Mars, the planet nearest to the earth has always been an interest of study. While NASA has a legal mandate to send people to Mars by 2033, it is important to determine if the red planet has water and air, the two basic elements for survival of life.
The US Geological Survey (USGS) scientists have revealed that the red planet used to have oceans about 4.2 billion years ago, which began drying out slowly and were reduced to oasis-like pools of water. These shallow pools sheltered microscopic alien life for hundreds of millions of years. However, today Mars is a frozen dry rock and has little air to breathe. Around 4.5 billion years ago, the scenario was quite different as 20 percent of the planet’s surface was covered with water and around 400-feet-tall mega tsunamis ran across the oceans.
Water supports life, and the red planet was no different! Life existed on Mars until the solar storms blew away the air and water 300 million years later. The USGS scientists created new maps of the Mars that revealed habitable oases at the bottom of Valles Marineris or Mariner Valley, (a vast canyon system that runs along the Martian equator) hundreds of millions of years after the oceans in Mars evaporated.
If groundwater continuously fed these puddles, pools, and lakes, there is a possibility of microbial life living there. Chris Okubo, an astrogeologist at USGS and an author of the new maps says, “There was a tremendous potential for a habitable environment here, and there’s a lot of promise for [microscopic] fossils, perhaps, or some biological signals.”
The Oases of ancient Mars
Underground water sources like a leaky aquifer feed an ideal oasis on the earth. Okubo and other scientists are of the opinion that a similar process happens on Mars as well. Okubo said in a USGS press release that the groundwater is plenty on Mars and at times it seeps onto the ground surface to form pools. These water bodies support life just as they do on earth.
The feature of the water seeping onto the ground surface is called as the “Great Canyon” of Mars, but it is about four times longer, nearly five times deeper and 20 times wider than earth’s Grand Canyon. Okubo claims of having seen thin layers of sediments in the basin that are piled up on each other for about 500 million years.
When such layers of sediments form, groundwater gurgles to the surface and forms a shallow pool which turns into a potentially habitable oasis, informs Okubo. Over a period, grit enters the water and pushes the water in an upward direction and another pool forms. When more sand comes, the cycle repeats and creates a flat plain surface of finely layered sediments. After a few billion years, the wind causes erosion, and these layers are exposed to scientists like Okubo.
Okubo and his USGS colleagues got a wider view and incredibly detailed images of the canyons with the help of the Mars Reconnaissance Orbiter’s HiRISE camera. The camera was used to capture the signs of ancient shallow pools. The analysis revealed the sediment layers over the massive canyon’s basin. Also, the maps hinted that the shallow pools were around 3.5 billion to 3 billion years old.
Okubo informed that “We only see the top of the pile. We don’t know what’s going on further back in time because we can’t see it – it’s buried.”
Even if these shallow pools existed at least 700 million years before or when the oceans on Mars began evaporating, they may have bridged a gap for microbial life on the red planet. To find out more on this, Okubo says that we need to send robots or people who can dig into the soil or take readings using ground-penetrating radar.
Does Mars still have water?
Scientists are of the opinion that Mars still has a water table which is hidden deep below its surface. Michael Meyer, a leading scientist at NASA’s Astrobiology Institute, says, “Although [satellites] in orbit around Mars haven’t found any subterranean aquifers, there’s a sneaking suspicion we’re only seeing the upper kilometer or so because radar’s a challenge.”
Over the past few years, scientists believe that a smoking gun for water on Mars, dark streaks in the sand, on the slopes of dry gullies called as recurring slope lineae (RSL) shows up around the same time every season.
Closer examination of more than 100 of RSL sites reveals absence of groundwater or its byproducts. It is not certain that Mars is dry today and astronauts will not be able to find water through drilling or other ways like burning methane using the Martian air with hydrogen fuel.
The planet’s significant despair doesn’t let the scientists lose hope. Detection of fossils that are billions of years old help in verifying the existence of alien life on Mars.