Sanuj Raj
8 min readAug 31, 2020



Spirit was the first out of the two sisters rover that was sent to Mars by NASA. Spirit and Opportunity are twin rovers that were sent to learn more about the planet Mars. These missions were part of Mars Exploration Rover (MER), which includes 3 previous successful missions. The previous missions consisted of two Viking landers in 1976 and one Mars Pathfinder probe in 1997. MER-A is named as the Spirit rover and MER-B is named as the Opportunity rover.

Spirit & Opportunity As they were Exactly the Same

Spirit and Opportunity were field geologists and their job was to look for water that may have flown on the surface of Mars millions of years ago. The names Spirit and Opportunity were selected by NASA in a student essay contest that drew nearly 10,000 entries. The total cost of building, launching, landing, and operating both rovers were $820 million. The scientific purpose of the mission was to study a wide variety of rocks that hold clues to past water activity on Mars.

Landing Site of Different Mars Rovers

As a matter of fact, both rovers continued to function beyond their scheduled mission, each of them received five mission extensions. The total cost of the first four missions was $104 million, and the last mission extension costing at least $20 million.
On 23rd March 2004, a news conference was held announcing “major discoveries” of evidence of past liquid water on the martian surface.

The main scientific objectives of the MER were:

  1. Determine the composition and distribution of rocks, minerals, and different solid sites.
  2. Perform calibration and validation of surface observations.
  3. Search for water and possible ancient life.


Spirit was the first rover out of the two to land on the surface of Mars. Spirit was launched from Cape Canaveral, Florida on 10th June 2003. It landed on the surface of Mars on 4th January 2004 in the Gusev crater. It was designed to roam on the surface of Mars for 90 martian days (92 Earth days)and travel up to 600 meters but Spirit lasted more than 5 years and traveled less than 5 miles. It was active until March 22, 2010.

Bad Sister

Spirit was called the bad sister not because she was bad in any way but because of the number of problems it created for the scientists as compared to its sister rover opportunity. As soon as it started its mission and touched its first rock its memory got full and it did not communicate with Earth. Once its memory got full the computer wouldn't boot up. To solve this scientists create new codes and told the rover to erase its memory and start again.
This happened because during the journey in the space we had one of the biggest solar flares ever recorded which caused all sorts of changes in its computer hence the root of the problem.

Stuck Wheel

The right front wheel of the rover ceased while working on 13th March 2006, while the rover was moving to the McCool Hill. So the only thing that could be done here was to drag the wheel, but this technique only worked until reaching a sandy area on the lower slopes. Here the rover spent the long Martian winter and waited for spring and increased power level suitable for driving.
This stuck wheel made a deep and noticeable footprint that could be clearly seen by the satellites above the Martian space.

Stuck Wheel of Spirit

This is the exact reason that made the Spirit dead because of a stuck wheel and made the rover a lander, forcing it to do all its science from a standstill.


The Opportunity was one of the most successful missions of NASA till now. It landed on 25th January 2004. It was launched on Delta II heavy spacecraft. It landed on the opposite of its sister rover Spirit. It was scheduled for 90 martian days but it lasted 5,111 martian days (about 15 Earth years) which is phenomenal in its own right. It was active until 12th June 2018 thanks to the sand dunes that have covered Mars which prevented the Opportunity to charge its battery and ultimately it did not make any contact with the scientists on Earth. As a result of that, it went into safe mode to preserve its battery but all the efforts couldn’t save it from dying.

After vs Before a Dust Storm that Killed Opportunity

On Sol 84, it reached the edge of Endurance crater and had a look inside, it searched for a good entry point as getting in wouldn’t be a problem but getting out would be. Scientists knew the crater had many layers of rocks to be investigated and wanted to have a closer look.
By Sol 127 scientists decided to drive the Opportunity into the crater even if it couldn't get out, as the value of the science was too promising to pass up. So on Sol 131, it carefully edged its way over the ridge and tried to reverse back to see if it could. As a matter of fact, the angle of the rim was only 18 inches well within the rover’s safety margin. It went in and did a lot of work and collected some amazing data during the 180 Sols it spent there. It finally left Endurace on Sol 315.

Sol 84, Starting to Enter Endurance Crater

The data collected here suggested that water didn’t just cover this area once but it was in fact episodic in nature, with floods that would have washed across this landscape before drying up again. Hence finding that Mars was a wet place once.

Out of This World Record

Curiosity holds the world record for the longest distance traveled on another planet. It has traveled a record 45.15 Km on Mars. Initially, it was intended to travel for less than a Km but it traveled much more than that as mentioned above.
Its record can only be broken by the rover Curiosity which has currently traveled 23.06 Km at the time of writing this article during its 2829 Sols spent on Mars.

World Record Held By Opportunity Rover

Final Words Before Dying

“My battery is low, and it’s getting dark” were the final words of the Opportunity rover. A large sandstorm across the Marian surface resulted in killing the rover. The storm was so severe that it never recovered from that. Dust gathered on all of its solar panels preventing it to charge its battery. Scientists tried to connect to the rover for about 8 months but it entered into safe mode to preserve its battery for heating purposes.
It spent about 15 years on Mars, more than it could have ever asked for. Indeed an incredible mission.


  • For landing these rovers an airbag system was used. This system made the landing safer. In the very last part during the descent stage airbag were inflated all over the rover which made it look like a ball of fluffy fibers. It took about 50 milliseconds to inflated the airbags. This was done to prevent the damage that was done during the landing on the surface of Mars. After hitting the surface with the airbags the rover bounced for about a mile before stopping. After stopping the rover stood still for about 45 minutes to check that its systems are ok then it took another 45 minutes for it to unpack itself and start its mission.
    An interesting thing happened with the Opportunity rover as it landed in a crater was named Eagle crater after bouncing for about a mile. Scientists call it a “hole in one”.
Airbag System Used for Landing
  • The rovers had one of the largest parachutes fitted to any aircraft ever. This was done to slow the rover down to a considerable margin. There on Mars, the job of the parachute especially becomes tough because Mars has about 1% atmospheric thickness of Earth’s atmosphere and it has to open at the exact time because it can be dangerous to not open at the perfect time as a lot of money is at stake. So it has to have a great design along with the precision to open at the exact time on Mars. It was somewhat based on the designs and experiences of Pathfinder and Vikings missions.
    The parachute was made of two durable, lightweight fabrics: polyester and nylon. A triple bridle made of Kevlar connects the parachute to the backshell.
  • The cameras of the rovers were one of the most powerful at the time that was sent to Mars, officially it was called PMA (Pancam mast Assembly). It captured the images in a panoramic setting which enabled it to take a photo of a large part of the surface more than usual. The photos were a high definition that it enables the scientists to zoom in very much to see everything in extreme detail. The cameras were mounted at a height of 5 feet 2 inches, the height of a regular person.
    It had a resolution of about 300 micro radians, three times better than the human eye.
    As a special feature, it could also take selfies with its pan cam.
Pancam on the Opportunity Rover
  • The opportunity was supposed to land on a plane surface but due to some regular technical differences it landed 25 Km away from its intended target and landed in a small crater, which was a kind of achievement for the Opportunity team as it landed in a small crater, scientists called it a “hole-in-one”.
Hole-in-one for Opportunity Lander



Sanuj Raj