JPL
Careers
Education
Science & Technology
JPL Logo
JPL Logo
Mars
.

NASA Explores a Winter Wonderland on Mars

Dec. 22, 2022
This image acquired on July 22, 2022 by NASA's Mars Reconnaissance Orbiter shows sand dunes moving across the landscape. Winter frost covers the colder, north-facing half of each dune.

The HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter captured these images of sand dunes covered by frost just after winter solstice. The frost here is a mixture of carbon dioxide (dry) ice and water ice and will disappear in a few months when spring arrives.

Credit: NASA/JPL-Caltech/University of Arizona
Full Image Details
This image acquired on May 6, 2021 by NASA's Mars Reconnaissance Orbiter, shows a unique polar dune field during northern spring, revealing some interesting patterns.

HiRISE captured these “megadunes,” also called barchans. Carbon dioxide frost and ice have formed over the dunes during the winter; as this starts to sublimate during spring, the darker-colored dune sand is revealed.

Credit: NASA/JPL-Caltech/University of Arizona
Full Image Details

Cube-shaped snow, icy landscapes, and frost are all part of the Red Planet’s coldest season.

When winter comes to Mars, the surface is transformed into a truly otherworldly holiday scene. Snow, ice, and frost accompany the season’s sub-zero temperatures. Some of the coldest of these occur at the planet’s poles, where it gets as low as minus 190 degrees Fahrenheit (minus 123 degrees Celsius).

Cold as it is, don’t expect snow drifts worthy of the Rocky Mountains. No region of Mars gets more than a few feet of snow, most of which falls over extremely flat areas. And the Red Planet’s elliptical orbit means it takes many more months for winter to come around: a single Mars year is around two Earth years.

Snow falls and ice and frost form on Mars, too. NASA’s spacecraft on and orbiting the Red Planet reveal the similarities to and differences from how we experience winter on Earth. Mars scientist Sylvain Piqueux of JPL explains in this video.

Credit: NASA/JPL-Caltech

Still, the planet offers unique winter phenomena that scientists have been able to study, thanks to NASA’s robotic Mars explorers. Here are a few of the things they’ve discovered:

Two Kinds of Snow

Martian snow comes in two varieties: water ice and carbon dioxide, or dry ice. Because Martian air is so thin and the temperatures so cold, water-ice snow sublimates, or becomes a gas, before it even touches the ground. Dry-ice snow actually does reach the ground.

“Enough falls that you could snowshoe across it,” said Sylvain Piqueux, a Mars scientist at NASA’s Jet Propulsion Laboratory in Southern California whose research includes a variety of winter phenomena. “If you were looking for skiing, though, you’d have to go into a crater or cliffside, where snow could build up on a sloped surface.”

How We Know It Snows

Snow occurs only at the coldest extremes of Mars: at the poles, under cloud cover, and at night. Cameras on orbiting spacecraft can’t see through those clouds, and surface missions can’t survive in the extreme cold. As a result, no images of falling snow have ever been captured. But scientists know it happens, thanks to a few special science instruments.

NASA’s Mars Reconnaissance Orbiter can peer through cloud cover using its Mars Climate Sounder instrument, which detects light in wavelengths imperceptible to the human eye. That ability has allowed scientists to detect carbon dioxide snow falling to the ground. And in 2008, NASA sent the Phoenix lander within 1,000 miles (about 1,600 kilometers) of Mars’ north pole, where it used a laser instrument to detect water-ice snow falling to the surface.

Cubic Snowflakes

Because of how water molecules bond together when they freeze, snowflakes on Earth have six sides. The same principle applies to all crystals: The way in which atoms arrange themselves determines a crystal’s shape. In the case of carbon dioxide, molecules in dry ice always bond in forms of four when frozen.

“Because carbon dioxide ice has a symmetry of four, we know dry-ice snowflakes would be cube-shaped,” Piqueux said. “Thanks to the Mars Climate Sounder, we can tell these snowflakes would be smaller than the width of a human hair.”

This image acquired on January 4, 2022 by NASA's Mars Reconnaissance Orbiter, shows a crater near 37 degrees south latitude. The south-facing slope has patchy bright frost, blue in enhanced color.

The HiRISE camera captured this image of the edge of a crater in the middle of winter. The south-facing slope of the crater, which receives less sunlight, has formed patchy, bright frost, seen in blue in this enhanced-color image.

Credit: NASA/JPL-Caltech/University of Arizona
Full Image Details

Jack Frost Nipping at Your Rover

Water and carbon dioxide can each form frost on Mars, and both types of frost appear far more widely across the planet than snow does. The Viking landers saw water frost when they studied Mars in the 1970s, while NASA’s Odyssey orbiter has observed frost forming and sublimating away in the morning Sun.

This image acquired on March 30, 2022 by NASA's Mars Reconnaissance Orbiter shows how water ice frozen in the soil splits the ground into polygons.

HiRISE captured this spring scene, when water ice frozen in the soil had split the ground into polygons. Translucent carbon dioxide ice allows sunlight to shine through and heat gases that escape through vents, releasing fans of darker material onto the surface (shown as blue in this enhanced-color image).

Credit: NASA/JPL-Caltech/University of Arizona
Full Image Details

Winter’s Wondrous End

Perhaps the most fabulous discovery comes at the end of winter, when all the ice that built up begins to “thaw” and sublimate into the atmosphere. As it does so, this ice takes on bizarre and beautiful shapes that have reminded scientists of spiders, Dalmatian spots, fried eggs, and Swiss cheese.

This “thawing” also causes geysers to erupt: Translucent ice allows sunlight to heat up gas underneath it, and that gas eventually bursts out, sending fans of dust onto the surface. Scientists have actually begun to study these fans as a way to learn more about which way Martian winds are blowing.

Get the Latest JPL News

SUBSCRIBE TO THE NEWSLETTER

News Media Contact

Andrew Good

Jet Propulsion Laboratory, Pasadena, Calif.

818-393-2433

andrew.c.good@jpl.nasa.gov

Karen Fox / Alana Johnson

NASA Headquarters, Washington

301-286-6284 / 202-358-1501

karen.c.fox@nasa.gov / alana.r.johnson@nasa.gov

2022-209

Related News

Mars .

NASA’s Perseverance Rover Completes Mars Sample Depot

Solar System .

NASA’s Juno Team Assessing Camera After 48th Flyby of Jupiter

Solar System .

NASA’s Psyche Mission Continues Preparation for Launch in 2023

Solar System .

NASA’s Lunar Flashlight Team Assessing Spacecraft’s Propulsion System

Solar System .

Juno Spacecraft Recovering Memory After 47th Flyby of Jupiter

Mars .

NASA Retires InSight Mars Lander Mission After Years of Science

Mars .

NASA’s Perseverance Rover Deposits First Sample on Mars Surface

Solar System .

40-Year Study Finds Mysterious Patterns in Temperatures at Jupiter

Mars .

NASA’s Perseverance Rover to Begin Building Martian Sample Depot

Solar System .

NASA’s Juno Exploring Jovian Moons During Extended Mission

Explore More

Image .

Ariadnes Colles

Image .

Curiosity Finds a Meteorite, Cacao

Image .

Daedalia Planum

Image .

Daedalia Planum

Image .

A New Impact Event

Image .

Going with the Flow

Image .

A Bear on Mars?

Image .

Gully Activity in Triolet Crater

Image .

Perseverance's Three Forks Sample Depot Map

Image .

WATSON Documents Final Tube Dropped at Three Forks Sample Depot

About JPL
Who We Are
Executive Council
Directors
Careers
Internships
The JPL Story
JPL Achievements
Documentary Series
Annual Reports
Missions
Current
Past
Future
All
News
All
Earth
Solar System
Stars and Galaxies
Subscribe to JPL News
Galleries
Images
Videos
Audio
Podcasts
Apps
Visions of the Future
Slice of History
Robotics at JPL
Events
Lecture Series
Team Competitions
Speakers Bureau
Calendar
Visit
Public Tours
Virtual Tour
Directions and Maps
Topics
JPL Life
Solar System
Mars
Earth
Climate Change
Exoplanets
Stars and Galaxies
Robotics
More
Asteroid Watch
NASA's Eyes Visualizations
Universe - Internal Newsletter
Social Media
Get the Latest from JPL
Follow Us

JPL is a federally funded research and development center managed for NASA by Caltech.

More from JPL
Careers Education Science & Technology Acquisitions JPL Store
Careers
Education
Science & Technology
Acquisitions
JPL Store
Related NASA Sites
Basics of Spaceflight
Climate Kids
Earth / Global Climate Change
Exoplanet Exploration
Mars Exploration
Solar System Exploration
Space Place
NASA's Eyes Visualization Project
Voyager Interstellar Mission
NASA
Caltech
Privacy
Image Policy
FAQ
Feedback
Site Managers: Veronica McGregor, Randal Jackson
Site Editors: Tony Greicius, Naomi Hartono
CL#: 21-0018