What Landers and Rovers Tell Us About Mars

What Landers and Rovers Tell Us About Mars

Landers have been landing on the surface of Mars since the 1970’s. Some landers piggyback rovers. Some successfully land and rove on Mars, sending back data for studies. One study claims life is found on the Martian surface; others dispute as a false positive reading. Later studies find that the Martian surface has chemical and mineral evidence that suggests habitability was once possible. Here we review some Landers and Rovers failures and successes prior to 2022.

Dr. MMM of AstroPicionary has taught astronomy to 10,000+ students over 15+ years at a USA Carnegie Level R1 University. Dr. MMM continues to teach astronomy and physics. She authors textbooks in astronomy that are in use worldwide. Here, Dr. MMM discusses a hot topic in today’s news – greenhouse effect, greenhouse gases, and global warming. Her goal here is to help put water vapor back in the top three list of major greenhouse gases. Another goal is to determine whether water vapor emissions by humans is a major contributor to global warming.

Missions to Mars – A Summary

The graphic below displays exploration missions to Mars. Zoom in to read the list and results of each mission: Notice that many missions in the 1960’s fail (12 o’clock position to 2 o’clock position). The early 1970’s prove no better (2 o’clock to 3 o’clock positions) but the latter half of the 1970’s improve (3 o’clock position). The 1980’s have few missions, and those that do occur eventually fail (3:30 o’clock position). The 1990’s have many failures but some successes (3:30 to 6 o’clock positions). The 2000’s (6 – 8:30 o’clock positions) and 2010’s (8:30 to 10:30 o’clock positions) prove to be much better in returning observational data. The 2020’s are promising (10:30 to 12 o’clock positions) to also return data for analysis.

Summary to 2020 graphic courtesy of NASA/JPL/Roscosmos/JAXA/ESA/ISRO/MBRSC/Jason Davis/Planetary Society under CC BY-NC 3.0

Which Landers Fail to Reach Mars?

Many of the missions in the 1960’s fail: USSR’s Korabl 4 and 5 never reach Earth’s orbit. Although USSR’s Korabl 11 and 13 made Earth’s orbit, both spacecrafts brake apart. USA Mariner’s 3 shroud fails to jettison. USSR Mars 1 and and Zond 2 radios fail, and USSR’s Mars 1969A and 1969B have launch vehicle failures.

The 1970’s and 1980’s have more successful missions, but still several failures:

  • USA Mariner 8 fails to launch
  • USSR’s Kosmos 419 never leaves Earth’s orbit
  • USSR lander Mars 2 is destroyed
  • USSR’s missions Mars 4 and Mars 7 fly past planet Mars
  • USSR Mars 6 fails upon descent to the Martian surface
  • USSR’s Phobos 2 lander is lost near Martian moon Phobos.

The 1990’s have more failures than successes: Russia’s Mars 96 never leaves Earth’s orbit, crashing back to Earth within days after launching. USA Mars Polar lander is lost upon arriving to the Martian surface; wreckage has not been found.

Since 2000, fewer failures occur: ESA Mars Express Beagle 2 lander successfully lands but fails to communicate with Earth. ExoMars EDL Demo Lander is lost upon arrival.

Landers and Rovers Launched to Mars

Many lander and rover missions launch to visit Mars. Many do not make it. However, some successfully land. Let’s look at some of these missions over the decades.

Which Landed on Mars in 1970’s?

The 1970’s are a busy time for landings on planet Mars. In 1971, the USSR Mars 3 lander successfully soft lands. It returns one gray image about 20 seconds of data before failure. This image shows no significant detail. Also in 1971, USA Mariner 9 successfully lands on planet Mars. It takes photos of the Martian surface and sends more than 7000 photos back to planet Earth.

In 1975, USA Viking 1 successfully lands and returns the first usable image of the surface of Mars. Besides in black and white, the lander also sends back color and panoramic images. The lander also conducts surface soil experiments: Although one experiment suggests life once exists on the Martian surface, the greater astronomical community claims the result as a false positive. The AstroPictionary YouTube website explains false positives in science:

One reason supporting a false positive is because the Martian atmosphere has a weak ozone layer. UV light from the Sun sterilizes the Martian surface. As such, no life should be possible on the surface that receives this UV light.

Also in 1975, USA Viking 2 lands with one leg on a Martian rock and others on flatter surfaces. It photographs the surface at an ~8 degree tilt and conducts experiments on the soil for more than 3.5 years. Experiments determine chemical abundances of Martian rock: The Martian soil contains about 1% water and 3-7% magnetic material by weight.

Which Landed on Mars in 1990’s?

The 1990’s has limited successful landings on, but excellent findings about, Mars: In 1996, USA Mars Pathfinder Sojourner successfully lands and becomes the first rover roving on Mars. The panoramic image shown below is that of the Pathfinder’s landing site. Various rocks and other features of Mars are labeled. As seen, the terrain is rocky where Pathfinder landed and sky is clear over horizon.

Mars Pathfinder landing site image courtesy of NASA under Public Domain

While roving the surface, Sojourner conducts technology experiments: Pebbles found near the landing sight suggest running water and a warmer planet once upon a time, long ago. Other findings include estimates of core size, and airborne dust is magnetic iron oxide. Images show many dust devils and gusts of wind mixing dust. Other images show water ice clouds in the lower Martian atmosphere. Abrupt changes from cold to warm measured in the early morning hours suggest convective heating from the Martian surface.

Which Landed on Mars in 2000’s?

The 2000’s had much more successful landings on Mars. In 2003, ESA Beagle 2 Lander fails to communicate with Earth while descending. It does soft land on Mars, though, and partially deploys its solar panels. In 2013 and 2014, NASA MRO observes the remains of the wreckage. The image below shows the landing site and possible locations of Beagle 2’s parachute and rear cover.

Beagle 2 landing site courtesy of NASA/JPL-Caltech/Univ. of Arizona/University of Leicester under Public Domain

In 2003, USA Mars Exploration Rover Spirit landed and roved for 6 years on the surface of Mars. Spirit’s goal was to search for signs of water once upon a time on Mars. One finding is a wetter and warmer time on Mars long ago. A second finding is that when Mars was once warmer and wetter, the soil could have sustained microbial life. However, microbial life has not been found.

In 2003, USA Mars Exploration Rover Opportunity also lands and roves for almost 15 years on the surface of Mars. See findings of USA’s Mars Exploration Rover Spirit, above.

In 2007, USA Phoenix Mars Lander successfully lands on the northern polar region. One goal is to study water history in this polar region. A second goal is to search for a habitable zone and assess biological potential at ice-soil boundary. One find is a flatter polar region than other polar regions; another is water and carbon dioxide ice a few inches below the surface. Fewer dust devils occur in this polar region. Snow falls from cirrus clouds; this snow is expected to be water ice crystals. Winds measure around 7-36 mph. Findings suggest that this polar region was wet or damp in the past. However, conditions are now arid.

Which Landed on Mars in the 2010’s?

The 2010’s prove to be most successful: In 2012, USA Mars Science Laboratory Rover Curiosity lands to explore habitability, namely whether Mars once had a potential for microbial life. Early results find chemical and mineral evidence, suggesting that habitability was once possible.

In 2016, ESA/Russia Schiaparelli EDL Demo Lander crash lands, having been lost during descent. MRO locates debris a couple days later. Images below blink from before impact in May 2016 to after in October 2016; the right blinking images are zooms of the left panels’ boxed region; black spot is crash site whereas white spot is lander’s parachute.

Images of the Schiaparelli orbiter landing site as viewed by Mars Reconnaissance Orbiter (MRO) blinking from May to October 2016 courtesy of NASA/JPL-Caltech/MSSS under Public Domain

In 2018, USA Mars InSight Lander touches down. Its mission is to study Martian interior: crust, mantle, and core. Crust varies from 12-45 miles; the mantle extends another ~970 miles deeper. Lithosphere is 400-600 km thick, or thicker than previous hypotheses. A thicker lithosphere implies higher concentrations of radioactive elements, which produces heat to keep the crust and mantle warm. Below these layers is a core of radius ~1130 miles, which is larger than mantle or crust. The core is found to be molten, which is unlike Earths solid inner core.

Another find is tectonic activity such as marsquakes: Mars often has one or more gentle quakes per day, registering <4.0 magnitudes. Sometimes no quakes register, which may be from surface winds shaking the ground that prevents accurate seismic measurements. Most quakes are from Cerberus Fossae, an active volcano region. A surprise finding is no detection of surface waves, which may be due to a highly fractured surface that diffuses surface waves. Surface fractures occur as Mars continues to cool and shrink.

Along with Mars InSight Lander, twin CubeSats successfully also successfully land. A goal is to test deep space communication from the Martian surface.

Which Landed on Mars in the 2020’s?

The start of the 2020’s is proving to be eventful for lander studies of Mars: In 2020, China’s Tianwen-1 Zhurong Rover successfully lands and deploys in 2021. An instrument on the rover can detect pockets of water beneath the surface that may contain life.

In 2020, USA Mars Perserverance Rover is launched to Mars and deploys in February 2021. The NASA video below shows the rover’s successful landing on the Martian surface:

Some mission goals are to search for signs of ancient life on Mars and to collect samples for return to Earth. Before embarking on its mission, rover Perseverance pauses to take a selfie with the Martian horizon in the background:


Rover Perseverance takes a selfie (image courtesy of NASA under Public Domain)


Many failed missions have been learning experiences for future missions to Mars. Decades have passed before landers could successfully soft land and rovers could successfully roam the surface of Mars. Many successful missions have occurred since the start of the 2010’s, and we have gained more knowledge. For example, a decade ago, Mars interior was hypothesized to be cold throughout. Because of successful rover and/or lander missions, we have learned that the interior of Mars is not dead: Mars still has a warm interior. More will be learned in the future with future missions to Mars.


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About the author

Michele M. Montgomery earned a B.S. Degree in Nuclear/Mechanical Engineering from the Pennsylvania State University, an M.S. Degree in Physics from The University of Alabama with a concentration in Solar Physics, and a Ph.D Degree in Physics from Florida Institute of Technology with a concentration in close binary star systems. She joined the faculty at The University of Central Florida Physics Department in 2004 where she regularly taught astronomy, astrophysics, and cosmology. In 2006, she noticed that a large, urban college nearby to UCF did not teach astronomy at one of their largest campuses. She began teaching astronomy at this East Campus of Valencia College, a college that has more than 60,000 students; she still teaches four courses of astronomy each fall, spring, and summer semesters. The astronomy program atValencia College East has grown significantly with several more faculty added who teach astronomy.

By 2019, Dr. Montgomery has taught astronomy to more than 10,000 college and university students, both online and face-to-face. Many of her students have gone on to take her astrobiology, astrophysics, and space physics courses. 

By 2016, Dr. Montgomery had co-authored several astronomy texts and quiz/exam banks. Her work appears in several domestic and international astronomy text books (e.g., Horizons by Cengage, Universe by Cengage, Foundations of Astronomy by Cengage) that are used both at the higher education as well as at the high school levels. Starting in Fall 2019, Dr. Montgomery switched gears to authoring digital textbooks and research full time, while still teaching 12 courses of astronomy and up to eight conceptual, algebra, and/or calculus-based physics courses each year. Her research interests are numerical simulations using Smoothed Particle Hydrodynamics of close binary star systems. She also regularly is granted telescope time on the NASA's Kepler space telescope for observing eclipsing binary star systems. She has also observed using Gemini South, Keck, and Kitt Peak ground-based telescopes. Her major teaching areas are Astronomy, Astrobiology, Astrophysics, Cosmology, Space Weather/Space Physics.