Science & Technology

We May Have Detected Liquid Water on Mars

Mars might have water hiding under its southern pole. A study published today in Science – based on radar observations from the Mars Express spacecraft – suggests a 20-kilometer (12.5-mile) zone of sediments with water in the Planum Australe region. If there is indeed water down there, that could be a spot for life on Mars. Watch the video below, then keep reading to learn the whole story of water on Mars.

A Once-Watery Planet

Mars used to be much wetter in the ancient past. All you need to do is look at its numerous canyons on the surface, or examine Martian rocks such as hematite — rocks that usually form in water. But the planet is a dry and dusty place today, shaped by wind instead of water. So where did all that water go?

The theory is that Mars used to have a much thicker atmosphere, like that of Earth. But over the eons, it slowly eroded away. Mars doesn't have a global magnetic field. This means that it's poorly protected from the sun's radiation. Slowly but surely, charged particles from the sun knocked away lighter molecules of the Red Planet's atmosphere and scattered them into space.

This newfound water reservoir — if it indeed exists, because not all scientists agree it's there — is probably a leftover of that wetter period on Mars, billions of years ago. (The science team was cautious to say that this discovery is probably sediments mixed in with water — not a lake, as some media have said.)

But we need more evidence to be sure this water is there, and to figure out exactly what is in the area. On Earth, scientists commonly use planes to beam radar at the ice in places like Antarctica to discover what's underneath. So we may not get an answer for sure until we can get a craft to peer at the Martian south pole from up close.

Is There Water on Mars Today?

Yes, there definitely is water on the Red Planet. All you need to do is look at the poles of Mars. There are layers of water ice (and in some cases, carbon dioxide ice) that wax and wane with the changing seasons on Mars. In summer, the caps are smaller as the water evaporates into the atmosphere. In winter, the caps expand as the atmosphere lets go of the water and the ice freezes up again. Mars may even have snowstorms.

But what about running water — water where microbes might like to live? A possible region of study is something called recurring slope lineae (RSL). These are strange patterns of dark streaks that appear on the sides of steep craters on the equator of Mars, or the warmest part of the planet, during the summer. Some researchers say it's running water seeping out from under the surface, kept liquid by salts. Others argue that the RSL are actually dry sand flows, or maybe contain water from the atmosphere.

There's even water ice under the surface of Mars, including in a huge zone in Utopia Planitia (in the mid-northern latitudes) that probably has an ice deposit with as much water as Lake Superior. It would take a little bit of digging to get it out of the ground, but NASA said in 2016 that this ice zone "identifies a possible resource for future astronauts."

While Mars isn't a place for water sports, it still seems a promising spot to set up a colony. SpaceX's Elon Musk, NASA and several other agencies are thinking about heading to Mars in a couple of decades. Could one of these water zones be where future humans settle? Probably, although concerns about how to protect the microbes from us will have to be answered first. Time to start thinking about it!

To hear how we might colonize the Red Planet from one of the most famous astronauts of all time, check out "Mission to Mars: My Vision for Space Exploration" by Buzz Aldrin. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

NASA at Mars: 20 Years of Exploration

Written by Elizabeth Howell July 25, 2018

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