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.”
Mars isn’t a planet well-known for its natural satellites but it actually does have two small moons. The larger, Phobos, is an irregularly-shaped, heavily grooved and cratered world only about 17 miles (27 km) across at its widest. It orbits Mars so closely that it completes 3 orbits every day, and isn’t even visible from some parts of the planet. But Phobos has an even smaller companion in orbit: Deimos, which at the most 7.5 miles across is half Phobos’ size. Deimos orbits Mars much further away as well, taking about 30 hours to complete one orbit.
Just to remind you that things are still indeed going “boom” in our Solar System, here is a cluster of fresh craters on Mars created by an impact that occurred sometime between 2008 and 2014.
The craters are a result of a meteorite that broke apart during entry, striking the surface as fragments within a localized area. The largest crater’s ejecta field spans about 100 meters across.
It’s kinda like Mars’ way of saying “how’s that space program coming along?”
Here’s a view of a section of a crater on Mars filled with a lacework of bright spidery fractures, acquired on Sept. 20, 2015 with the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter. The crater is approximately 3 miles (5 km) wide and located in Mars’ north polar region, and its old, infilled interior has undergone countless millennia of freeze/thaw cycles that have broken the surface into polygons of all sizes, outlined by frost-filled cracks.
The fractured segments get increasingly more compressed closer to the crater rim, which contains the outward freeze expansion.
According to the image description from the HiRISE team:
The crater rim constrains the polygon formation within the crater close to the rim, creating a spoke and ring pattern of cracks. This leads to more rectangular polygons than those near the center of the crater. The polygons close to the center of the crater display a more typical pattern. A closer look shows some of these central polygons, which have smaller polygons within them, and smaller polygons within those smaller polygons, which makes for a natural fractal!
Source: HiRISE/University of Arizona
So on the same week that the highly-anticipated film “The Martian” opens in U.S. theaters (you are going to go see it, I assume) NASA revealed the latest discovery regarding the Red Planet: there is water on the surface there, salty rivulets that periodically run down steep slopes in Hale Crater and stain its sands with dark streaks.
It might not be something that Mark Watney would want to guzzle a glassful of, but it is a major finding for planetary scientists!