In many ways, Mars is the planet that most closely resembles Earth. The red world has polar ice caps, a nearly 24 hour period of rotation (roughly 24 hours and 37 minutes), mountains, plains, dust storms, volcanoes, a population of robots many of which are old and no longer working, and even some sort of grand Canyon. The ‘Grand Canyon’ on Mars is actually far larger than any Arizona canyon. Valles Marineris dwarfs the 4,000 km long Grand Canyon in the southwestern United States (the distance between LA and New York City) and plunges 7 kilometers into the Martian crust (compared to a meager 2 km in the Grand Canyon). Newly released photos from the high-resolution Imaging Science Experiment (HiRISE) aboard the Mars Reconnaissance Orbiter (MRO) reveal breathtaking views of eroding rock walls in Candor Chasma, a gigantic canyon that encompasses part of the Valles Marineris system.
Three step-by-step closer observations of the HiRISE image side (represented by the white rectangle) in Candor Chasma. Photo credit: Google Mars
This spectacularly detailed look at the geographic features of Candor Chasma provides a detailed look at sedimentary rock layers and helps to deepen our understanding of the deposition processes that laid these layers over billions of years. The resolution of the images with visible wavelengths shows details down to the scale of a single meter and enables the visualization of rocks that are as small as the average Golden Retriever. HiRISE also observes in the near infrared of the electromagnetic spectrum, and the resolution of these IR images gets pixels only 30 centimeters wide, more like the size range of a miniature poodle (it’s not necessary to state the resolution in terms of dogs, but it can be helpful in conveying the size of such images to people who are less familiar with space.
The High Resolution Imaging Science Experiment or HiRISE camera system (shown before flying to Mars) Photo credit: NASA / JPL / University of Arizona Valles Marineris stretches thousands of kilometers across Mars. Photo credit: NASA
A closer look at the HiRISE images reveals jagged bedrock protruding from windswept sand and dust, as well as channel-like channels, possibly due to seasonal runoff of liquid water over the sloping cliffs. As with most detailed image acquisition systems, HiRISE sacrifices the field of view for a razor-sharp, very detailed view of the object planet. In order to be able to select good HiRISE targets, a broader view is required. MRO uses a different instrument with a much wider field of view to provide a context from which scientific observational decisions can be made. This context collecting camera is called a context camera or CTX. CTX offers a huge view of Mars and reveals large-scale geological features (Geo is Greek for earth, maybe it should be aresological?) That paint a big picture of the planet.
The Context Camera (CTX) on board the Mars Reconnaissance Orbiter gives other instruments a general view of the terrain surrounding smaller rock and mineral targets. Photo credit: NASA / JPL / University of Arizona
This type of wide-angle instrument combined with a detailed close-up camera is reminiscent of more down-to-earth settings that Universe Today readers may already be familiar with. CTX can be thought of as a kind of finderscope, in a way, like a telescope. An amateur astronomer would first use his finderscope to aim at a wide area of interest and locate a particular part of the sky, then examine deeply with the much narrower view offered by the main telescope, or in this case HiRISE.
Another HiRISE image from Candor Chasma shows bright mineral deposits in the canyon. Photo credit: NASA / JPL / University of Arizona A comprehensive overview of a CTX-imaged crater on Mars. Oddly enough, smaller features in the crater have led to the uncanny resemblance to a “happy face”. Photo credit: NASA / JPL / Malin Space Science Systems
By collecting broad overall views while taking amazing high-resolution close-ups, we get a better feel for the structure of Candor Chasma, Valles Marineris, and all of the geological processes and deep history of Mars. Unlike the Arizonan Canyon, Valles Mariners were not formed by surface erosion.
What geological process could be behind the formation of the largest canyon known to mankind? Is it a dry process like submerging a piece of crust along parallel faults known as digging? Another possibility that may be responsible for the formation of such features is the dissolution of various rocks by underground water in what geologists call karst.
Mars Perseverance will take off from Cape Canaveral on July 30, 2020. Photo credit: NASA / Joel Kowsky
Mars’ watery past is a big part of what makes studying such a fascinating planet. The Mars Perseverance Rover, which is already underway and scheduled to land in mid-February 2021, will land on the coast of an ancient Martian ocean. Large bodies of liquid are very rare outside of Earth and are considered a necessary ingredient for the ascension of living things. It goes without saying that finding evidence of life on another planet, even if it is now extinct, would be as powerful a scientific discovery as possible.
Main image: The HiRISE image by Candor Chasma shows layers upon layers of sedimentary rocks on Mars. Photo credit: NASA / JPL / University of Arizona
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MORE:
HiRISE instrument page
CTX instrument page
MRO
Mars Perseverance Rover
Universe today HiRISE stories
Google Mars Interactive Map
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