Ever since it landed on the Red Planet in 2012, the Curiosity rover has showed no signs of slowing down! For the past six years, it has ventured across the Gale Crater, scaled Mount Sharp, and taken numerous drill samples. And in the process, it has found evidence that liquid water (and possibly even life) once existed on the Martian surface.
It has also taken many breathtaking pictures that have catalogued its progress. Last month (on Aug. 9th), the rover took another 360-degree panoramic photo of its location. In addition to showing how the skies were still darkened by the fading dust storm and the rover’s dust-covered body, the picture also captured and the site where the latest drill sample was obtained.
Scientists first observed the Medusae Fossae Formation (MFF) in the 1960s, thanks to the efforts of the Mariner spacecraft. This massive deposit of soft, sedimentary rock extends for roughly 1,000 km (621 mi) along the equator and consists of undulating hills, abrupt mesas, and curious ridges (aka. yardangs) that appear to be the result of wind erosion. What’s more, an unusual bump on top of this formation also gave rise to a UFO conspiracy theory.
Needless to say, the formation has been a source of scientific curiosity, with many geologists attempting to explain how it could have formed. According to a new study from Johns Hopkins University, the region was the result of volcanic activity that took place on the Red Planet more than 3 billion years ago. These findings could have drastic implications for scientists’ understanding of Mars’ interior and even its past potential for habitability.
Ojha’s past work includes finding evidence that water on Mars occurs in seasonal brine flows on the surface, which he discovered in 2010 as an undergraduate student. Lewis, meanwhile, has dedicated much of his academic carreer to the in-depth study of the nature of sedimentary rock on Mars for the sake of determining what this geological record can tell us about that planet’s past climate and habitability.
As Ojha explained, the study of the Medusa Fossae Formation is central to understanding Mars geological history. Much like the Tharsus Montes region, this formation was formed at a time when the planet was still geologically active. “This is a massive deposit, not only on a Martian scale, but also in terms of the solar system, because we do not know of any other deposit that is like this,” he said.
Basically, sedimentary rock is the result of rock dust and debris accumulating on a planet’s surface and becoming hardened and layered over time. These layers serve as a geological record, indicating what types of processes where taking place on the surface at the time that the layers were deposited. When it comes to the Medusae Fossae Formation, scientists were unsure whether wind, water, ice or volcanic eruptions were responsible for the deposits.
In the past, radar measurements were made of the formation that suggested that Medusae Fosssae had an unusual composition. However, scientists were unsure whether the formation was made of highly porous rock or a mixture of rock and ice. For the sake of their study, Ojha and Lewis used gravity data from various Mars orbiters to measure the formation’s density for the first time.
What they found was that the rock is unusually porous and about two-thirds as dense as the rest of the Martian crust. They also used radar and gravity data to show that the Formation’s density was too great to be explained by the presence of ice. From this, they concluded that the heavily-porous rock had to have been deposited by volcanic eruptions when Mars was still geologically active – ca. 3 billion years ago.
As these volcanoes exploded, casting ash and rock into the atmosphere, the material would have then fallen back to the surface, building up layers and streaming down hills. After enough time, the ash would have cemented into rock, which was slowly eroded over time by Martian winds and dust storms, leaving the Formation scientists see there today. According to Ojha, these new findings suggest that Mars’ interior is more complex than previously thought.
While scientists have known for some time that Mars has some volatiles – i.e. water, carbon dioxide and other elements that become gas with slight increases in temperature – in its crust that allow for periodic explosive eruptions to occur on the surface, the kind of eruption needed to create the Medusa Fossae region would have been immense. This indicates that the planet may have massive amounts of volatiles in its interior. As Ojha explained:
“If you were to distribute the Medusae Fossae globally, it would make a 9.7-meter (32-foot) thick layer. Given the sheer magnitude of this deposit, it really is incredible because it implies that the magma was not only rich in volatiles and also that it had to be volatile-rich for long periods of time.”
In addition, this activity would have had a drastic impact on Mars’ past habitability. Basically, the formation of the Medusae Fossae Formation would have occurred during a pivotal point in Mars’ history. After the eruption occurred, massive amounts of carbon dioxide and (most likely) methane would have been ejected into the atmosphere, causing a significant greenhouse effect.
In addition, the authors indicated that the eruption would have ejected enough water to cover Mars in a global ocean more than 9 cm (4 inches) in thickness. This resulting greenhouse effect would have been enough to keep Mars’ surface warm to the point that the water would remain in a liquid state. At the same time, the expulsion of volcanic gases like hydrogen sulfide and sulfur dioxide would have altered the chemistry of Mars’ surface and atmosphere.
All of this would have had a drastic impact on the planet’s potential habitability. What’s more, as Kevin Lewis indicated, the new study shows that gravity surveys have the potential to interpret Mars’ geological record. “Future gravity surveys could help distinguish between ice, sediments and igneous rocks in the upper crust of the planet,” he said.
Studying Mars surface features and geological history is a lot like peeling an onion. With every layer we peel back, we get another piece of the puzzle, which together adds up to a rich and varied history. In the coming years and decades, more robotic missions will be studying the Red Planet’s surface and atmosphere in preparation for an eventual crewed mission by the 2030s.
All of these missions will allow us to learn more about Mars warmer, wetter past and whether or not may have existed there at some time (or perhaps, still does!)
Mars modern landscape is something of a paradox. It’s many surface features are very similar to those on Earth that are caused by water-borne erosion. But for the life of them, scientists cannot imagine how water could have flown on Mars’ cold and desiccated surface for most of Mars’ history. Whereas Mars was once a warmer, wetter place, it has had a very thin atmosphere for billions of years now, which makes water flow and erosion highly unlikely.
In fact, while the surface of Mars periodically becomes warm enough to allow for ice to thaw, liquid water would boil once exposed to the thin atmosphere. However, in a new study led by an international team of researchers from the UK, France and Switzerland, it has been determined that a different kind of transport process involving the sublimation of water ice could have led to the Martian landscape becoming what it is today.
The study, which was led Dr. Jan Raack – a Marie Sklodowska-Curie Research Fellow at The Open University – was recently published in the scientific journal Nature Communications. Titled “Water Induced Sediment Levitation Enhances Downslope Transport on Mars”, this research study consisted of experiments that tested how processes on Mars’ surface could allow water transport without it being in liquid form.
To conduct their experiments, the team used the Mars Simulation Chamber, an instrument at The Open University that is capable of simulating the atmospheric conditions on Mars. This involved lowering the atmospheric pressure inside the chamber to what is normal for Mars – about 7 mbar, compared to 1000 mbar (1 bar or 100 kilopascals) here on Earth – while also adjusting temperatures.
On Mars, temperatures range from a low of -143 °C (-255 °F) during winter at the poles to a high of 35 °C (95 °F) at the equator during midday in the summer. Having recreated these conditions, the team found that when water ice exposed to the simulated Martian atmosphere, it would not simply melt. Instead, it would become unstable and begin violently boiling off.
However, the team also found that this process would be capable of moving large amounts of sand and sediment, which would effectively “levitate” on the boiling water. This means that, compared to Earth, relatively small amounts of liquid water are capable of moving sediment across the surface of Mars. These levitating pockets of sand and debris would be capable of forming tje large dunes, gullies, recurring slope lineae, and other features observed on Mars.
In the past, scientists have indicated how these features were the result of sediment transportation down slopes, but were unclear as to the mechanisms behind them. As Dr. Jan Raack explained in a OUNews press release:
“Our research has discovered that this levitation effect caused by boiling water under low pressure enables the rapid transport of sand and sediment across the surface. This is a new geological phenomenon, which doesn’t happen on Earth, and could be vital to understanding similar processes on other planetary surfaces.”
Through these experiments, Dr. Raack and his colleagues were able to shed light on how conditions on Mars could allow for features that we tend to associate with flowing water here on Earth. In addition to helping to resolve a somewhat contentious debate concerning Mars’ geological history and evolution, this study is also significant when it comes to future exploration missions.
Dr. Raack acknowledges the need for more research to confirm their study’s conclusions, and indicated that the ESA’s ExoMars 2020 Rover will be well-situated to conduct it once it is deployed :
“This is a controlled laboratory experiment, however, the research shows that the effects of relatively small amounts of water on Mars in forming features on the surface may have been widely underestimated. We need to carry out more research into how water levitates on Mars, and missions such as the ESA ExoMars 2020 Rover will provide vital insight to help us better understand our closest neighbour.”
It is now a well-understood fact that Mars once had quite a bit of liquid water on its surface. In fact, according to a recent estimate, a large sea in Mars’ southern hemisphere once held almost 10 times as much water as all of North America’s Great Lakes combined. This sea existed roughly 3.7 billion years ago, and was located in the region known today as the Eridania basin.
However, a new study based on data from NASA’s Mars Reconnaissance Orbiter (MRO) detected vast mineral deposits at the bottom of this basin, which could be seen as evidence of ancient hot springs. Since this type of hydrothermal activity is believed to be responsible for the emergence of life on Earth, these results could indicate that this basin once hosted life as well.
Together, this international team used data obtained by the MRO’s Compact Reconnaissance Spectrometer for Mars (CRISM). Since the MRO reached Mars in 2006, this instrument has been used extensively to search for evidence of mineral residues that form in the presence of water. In this respect, CRISM was essential for documenting how lakes, ponds and rivers once existed on the surface of Mars.
In this case, it identified massive mineral deposits within Mars’ Eridania basin, which lies in a region that has some of the Red Planet’s most ancient exposed crust. The discovery is expected to be a major focal point for scientists seeking to characterize Mars’ once-warm and wet environment. As Paul Niles of NASA’s Johnson Space Center said in a recent NASA press statement:
“Even if we never find evidence that there’s been life on Mars, this site can tell us about the type of environment where life may have begun on Earth. Volcanic activity combined with standing water provided conditions that were likely similar to conditions that existed on Earth at about the same time — when early life was evolving here.”
Today, Mars is a cold, dry place that experiences no volcanic activity. But roughly 3.7 billion years ago, the situation was vastly different. At that time, Mars boasted both flowing and standing bodies of water, which are evidenced by vast fluvial deposits and sedimentary basins. The Gale Crater is a perfect example of this since it was once a major lake bed, which is why it was selected as the landing sight for the Curiosity rover in 2012.
Since Mars had both surface water and volcanic activity during this time, it would have also experienced hydrothermal activity. This occurs when volcanic vents open into standing bodies of water, filling them with hydrated minerals and heat. On Earth, which still has an active crust, evidence of past hydrothermal activity cannot be preserved. But on Mars, where the crust is solid and erosion is minimal, the evidence has been preserved.
“This site gives us a compelling story for a deep, long-lived sea and a deep-sea hydrothermal environment,” Niles said. “It is evocative of the deep-sea hydrothermal environments on Earth, similar to environments where life might be found on other worlds — life that doesn’t need a nice atmosphere or temperate surface, but just rocks, heat and water.”
Based on their study, the researchers estimate that the Eridania basin once held about 210,000 cubic km (50,000 cubic mi) of water. Not only is this nine times more water than all of the Great Lakes combined, it is as much as all the other lakes and seas on ancient Mars combined. In addition, the region also experienced lava flows that existed after the sea is believed to have disappeared.
From the CRISM’s spectrometer data, the team identified deposits of serpentine, talc and carbonate. Combined with the shape and texture of the bedrock layers, they concluded that the sea floor was open to volcanic fissures. Beyond indicating that this region could have once hosted life, this study also adds to the diversity of the wet environments which are once believed to have existed on Mars.
Between evidence of ancient lakes, rivers, groundwater, deltas, seas, and volcanic eruptions beneath ice, scientists now have evidence of volcanic activity that occurred beneath a standing body of water (aka. hot springs) on Mars. This also represents a new category for astrobiological research, and a possible destination for future missions to the Martian surface.
The study of hydrothermal activity is also significant as far as finding sources of extra-terrestrial, like on the moons of Europa, Enceladus, Titan, and elsewhere. In the future, robotic missions are expected to travel to these worlds in order to peak beneath their icy surfaces, investigate their plumes, or venture into their seas (in Titan’s case) to look for the telltale traces of basic life forms.
The study also has significance beyond Mars and could aid in the study of how life began here on Earth. At present, the earliest evidence of terrestrial life comes from seafloor deposits that are similar in origin and age to those found in the Eridania basin. But since the geological record of this period on Earth is poorly preserved, it has been impossible to determine exactly what conditions were like at this time.
Given Mars’ similarities with Earth, and the fact that its geological record has been well-preserved over the past 3 billion years, scientists can look to mineral deposits and other evidence to gauge how natural processes here on Earth allowed for life to form and evolve over time. It could also advance our understanding of how all the terrestrial planets of the Solar System evolved over billions of years.
In addition to all that, engineers at the Jet Propulsion Laboratory in Pasadena, California, are busy preparing the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) Lander for its scheduled launch in 2018. Once deployed to Mars, the lander will reveal things about Mars’ interior geology and composition, shedding new light on the history of the Red Planet’s formation and evolution.
Originally scheduled for launch in 2016, the lander’s deployment was delayed due to the failure of a key component – a chamber that housed the Seismic Experiment for Interior Structure (SEIS). Having finished work on a new vacuum enclosure for this instrument, the technicians at Lockheed Martin Space Systems are back at work, assembling and testing the spacecraft in a clean room facility outside of Denver, Colorado.
As Stu Spath, the spacecraft program manager at Lockheed Martin, said in a NASA press statement:
“Our team resumed system-level integration and test activities last month. The lander is completed and instruments have been integrated onto it so that we can complete the final spacecraft testing including acoustics, instrument deployments and thermal balance tests.”
Beyond the exploration of Mars, the InSight mission is also expected to reveal information about how all terrestrial (i.e. rocky) planets in the Solar System formed over four billion years ago. Mars is an especially opportune target for this type of research since it has been relatively inactive for the past three billion years. However, when the planet was still young, it underwent geological processes that were analogous to Earth’s.
In other words, because the interior of Mars has been subject to less convection over the past three billion years, it has likely preserved evidence about its early geological history better than Earth has. InSight will study this preserved history through a series of instruments that will measure the planet’s seismology, heat loss, and the state and nature of its core.
Once it reaches Mars, the stationary lander will set down near Mars’ equator and deploy its two fold-out solar cells, which kind of resemble large fans. Within a few weeks of making its landing, it will use a robotic arm to place its two main instruments onto the Martian surface – the aforementioned Seismic Experiment for Interior Structure (SEIS) and the Heat Flow and Physical Properties Probe (HP³).
The SEIS instrument – which was developed by France’s National Center for Space Studies (CNES) in collaboration with NASA and several European scientific institutions – has a sensitivity comparable to the best research seismometers here on Earth. This instrument will record seismic waves from “marsquakes” and meteor impacts, which will reveal things about the planet’s interior layers.
The HP³ probe, supplied by the German Aerospace Center (DLR), will use a Polish-made self-hammering mechanism to bury itself to a depth of 3 meters (10 feet) or more. As it descends, the probe will extend a tether that contains temperature sensors every ~10 cm, which measure the temperature profile of the subsurface. Combined with surface measurements, the instrument will determine the amount of heat escaping from the planet’s interior.
A third experiment, known as Rotation and Interior Structure Experiment (RISE), will also come into play. This instrument will use the lander’s X-band radio link to conduct Doppler tracking of the lander’s location, which will also allow it to measure variations in Mars’ rotation axis. Since these variations are primarily related to the size and state of Mars’ core, this experiment will shed light on one of Mars’ greatest mysteries.
Thanks to multiple missions that have studies Mars’ surface and atmosphere, scientists now know that roughly 4.2 billions of years ago, Mars lost its magnetic field. Because of this, Mars’ atmosphere was stripped away by solar wind during the next 500 million years. It is believed that it was this process that allowed the planet to go from being a warmer, wetter environment in the past to the cold, desiccated and irradiated place it is today.
As such, determining the state of Mars’ core – i.e. whether it is solid or liquid, or differentiated between a solid outer core and liquid inner core – will allow scientists to gain a more comprehensive understanding of the planet’s geological history. It will also allow them to answer with a fair degree of certainty how and when Mars lost its magnetic field (and hence, its denser, warmer atmosphere).
The spacecraft’s science payload is also on track for next year’s launch. At present, the mission is scheduled to launch on May 5th, 2018, though this window could be moved to anytime within a five-week period. Regardless of what day it launches, mission planners indicate that the flight will reach Mars on November 26th, 2018 (the Monday after Thanksgiving).
As noted, the mission was originally planned to launch in March of 2016, but was canceled due to the presence of a leak in the special metal container designed to maintain near-vacuum conditions around the SEIS’s main sensors. Now that a redesigned vacuum vessel has been built and tested (and integrated with the SEIS) the spacecraft is ready for its new launch date.
Back in 2010, the InSight mission was selected from a total of 28 proposals, which were made as part of the twelfth round of selections for NASA’s Discovery Program. In contrast to New Frontiers or Flagship programs, Discovery missions are small-budget enterprises that aid in larger scientific pursuits. Along with two other finalists – the Titan Mare Explorer (TiME) and the Comet Hopper (CHopper) – InSight was awarded funding for further development.
Bruce Banerdt of NASA’s Jet Propulsion Laboratory is the Principle Investigator (PI) for the InSight mission.
Be sure to check out this video of the InSight mission (courtesy of NASA JPL) as well: