Mars Exploration Rover B (Opportunity)

Artist's conception of Mars Exploration Rover on the surface of Mars. Credit: NASA/JPL/Cornell University/Maas Digital LLC

Official name: Mars Exploration Rover B (Opportunity)
Spacecraft name: Mars Exploration Rover 1 (MER 1)
COSPAR ID: 2003-032A
Nation: USA
Mission design and management: NASA / JPL
Launch date and time: 8 July 2003, 03:18:15 UT
Launch vehicle: Delta 7925H (no. D299)
Launch site: Cape Canaveral Air Force Station, SLC-17B
Objective: Mars surface lander and rover

Mars Exploration Rover B (Opportunity) was launched on July 8, 2003. It landed in Meridiani Planum on the surface of Mars on January 25, 2004, embarking on a more than 14-year mission. The total distance driven by the rover was 45.16 km and the last communication with it was on June 10, 2018, when a severe Mars-wide dust storm blanketed its location.

   Opportunity was one of two rovers launched to Mars in mid-2003 (the other was Spirit). The rovers arrived at Mars in January of 2004. The scientific goals of the rover missions were to gather data to help determine if life ever arose on Mars, characterize the climate of Mars, characterize the geology of Mars, and prepare for human exploration of Mars. To achieve these goals, seven science objectives were called for:

1) search for and characterize a variety of rocks and soils that hold clues to past water activity,

2) determine the distribution and composition of minerals, rocks, and soils surrounding the landing sites,

3) determine what geologic processes have shaped the local terrain and influenced the chemistry

4) perform "ground truth" of surface observations made by Mars orbiter instruments,

5) search for iron-bearing minerals, identify and quantify relative amounts of specific mineral types that contain water or were formed in water,

6) characterize the mineralogy and textures of rocks and soils and determine the processes that created them, and

7) search for geological clues to the environmental conditions that existed when liquid water was present and assess whether those environments were conducive to life.

Spirit and Opportunity Mars rovers being tested on February 10, 2003. Credit: NASA/JPL-Caltech

In the Payload Hazardous Servicing Facility, the Mars Exploration Rover-1 (MER-B) awaits further preflight processing atop a spin table on May 29, 2003. Credit: NASA/KSC

   The Mars Exploration Rover consisted of a box-like chassis mounted on six wheels. The chassis contained the warm electronics box (WEB). On top of the WEB was the triangular rover equipment deck, on which was mounted the Pancam mast assembly, high gain, low gain, and UHF antennas, and a camera calibration target. Attached to the two forward sides of the equipment deck were solar arrays which were level with the deck and extend outward with the appearance of a pair of swept-back wings. Attached to the lower front of the WEB was the instrument deployment device, a long hinged arm which protrudes in front of the rover.

   The wheels were attached to a rocker-bogie suspension system. Each wheel had its own motor and the two front and two rear wheels were independently steerable. The rover had a top speed of about 3.75 cm per second, but the average speed over time on flat hard ground was 1 cm/sec or less due to the hazard avoidance protocols. The rover was designed to withstand a tilt of 45 degrees without falling over, but was programmed to avoid exceeding tilts of 30 degrees. The warm electronics box housed the computer, batteries, and other electronic components. The box was designed to protect these components and control their temperature. Thermal control was achieved through the use of gold paint, aerogel insulation, heaters, thermostats, and radiators.

   Power was provided by the solar arrays, generating up to 140 W of power under full Sun conditions. The energy was stored in two rechargeable batteries. Communications with Earth were in X-band via the high gain directional dish antenna and the low gain omni-directional antenna. Communications with orbiting spacecraft were through the UHF antenna. The onboard computer had 128 Mb RAM. An inertial measurement unit provided 3-axwas information on position.

   The rover carried a suite of instruments for science and navigation. The panoramic camera (Pancam) and navigation cameras were mounted on top of the Pancam mast assembly, at a height of about 1.4 meters from the base of the wheels. The mast, mounted at the front of the equipment deck, also acted as a periscope for the Miniature Thermal Emission Spectrometer (Mini-TES). Attached to the end of the instrument deployment device were the Alpha Particle X-Ray Spectrometer (APXS), Mossbauer Spectrometer (MB), Microscopic Imager (MI), and Rock Abrasion Tool (RAT). A magnet array was attached to the front of the equipment deck. Two hazard avoidance cameras were mounted on the front of the rover and two on the rear. The group of science instruments (Pancam, Mini-TES, APXS, MB, MI, and RAT) was known as the Athena science package.

The rover was compactly stowed in a tetrahedron shaped landing platform and encased in an aeroshell consisting of a heat shield and a backshell for launch, cruise, and atmospheric entry. The rover mass was 185 kg. The lander platform had a mass of 348 kg, the backshell and parachute 209 kg, and the heat shield 78 kg. The cruise stage mass was 193 kg and propellant mass was 50 kg. Total spacecraft mass was 1,062 kg.

Scientific Instruments:

1. Panoramic Mast Assembly
– panoramic cameras (Pancam)
– navigation cameras (Navcam)
– miniature thermal emission spectrometer (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)

Delta II Heavy lifting off from pad 17B in Cape Canaveral carrying the second Mars Exploration Rover, Opportunity. Credit: NASA

   Opportunity was launched on a heavy Delta II 7925H on July 8, 2003 at 03:18:15 UT. After insertion into a circular Earth parking orbit, the spacecraft third stage reignited and put the craft on a trajectory to Mars, after which the aeroshell, lander, and rover separated from the third stage. The cruise phase to Mars ended on December 11, 2003, 45 days before Mars entry. The approach phase lasted from this date until martian atmospheric entry on January 25, 2004. On entry the lander and components had a mass of 827 kg and were travelling at 19,300 km/h. The aeroshell decelerated the lander in the upper martian atmosphere for about four minutes to a velocity of 1600 km/h, followed by deployment of a parachute. The parachute slowed the spacecraft to about 300 km/h. A series of tones transmitted by the spacecraft during entry and after landing indicated the successful completion of each phase. Just prior to impact, at an altitude of about 100 m, retrorockets slowed the descent and airbags inflated to cushion the impact. The craft hit at roughly 50 km/h and bounced and rolled along the surface, stopping in a small crater. The airbags deflated and retracted, the petals opened, and the rover deployed its solar arrays. The landing took place at 04:54:22.7 UT (05:05:26.6 UT Earth received time) or approximately 1:15 p.m. local time, about two and a half hours before Earth set at Terra Meridiani. On Mars it was the latter half of southern summer. The spacecraft came to rest in a 20 m diameter crater, known as Eagle, at 1.9483° S and 354.47417° E. This area now became known as the Challenger Memorial Station, in tribute to the Space Shuttle crew lost in 1986. Terra Meridiani is also known as the "Hematite Site" because it displays evidence of coarse-grained hematite, an iron-rich mineral which typically forms in water. It also appears to be one of the smoothest and therefore safest areas for a landing.

   An egress phase took place over the first 4 days, involving deployment of the Pancam mast and high gain antenna, rover stand up, imaging and calibration, selection of proper egress path, and finally driving of the rover off the lander deck onto the martian surface. 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 750 meters away. After exiting Eagle, the rover took some spectacular shots of the abandoned area where the lander, backshell, and parachute were still visible.

The interior of a crater, known as Eagle, surrounding the Mars Exploration Rover Opportunity at Meridiani Planum on Mars can be seen in this color image from the rover's panoramic camera. This is the darkest landing site ever visited by a spacecraft on Mars. The rim of the crater is approximately 10 meters from the rover. The crater is estimated to be 20 meters in diameter. Scientists were intrigued by the abundance of rock outcrops dispersed throughout the crater, as well as the crater's soil, which appears to be a mixture of coarse gray grains and fine reddish grains.

   Data taken from the camera's near-infrared, green and blue filters were combined to create this approximate true color picture, taken on the first day of Opportunity's journey. The view is to the west-southwest of the rover. Credit: NASA/JPL/Cornell

   In 2005, the rover got stuck after driving into an area where several of its wheels were buried in sand. Controllers at NASA's Jet Propulsion Laboratory in Pasadena, California, were able to maneuver the vehicle a few inches at a time and to free Opportunity in June 2005 after six weeks. Through the remainder of 2005 and into 2006, the rover headed slowly south toward Victoria crater, first arriving at Erebus, a highly eroded impact crater about 300 meters in diameter. After a 21-month trip, Opportunity finally arrived at Victoria, a crater that stretches 800 meters in diameter, in September 2006 and sent back striking pictures of its rim. On Sept. 11, 2007, the rover entered Victoria Crater, staying inside for almost a year and sending back a wealth of information on its soil. Opportunity’s next target was the enormous Endeavour Crater, about 22 kilometers in diameter. After a journey of nearly three years and about 21 kilometers, Opportunity arrived at Endeavour crater on August 9, 2011. Since then, Opportunity has continued to explore the western rim of the Endeavour Crater.

   Opportunity explored Meridiani Terra, returning images and data from its scientific instruments, for over 14 years. The final communication from the rover was received on June 10, 2018, when a severe Mars-wide dust storm blanketed its location, reducing the light to just 0.002 percent of its usual level. As Opportunity relied on solar power to survive, these conditions were unbearable. Despite trying to hibernate through the storm by entering safe mode, when the storm finally abated in late 2018 the rover failed to wake up again. On February 13, 2019, NASA said it would cease attempts to contact the rover. The total distance driven by the rover was 45.16 km.

This image taken by the panoramic camera aboard the Mars Exploration Rover Opportunity shows the rover's empty lander platform, the Challenger Memorial Station, at Meridiani Planum. The image was acquired on the rover's 24 sol, or Martian day Time. Credit: NASA/JPL-Caltech/Cornell University

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 continues to move farther into "Endurance Crater." The image was taken on sol 180 (July 26, 2004). Credit: NASA/JPL

The heat shield impact site of NASA's Mars Exploration Rover Opportunity. This is an approximately true-color mosaic of panoramic camera images taken through the camera's 750-, 530-, and 430-nanometer filters.

  The mosaic was acquired on Opportunity's sol 330 (Dec. 28, 2004), shortly after Opportunity arrived to investigate the site where its heat shield hit the ground south of "Endurance Crater" on Jan. 24, 2004. On the left, the main heat shield piece is inverted and reveals its metallic insulation layer, glinting in the sunlight. The main piece stands about 1 meter tall and about 13 meters from the rover.

  The other large, flat piece of debris near the center of the image is about 14 meters away. The circular feature on the right side of the image is the crater made by the heat shield's impact. It is about 2.8 meters in diameter but only about 5 to 10 centimeters deep. The crater is about 6 meters from Opportunity in this view. Smaller fragments and debris can be seen all around the impact site.

  The impact excavated a large amount of reddish subsurface material. Darker materials cover part of the crater's flat floor and have formed a streak or jet of material pointing toward the two largest heat shield fragments. Image credit: NASA/JPL/Cornell 

The rim of Santa Maria, an 80-meter-wide crater that Opportunity explored on the way to Endeavour. This is a color-composite made from a total of 12 images captured on Dec. 19, 2010 (mission sol 2454). Credit: NASA/JPL-Caltech/Jason Major

A portion of the west rim of Endeavour crater (a crater with a diameter of about 22 kilometers) on August 6, 2011 (mission sol 2,678). Credit: NASA/JPL-Caltech/Cornell/ASU

The image of a Martian dust devil twisting through the valley below the rover. 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

The panorama made from raw images acquired on April 10, 2017 (mission sol 4697) from NASA's Opportunity rover, now in its 14th year of operation on Mars. The image was made by combining three monochrome images acquired in near-infrared, green, and near-UV color channels. Color is not calibrated but has been adjusted to be close to what our eyes might see. Credit: NASA/JPL-Caltech/Jason Major

This is the final image taken by Mars Exploration Rover B (Opportunity). It was received on June 10, 2018 (mission sol 5,111), when a severe Mars-wide dust storm blanketed its location.

   The blackness here is caused by the storm, while the white specks are static due to noise from the camera. The black bar at the bottom is data that was not received from the rover, as its transmission back to Earth was interrupted and the rover switched off. Credit: NASA

This traverse map for NASA's Opportunity rover shows where the rover was located within Perseverance Valley on June 10, 2018, the last date it made contact with its engineering team.

  Visible in this map is a yellow traverse route beginning at Opportunity's landing site, Eagle Crater, and ranging 28.06 miles (45.16 kilometers) to its final resting spot on the rim of Endeavour Crater. The rover was descending down into the crater in Perseverance Valley when the dust storm ended its mission. Credit: NASA/JPL-Caltech/MSSS

Opportunity: NASA Rover Completes Mars Mission. Drive along with the NASA’s Opportunity Mars rover and hear the voices of scientists and engineers behind the mission. Credit: NASA:

© 2026, Andrew Mirecki