This is why Martian Colonists are Going to Wish They had an Atmosphere Above Them

There will be all sorts of risks for any future colonists on Mars, such as extreme weather and temperatures, radiation, and the human physiological problems associated with living in with decreased gravity. But another issue means colonists on Mars will have to be on a constant lookout above their heads.

While Mars and Earth are both hit by space debris regularly – dust, small rocks and bigger meteoroids — on our planet, meteors usually vaporize in the atmosphere.

“On Mars however, with a surface pressure 1/100th that of the Earth, the impactors generally make it to the surface,” says the team from the HiRISE camera on the Mars Reconnaissance Orbiter (MRO).

A small impact crater on Mars that was created within the past 5 years, seen by the HiRISE camera on the Mars Reconnaissance Orbiter. Credit: NASA/JPL/UArizona.

HiRISE (High Resolution Imaging Science Experiment) on board MRO took this image of a small impact crater that was formed sometime in the last 5 years. Although the crater is small, the rays of ejecta thrown out by the impact are easy to spot, stretching out almost a kilometer.

How often does this happen on Mars? A 2013 study estimated that the Red Planet gets womped by more than 200 small asteroids or bits of comets per year, forming craters at least 3.9 meters (12.8 feet) across. Like on Earth, even a small impact would wreak havoc on any Martian settlement. But impacts of this size on Mars happen more frequently.

Related: What will it take to feed a million people on Mars?

Mars is about half the size of Earth by diameter and the thinner air surrounding the planet has an atmospheric volume less than 1% of Earth’s. The atmospheric composition is also significantly different: primarily carbon dioxide-based, while Earth’s is rich in nitrogen and oxygen.

MRO has been in orbit of Mars since 2006, and one of the benefits of having a spacecraft in orbit around another planet for several years is the ability to make long-term observations and interpretations. HiRISE images over the years have detected numerous “fresh” craters that have formed, and since it has repeatedly imaged several regions on Mars, scientists can study the before-and-after images to calculate the impact rate based on new craters.

A 2010 image of ice excavated on Mars after a recent meteorite impact. Image from the Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) camera. Credit: NASA/JPL-Caltech/Univ. of Arizona

The 2013 study showed that the rate for how frequently new craters are formed, which are at least 3.9 meters in diameter is about one each year on each area of the Martian surface roughly the size of the U.S. state of Texas.

Just one more thing that will be a challenge for anyone who dares to try and live on Mars.

See the original image and more details from MRO on the HiRISE website.

Nancy Atkinson

Nancy has been with Universe Today since 2004, and has published over 6,000 articles on space exploration, astronomy, science and technology. She is the author of two books: "Eight Years to the Moon: the History of the Apollo Missions," (2019) which shares the stories of 60 engineers and scientists who worked behind the scenes to make landing on the Moon possible; and "Incredible Stories from Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos" (2016) tells the stories of those who work on NASA's robotic missions to explore the Solar System and beyond. Follow Nancy on Twitter at and and Instagram at and

Recent Posts

A Recently Discovered Double Binary System is Unstable. Stars Could Collide, Leading to a Supernova

A quadruple binary star system may reveal a common source of the supernovae we use…

21 hours ago

Cosmic Rays can Help Keep the World's Clocks in Sync

The world has a robust, accurate timekeeping system that regulates our clocks. Humanity uses it…

22 hours ago

A CubeSat is Flying to the Moon to Make Sure Lunar Gateway’s Orbit is Actually Stable

To validate the Lunar Gateway's orbit around the lunar poles (a halo orbit), NASA is…

2 days ago

What’s the Right Depth to Search for Life on Icy Worlds?

Are we alone? Is there life beyond Earth? These are the questions that plague the…

4 days ago

Astronomers Finally Catch a Nova Detonating on a White Dwarf as it's Happening

On July 7, 2020, the X-ray instrument eROSITA captured an astronomical event that – until…

4 days ago

This is it! Meet the Supermassive Black Hole at the Heart of the Milky Way

The Event Horizon Telescope has just released the first images of Sagittarius A*, the supermassive…

4 days ago