One of the biggest topics in Mars research right now is understanding the history of water on the planet. Scientists know that there was once abundant liquid water on its surface, though now all that water has disappeared and the planet is arid. The only remaining water on Mars’s surface today is in the form of water ice near its poles or in deep canyons. To understand what happened to all the water which was present billions of years ago, researchers are trying to piece together a geological history of the planet.
Most researchers thought that the water on Mars evaporated around 3 billion years ago, but new research is questioning this figure. Recent data from NASA’s Mars Reconnaissance Orbiter (MRO) suggests that there could have been water on Mars as recently as 2 billion years ago, meaning we may have to re-configure our understanding of the planet’s history.
The researchers used data from the MRO to look at salt deposits that were left behind when water evaporated. They looked for these deposits in areas with impact craters caused by asteroid impacts, which can be used for dating as more craters generally mean older terrain. By combining information about the number of craters and the extent of salt deposits, they could estimate the date of water evaporation.
“What is amazing is that after more than a decade of providing high-resolution image, stereo, and infrared data, MRO has driven new discoveries about the nature and timing of these river-connected ancient salt ponds,” said Bethany Ehlmann, deputy principal investigator for MRO’s Compact Reconnaissance Imaging Spectrometer for Mars instrument, in a statement.
MRO has been capturing high-resolution images of the Mars surface since it arrived at the planet in 2006, and it continues to provide more data to help understand the planet.
“Part of the value of MRO is that our view of the planet keeps getting more detailed over time,” said Leslie Tamppari, the mission’s deputy project scientist at JPL. “The more of the planet we map with our instruments, the better we can understand its history.”
The research is published in the journal AGU Advances.