Nav: Home

How hard did it rain on Mars?

May 16, 2017

Heavy rain on Mars reshaped the planet's impact craters and carved out river-like channels in its surface billions of years ago, according to a new study published in Icarus. In the paper, researchers from the Smithsonian Institution and the Johns Hopkins University Applied Physics Laboratory show that changes in the atmosphere on Mars made it rain harder and harder, which had a similar effect on the planet's surface as we see on Earth.

The fourth planet from the sun, Mars has geological features like the Earth and moon, such as craters and valleys, many of which were formed through rainfall. Although there is a growing body of evidence that there was once water on Mars, it does not rain there today.

But in their new study, geologists Dr. Robert Craddock and Dr. Ralph Lorenz show that there was rainfall in the past -- and that it was heavy enough to change the planet's surface. To work this out, they used methods tried and tested here on Earth, where the erosive effect of the rain on the Earth's surface has important impacts on agriculture and the economy.

Valley networks on Mars show evidence for surface runoff driven by rainfall. "Many people have analyzed the nature of rainfall on the Earth, but no one had thought to apply the physics to understanding the early Martian atmosphere," said Dr. Craddock of the Smithsonian Institution.

To understand how rainfall on Mars has changed over time, the researchers had to consider how the Martian atmosphere has changed. When Mars first formed 4.5 billion years ago, it had a much more substantial atmosphere with a higher pressure than it does now. This pressure influences the size of the raindrops and how hard they fall.

Early on in the planet's existence, water droplets would have been very small, producing something like fog rather than rain; this would not have been capable of carving out the planet we know today. As the atmospheric pressure decreased over millions of years, raindrops got bigger and rainfall became heavy enough to cut into the soil and start to alter the craters. The water could then be channeled and able to cut through the planet's surface, creating valleys.

"By using basic physical principles to understand the relationship between the atmosphere, raindrop size and rainfall intensity, we have shown that Mars would have seen some pretty big raindrops that would have been able to make more drastic changes to the surface than the earlier fog-like droplets," commented Dr. Lorenz of John Hopkins APL, who has also studied liquid methane rainfall on Saturn's moon Titan, the only other world in the solar system apart from Earth where rain falls onto the surface at the present day.

They showed that very early on, the atmospheric pressure on Mars would have been about 4 bars (the Earth's surface today is 1 bar) and the raindrops at this pressure could not have been bigger than 3mm across, which would not have penetrated the soil. But as the atmospheric pressure fell to 1.5 bars, the droplets could grow and fall harder, cutting into the soil. In Martian conditions at that time, had the pressure been the same as we have on Earth, raindrops would have been about 7.3mm - a millimeter bigger than on Earth.

"There will always be some unknowns, of course, such as how high a storm cloud may have risen into the Martian atmosphere, but we made efforts to apply the range of published variables for rainfall on Earth," added Dr. Craddock. "It's unlikely that rainfall on early Mars would have been dramatically different than what's described in our paper. Our findings provide new, more definitive, constraints about the history of water and the climate on Mars."
-end-
Notes for editors

The article is "The changing nature of rainfall during the early history of Mars," by Robert A. Craddock and Ralph D. Lorenz (https://doi.org/10.1016/j.icarus.2017.04.013). It appears in Icarus, volume 293, (September 2017), published by Elsevier.

Copies of this paper are available to credentialed journalists upon request; please contact Elsevier's Newsroom at newsroom@elsevier.com or +31 20 485 2492.

About Icarus

Icarus is devoted to the publication of original contributions in the field of Solar System studies. Manuscripts reporting the results of new research - observational, experimental, or theoretical - concerning the astronomy, geology, meteorology, physics, chemistry, biology, and other scientific aspects of our Solar System or extrasolar systems are welcome.

About Elsevier

Elsevier is a global information analytics company that helps institutions and professionals progress science, advance healthcare and improve performance for the benefit of humanity. Elsevier provides digital solutions and tools in the areas of strategic research management, R&D performance, clinical decision support, and professional education; including ScienceDirect, Scopus, ClinicalKey and Sherpath. Elsevier publishes over 2,500 digitized journals, including The Lancet and Cell, more than 35,000 e-book titles and many iconic reference works, including Gray's Anatomy. Elsevier is part of RELX Group, a global provider of information and analytics for professionals and business customers across industries. http://www.elsevier.com

Media contact

Elisa Nelissen
Press Officer, Elsevier
+31 20 485 2492
e.nelissen@elsevier.com

Elsevier

Related Mars Articles:

The seismicity of Mars
Fifteen months after the successful landing of the NASA InSight mission on Mars, first scientific analyses of ETH Zurich researchers and their partners reveal that the planet is seismically active.
Journey to the center of Mars
While InSight's seismometer has been patiently waiting for the next big marsquake to illuminate its interior and define its crust-mantle-core structure, two scientists, have built a new compositional model for Mars.
Getting mac and cheese to Mars
Washington State University scientists have developed a way to triple the shelf life of ready-to-eat macaroni and cheese, a development that could have benefits for everything from space travel to military use.
A material way to make Mars habitable
New research suggest that regions of the Martian surface could be made habitable with a material -- silica aerogel -- that mimics Earth's atmospheric greenhouse effect.
Life on Mars?
Researchers from Hungary have discovered embedded organic material in a Martian meteorite found in the late 1970s.
New evidence of deep groundwater on Mars
Researchers at the USC Arid Climate and Water Research Center (AWARE) have published a study that suggests deep groundwater could still be active on Mars and could originate surface streams in some near-equatorial areas on Mars.
Why we won't get to Mars without teamwork
If humanity hopes to make it to Mars anytime soon, we need to understand not just technology, but the psychological dynamic of a small group of astronauts trapped in a confined space for months with no escape, according to a paper published in American Psychologist, the flagship journal of the American Psychological Association.
Mars: Not as dry as it seems
Two new Oxford University papers have shed light on why there is no life on Mars.
More evidence of water on Mars
River deposits exist across the surface of Mars and record a surface environment from over 3.5 billion years ago that was able to support liquid water at the surface.
How hard did it rain on Mars?
Heavy rain on Mars reshaped the planet's impact craters and carved out river-like channels in its surface billions of years ago, according to a new study published in Icarus.
More Mars News and Mars Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Speedy Beet
There are few musical moments more well-worn than the first four notes of Beethoven's Fifth Symphony. But in this short, we find out that Beethoven might have made a last-ditch effort to keep his music from ever feeling familiar, to keep pushing his listeners to a kind of psychological limit. Big thanks to our Brooklyn Philharmonic musicians: Deborah Buck and Suzy Perelman on violin, Arash Amini on cello, and Ah Ling Neu on viola. And check out The First Four Notes, Matthew Guerrieri's book on Beethoven's Fifth. Support Radiolab today at Radiolab.org/donate.