wheeled vehicle in red desert

Artist's rendering of the Opportunity rover. Credit: NASA/JPL-Caltech

Opportunity was designed to explore the surface of Mars for at least 90 Martian days, or "sols." Instead, it worked for more than 5,000 sols over the course of more than 14 Earth years — transforming our understanding of the Red Planet along the way.

NASA's Mars Exploration Rovers, Opportunity and its twin Spirit, were tasked to study the history of climate and water at sites on Mars where conditions may once have been favorable to life. Each rover was equipped with a suite of science instruments to read the geologic record at each site, to investigate what role water played there and to determine how suitable the conditions would have been for life. Both rovers far exceeded their design specifications during their missions on the Red Planet.

Opportunity, the second rover to land on Mars, returned dramatic evidence that its area of Mars stayed wet for an extended period of time long ago, with conditions that could have been suitable for sustaining microbial life. Scientists believe that Opportunity's Meridiani Planum landing site "was once the shoreline of a salty sea on Mars." Opportunity also analyzed exposed rock layers recording how environmental conditions changed over time.

In July 2014, Opportunity set the off-Earth roving distance record after accruing 25 miles (40 kilometers) of driving, beating the record held by the Soviet Union's Lunokhod 2 rover. By the end of the mission, Opportunity covered more than 28 miles (45 kilometers) across the surface of Mars.

Nation United States
Objective(s) Mars surface exploration
Spacecraft Mars Exploration Rover 1 (MER 1)
[became MER-B]
Spacecraft Mass 2,341 pounds (1,062 kilograms)
Mission Design and Management NASA / JPL
Launch Date and Time July 8, 2003 / 03:18:15 UT
Launch Site Cape Canaveral Air Force Station /
SLC-17B
Scientific Instruments 1. Panoramic Mast Assembly
a. panoramic cameras (Pancam)
b. navigation cameras (Navcam)
c. miniature thermal emission spectrome-
ter (Mini-TES)
2. Mössbauer spectrometer (MB)
3. alpha particle x-ray spectrometer (APXS) 4. magnets (to collect dust particles)
5. microscopic imager (MI)
6. rock abrasion tool (RAT)

Firsts

  • First human enterprise to exceed marathon distance of travel on another world
  • Steepest slope driven by any rover on Mars

Key Dates

Launch: July 8, 2003 | 03:18:15 UT

Mars Landing: Jan. 25, 2004 | 04:54 UT

Mission End: Feb. 13, 2019

Results

Spirit and Opportunity were two rovers that together represented the Mars Exploration Rover Mission (MER), itself part of NASA’s Mars Exploration Program. The twin missions’ main scientific objective was to search for a range of rocks and soil types and then look for clues for past water activity on Mars. Each rover, about the size of a golf cart and seven times heavier (408 pounds or 185 kilograms) than the Sojourner rover on Mars Pathfinder, was targeted to opposite sides of the planet in locales that were suspected of having been affected by liquid water in the past.

The plan was for the rovers to move from place to place and perform on-site geological investigations and take photographs with mast-mounted cameras (about five feet or 1.5 meters off the ground) providing 360° stereoscopic views of the terrain. A suite of instruments (MB, APXS, the magnets, MI, and RAT) were deployed on a robotic arm (known as the Instrument Deployment Device, IDD). The arm would place the instruments directly against soil or rock and activate the instruments.

After launch, the Opportunity rover was dispatched on its six-month trek to Mars. After a final course correction on Jan. 16, 2004, the spacecraft dived into the Martian atmosphere on Jan. 25, 2004. The descent to the surface was uneventful with no anomalies. The lander, enclosed in the airbags, touched down at 04:54 UT and then bounced at least 26 times before coming to rest in Meridiani Planum at 1.9483° S / 354.47417° E, about 9 miles (14.9 kilometers) from the intended target. This area was now named the Challenger Memorial Station, in tribute to the Space Shuttle crew lost in 1986. Opportunity landed in a relatively flat plain but within an impact crater known as Eagle.

After extensive studies within Eagle, on March 22, 2004, Opportunity climbed up the edge of the crater and rolled out and headed for a new phase of its mission in Endurance Crater, about 820 yards (750 meters) away. Having exited Eagle, the rover took some spectacular shots of the abandoned area where the lander, backshell, and parachute were still visible. Near its discarded heat shield, Opportunity discovered an unusual basketball-sized rock in January 2005 (known as “Heat Shield Rock”) that turned out to be an iron-nickel meteorite.

rover casting a shadow
This self-portrait of NASA's Mars Exploration Rover Opportunity comes courtesy of the Sun and the rover's front hazard-avoidance camera. The dramatic snapshot of Opportunity's shadow was taken as the rover moved into "Endurance Crater." The image was taken on sol 180 (July 26, 2004), a date that marked double the rover's primary 90-sol mission. Many more sols would were to come. Credit: NASA/JPL-Caltech

Later that year, the rover drove into an area where several of its wheels were buried in sand, rendering the vehicle immobile. JPL controllers were able to maneuver the vehicle a few inches at a time and free Opportunity in June 2005 after six weeks of rest. Through the remainder of the year and into 2006, the rover headed slowly in a southward direction towards the half-mile (800-meter) diameter Victoria crater, first arriving at Erebus, a highly eroded impact crater about 980 feet (300 meters) in diameter. In March 2006, it then began its 1.2-mile (2-kilometer) journey to Victoria, a crater wider and deeper than any yet examined by the two rovers.

After a 21-month trip, Opportunity arrived at Victoria in September 2006 and sent back striking pictures of its rim. The following year, 2007, was an important test for Opportunity given the severe dust storms that plagued Mars. By July 18, the rover’s solar panels were reporting power at only 128 watt hours, the lowest for either rover at that point. All science activities were indefinitely suspended for Opportunity which faced much more severe conditions than Spirit. After about six weeks and abatement of the dust storms, Opportunity was back in action, and on Sept. 11 2007, it entered Victoria Crater, staying inside for almost a year and sending back a wealth of information on its soil.

cliff at crater rim in red-colored desert
Opportunity captured this vista of "Victoria Crater" from the viewpoint of "Cape Verde," one of the promontories that are part of the scalloped rim of the crater. Opportunity drove onto Cape Verde shortly after arriving at the rim of Victoria in September 2006. Credit: NASA/JPL-Caltech/Cornell

Opportunity’s next target was the enormous Endeavour Crater, about 13 miles (22 kilometers) in diameter. On the way there, the rover found the so-called Marquette Island rock, “different in composition and character from any known rock on Mars or meteorite from Mars,” according to Steve Squyres (1956– ), the principal investigator for the rovers. The rock appeared to have originated deep in the Martian crust and someplace far away from the landing site, unlike almost all the rocks previously studied by Opportunity. On March 24, 2010, Opportunity passed the 20-kilometer milestone (about 12 miles) on Mars, more than double the distance recorded by Spirit, and far in excess of what was originally considered a nominal mission—600 meters or 1,968 feet. Two months later, on May 20—with Spirit already inactive—Opportunity broke the record set by the Viking 1 Lander for the longest continuous operation on the surface of Mars, 6 years and 116 days. Another milestone was passed when Opportunity, still heading towards Endeavour Crater, passed the 30-kilometer mark (about 18 miles) on June 1, 2011.

Finally, after a journey of nearly three years and about 13 miles (21 kilometers), Opportunity arrived at Endeavour crater on Aug. 9, 2011. In September 2011, NASA announced that an aluminum cuff that served as a cable shield on each of the RATs on the rovers was made from aluminum recovered from the World Trade Center towers, destroyed during the terrorist attacks on Sept. 11, 2001. Honeybee Robotics, which helped build the tool, had its offices in New York that day not far from the attacks. As a memorial to the victims, JPL and Honeybee worked together to include the aluminum on the Mars rovers.

Through late 2012 and into 2013, Opportunity worked around a geographic feature named Matijevic Hill (which overlooks the Endeavour crater), analyzing rocks and soil. On May 16, 2013, NASA announced that Endeavour had passed the previous record for the farthest distance traveled by any NASA vehicle on another celestial body, 22.21 miles (35.744 kilometers), a record set by the Apollo 17 Lunar Roving Vehicle in December 1972. By August 2013, Opportunity was at Solander Point, an area of contact between a rock layer that was formed in acidic wet conditions long before and an older one from a more “neutral” environment. Both Cape York (location of Matijevic Hill) and Solander Point are raised segments near the western rim of the Endeavour crater. On Jan. 4, 2014, Opportunity passed 10 years on the surface of Mars, now with relatively clean surfaces on the solar panels that had allowed increased power to the rover. A “selfie” from March 2014 showed a rover cleaned by wind events earlier in the month that raised hopes for continuing the mission.

solar panels on rover seen from above
This self-portrait of NASA's Mars Exploration Rover Opportunity shows effects of wind events that had cleaned much of the accumulated dust off the rover's solar panels. It combines multiple frames taken by Opportunity's panoramic camera (Pancam) through three different color filters from March 22 to March 24, 2014. Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

As it continued its exploration mission on the Martian surface, on July 28, 2014, NASA announced that Opportunity had passed the distance record set on another celestial body, set by Lunokhod 2, when the American rover’s odometer showed 25.01 miles (40.25 kilometers), exceeding the Soviet vehicle’s record of 24 miles (39 kilometers). However, Russian analysis from LRO images suggest that Lunokhod 2 may have traveled as much as 26 miles (42 kilometers), rather than the revised 24 (itself a “revision” up from 23 miles or 37 kilometers).

While the rover was generally in good health, because of the large number of computer resets in the preceding month, which interfered with its science goals, mission planners implemented a complete reformat of its flash memory on Sept. 4, 2014. The same day, NASA announced a further (ninth) extension of the mission of Opportunity to another two years with a mission to nearby Marathon Valley. At the beginning of September, it had covered about 25 miles (40.69 kilometers). At launch, like its sister rover, Spirit, Opportunity was designed to have a lifetime of 90 sols (Martian days)—about three Earth months. In December 2014, NASA announced that the rover had been plagued with problems with saving telemetry information into its “non-volatile” (or flash) memory, a problem traced to one of its seven memory banks (Bank 7). By May 2015, NASA controllers configured the memory so the rover was operating only in RAM-only mode.

On March 25, 2015, NASA announced that, having traveled 26.219 miles (42.195 kilometers), Opportunity became “the first human enterprise to exceed marathon distance of travel on another world.” In June 2015, because Mars passed almost directly behind the Sun (from Earth’s perspective) and therefore communications were curtailed. Later, through its seventh Martian winter (during Earth winter 2015–2016), at a time when it was kept at “energy-minimum” levels due to the relative lack of solar energy, Opportunity kept busy, using its Rock Abration Tool to remove surface dust from a target called “Private John Potts,” the name a reference to a member of the Lewis and Clark Expedition. During this period, Opportunity continued to explore the western rim of the 13-mile (22-kilometer) wide Endeavour crater, particularly the southern side of Marathon Valley, which slices through Endeavour crater’s rim from west to east.

rover tracks on a hillside with a dust devil seen in the distance
From its perch high on a ridge, NASA's Mars Exploration Rover Opportunity recorded this image of a Martian dust devil twisting through the valley below. The view looks back at the rover's tracks leading up the southern edge of "Marathon Valley" in Endeavour Crater. Opportunity took the image on March 31, 2016, during the 4,332nd Martian day, or sol, of the rover's work on Mars. Credit: NASA/JPL-Caltech

On March 10, 2016, while making its closest approach to a target near the crest of Knudsen Crater, it drove at a tilt of 32°, breaking the record for the steepest slope driven by any rover on Mars (a record previously set by Opportunity during a climb in January 2004).

In October 2016, Opportunity began a two-year extended mission that included investigations in the “Bitterroot Valley” portion of the western rim of the Endeavour Crater. The plan was for the rover to travel into a gully that slices Endeavor and is about two football fields in length. Opportunity Principal Investigator Steve Squyres noted that scientists were “confident [that] this is a fluid-carved gully, and that water was involved.”

On Feb. 7, 2017, Opportunity passed the 44-kilometer mark on its odometer, as it made slow progress towards its next major scientific objective, a gully named Perseverance Valley, which it reached by the first week of May. Having collected several panoramas of high-value targets in the gully, on June 4, the rover experienced a problem due to a stall on the left front wheel, which left the wheel “toed out” by 33 degrees. Fortunately, after several straightening attempts, the wheel appeared to be steering straight again, although controllers could identify any conclusive cause for the problem. For about three weeks during June and July, there was reduced communication with the rover due to a solar conjunction (when the Sun comes between Earth and Mars). In mid-July, Opportunity finally entered Perseverance Valley and began driving down into the gully during which time, rover energy levels dropped due to reduced Sun exposure.

Opportunity went quiet during a historic global dust storm in 2018 that reduced the energy available to the rover's solar panels. The last signal from the spacecraft was heard on Sol 5111 (June 10, 2018). Opportunity likely experienced a low-power fault, a mission clock fault and an up-loss timer fault.

When NASA declared the mission complete on Feb. 13, 2019, total rover odometry was 28.06 miles (45.16 kilometers).

vast plain of dunes with rover tracks leading to horizon
This panoramic image, dubbed "Rub al Khali," was acquired by NASA's Mars Exploration Rover Opportunity on the plains of Meridiani during the period from the rover's 456th to 464th sols on Mars (May 6 to May 14, 2005). Opportunity was about 1.2 miles (2 kilometers) south of "Endurance Crater" at a place known informally as "Purgatory Dune." Credit: NASA/JPL/Cornell

Additional Resources

NASA: Opportunity

NASA Mars Program: Opportunity

National Space Science Data Center Master Catalog: Opportunity

Mars Exploration Program

Sources

Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.

Related News