While the surface of Mars looks relatively unchanging now, it wasn’t always so. The tallest mountain in the Solar System is Olympus Mons, a giant shield volcano on Mars that reaches 21.9 km (13.6 miles) high, 2.5 times higher than Mount Everest here on Earth. Ancient lava flows surround the volcanic caldera, evidence of an active time.
New images from ESA’s Mars Express show how these lava flows created extremely sharp cliffs, as high as 7 km (4.3 miles) in some areas, which suddenly collapsed in mind-boggling landslides. One of these landslides occurred several 100 million years ago when a chunk of the volcano broke off and spread across the surrounding plains. If we could look back in time and see as it happened, it was certainly a very dramatic and turbulent epoch on Mars.
Olympus Mons, located at the northwest edge of the Tharsis Montes region on Mars, was appropriately named. Based on readings obtained by the Mars Orbiter Laser Altimeter (MOLA), an instrument aboard NASA’s Mars Global Surveyor (MGS), this mountain is the tallest in the Solar System, standing 21.9 km (13.6 mi) tall – about two and a half times the height of Mount Everest (8.85 km; 5.5 mi). According to current estimates, this extinct shield volcano formed during Mars’ Hesperian Period (ca. 3.7 to 3 billion years ago), which was characterized by widespread volcanic activity and catastrophic flooding.
This coincides with a period when Mars had a denser atmosphere, a warmer environment, and flowing water on its surface. This included a global ocean that spanned much of the northern hemisphere, known today as the Northern Lowlands, encompassing Olympus Mons. According to a recent study led by researchers from the Centre National de Recherches Scientifique (CNRS), features found on the slopes of Olympus Mons indicate that it could have been a massive volcanic island where volcanic eruptions flowed into the ocean, similar to ones found on Earth.
The study of exoplanets has advanced by leaps and bounds in the past few decades. Between ground-based observatories and spacecraft like the Kepler mission, a total of 3,726 exoplanets have been confirmed in 2,792 systems, with 622 systems having more than one planet (as of Jan. 1st, 2018). And in the coming years, scientists expect that many more discoveries will be possible thanks to the deployment of next-generation missions.
These include NASA’sJames Webb Space Telescope (JWST) and several next-generation ground based observatories. With their advanced instruments, these and other observatories are not only expected to find many more exoplanets, but to reveal new and fascinating things about them. For instance, a recent study from Columbia University indicated that it will be possible, using the Transit Method, to study surface elevations on exoplanets.
The study, which recently appeared online under the title “Finding Mountains with Molehills: The Detectability of Exotopography“, was conducted by Moiya McTier and David Kipping – and graduate student and an Assistant Professor of Astronomy at Columbia University, respectively. Based on models they created using bodies in our Solar System, the team considered whether transit surveys might be able to reveal topographical data on exoplanets.
To recap, the Transit Method (aka. Transit Photometry) is currently the most popular and reliable means for detecting exoplanets. It consists of astronomers measuring the light curve of distant stars over time and looking for periodic dips in brightness. These dips are the result of exoplanets passing in front of the star (i.e. transiting) relative to the observer.
By measuring the rate at which the star’s light dips, and the period with which the dimming occurs, astronomer are not only able to determine the presence of exoplanets, but also place accurate constraints on their size and orbital periods. According to McTier and Kipping, this same method could also reveal the presence of geographical features – for instance, mountain ranges, volcanoes, trenches, and craters.
As they indicate in their study, in lieu of direct imaging, indirect methods are the only means astronomers have for revealing data on an exoplanet’s surface. Unfortunately, there is no conceivable way that the radial velocity, microlensing, astrometry, and timing methods could reveal exotopography. This leaves the transit method, which has some potential in this respect. As they state:
“The transit method directly measures the sky-projected area of a planet’s silhouette relative to that of a star, under the assumption that the planet is not luminous itself… This fact implies that there is indeed some potential for transits to reveal surface features, since the planet’s silhouette is certainly distorted from a circular profile due to the presence of topography.”
In other words, as a planet transits in front of its host star, the light passing around the planet itself could be measured for small variations. These could indicate the presence of mountain ranges and other large-scale features like massive chasms. To test this theory, they considered planets in the Solar System as templates for how the scattering of light during a transit could reveal large-scale features.
As an example, they consider what an Earth analog planet would reveal if the Himalayan mountain range ran from north to south and was wide enough to span 1° in longitude:
“Now assume that the planet completes half of one rotation as it transits its parent star from our point of view, which is all that is necessary to see all of the planet’s features appear on its silhouette without repeating. As our hypothetical planet rotates and the Himalayan block moves into and out of view, the change in silhouette will result in different transit depths…”
Ultimately, they consider that Mars would be the ideal test case due to its combination of small size, low surface gravity, and active internal volcanism, which has caused it become what they describe as the “bumpiest body in the Solar System”. When paired with a white dwarf star, this presents the optimal case for using light curves to determine exotopography.
At a distance of about 0.01 AU (which would be within a white dwarf’s habitable zone), they calculate that a Mars-sized planet would have an orbital period of 11.3 hours. This would allow for many transits to be observed in a relatively short viewing period, thus ensuring a greater degree of accuracy. At the same time, the team admits that their proposed methods suffers from drawbacks.
For instance, due to the presence of astrophysical and instrumental noise, they determined that their method would be unproductive when it comes to studying exoplanets around Sun-like stars and M-type (red dwarf) stars. But for Mars-like planets orbiting low mass, white dwarf stars, the method could produce some highly valuable scientific returns.
While this might sound rather limited, it would present some rather fascinating opportunities to learn more about planets beyond our Solar System. As they explain:
“Finding the first evidence of mountains on planets outside our solar system would be exciting in its own right, but we can also infer planet characteristics from the presence and distribution of surface features. For example, a detection of bumpiness could lead to constraints on a planet’s internal processes.”
In short, planets with a high degree of bumpiness would indicate tectonic activity or the buildup of lava caused by internal heating sources. Those with the highest bumpiness (i.e. like Mars) would indicate that they too experience a combination internal processes, low surface gravity, volcanism, and a lack of tectonic plate movement. Meanwhile, low-bumpiness planets are less likely to have any of these internal processes and their surfaces are more likely to be shaped by external factors – like asteroid bombardment.
Based on their estimates, they conclude that the various super telescopes that are scheduled to be commissioned in the coming years would be up to task. These include the ESO’s OverWhelmingly Large (OWL) Telescope, a 100-meter proposed optical and near-infrared telescope that would build on the success of the Very Large Telescope (VLT) and the upcoming Extremely Large Telescope (ELT).
Another example is the Colossus Telescope, a 74-meter optical and infrared telescope that is currently being commissioned by an international consortium. Once operational, it will be the largest telescope optimized for detecting extrasolar life and extraterrestrial civilizations.
In the past, the success of exoplanet hunters has come down to a combination of factors. In addition to greater levels of cooperation between institutions, amateur astronomers and citizen scientists, there has also been the way in which improved technology has coincided with new theoretical models. As more data become available, scientists are able to produce more educated estimates on what we might be able to learn once new instruments come online.
When the next-generation telescopes take to space or are finished construction here on Earth, we can anticipate that thousands more exoplanets will be found. At the same time, we can anticipate that important details will be also discovered about these planets that were not possible before. Do they have atmospheres? Do they have oceans? Do they have mountain ranges and chasms? We hope to find out!
Today, it is well understood that Mars is a cold, dry, and geologically dead planet. However, billions of years ago when it was still young, the planet boasted a denser atmosphere and had liquid water on its surface. Millions of years ago, it also experienced a significant amount of volcanic activity, which resulted in the formation of it’s massive features – like Olympus Mons, the largest volcano in the Solar System.
Until recently, scientists have understood that Martian volcanic activity has been driven by sources other than tectonic movement, which the planet has been devoid of for billions of years. However, after conducting a study of Martian rock samples, a team of researchers from the UK and United States concluded that eons ago, Mars was more volcanically active than previously thought.
On Earth, the majority of volcanism occurs as a result of plate tectonics, which are driven by convection in the Earth’s mantle. But on Mars, the majority of volcanic activity is the result of mantle plumes, which are highly-localized upwellings of magma that rise from deep within the mantle. This is due to the fact that Mars’ surface has remained static and cool for the past few billion years.
Because of this, Martian volcanoes (though similar in morophology to shield volcanoes on Earth), grow to much larger sizes than those on Earth. Olympus Mons, for example, is not only the largest shield volcano on Mars, but the largest in the Solar System. Whereas the tallest mountain on Earth – Mt. Everest – is 8,848 m (29,029 ft) in height, Olympus Mons stands some 22 km (13.6 mi or 72,000 ft) tall.
For the sake of their study, Dr. Cohen and his colleagues used radioscopic dating techniques, which are commonly used to determine the age and eruption rate of volcanoes on Earth. However, such techniques have not been previously used for shield volcanoes on Mars. As a result, the team’s study of Martian meteorite samples was the first detailed analysis of growth rates in Martian volcanoes.
The six samples they examined are known as nakhlites, a class of Martian meteorite that formed from basaltic magma roughly 1.3 billion years ago. These came to Earth roughly 11 million years ago after being were blasted from the face of Mars by an impact event. By conducting an analysis of Martian meteorites, the team was able to uncover about 90 million years’ worth of new information about Mars’ volcanic past.
“We know from previous studies that the nakhlite meteorites are volcanic rocks, and the development of age-dating techniques in recent years made the nakhlites perfect candidates to help us learn more about volcanoes on Mars.”
The first step was to demonstrate that the rock samples were indeed Martian in origin, which the team confirmed by measuring their exposure to cosmogenic radiation. From this, they determined that the rocks were expelled from the Martian surface 11 million years ago, most likely as a result of an impact event on the Martian surface. They then applied a high-precision radioscopic technique known as 40Ar/39Ar dating.
This consisted of using a noble gas mass spectromomer to measure the amount of argon built up in the samples, which is the result of the natural radioactive decay of potassium. From this, they were able to obtain 90 million years’ worth of new information about the Martian surface. The results of their analysis indicated that there are significant differences in volcanic history between the Earth and Mars. As Dr. Cohen explained:
“We found that the nakhlites formed from at least four eruptions over the course of 90 million years. This is a very long time for a volcano, and much longer than the duration of terrestrial volcanoes, which are typically only active for a few million years. And this is only scratching the surface of the volcano, as only a very small amount of rock would have been ejected by the impact crater – so the volcano must have been active for much longer.”
In addition, the team was also able to narrow down which volcanoes their rock samples came from. Previous studies conducted by NASA revealed several candidates for the possible nakhlite source crater. However, only one of the locations matched their results in terms of the age of the volcanic eruptions and the impact that would have ejected the samples into space.
This particular crater (which is currently unnamed) is located in the volcanic plains known as Elysium Planitia, roughly 900 km (560 mi) away from summit of the Elysium Mons volcano – which stands 12.6 km (7.8 mi) tall. It is also located about 2000 km (1243 mi) north of where the NASA Curiosity rover currently is. As Cohen explained, NASA has some wonderfully detailed satellite images of this particular crater.
“It is 6.5 km wide, and has preserved ejecta rays of debris,” he said. “And we were able to see multiple horizontal bands on the crater walls – which indicating the rocks form layers, with each layer interpreted as a separate lava flow. This study has been able to provide a clearer picture into the history of the nakhlite meteorites, and in turn the largest volcanoes in the solar system.”
In the future, sample return and crewed missions to Mars are sure to clear up this picture even further. Given that Mars, like Earth, is a terrestrial planet, knowing all we can about its geological history will ultimately improve our understanding of how the rocky planets of the Solar System formed. In short, the more we know about Mars’ volcanic history, the most we will be able to learn about the Solar System’s formation and evolution.
What is up with the fossils on Mars? Found – a dinosaur skull on Mars? Discovered – a rat, squirrel or gerbil on Mars? In background of images from Curiosity, vertebrae from some extinct Martian species? And the human skull, half buried in photos from Opportunity Rover. All the images are made of stone from the ancient past and this is also what is called Pareidolia. They are figments of our imaginations, and driven by our interest to be there – on Mars – and to know that we are not alone. Altogether, they make a multitude of web pages and threads across the internet.
Rock-hounds and Martian paleontologists, if only amateur or retired, have found a bounty of fascinating rocks nestled among the rocks on Mars. There are impressive web sites dedicated to each’s eureka moment, dissemination among enthusiasts and presentation for discussion.
Be sure to explore, through the hyperlinks, many NASA, NASA affiliates’ and third party websites – embedded throughout this article. Also, links to specific websites are listed at the end of the article.
The centerpiece of recent interest is the dinosaur skull protruding from the Martian regolith, teeth still embedded, sparkling efferdent white. There are no sockets for these teeth. Dinosaur dentures gave this senior citizen a few extra good years. The jaw line of the skull has no joint or connection point with the skull. So our minds make up the deficits, fill in the blanks and we agree with others and convince ourselves that this is a fossilized skull. Who knows how this animal could have evolved differently.
But evolve it did – within our minds. Referencing online dictionaries [ref], “Pareidolia is the imagined perception of a pattern (or meaning) where it does not actually exist, as in considering the moon to have human features.” I must admit that I do not seek out these “discoveries” on Mars but I enjoy looking at them and there are many scientists at JPL that have the same bent. Mars never fails to deliver and caters to everyone, but when skulls and fossils are seen, it is actually us catering to the everyday images and wishes we hold in our minds.
The “Rat on Mars” (main figure, top center) is actually quite anatomically complete and hunkered down, having taken its final gasps of air, eons ago, as some cataclysmic event tore the final vestiges of Earth-like atmosphere off the surface. It died where it once roamed and foraged for … nuts and berries? Surprisingly, no nuts have been found. Blueberries – yes – they are plentiful on Mars and could have been an excellent nutritional source for rats; high in iron and possibly like their Earthly counterpart, high in anti-oxidants.
The blueberries were popularized by Dr. Steve Squyres, the project scientist of the Mars Exploration Rover (MER) mission. Discovered in Eagle crater and across Meridiani Planum, “Blueberries” are spherules of concretions of iron rich minerals from water. It is a prime chapter in the follow-the-water story of Mars. And not far from the definition of Pareidolia, Eagle Crater refers to the incredible set of landing bounces that sent “Oppy” inside its capsule, surrounded by airbags on a hole-in-one landing into that little crater.
Next, is the face of Mars of the Cydonia region (Images of Cydonia, Mars, NSSDC). As seen in the morphed images, above, the lower resolution Viking orbiter images presented Mars-o-philes clear evidence of a lost civilization. Then, Washington handed NASA several years of scant funding for planetary science, and not until Mars Global Surveyor, was the Face of Cydonia photographed again. The Mars Orbiter Camera from the University of Arizona delivered high resolution images that dismissed the notion of a mountain-sized carving. Nonetheless, this region of Mars is truly fascinating geologically and does not disappoint those in search of past civilizations.
And long before the face on Mars in Cydonia, there were the canals of Mars. Spotted by the Mars observer Schiaparelli, the astronomer described them as “channels” in his native language of Italian. The translation of the word turned to “Canals” in English which led the World to imagine that an advanced civilization existed on Mars. Imagine if you can for a moment, this world without Internet or TV or radio and even seldom a newspaper to read. When news arrived, people took it verbatim. Canals, civilizations – imagine how imaginations could run with this and all that actually came from it. It turns out that the canals or channels of Mars as seen with the naked eye were optical illusions and a form of Pareidolia.
So, as our imagery from Mars continues to return in ever greater detail and depth, scenes of pareidolia will fall to reason and we are left with understanding. It might seem sterile and clinical but its not. We can continue to enjoy these fascinating rocks – dinosaurs, rats, skulls, human figures – just as we enjoy a good episode of Saturday Night Live. And neither the science or the pareidolia should rob us of our ability to see the shear beauty of Mars, the fourth rock from the Sun.
In the article’s main image, what should not be included is the conglomerate rock on Mars. NASA/JPL scientists and geologists quickly recognized this as another remnant of Martian hydrologics – the flow of water and specifically, the bottom of a stream bed (NASA Rover Finds Old Streambed on Martian Surface). Truly a remarkable discovery and so similar to conglomerate rocks on Earth.
India’s Mars Orbiter Mission (MOM) has delivered another sweet treat – a stunning view of our Solar System’s largest volcano and the largest canyon.
Just days ago, MOM captured a new global image of the Red Planet dominated by Olympus Mons and Valles Marineris – which is the largest known volcano and the largest known canyon in the Solar System, respectively.
Situated right in between lies a vast volcanic plateau holding a trio of huge volcanoes comprising the Tharsis Bulge: Arsia Mons, Pavonis Mons, and Ascraeus Mons. All four volcanoes are shield volcanoes.
To give an idea of its enormity, Olympus Mons stands about three times taller than Mount Everest and is about the size of Arizona.
Olympus Mons is located in Mars’ western hemisphere and measures 624 kilometers (374 miles) in diameter, 25 km (16 mi) high, and is rimmed by a 6 km (4 mi) high scarp.
Valles Marineris is often called the “Grand Canyon of Mars.” It spans about as wide as the entire United States.
The Indian Space Research Organization (ISRO), India’s space agency which designed and developed the orbiter released the image on Oct. 17, barely two days ahead of the planet’s and spacecrafts’ extremely close encounter with comet Siding Spring.
By the way, a relieved ISRO tweeted MOM’s survival of her close shave with the once-in-a-lifetime cometary passage with gusto, soon after the swingby:
“Phew! Experience of a lifetime. Watched the #MarsComet #SidingSpring whizzing past the planet. I’m in my orbit, safe and sound.”
The new global image was taken by the tri-color camera as MOM swooped around the Red Planet in a highly elliptical orbit whose nearest point to Mars (periapsis) is at 421.7 km and farthest point (apoapsis) at 76,993.6 km, according to ISRO.
To date ISRO has released four global images of the Red Planet, including a 3-D view, reported here.
Olympus Mons, the Tharsis Bulge, and Valles Marineris are near the equator.
Valles Marineris stretches over 4,000 km (2,500 mi) across the Red Planet, is as much as 600 km wide, and measures as much as 7 kilometers (4 mi) deep.
Here’s a comparison view of the region taken by NASA’s Viking 1 orbiter in the 1970s.
MOM is India’s first deep space voyager to explore beyond the confines of her home planet’s influence and successfully arrived at the Red Planet only one month ago after the “history creating” orbital insertion maneuver on Sept. 23/24 following a ten month journey.
The $73 million MOM mission is expected to last at least six months.
MOM’s success follows closely on the heels of NASA’s MAVEN orbiter which also successfully achieved orbit barely two days earlier on Sept. 21 and could last 10 years or more.
With MOM’s arrival, India became the newest member of an elite club of only four entities that have launched probes that successfully investigated Mars – following the Soviet Union, the United States, and the European Space Agency (ESA).
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
[/caption]Planet Mars’ Olympus Mons holds the record for the tallest known peak in the entire Solar System. Having a height three times taller than Mount Everest’s and a base wide enough to prevent an observer at the base from seeing the top, you would have expected Mars to be on a relatively big planet. But did you know that Mars is much smaller than Earth? So how big is Mars?
The radius of Mars is only about half that of the Earth’s radius; roughly 3,396 km at the equator and 3,376 km at the poles. For comparison, the earth’s equatorial radius is 6,378 km, while its polar radius is 6,357 km.
These radii give Mars a surface area roughly only 28.4% of Earth’s or 144,798,500 km2. The Pacific Ocean is even larger, with an area of roughly 169,200,000 km2.
The dimensions of Mars also gives it a volume approximately equal to 1.6318×1011 km2 and a mass approximately equal to 6.4185×1023 kg. That’s only about 15.1% and 10.7% that of the Earth’s, respectively.
Despite its noticeably smaller size than the Earth, Mars has more majestic geographical features.
For instance, there’s Valles Marineris, a 4,000 km-long and 7 km-deep canyon that spans about one-fifth of the entire planet’s circumference. It is so long that it’s even longer than the length of Europe. If you compare the Grand Canyon to it, Colorado’s pride and joy won’t look so grand anymore.
Want to know how long the Grand Canyon is? 446 km. That’s very long, yes. But that’s only a little over 10% the length of Valles Marineris.
That’s not the only large geographical feature on Mars. Ma’adim Vallis, is another canyon on Mars that’s larger then the Grand Canyon, with a length of 700 km. Then there’s an impact crater that’s been found to be larger than the combined surface area of the continents of Asia, Europe, and Australia.
Now that you know about these extremely majestic geographical features on Mars, the next time someone asks you, “How big is Mars?” you can tell them how it is much smaller than the Earth … but you can also add the salient features that make the Red Planet much more interesting when it comes to a discussion on sizes.