Background on NASA's Mars Exploration Rovers: Two American Rovers Are Working On Mars For the first time since America's twin Viking landers touched down on the Red Planet in 1976, NASA has two working spacecraft on the surface of Mars. NASA now has completed successfully five out of its six attempts to land on the Red Planet. The rover Spirit was launched from Earth on June 10, 2003, and landed on Mars on January 4, 2004, at Gusev Crater, which may be an ancient lake. Its twin, Opportunity, was launched on July 8, 2003, and landed on Mars on January 25, 2004, at Meridiani Planum, which has minerals associated with water.
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A NASA artist imagines the 2003 Mars exploration rovers named Spirit and Opportunity look like this on the Red Planet. click to enlarge
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NASA sent the identical six-wheeled science buggies to land on opposite sides of the Red Planet where they are prospecting for geologic evidence that Mars once had enough water to support life. first pictures from Spirit
Spirit and Opportunity are mobile robots the size of a riding lawnmower. They drive across the Martian surface to wherever scientists want them to go.
Both rovers have greater mobility than the 1997 Mars Pathfinder rover. In 2004, these robotic explorers are able to trek up to 110 yards across the planet's surface each Martian day to help us learn about ancient water and climate on the Red Planet. Each was outfitted with a sophisticated set of instruments to search for evidence of liquid water that may have been present on the planet in the past.
Names. The rover names Spirit and Opportunity were selected from among 10,000 suggested by U.S. school students. Sofi Collis, 9, of Scarsdale, Arizona, submitted both names. She had been born in Siberia, then adopted and brought to the United States at age 2.
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Launching toward Mars
The Mars Exploration Rovers launch campaign window opened on May 22, 2003. The Delta rockets lifted off on June 10 and July 8.
Launch of Spirit on June 10, 2003
click to enlarge nasa photo
Launch of Opportunity on July 8, 2003
click to enlarge nasa photoThe launch of Opportunity had been delayed several days by weather, by a fishing boat intruding in restricted waters near the launch site, by problems with adhesive that attached cork insulation to the aluminum rocket, and by a failed battery in the rocket's flight termination system. NASA
- NASA launched Mars Exploration Rover Spirit, formerly known as MER-B, on June 10, 2003, UTC atop a Boeing Delta-2 rocket from Pad 17-A at Cape Canaveral Air Force Station, Florida.
- NASA launched Mars Exploration Rover Opportunity, formerly known as MER-A, on July 8, 2003, UTC atop a Boeing Delta-2 Heavy rocket from Pad 17-B at Cape Canaveral.
Closest to Earth. The twin rovers were launched at a time when Mars was closest to Earth as both planets circle the Sun.
At the time of the launch of Spirit, Mars was a mere 65 million miles from Earth. That meant a relatively short trip for the spacecraft.
By the time of the launch of Opportunity, Mars had moved a bit farther away from Earth at 89 million miles – still a relatively short trip for the spacecraft. However, that greater distance necessitated the use of a more powerful version of the Delta 2 rocket.
Careful preparation. Recalling its heartbreaking loss of two Mars spacecraft in 1999, NASA very carefully prepared the 2003 rovers and their rockets for launch.An early glitch. Despite NASA's careful preparation, the Mossbauer spectrometer malfunctioned during remote in-flight testing as Spirit travelled toward Mars early in August 2003. That instrument still might be able to show the presence of iron-bearing minerals in the soil, but not their abundance.
- Back in 1999, Mars Climate Orbiter flew too close to the Red Planet because its designers had mixed metric and English measurements.
- Six months later, Mars Polar Lander probably crashed on the planet's surface after its descent rockets shut down early.
Knowledge of the iron-bearing minerals would help planetary scientists determine whether Mars ever was warmer, wetter and capable of sustaining life. Scientists hope to be able to figure out a fix for the Mossbauer spectrometer before Spirit lands on Mars on January 3, 2004. If not, other instruments might be able to pick up the slack and reveal the abundance of iron-bearing minerals on Mars.
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Landing on Mars
After a seven month cruise outward from Earth, the rover Spirit entered Mars' atmosphere and land on January 4, 2004 universal time or GMT (evening of January 3 Eastern and Pacific Standard Time).
The rover Opportunity bounced to a stop on the Martian surface on January 25, 2004 universal time or GMT (evening of Jan. 24 Eastern and Pacific Standard Time). Opportunity landed an January 25, 2004 (universal time).
Descent. When they arrived in Mars' atmosphere, each spacecraft deployed a parachute to slow itself and then inflate a cluster of airbags. Like Pathfinder, the 2003 spacecraft bounced down on Mars inside protective cushons of airbags. The spacecraft bounced several times, eventually coming to rest and unfolding like a petal. LANDING DETAILS IN JANUARY NEWS
An elite group. Of nine spacecraft that have tried to land on Mars, only three ever have succeeded – the two Viking landers of 1976 and Mars Pathfinder in 1997.
During the 1997 Pathfinder mission, the 23-lb. Sojourner rover moved about 100 yards across Mars. The 300-lb. 2003 rovers are able to cover far more ground at their tortoise pace. They are be able to roam up to 0.6 miles (1 kilometer). In fact, the larger 2003 rovers are able to travel as far in a "sol," which is a Martian day, as Sojourner could in its lifetime.
Stats: Mars and Rovers
The Planet Mars:Year: 687 Earth days Temperature:
Summer 81°F
Winter -207°FTo Earth:
235 million miles max
66 million miles minMoons: 2 Name: Roman war god
2003 Mars Rovers:Names: Spirit and Opportunity Launch: June 10 and July 8, 2003 Arrival: January 4 and 25, 2004 Science instruments:
– Panoramic Camera
– Miniature Thermal Emission
Spectrometer (Mini-TES)
– Mossbauer Spectrometer
– Alpha Particle X-Ray
Spectrometer (APXS)
– Microscopic ImagerRange: 0.6 miles (1 kilometer) Objectives: geology, water, life
Airbags. The landing for each would resemble the way Pathfinder landed. After arrival in Mars' atmosphere, a parachute would deploy to slow the spacecraft. Then, rockets would fire to slow it further just before impact. Airbags would inflate to cushion the landing.
Upon reaching the Martian surface, the spacecraft bounced about a dozen times. It could roll as far as six-tenths of a mile (one kilometer).
When the lander came to a stop, its airbags deflated and retracted, and its protective petals opened up. That brought the lander to an upright position and exposed the rover.
Landing sites. During the first successful Mars landings in seven years, the rovers dropped down on different sites in regions on opposite sides of the Red Planet where scientists thought conditions may once have been right for life.
The landing sites are Gusev Crater and part of a region known as Terra Meridiani.
Those are places where astronomers thought there may be evidence of surface water sometime in the past. They are places displaying mineralogical evidence that water may have produced unique chemical fingerprints, as well as places where it seems likely water formed ponds in depressions for enough time to modify the geology.
Engineers picked the sites using data received on Earth from our spacecraft already orbiting the Red Planet – the 1997 Mars Global Surveyor and the 2001 Mars Odyssey.
These landing sites were thought to offer the fewest hazards, and that seems to have been correct. The 2003 rovers navigated around obstacles as they drove across the martian surface.
How targets were selected. Candidate landing sites had to be near the equator, low in elevation, not too steep, not too rocky and not too dusty. A total of 155 sites were examined in images and measurements from the two NASA spacecraft already orbiting Mars — Mars Global Surveyor and Mars Odyssey. They provided details on potential landing site topography, composition, rockiness and geological context.
The two sites selected were scientifically compelling for the twin rovers to explore the surface of Mars:TOP OF THIS PAGE
- Gusev Crater is a giant bowl-shaped depression in the surface that once may have held a lake. It is 15 degrees south of Mars' equator. The hole in the ground has what is thought to be a dry riverbed in it. That means there may have been a lake in Gusev at some point.
- Meridiani Planum is a broad outcropping of a mineral that usually forms in the presence of liquid water. The area was thought to have deposits of an iron oxide mineral – gray hematite. It is about two degrees south of the equator and halfway around the planet from Gusev. Meridiani has a chemical signature of past water. Gray hematite usually is produced, but not always, in an environment where there is liquid water.
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On the Martian Surface
Spirit and Opportunity are very different from Mars Pathfinder, which landed in 1997 with its science instruments on both the lander and the tiny Sojourner rover. By contrast, the 2003 landers are larger rovers carrying all of their instruments around with them.
Each of the flat-top buggies has bat-wing solar panels and a 5-ft.-high mast. Each rover's camera, atop the mast, can record 360-degree, stereo views of the terrain.
Upon landing, each rover conducted reconnaissance of its landing site by recording a 360-degree panoramic photo in visible color and infrared light. Then each left its protective petal structure behind and drive off to explore. first pictures from Spirit
Mobile geology labs. NASA describes each of the 300-lb. rovers as a robot field geologist, equipped to read the geologic record at its landing site and to learn what the conditions were like back when the rocks and soils there were formed.
Rolling from place to place, each slow-moving rover could be considered the mechanical equivalent of a geologist walking the surface of Mars searching for evidence of past water and an environment suitable for life.
Designed after the highly successful and popular 1997 Pathfinder lander and its Sojourner rover, the 2003 rovers carry out a more rigorous science program as they study rock and soil samples. The 2003 rover science packages are called Athena.
The 300-lb. mobile laboratories look and act alike. Rocks and soil are analyzed with a set of five instruments on each rover.
The rover's robot arm can move much the same as a human arm with an elbow and wrist. It can push instruments directly up against interesting rock and soil targets.
Rover Science
Panoramic Camera (Pancam) for examining the mineralogy, texture, and structure of the local terrain. The camera atop a five-foot mast provides 360-degree stereo views of the terrain.
Microscopic Imager (MI) for obtaining close-up, high-resolution photos of rocks and soils.
Robot Arm moves much like a human arm with an elbow and wrist as it presses instruments directly against rocks and soil. The mechanical fist grasps a microscopic camera reminiscent of a geologist's handheld magnifying lens.
Rock Abrasion Tool (RAT) for removing dusty and weathered rock surfaces and exposing fresh material underneath. The robot arm's so-called RAT, for Rock Abrasion Tool, works something like a geologist's rock hammer to expose the insides of rocks.
Miniature Thermal Emission Spectrometer (Mini-TES) for identifying promising rocks and soils for closer examination and for determining the processes that formed Martian rocks. The instrument also looks up from time to time to the Martian sky to provide temperature profiles of the atmosphere.
Mössbauer Spectrometer (MB) for close-up examinations of the mineralogy of iron-bearing rocks and soils.
Alpha Particle X-Ray Spectrometer (APXS) for close-up analysis of the elements that make up rocks and soils.
Magnets were be used to collect magnetic dust particles for the spectrometers to analyze. Magnetic dust particles are analyzed by the spectrometers and the ratio of magentic to nonmagnetic particles are calculated. The spectrometers also analyzed the composition of magnetic minerals in airborne dust and rocks that have been ground up by the RAT.
Travel They planned for each robot geologist to move up to 44 feet per day. The total distance traveled by each rover then would total about two-thirds of a mile during its 90 research mission on Mars.
A special tool called RAT — Rock Abrasion Tool — exposes fresh rock surfaces for study. RAT works something like a geologist's rock hammer as it exposes the insides of rocks.
The robot arm has a mechanical fist holding a microscopic camera that serves the same function as a geologist's handheld magnifying lens.
Driving around. Each Mars Exploration Rover first examined its landing site for geological evidence of water and past environments hospitable to life. Then, each moved out to examine targets farther afield.
Each rover recorded images and spectra each day. Researchers back on Earth used those photos and data to guide each vehicle to rocks and soil targets of interest. Then, they evaluated the composition of soil and rocks seen in the photos and measured their texture at microscopic scales.
Each rover was built to drive as much as 44 yards a day, for a total surface tour of 0.6 mi. (1 km).
Dusty solar panels. Each rover's main work on the planet surface lasts at least 90-120 "sols" – Martian days. That's 92 or more Earth days extending to late May 2004.
The rovers are solar-powered. In 90 days, dust accumulating on the solar arrays probably diminishes the electricity output from the power supply.
Whether work can continue after that depends upon the condition of the rovers.
Orbiter radio connection. NASA's spacecraft already orbiting Mars before the arrival of the rovers, 2001 Mars Odyssey and Mars Global Surveyor, are key communication links for the 2003 Mars exploration rovers.
Signals from Spirit and Opportunity on the Martian surface are received by the orbiters overhead and relayed on to Earth. first pictures from Spirit
The 2003 Mars Exploration Rover project is managed by NASA's Jet Propulsion Laboratory (JPL), Pasadena, California, a division of Caltech.
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Others to Arrive at Mars
The 2003 Mars Exploration Rovers Spirit and Opportunity were in an international flotilla of interplanetary probes arriving at Mars at the end of 2003 and the beginning of 2004 – including Mars orbiters from Europe and Japan &ndash Mars Express and Nozomi – and the Mars lander Beagle 2 from Great Britain.
Together, those spacecraft offer the most intensive exploration of another planet in history.
See how the others turned out: Mars Express Beagle 2 Nozomi
Japan: Planet B Nozomi Planet B Nozomi Europe: Mars Express Beagle 2 Lander USA: JPL Mars Exploration Rovers flight watch
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