices about which objects in the area make the best targets for approaching to examine with other instruments. Roger Wiens of Los Alamos National Laboratory, Los Alamos, N.M., is the principal investigator. The rover’s Radiation Assessment Detector will characterize the radiation environment at the surface of Mars. This information is necessary for planning human exploration of Mars and is relevant to assessing the planet’s ability to harbor life. The principal investigator is Donald Hassler of Southwest Research Institute, Boulder, Colo. In the two minutes before landing, the Mars Descent Imager will capture color, high-definition video of the landing region to provide geological context for the investigations on the ground and to aid precise determination of the landing site. Michael Malin is principal investigator. Spain’s Ministry of Education and Science is providing the Rover Environmental Monitoring Station to measure atmospheric pressure, temperature, humidity, winds, plus ultraviolet radiation levels. The principal investigator is Javier Gómez-Elvira of the Center for Astrobiology, Madrid, an international partner of the NASA Astrobiology Institute. The team for this investigation includes the Finnish Meteorological Institute as a partner.
Russia’s Federal Space Agency is providing the Dynamic Albedo of Neutrons instrument to measure subsurface hydrogen up to one meter (three feet) below the surface. Detections of hydrogen may indicate the presence of water in the form of ice or bound in minerals. Igor Mitrofanov of the Space Research
Institute, Moscow, is the principal investigator. In addition to the science payload, equipment of the rover’s engineering infrastructure will contribute to scientific observations. Like the Mars Exploration Rovers, Curiosity will have a stereo navigation camera on its mast and lowslung, stereo hazard-avoidance cameras. Equipment called the Sample Acquisition/ Sample Preparation and Handling System includes tools to remove dust from rock surfaces, scoop up soil, drill into rocks and collect powdered samples from rocks’ interiors, sort samples by particle size with sieves, and deliver samples to laboratory instruments.
The Mars Science Laboratory Entry, Descent and Landing Instrument Suite is a set of engineering sensors designed to measure atmospheric conditions
and performance of the spacecraft during the arrival-day plunge through the atmosphere, to aid in design of future missions.
The principal investigator is Paul Mahaffy of NASA’s Goddard Space Flight Center, Greenbelt, Md. An X-ray diffraction and fluorescence instrument called CheMin will also examine samples gathered by the robotic arm. It is designed to identify and quantify the minerals in rocks and soils, and to measure bulk composition. The principal investigator is David Blake of NASA’s Ames Research Center, Moffett Field, Calif. Mounted on the arm, the Mars Hand Lens Imager will take extreme close-up pictures of rocks, soil and, if present, ice, revealing details smaller than the width of a human hair. It will also be able to focus on hard-to-reach objects more than an arm’s length away. The principal investigator is Kenneth Edgett of Malin Space Science Systems, San Diego. Also on the arm, the Alpha Particle X-ray Spectrometer for Mars Science Laboratory will determine the relative abundances of different elements in rocks and soils. Dr. Ralf Gellert of the University of Guelph, Ontario, Canada, is principal investigator for this instrument, which will be provided by the Canadian Space Agency. The Mars Science Laboratory Mast Camera, mounted at about human-eye height, will image the rover’s surroundings in high-resolution stereo and color, with the capability to take and store high-definition video sequences. It will also be used for viewing materials collected or treated by the arm. The principal investigator is Michael Malin of Malin Space Science Systems. An instrument named ChemCam will use laser pulses to vaporize thin layers of material from Martian rocks or soil targets up to 9 meters (30 feet) away. It will include both a spectrometer to identify the types of atoms excited by the beam, and a telescope to capture detailed images of the area illuminated by the beam.
The laser and telescope sit on the rover’s mast and share with the Mast Camera the role of informing researchers’ choices about which objects in the area make the best targets for approaching to examine with other instruments. Roger Wiens of Los Alamos National Laboratory, Los Alamos, N.M., is the principal investigator. The rover’s Radiation Assessment Detector will characterize the radiation environment at the surface of Mars. This information is necessary for planning human exploration of Mars and is relevant to assessing the planet’s ability to harbor life. The principal investigator is Donald Hassler of Southwest Research Institute, Boulder, Colo. In the two minutes before landing, the Mars Descent Imager will capture color, high-definition video of the landing region to provide geological context for the investigations on the ground and to aid precise determination of the landing site. Michael Malin is principal investigator. Spain’s Ministry of Education and Science is providing the Rover Environmental Monitoring Station to measure atmospheric pressure, temperature, humidity, winds, plus ultraviolet radiation levels. The principal investigator is Javier Gómez-Elvira of the Center for Astrobiology, Madrid, an international partner of the NASA Astrobiology Institute. The team for this investigation includes the Finnish Meteorological Institute as a partner.
Russia’s Federal Space Agency is providing the Dynamic Albedo of Neutrons instrument to measure subsurface hydrogen up to one meter (three feet) below the surface. Detections of hydrogen may indicate the presence of water in the form of ice or bound in minerals. Igor Mitrofanov of the Space Research
Institute, Moscow, is the principal investigator. In addition to the science payload, equipment of the rover’s engineering infrastructure will contribute to scientific observations. Like the Mars Exploration Rovers, Curiosity will have a stereo navigation camera on its mast and lowslung, stereo hazard-avoidance cameras. Equipment called the Sample Acquisition/ Sample Preparation and Handling System includes tools to remove dust from rock surfaces, scoop up soil, drill into rocks and collect powdered samples from rocks’ interiors, sort samples by particle size with sieves, and deliver samples to laboratory instruments.
The Mars Science Laboratory Entry, Descent and Landing Instrument Suite is a set of engineering sensors designed to measure atmospheric conditions
and performance of the spacecraft during the arrival-day plunge through the atmosphere, to aid in design of future missions.