Eight Places To Get Ice Cubes On Mars

A cross-section of underground ice is exposed at the steep slope that appears bright blue in this enhanced-color view from NASA’s Mars Reconnaissance Orbiter. The scene is about 550 yards wide. The scarp drops about 140 yards from the level ground in the upper quarter of the image. NASA/JPL-Caltech/UA/USGS

My kids and wife stay properly hydrated. They always have a bottle at the ready. I drink water when I think of it and would never pass a hydration test. Water is crucial to life. If we ever build a colony on Mars, we’ll need ready access to to Martian ice that can be melted and purified into drinking water. Now, researchers using NASA’s Mars Reconnaissance Orbiter (MRO) have found eight sites where thick deposits of ice beneath Mars’ surface are exposed in faces of eroding slopes and easily accessible.

“Astronauts could essentially just go there with a bucket and a shovel and get all the water they need,” said Shane Byrne (University of Arizona Lunar and Planetary Laboratory).

These eight scarps, with slopes as steep as 55 degrees, reveal new information about the internal layered structure of previously detected underground ice sheets in Mars’ middle latitudes. Middle is key because a manned mission to the Red Planet and any future colonization efforts would avoid the hostile polar regions because they’re bitterly cold. Winter temperatures there dip to –207° F (–133° C). Mid-latitudes in contrast are more temperate just as they are here on Earth.

In this wide view, we can better see the context of the icy slope in the first photo — a large collapsed pit on Mars. The steep slope at the northern edge (toward the top of the image) exposes a cross-section of a thick sheet of underground water ice. The central swath is color-enhanced. NASA/JPL-Caltech/UA/USGS

The ice, likely deposited as snow long ago, now lies exposed along the faces of the slopes. It’s relatively pure and capped by a yard or two (1-2 meters) of ice-cemented rock and dust. Future astronauts or robotic rovers might study the ice to learn more about Mars’ climate history the same way we’ve peeled back more than 100,000 years of long-term climate variations by studying ice cores from the Greenland ice sheet. The newly-studied Martian sites expose ice at least 325 feet (100 meters) deep.

“It’s like having one of those ant farms where you can see through the glass on the side to learn about what’s usually hidden beneath the ground, said Byrne.

Using measurements from MRO’s ground-penetrating radar and CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) instrument the researchers positively identified the material as water ice and reported the findings in the journal Science yesterday. The sites are in both northern and southern hemispheres of Mars, at latitudes from about 55° to 58°, equivalent on Earth to northern Alberta or the tip of South America.

The slopes provide a glinty hint at how pervasive ice is on Mars outside the polar caps; through remote sensing by orbiting satellites, scientists have determined it exists under about a third of the Martian surface.

Long-term patterns in Mars’ climate are related to the tilt of its axis. Today Earth’s and Mars’ tilts are about the same (Earth 23.5°, Mars 25°), but they can vary. Changes in Mars’ and Earth’s axial tilts are caused by long-term gravitational interactions with the other planets in the solar system, but Earth’s “tippiness” is kept to a minimum by the steady hand of our big moon. Mars has no such large satellite and experiences drastic swings from 0° up to 60° over millions of years. When Mars is tilted more steeply, climate conditions may favor buildup of middle-latitude ice.

Dundas and co-authors say that banding and color variations apparent in some of the scarps suggest layers “possibly deposited with changes in the proportion of ice and dust under varying climate conditions.”

Nice to know that later this century (we hope), astronauts will know where to go for ice cubes for that favorite drink.