Mars, the smaller, redder, and colder cousin of Earth, most probably had a wet history.
Scientists have long hypothesized that, with liquid water flowing on its surface for more than a billion years, Mars formerly had oceans, continents, and a dense atmosphere. And new data and observations are uncovering more about its fascinating past while also raising new questions about the tantalizing possibility of life on Mars.
Now, based on data gathered during China's Tianwen-1 mission, scientists have discovered evidence that a large impact basin on Mars hosted liquid water during the Amazonian epoch, according to a study published in Science Advances.
The latest discovery adds to a growing body of evidence that suggests liquid water activity on Mars may have existed for far longer than we previously thought. And, since this location now holds significant amounts of water in the form of hydrated minerals and maybe ground ice, future astronauts could potentially use this untapped resource during crewed Mars missions.
What is the Amazonian period?
The discovery was made by China's first-ever independent interplanetary mission, Tianwen-1, which has made significant achievements while also offering numerous surprises. It has been triumphantly revealing Mars' secrets since the rover, Zhurong, safely landed on Mars on May 14, 2021, after going through nine minutes of terror.
Zhurong has investigated several geologic features and returned images and panoramas of its numerous adventures, covering a total of 5,000 feet (1,537 meters) as of February 4, according to Space.com. And, as the newest find shows, it is far from finished with its travels.
Even though scientists' long-held belief that ancient Mars was wet and habitable, the planet’s most recent geologic epoch, the Amazonian, began around three billion years ago, and is generally believed to have cold and dry conditions. This geologic system and time period can be characterized by low rates of meteorite and asteroid impacts and cold and arid conditions that are similar to those seen on the planet today.
Uncovering Martian water's mysteries
However, the recent study has found evidence that water flowed across the Amazonian terrain. This indicates that liquid water may have molded the Martian surface in its recent geologic history.
The study was conducted by a team of researchers, Yang Liu and colleagues, which used data from the Zhurong rover on the sedimentary and mineral properties of southern Utopia Planitia, the biggest recorded impact basin in Mars' northern lowlands. The data was collected using Zhurong's laser-induced breakdown spectrometer, telescopic microimaging camera, and SWIR (short-wave infrared) spectrometer, which measures the mineralogy of the Martian surface from 1.6 to 7 meters away.
The researchers discovered bright-toned rocks that they interpreted as a layer of “duricrust” that would have been formed by the activities of a significant volume of liquid water, which might have been rising groundwater or melting underlying ice.
With its current low air pressure and temperature, pure liquid water cannot exist in a stable state on the surface of Mars, save at the lowest elevations for a few hours. With the recently explored impact site holding significant amounts of water in the form of hydrated minerals and maybe ground ice, this holds the possibility of astronauts using the untapped water resources during crewed Mars missions in the future.
For example, a team of scientists has already developed a device capable of converting water into fuel and oxygen for future Mars expeditions. Such gadgets might be among the technology humans will need to bring to enable visits to Mars — and fuel trips back home.