Mars Missions – Rovers


There are many missions that have lasted beyond their original design, but only the rovers have continued to work while also capturing the hearts of the public. Creating to explore Mars for only one week to three months, the later rovers lasted for years after expectation and continued to roll through the Mars landscape sending images back to Earth and accomplishing the experiments.

Curiosity Work Mars

There have been four rovers that were sent to Mars, the original Sojourner, Spirit, Opportunity, and Curiosity. The six-wheeled creations were crafted to move around, investigate a few locations, and send the results of their onboard laboratories home to Earth.

Rovers were the next evolution of technology from sending landers that were stationary, and the mobility of the rovers gave them an advantage like no other robotic explorer.

The information, data, and images that have been sent by the rovers to Earth have been some of the most valuable collected by any mission. No other robot or spacecraft had continued transmission for a single target for such a duration of time.

Thanks to the rovers, scientists now know more about Mars as a planet, including its composition and weather patterns, as well as some new data about its formation in the past and possible presence of liquid water throughout its history.

The Rovers by Name; Sojourner:

The first rover sent to Mars was Sojourner, and it was given the name of the early activist for women’s rights and abolitionist, Sojourner Truth. As part of the Pathfinder Mission, Sojourner landed on Mars on the U.S. Independence Day, July 4, 1997 and became the first probe since the 1976 Viking landers to be on Mars.

The touchdown location was an ancient, large flood plain called Ares Vallis, and was selected because the surface was easier to move around and accomplish the job of analyzing the rocks there.

Sojourner was small compared to the size of later rovers. NASA’s description of Sojourner was that it was a “microrover,” around the size of a filing cabinet drawer. Sojourner was only 26 in/66 cm long, 19 in/48 cm wide, and 12 in/30 cm tall.

It had six 5-in/13 cm wheels that moved independently and it was designed so that if one was stuck in the soft sand of Mars, the other wheels could work together to move it forward. The little rover was slow, moving at its fastest speed of 0.015 mph/0.024 kmh.

Sojourner was equipped with both rear and front cameras along with scientific experiment equipment, and tt got its power from a solar panel that was on top of the unit. The goal that was set for Sojourner was to analyze the rocks that were located near the site of landing.

To identify the rocks and have a little fun, the team on Earth gave names to the rocks such as: Scooby-Doo, Barnacle Bill, and Yogi. This practice continued with all of the rovers and helped researchers differentiate the various contents and shapes.

The results of the experiments done by Sojourner suggested that the Ares Vallis area had once had a past that made it water-rich and flooding had occurred near the landing site.

Sojourner was only designed to function for a week, yet kept on doing its job and moving around for three months. It traveled about 300 ft/100 m from the Pathfinder and returned over 550 images of Mars.

The last communication from Pathfinder on this mission was Sept. 27, 1997. They think that Sojourner stopped functioning because of an overloaded battery due to so many charges and de-charges.

The Rovers by Name; Spirit and Opportunity:

Scientists and engineers learned a lot from Sojourner, so for the next rover they designed them as a set of twins that were golf-cart sized. These were 4.9 ft/1m tall and weighed in at 400 lb/180 kg,

The name of the rovers were chosen when NASA and the Lego Co. of Demark, along with The Planetary Society in Pasadena, California, held a contest for school kids.


The winner was a third grader named Sofi Collis and the 9 year-olds selection was chosen from over 10,000 that were submitted. In her essay, Sofi included the following for her reasons to name the rovers Spirit and Opportunity:

“I used to live in an orphanage. It was dark and cold and lonely. At night, I looked up at the sparkly sky and felt better. I dreamed I could fly there. In America, I can make all my dreams come true. Thank you for the ‘Spirit’ and the ‘Opportunity.'” 

 Both of the rovers were sent to the surface surrounded and protected by airbags. The bags were kind of like balls and once they hit the surface they “bounced” until they came to a complete stop. At that time, the airbags released and the landing craft opened to let the rovers roll out.

Each rover immediately began taking images of its panoramic surroundings. The photographs helped the scientists to select the target locations to roll to. Once decided, the rovers were sent their instructions and they drove over and started to perform their investigations and experiments.

The rovers were launched separately, landing January 3rd and the 24th, 2004. The touchdown location for Spirit was in an area called Gusev Crater that was thought to have once been a lake in the past. Spirit tested some of the rocks and found that they had been formed due to interaction with water.

In 2005, Spirit was given the job of going up a mountain that was as tall as the Statue of Liberty, and then recorded the Martian “dust devils” as they were forming. NASA received this transmission and later on, created a video for public viewing.

The NASA team call the landing of Opportunity a “hole-in-one.” They had planned for Opportunity land inside of a crater that they named Eagle Crater later.

The landing at Meridiani Planum, a possible former lake in the giant impact crater was perfect. Opportunity started working, examining the plains, meteorites, and then traveling over sand dunes.

Opportunity sent back incredible photos, some of which included little pebbles that were iron-rich and nicknamed “blueberries.” These little spheres appeared all over one area and are only formed in the presence of water.

The rovers had scientific goals set for them to search for and then characterize a lot of different soils and rocks to see if Mars had ever had water activity in its past. The rovers were on opposite sides of Mars and they targeted areas that had the appearance of having had past water.

Both Spirit and Opportunity changed the way we understand Mars. We once thought that Mars was an empty, dead, world that looked more like a desert and thanks to the rovers, we know that it had an interesting and complex geological history that could have once been home to living organisms.

The rovers original design to last only 90 days ended up lasting twenty times longer than the scientists had planned. While the mission officially ended in 2010, Opportunity continued to work for almost 15 years.

The last time they received a communication from the rover was on June 10, 2018. This was during the same time as a dust storm was hitting the entire planet. They believe the dust covered the rover’s solar-power. Opportunity set a new record for travel on an extraterrestrial location by driving a total of 2806 mi/45.16 km.

The Rovers by Name, Curiosity:

On August 6, 2012, the most recent rover landed on Mars. Named “Curiosity,” it was the largest rover to be placed on the surface of Mars. It is the size of an SUV and weighs in at around 1 ton.

It is so large that it required the design of an elaborate mechanism called a sky-crane to lower it to the surface. This was such a dangerous part of the mission that the NASA engineers called it the “seven minutes of terror,” because during the lowering process they lacked contact with the robot.

Curiosity became the first rover that wasn’t solar-powered. Instead, it used a nuclear radioisotope thermoelectric generator. This creates electricity from the heat of plutonium-238 radioactive decay, allowing the rover to travel around 660 ft/200m per day.

The main goal for Curiosity was to accomplish tests to see if Mars had ever had the ability to be host to living organisms. It landed in Gale Crater and had an entire onboard laboratory of instruments.

Mars Surveyor Rover

Curiosity had multiple cameras as well as spectrometers to check out the rock chemical compositions; atmospheric and weather sensors, and also included a special laser that could vaporize chunks of Mars and then analyze them.

In 2018, Curiosity made a momentous discovery when the robot found organic materials in rocks that were 3.5 billion years old. These are the building blocks of life and in finding the material, Curiosity succeeded in its mission.

Of all of the rovers, Curiosity seemed to become more of a media darling due to its habit of taking “selfies.”  Curiosity continued to transmit information and data until September 12, 2018. Scientists aren’t sure why the rover stopped sending data and believe it might be a glitch.

Rover Instruments:

Parts on Spirit and Opportunity:

The rover has a:

  • A Body: An enclosure that protects all of the internal organs.
  • Brains: Computers designed to process data and information.
  • Temperature Controls: A layer of insulation as well as internal heaters, and more. A “head and neck” A mast for the cameras to give the rovers human-scale view

Eyes and other Sensors Instruments and cameras so that the rovers can collect. Information about their environment and surrounds.

  • An Arm: A device that allows the rover to extend its reach.

Legs and Wheels: Parts of the rover’s mobility technology.

  • Energy: Solar panels and batteries.
  • Communications: Antennas for both listening and speaking by transmitting

Data back to Earth.

Interesting Information:

  • Between all four of the rovers, scientists have learned an incredible amount of information about Mars today and its long history.
  • When Opportunity landed it immediately found the mineral hematite at its landing location. Hematite is formed in water, which is one of the keys to life. At one point, the landing site contained salty water.
  • During Spirit’s travels it found a location called “Comanche” where the rocks are ten times richer in the important chemicals of iron carbonates and magnesium than any of the previously studied Mars rocks. The importance of the chemicals is that the rocks formed when Mars was warmer and wetter than it is today. It had a thicker carbon-dioxide atmosphere and, all of these characteristics show that it could have supported life at one time.
  • At one point, Spirit had broken one of its wheels and began dragging the wheel. During the process of dragging, Spirit churned up dust and soil that was found to be 90% pure silicate. The scientists named this area “Home Plate.”  Silica on Earth typically exists in hot steam vents or hot springs. Both of these types of environments are perfect for supporting life.
  • While examining the area called “Home Plate,” Spirit found that the location once had an ancient volcano that had erupted there. If there were powerful steam eruptions due to warmed water that was underground, it could have created the explosions from a volcano. This kind of activity helps to support microbial life on Earth and led scientists to believe that it might have happened long ago on Mars.
  • As Opportunity was investigating Endeavor Crater’s rim it found veins of brightly colored gypsum rocks. Scientists know that this type of rock is usually formed when water has flowed through underground rocks that are fractured. It leaves the calcium behind and is an absolute sign that at one time Mars had an environment that was more hospitable than the one that we see today.
  • Opportunity also found additional signs that Mars had a watery history. The clay minerals that formed in neutral-pH water were found in the Endeavor Crater. These materials are some of the best for microbial life and show that at one time, Mars may have supported life.