A (Size) Comparison of Different Generations of Mars Rovers

As of May 2021, there have been six successful robotically operated Mars rovers. Here is how they compare in size.

A size comparison of three generations of Mars rovers. The one on the bottom is Sojourner, the one on the left is a Mars Exploration Rover (two were launched, Spirit and Opportunity), and the one on the right is Curiosity (click image to enlarge). Image credit: NASA

We all know Mars rovers – motor vehicles that travel across the surface of the Red Planet upon arrival. However, most people are unaware of how small or big they are in real life.

These little/big machines have several advantages over stationary landers: they can examine more territory, be directed to interesting features, place themselves in sunny positions to weather winter months, and can advance the knowledge of how to perform very remote robotic vehicle control.

Let’s look at them more closely, especially their size.

Sojourner Rover

The Mars Pathfinder mission, designed to demonstrate a low-cost method for delivering a set of science instruments to the Red Planet, was launched December 4, 1996 and landed the Sojourner rover on Mars’ Ares Vallis on July 4, 1997. The 280-millimeter (11 inches)-high rover, with ground clearance of 130 mm (5 inches) not only accomplished this goal but also returned an unprecedented amount of data and outlived its primary design life. In fact it was designed for a mission lasting 7 sols, with a possible extension to 30 sols, but in the end it was active for as long as 83 sols. (A sol is a Martian day that is slightly longer than an Earth day. It is approximately 24 hours, 39 minutes, 35 seconds long.)

The Sojourner rover in the production phase. It was much smaller than its more recent counterparts. Source

Mars Exploration Rover

NASA’s Mars Exploration Rover (MER) mission was a robotic space mission involving two Mars rovers, Spirit and Opportunity, sent to explore the planet Mars. The mission began in 2003 with the launch of the two rovers: MER-A Spirit and MER-B Opportunity – to explore Mars’ surface and geology. Both rovers landed on Mars at separate locations in January 2004 and both of them far outlived their planned missions of 90 Martian solar days: MER-A Spirit was active until 2010, and MER-B Opportunity until 2018. The latter holds the record for the longest distance driven by any off-Earth wheeled vehicle.

Mars Exploration Rover (left) compared to Sojourner and Curiosity. Image credit: NASA

Curiosity

Curiosity is a car-sized Mars rover designed to explore Gale Crater on the planet as part of NASA’s Mars Science Laboratory mission (MSL). Curiosity was launched from Cape Canaveral, Florida, on November 26, 2011, and landed on Aeolis Palus in Gale Crater on Mars on August 6, 2012. The rover’s mission include an investigation of the Martian climate and geology; assessment of whether the selected field site inside Gale Crater has ever offered environmental conditions favorable for microbial life, with a focus on the role water plays; and planetary habitability studies in preparation for human exploration. In December 2012, Curiosity’s two-year mission was extended indefinitely.

Size of Curiosity Rover compared to a human. Image credit: NASA

Here’s how the wheels of the above three Mars rovers compare to each other

Wheel size comparison of Sojourner, Mars Exploration Rover (Spirit/Opportunity) and Mars Science Laboratory (Curiosity). Image Credit: Dutch Slager/NASA/JPL

Perseverance

Perseverance, nicknamed Percy, is a car-sized Mars rover similar to its predecessor rover Curiosity, designed to explore the crater Jezero on Mars as part of NASA’s Mars 2020 mission. It was manufactured by Jet Propulsion Laboratory and successfully landed on Mars on 18 February 2021. As of 29 June 2021, Perseverance has been active on Mars for 128 sols (131 Earth days) since its landing. Following its arrival, NASA named Perseverance’s landing site Octavia E. Butler Landing. As for the rover’s actual size, check this out:

Perseverance is ready to take on the Red Planet. Image credit: NASA

Besides seven primary payload instruments, nineteen cameras, and two microphones, the rover also carried the mini-helicopter Ingenuity to Mars, an experimental aircraft that made the first ever powered flight on another planet on 19 April 2021.

Perseverance’s mission is to identify ancient Martian environments capable of supporting life, seeking out evidence of former microbial life existing in those environments, collecting rock and soil samples, and testing oxygen production from the Martian atmosphere to prepare for future crewed missions.

Preparing for the big one.

Sources: 1, 2, 3, 4, 5

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