What Is the Weather Like on Mars? Learn About the Martian Atmosphere and the Possibility Of Human Exploration to the Red Planet

Mars is the fourth planet from the sun Earth’s solar system. Named for the Roman God of war and often called the “red planet,” Mars has long captivated scientist’s imagination due to its proximity to Earth, its visibility in the night sky, and its deep red coloring. Though similar in size and relatively close to Earth, Mars has a distinct atmosphere, climate, and weather patterns that could support life (and indeed may once have).

Mars is alluring because it has an atmosphere, water, and geothermal heat—meaning there may be fossils there, or even life itself. Understanding the origins and course of life on Mars would tell us about life’s evolution in our solar system. Thus, exploring Mars is as much about exploring the origins of life as it is about exploring the entire planet.

Mars is also interesting from a scientific point of view because, of all the other planets in the solar system, its proximity, atmosphere, and climate make it the likeliest to support human colonization.

The Martian atmosphere is quite thin as the planet lacks a magnetic shield and substantial atmospheric pressure; it is distinct from Earth’s atmosphere in that it is mostly composed of carbon dioxide. The atmosphere of Mars contains:

• 96% carbon dioxide
• 1.9% argon
• 1.9% nitrogen
• Trace amounts of the oxygen; carbon monoxide; water vapor; and methane

Scientists have discovered that over 3.5 billion years ago, the Martian atmosphere was thick enough to support running surface water on Mars. Yet, for reasons that scientists have yet to understand, Mars’s atmosphere thinned to the point that surface water was no longer viable.

Since Mars has a thin atmosphere and is further from the sun, the weather on Mars is much colder than that on Earth with lower temperatures.

• The average temperature is roughly -80 F (-60 C)
• The day-to-day temperature varies from -195 F (-125 C) at the planet’s poles during the winter to a quite comfortable equatorial temperature of 70 F (20 C) at midday

Dust forms a central component of the Martian weather system. Giant dust devils, which are like fair-weather tornadoes, are a regular feature on the planet, kicking up oxidized iron dust from the Martian surface. These dust storms are the largest in the solar system and have been known to cover the planet for months at a time. Yet even in the absence of a dust devil, dust remains a permanent part of the Martian atmosphere.

It also occasionally snows on Mars. Snowflakes are composed of carbon dioxide rather than water. It is believed that these small frozen CO2 particles actually create a fog-like effect and don’t appear as falling snow. Frozen CO2 also makes up the ice caps in the polar regions.

Studying the weather and climate on Mars are key to making exploration and settlement possible. Orbital observation satellites like Mars Maven and the Mars Reconnaissance Orbiter, and surface missions like NASA’s Mars Curiosity Rover and Mars Opportunity Rovers have been deployed to better understand the planet’s climate and weather. Future surface missions like NASA’s Mars 2020 and the ESA’s ExoMars (Mars Express) will further investigate these conditions.

One of the greatest impacts of a mission to Mars would be finding life or evidence of extinct life, no matter how simple that life may be. It would not only answer the question of whether we are alone in the cosmos, but would also indicate that there is potential for life everywhere in the universe.

Humans have long studied the possibility of life on Mars, notably with the Viking landers of the late 1970s, which expected but ultimately failed to find convincing proof of life on Mars. Yet the possibility of life on Mars continues to entice scientists, especially considering the planet’s geological history:

• Scientists believe that millions of years ago oceans may have covered the surface of Mars.
• This would have provided an opportunity for life to develop.
• Liquid water may still exist underground, offering a habitable refuge for any water-based life forms to survive.

Humans have long wanted to explore the Martian surface, both to learn more about the origins of life in our solar system and also to explore the possibility of surface exploration and ultimately habitation. Yet so far we’ve agreed that it has been too dangerous for humans to go look. Even our robotic missions have failed 50% of the time just trying to get there. There are both business and scientific benefits to come from the risks of exploration.

The technical and engineering challenge to get to Mars is daunting for a number of reasons:

• Mars and Earth both orbit the sun, which means the distance between the two planets is constantly changing. If we wait for the optimal alignment and use the best engines we’ve devised, it’s still about five months to get there.
• That’s a long voyage into the unknown with an unproven ship, hauling everything you need, with no way to resupply critical items. And that’s just the beginning.
• On arrival you have to somehow slow to orbital speed, descend through Mars’s very different atmosphere, and safely land. Not to mention doing it all in reverse to come home to Earth.

Due to these difficult conditions, one of the best solutions for human travel to Mars is to not have to bring everything in a spaceship. Instead, scientists could send a cargo ship in advance and start building a small robotic base, remotely taking advantage of resources already on Mars, in a process referred to as in-situ resource utilization (ISRU).

The Sabatier process is key for this approach as it creates hydrogen, oxygen, and methane making drinking water, fertilizer, fuel. On Mars, there is a thin carbon dioxide atmosphere, as well as a large amount of water ice below the surface and at high latitudes. If the ISRU robot lands in the right place, it can process the local Martian air and ice to produce water to drink, oxygen to breathe, and even fuel. All it needs is the right equipment and an electric power source, like solar.

Under these conditions, a crew traveling to Mars could arrive to a richness of ready-to-use vital resources.

Learn more about space exploration in former astronaut Chris Hadfield’s MasterClass.