Mars stands out in our solar system as one of its brightest planets, boasting a reddish surface dotted with craters and giant volcanoes such as Olympus Mons.
Mariner space probes provided us with our first close-up images of Mars in 1965, and since then scientists have studied it carefully, uncovering evidence of past life on its surface.
1. Volcanoes
Mars lacks plate tectonics to relieve pressure from its rapidly churning mantle, so instead volcanoes have formed around mantle hot spots – creating giant shield volcanoes like Olympus Mons, which has nearly three times more craters than Mauna Loa in Hawaii.
Due to hot rock’s lower density than cool rock, its heat rises through the mantle and forms lava domes that eventually build mountain chains – altering rivers and altering climate change on planet earth in their wake.
Scientists recently made an exciting discovery: an explosive volcanic deposit located in one of Mars’ dramatic regions. If confirmed, this find could help scientists better understand how magmas on Mars have changed over time; an identical eruption on Earth would produce an avalanche of hot ash, toxic gas, and rock known as pyroclastic flow that buried ancient Roman cities Pompeii and Herculaneum under tons of debris.
This new deposit comes from an immense volcano which scientists have tentatively named Noctis, meaning “labyrinth of the night.” Located nearby Noctis Labyrinthus and Valles Marineris (Mariner Valley), its immense size and complex modification history suggest it has been active for an extended period.
Researchers employed images from Mars Reconnaissance Orbiter’s Context Camera to investigate Noctis. After performing a technique known as crater counting to date caldera surfaces and lava flows, their timeline and mapping gave insight into rates and durations of eruptions as well as whether volcanic activities were explosive or effusive in nature.
2. Canyons
As breathtaking as Mars’ mountains may be, perhaps its canyons are even more remarkable. Of note is Valles Marineris on Mars which spans 2,500 miles along its equator and covers approximately one quarter of the planet’s circumference – 10x longer and fivex deeper than Earth’s Grand Canyon!
Scientists don’t fully understand how Valles Marineris emerged, but they suspect it cracked open billions of years ago when a cluster of volcanoes including Olympus Mons erupted nearby and magma bubbled through this “crack,” stretching, ripping and collapsing to form its present-day terrain of troughs and valleys that now make up Valles Marineris.
Science has discovered evidence of water throughout Valles Marineris, including channels and deposits which only form when flowing liquid is present. Unfortunately, most of Mars’ water remains frozen in its polar regions as water-ice.
Mars Express discovered sulfate minerals indicative of water-bearing ice beneath Valles Marineris in 2015, while in 2016 an orbiter called ExoMars Trace Gas Orbiter identified an abundance of hydrogen in the uppermost layer of Mars soil near Candor Chasma at the center of Martian canyon system.
Though its exact nature remains unknown, these findings suggest that Mars once had a much denser atmosphere that supported more liquid water than is present today – an essential piece in unravelling how life might have first arisen on this mysterious world. Scientists are working diligently on their analyses of data in an attempt to comprehend this extraordinary mystery.
3. Craters
Craters are among the most striking features on Mars. Even at its lower latitudes, their surface is covered by them – providing insight into conditions present when they formed; for instance, long elongated craters could have been created by debris drifting in orbital paths instead of by direct impact from spacecraft or meteorite impacts.
Space missions have long focused on studying these features of Mars. Its famed rust hue can be attributed to iron minerals found within its regolith, loose dust and rock that covers its surface, which oxidize to give off red hues when exposed to oxygen.
Astronomers have discovered evidence of Mars once having lakes and oceans, though water supplies appear to have been short-lived due to collapsed ozone layers exposing its surface to UV radiation from solar ultraviolet radiation sources.
Mars can be understood through its craters. Larger craters indicate when Mars was much younger while smaller ones indicate an older surface. One such ancient surface area has been identified: Argyre basin covers an expanse of over 2,000 miles and its name–“Plain of Paradise”–has inspired science fiction speculation about whether its vast flat terrain ever supported life on the Red Planet.
Other areas are distinguished by a lack of craters, and have been given names honoring scientists, science fiction writers and towns with populations under 100,000 people – such as Jezero crater which the Perseverance rover has been exploring, named after a Bosnian town and Belva which honors a West Virginia town in memory of an influential suffragist.
4. Plains
The northern plains on Mars are an extensive region of flat land. Covering nearly one third of its surface area and comprising its largest lowlands region, these plains contain material shed by erosion of ancient highlands as well as volcanic flows and deposits from eruptions; also evidence exists for extensive tectonic deformation and reworking.
The southern highlands on Mars resemble Earth’s battered highland areas in their rugged, heavily-cratered terrain, while its two hemispheres have distinct topographies due to differences between their masses and sizes; Mars has smaller mass which causes its axis tilt more irregularly than that of the Earth, leading to climate fluctuations on this distant world over time.
Noachian Period 4.6 Billion Years Ago When impact events began reshaping our planet’s surface at an increasing pace, volcanic activity became very active while some polar caps may have had water ice covering them. Noachian Era ended about 2.5 Billion Years Ago when Hesperian Period started.
This period was marked by an overall reduction in volcanic activity and surface cratering rates, although polar caps likely still existed but their size may have decreased over time.
Tharsis bulge and Elysium basin regions on Mars feature ancient, cone-shaped volcanoes measuring 500 km wide by 25 km high, such as Olympus Mons pictured here which looms 16 km above its surroundings and covers more area than Texas itself! Olympus Mons is located within Hesperian belt in northern part of Mars as a so-called hotspot volcano.
5. Ice Caps
Mars’ north and south polar caps grow thicker each winter, adding layers of frozen carbon dioxide ice approximately one meter (three feet) thick. This layer stands in stark contrast to water ice that fluctuates throughout the year due to winds; additionally, their surfaces feature pits, cracks and knobs similar to cottage cheese due to the Coriolis effect, which causes fluids on different parts of planet to rotate differently.
At the north polar cap lies an expansive layer of dry ice that covers more than six miles (10 kilometers). This dry ice, composed of fluffy-textured ice particles, seems to have formed from air containing 95% carbon dioxide. Conversely, at the south polar cap lies predominantly water ice; however, two meters (6 feet) thick carbon dioxide ice has also formed on this expanse of land ice. Both caps also fluctuate seasonally affecting their surroundings as they change shape.
Researchers using the Mars Express spacecraft have examined radar data to analyze the shape and distribution of an ice cap on Mars, searching for subglacial water sources. Their analyses show that its northern polar cap contains eight times more deuterium-enriched ice than Earth’s oceans do – evidence suggesting a much deeper ocean was once covered by it.
Researchers also used satellite laser-altimeter measurements to observe the top surface of an ice cap, finding that its undulations corresponded with computer models showing how an overlying body of liquid water might alter the shape of an underlying ice sheet.