If you’ve ever visited the Grand Canyon in the southwestern U.S. you know why it has the name it does—the vistas from the rim of this geological wonder are simply breathtaking, and it’s even more amazing to realize that it was all carved over the course of millions of years through the erosive action of the Colorado River. But there’s an even grander canyon system in our Solar System, and it’s not on Earth: it’s Mars’ Valles Marineris, which spans over 2,500 miles and is four times deeper than the Grand Canyon in Arizona—in fact, if Valles Marineris were on Earth it could stretch clear across the continental United States!
It’s thought that Mars’ canyon was created as the planet cooled, its crust contracting and splitting apart (as opposed to gradual excavation by a flowing river.) But there are sections of Valles Marineris that appear to have had a watery past, and new maps made by the USGS from data acquired by the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter—which has been in orbit around Mars since March 2006—reveal regions that were once likely covered by liquid water.
“The major finding of this work is that the layers of rock exposed within what is called western Candor Chasma record a past environment where groundwater was abundant and occasionally seeped onto the ground surface, forming pools,” said USGS scientist Dr. Chris Okubo, lead author of the maps. “These pools would have been habitable for life, just as they are on Earth. Dust and sand blown into these pools may have buried and preserved evidence of past Martian life, which would be present as fossils within the rocks that we see today.”
On March 17, 2002, a pair of satellites nicknamed “Tom” and “Jerry” launched aboard a Russian Rockot vehicle from the Plesetsk Cosmodrome in Russia. It was the start of the Gravity Recovery and Climate Experiment, aka GRACE, a partnership mission between NASA and the German space agency (DLR) to map Earth’s gravity field and how it changes over time due to the movement and variations of surface and ground water. Originally planned to be a five-year mission, GRACE has now been continuously operating in orbit for over 15 years, and has revealed much about what’s been happening to the water on—and in—our planet.
Everything we’ve observed so far about the surface of Mars points to an ancient past that was warmer, wetter, and very possibly habitable for life as we know it. From the scars of enormous floods and vast branching river deltas that are etched into the Martian surface to the rounded pebbles of ancient stream beds to the chemical signatures of materials formed only in the presence of water, the evidence for Mars’ wet history seems overwhelming. But there’s one big question that still stymies scientists: what happened to all of Mars’ carbon dioxide?
Even though Mars’ atmosphere is 96% CO2 today, it is incredibly thin—only 1% as dense as Earth’s. It’s thought that Mars once had a much thicker atmosphere in its early history, but was there enough of the greenhouse gas even then to keep it warm enough (with a cooler young Sun) to maintain liquid water on its surface? According to a new analysis of data from NASA’s Curiosity rover, Mars just didn’t have enough carbon dioxide 3.5 billion years ago to provide enough warming to prevent water from freezing solid.
“We’ve been particularly struck with the absence of carbonate minerals in sedimentary rock the rover has examined,” said Thomas Bristow of NASA’s Ames Research Center. “It would be really hard to get liquid water even if there were a hundred times more carbon dioxide in the atmosphere than what the mineral evidence in the rock tells us.”
But with all the physical evidence pointing at liquid water—even without the CO2—could something else have been keeping Mars warm?
Read the full story from NASA here: NASA’s Curiosity Rover Sharpens Paradox of Ancient Mars
Using data gathered by ESA’s Venus Express researchers have determined what likely happened to Venus’ water: it was “zapped” away by a surprisingly strong electric field generated by the planet’s atmosphere and the incoming solar wind. Without a protective magnetosphere like Earth has, Venus’ upper atmosphere directly interacts with energetic particles streaming out from the Sun. The result is an electric field that’s at least five times more powerful* than those that might exist on Earth or Mars, strong enough to strip away oxygen ions—one of the two key ingredients for water.
It’s truly an electrifying discovery. (When you’re done groaning, read on…)
A crowning achievement of the Cassini mission to Saturn is the discovery of water vapor jets spraying out from Enceladus‘ southern pole. First witnessed by the spacecraft in 2005, these icy geysers propelled the little 320-mile-wide moon into the scientific spotlight. After 22 flybys of Enceladus during its nearly twelve years in orbit around Saturn, Cassini has gathered enough data to determine that there is a global subsurface ocean of salty liquid water beneath Enceladus’ frozen crust—an ocean that gets literally sprayed into space. Now, new findings from Cassini and researchers at the Planetary Science Institute—with a little help from a star called Epsilon Orionis—has shown that at least some of the vapor jets get a boost in activity when Enceladus is farther from Saturn.