Researchers in the LSU College of Science are leading the way in answering questions about Mars, its geology and its potential for supporting life. The National Aeronautics and Space Administration (NASA) is developing the capabilities needed to send humans to Mars, with the goal of sending a human mission to Mars in the 2030’s. LSU researchers are helping to answer questions relevant to that mission, such as whether humans might contaminate Mars with Earth microbes possessing the potential to survive there, and to design equipment and experiments that may go on new missions to Mars.
This week, the NASA social media team leads various selected science communicators, including myself, on a behind the scenes tour of the #JourneytoMars at the Michoud Assembly Facility in New Orleans, Louisiana. So the College of Science went behind the scenes with our own faculty and graduate students who conduct Mars-related research, to ask them your everyday questions about Mars! Enjoy!
LSU College of Science: Why is Mars Red?
Gary King, Professor, LSU Biological Sciences: The red soil of Mars is a signature of oxidized iron in its regolith [surface rocks]. See as an example on Earth the red soils of the Mauna Kea volcano on Hawaii.
Dr. Suniti Karunatillake, Assistant Professor in Department of Geology and Geophysics: While Mars looked red to early observers from Earth, its surface color, as would be seen on the ground by a human explorer, is variable. Mars’ redness as seen at a distance, especially from orbit, as well as the reddish earth-colored tones of its soil, are derived from a layer of fine particles. The layer is found at each of the six landing sites to date but is typically only millimeters thick and moves easily when disturbed to reveal darker soils beneath. This is evident in the rover track image taken by Curiosity above. The fines, informally called dust, owe their reddish hue primarily to nanophase ferric oxides [like what we know as rust], with nanocrystalline red hematite (alpha-Fe2O3) suggested as the volumetrically dominant mineral based on infrared spectroscopy from satellites. Iron [Fe] is more common in Mars’ crust than Earth’s.
LSU College of Science: Are there volcanoes on Mars?
Gary King, Professor, LSU Biological Sciences: Yes! Mars even has the largest volcano in the solar system, Olympus Mons. However, the volcanoes on Mars have long been extinct. This is because of Mars’ relatively small size. Volcanic activity depends on a hot core and mantle, and Mars lost its primordial heat. Thus, as spectacular as some of its volcanic vistas are, they are portraits of its past.
Nicki Button, graduate student in Department of Geology and Geophysics: Yes, Mars has the largest volcano in the solar system with a height of nearly 22 kilometers [nearly 14 miles]! In comparison, Mount Everest is only 8.872 kilometers high. It spans a horizontal distance as wide as Arizona. Olympus Mons is a shield volcano, like Mauna Kea, Hawaii. The formation of shield volcanoes on Mars and Earth is similar, but Olympus Mons most likely grew larger than terrestrial shield volcanoes due to the lack of plate tectonics. On Earth, plate tectonics move the crust away from a hotspot like Hawaii. On Mars, since there are no plate tectonics to move the crust a volcano like Olympus Mons keeps growing larger.
Nicki Button is a PhD student in the Planetary Sciences Lab. As a member of the NASA FINESSE team (Field Investigations to Enable Solar System Science and Exploration), Button has conducted fieldwork at the Craters of the Moon National Monument and Preserve in Idaho to better understand what volcanic environments on Mars might have looked like. In addition, she participated in the Mojave Volatiles Prospector (MVP) Rover Mission at NASA Ames in October 2014. This year Button submitted research on volcanic and glacial rocks types on Mars and worked with Suniti Karunatillake to determine the presence of water trapped in martian soil.
LSU College of Science: What three items would you bring with you to Mars, beyond the essentials for survival?
Gary King, Professor, LSU Biological Sciences: 1) A laptop with lots of books, poetry and images of my favorite works of art. 2) A boomerang. 3) An ant farm.
Dr. Suniti Karunatillake, Assistant Professor in Department of Geology and Geophysics: To maximize the discoveries I would make, and assuming that my space suit generates excess solar power beyond maintaining survival equipment, I will bring a portable infrared spectrometer and a portable X-ray fluorescence spectrometer with me.
Suniti Karunatillake leads the Planetary Science Laboratory at LSU. The mission of his lab is to explore processes on planetary bodies extending from the weathering of surfaces to the depths of igneous evolution. Karunatillake has published a large number of studies that help us better understand martian geology.
LSU College of Science: Could humans on Mars find a way to extract water from the soil?
Dr. Suniti Karunatillake, Assistant Professor in Department of Geology and Geophysics: Yes, there are already several methods being developed by NASA scientist-engineer teams. What methods would work best will depend on how water resides in soil.
Our paper this year suggested that water may chemically bind to iron sulfates in bulk martian soil. Using gamma spectra emanating from Mars we sampled only about half a meter deep. Deeper ground, especially beyond about +/- 50 degrees latitude, may contain local water ice deposits that would evolve water differently than iron sulfates. Most current engineering methods to extract water, regardless of the nature of the water in soil, rely on thermal [heating] effects.
LSU College of Science: Would the sky of Mars ever have looked blue?
Don Hood, graduate student in Department of Geology and Geophysics: Actually the martian sky looks blue today! Some images show martian sunsets as blue, though some images don’t show this since they are not “true color” images. There are two effects at play here. First and foremost is the martian dust, which gives the surface and atmosphere the characteristic rust-red color. There is enough dust suspended in the air to give the atmosphere the dull red-gray appearance that we often see in images. The same mechanism that makes our sky blue still works on mars, but the thinness of the atmosphere makes this blue color far less rich. The net effect is that at midday, the sky is a pale red-gray, and sometimes a pale blue-gray. At sunset however, the red dust reflects much of the red light, so more of the blue light comes through, hence the blue sunset.
Another interesting difference between martian sunsets and earthly sunsets is caused by the thin atmosphere. On earth, we get this great twilight, which is caused by the atmosphere scattering light, so we get lots of indirect light bouncing around. On Mars, the thin atmosphere weakens this effect, so that you go from direct to indirect very quickly, meaning there isn’t too much of a twilight on Mars.
Don Hood is a graduate student in the LSU Planetary Sciences lab. Hood has studied volcanoes in Hawaii as analogs to Mars’ early history. In his research on martian soils, he has found that Calcium Sulfates, such as gypsum, may be important carriers of water in the soil on Mars.
LSU College of Science: What does the most recent research say about the possibility of past or current microbial life on Mars?
J.R. Skok, Adjunct Assistant Research Professor in Department of Geology and Geophysics: Astrobiological research of extreme environments has shown that life can survive in just about every known environment in the near Earth system. This ranges from boiling hot springs to nuclear sites, hyper-arid deserts in the Atacama, Chile and Antarctica, and the high atmosphere and deep subsurface. Based on this understanding of life on Earth and evidence of past environments on Mars, Mars would have been very habitable for a variety of known microbes in its ancient past. However, modern Mars has a more inhospitable surface that combines radiation and hyper-arid conditions that would make growth and even survival of cells [like microbes] very difficult.
In the deep subsurface of Mars, it is likely that you have active water flow in a protected environment that could support microbial life even today. The key question is if Mars had the spark that started life in the first place. Evidence is pointing to oceanic hot springs as a likely origin of life on Earth. It is very possible that these existed at some point on a volcanically active and water-rich early Mars.
J.R. Skok is a researcher with the Planetary Sciences Lab at LSU and at the SETI Institute. He is currently conducting fieldwork in Iceland to understand Mars’ deep history and to develop strategies for seeking signs of life.
Gary King, Professor, LSU Biological Sciences: While there are good reasons to be skeptical about microbial life at the surface of Mars, the presence of brines at recurring slope lineae [places where salty water may flow on Mars today] open the door, at least a crack. The unknowns are whether there is enough energy flow that can be harvested for cell maintenance, whether cells could be adequately protected from radiation damage, whether in the brines water is usable for cells, and whether perchlorate or other salts might be too toxic for life. At this point, we have some ideas about theoretical limits for growth [for microbes], but not limits for survival. The ability of microbes to survive for very long periods in permafrost, the deep sub-surface and in salt crystals gives us some reason to keep looking on Mars.
Gary King studies microbes living in extreme environments. While no environment on Earth is exactly like what would be found on Mars, King is trying to determine the limits for growth and survival of microbes on Earth with implications for understanding whether microbial life would be possible on Mars. In 2015, King published a paper investigating carbon monoxide as a metabolic energy source for extremely halophilic or salt-loving microbes, with implications for microbial activity on Mars.
LSU College of Science: Why is Mars so small compared to Earth?
Gary King, Professor, LSU Biological Sciences: This has to do with the distribution of debris in the orbit of Mars as it first formed. The distribution of molecules, dust and small bits of comets/meteorites, etc. determines what can get swept up to form a planet.
Dr. Suniti Karunatillake, Assistant Professor in Department of Geology and Geophysics: Some scientists model Mars as a planetary "embryo" that didn't quite grow into "adulthood." But the planetary community agrees that Mars differentiated into crust, mantle, and core, like Earth.
Mars may have accreted [accumulated under the influence of gravitation] less matter in forming. It may also have lost some of its original mass even before its oldest Noachian Eon, perhaps due to a giant impact that eventually formed the northern lowlands [the “northern waste”]. I don't think the current models on how planets accreted from a debris cloud during the solar system's "birth" is sufficiently precise yet to estimate what size is likely for a planet located between Earth and Jupiter.
LSU College of Science: What makes this planet so exciting for humans?
Gary King, Professor, LSU Biological Sciences: Mars has long been part of human imagination, well before the idea of a planet existed in any scientific context. It features in mythology across many cultures. People deep in the past thought the planet (or the god it symbolized) had powers over human life.
With the advent of telescopes, some of Mars’ features became visible enough that they were interpreted as engineered. This led to ideas about alien life that persist today in both scientific and non-scientific forms.
The keen interest and the fascination with Mars today is that we know that conditions in the past could have been conducive to microbial life. It is remotely possible that microbial life still exists on Mars. These ideas, that life lingers on Mars or that we could find evidence of past life, go to the heart of questions that have been part of human thought for as long as thoughts have been recorded. Is it just us? Are we alone?
There are, of course, other basic questions that are important. If life existed on Mars, what happened to it? Is it possible to re-establish life on Mars? Is it possible to convert Mars into a planet habitable for humans? Answers to these questions will ultimately tell us more about ourselves than Mars, so they take a central place in discussions about the present and future.
LSU College of Science: What microbes on Earth might look most like potential microbes on Mars?
Gary King, Professor, LSU Biological Sciences: If there are microbes on Mars, or if there were microbes on Mars, both big ifs, they likely would differ little from microbes on Earth in physical appearance. That’s because there are physical constraints that limit shape at microbial sizes. Also, microbes on Earth have surely explored all the possibilities over the last 3.8+ billion years. It’s conceivable that the low pressure or other factors on Mars might lead to some skew in shapes or sizes, but Mars is not so different from Earth that microbes would assume unheard of shapes.
The bigger question is what kinds of things would microbes on Mars do? Would they do things that don’t happen on Earth? Would they do some of the same things, but with different mechanisms?
We can predict that many of the basic aspects of metabolism at the cellular level and within microbial communities would be similar, but there is no doubt that there would also be some big surprises, again assuming that there is any life on Mars at all.
There is also the remote possibility that microbial life originated on Mars and was transported to Earth via meteorites, or vice versa. I think of this as a very low likelihood personally, but it can’t be ruled out. The point is that if life moved in either direction, then there could be many shared traits.
LSU College of Science: Where can we go on Earth that looks most like Mars?
Gary King, Professor, LSU Biological Sciences: The lava flows and weathered basalts and ash deposits of Hawaii Island are certainly evocative of something extraterrestrial. When standing on the edge of a lava escarpment on the south shore of Hawaii, it is easy to imagine an ancient volcanic shoreline washed by an ancient Mars ocean.
J.R. Skok, Adjunct Assistant Research Professor in Department of Geology and Geophysics: It is also useful to think in terms of temporal analogs. Iceland is often seen as an analog to the ancient Noachian Mars, when volcanics, ice and water worked to alter the surface to clays in a variety of processes. The Dry Valleys of Antarctica are used as an analog to the dry modern Mars. The Dry Valleys is the coldest, driest rocky spot on Earth. Even though it is much warmer and wetter than Mars, it can simulate many of the gully formations and polygonal terrains seen on Mars. However it can create that morphology in decades, while Mars may take a million years.
LSU College of Science: In a school on Mars, what could we use for "chalk" to write on our chalkboards?
Dr. Suniti Karunatillake, Assistant Professor in Department of Geology and Geophysics: We could mine gypsum [a soft sulfate mineral] from the dunes of Olympia Undae near the martian arctic circle, where it is more concentrated, or mine local soil with extensive subsequent processing. This would provide the same softness associated with commonly used chalk sticks on Earth.
We could could mine magnesite to make chalk, though it is a tad harder than the calcite we sometimes use to make chalk sticks. That said, chalkboards could serve as a last-resort simple option should digital media fail unexpectedly when a solar flare struck a hypothetical future martian colony.
Gary King, Professor, LSU Biological Sciences: Ohhhh, interesting question. Chalk is calcium carbonate [main component of marine coral skeletons on Earth for example]. On Earth calcium carbonate has been deposited as a consequence of chemical, biological and geological processes working together in the oceans and marine sediments. There are calcium and magnesium carbonates on Mars, consistent with water early in its history, but these carbonates likely formed under conditions somewhat different than on Earth. They are significant enough in distribution though that it might be possible to fashion chalk.
Of course, it’s hard to imagine chalkboards on Mars rather than LED screens of various kinds. Who would want or use chalk?
LSU College of Science: What are some of the different types of rocks on Mars? Do any of them have properties we would recognize from rocks on Earth?
Dr. Suniti Karunatillake, Assistant Professor in Department of Geology and Geophysics: All the way through to the core-mantle boundary, the two planets are compositionally analogous in bulk, dominated by silicon, oxygen, and iron forming a diversity of silicate minerals. As expected, the two extreme rock categories are analogous to those on Earth: minimally weathered igneous rocks [volcanic or magma chamber derived rocks in the subsurface or surface] and weathered sedimentary rocks. But while each planet possesses the same rock types as the other, their abundances vary dramatically, causing much excitement in my community of planetary scientists.
Carbonate outcrops are a long-awaited rock type on Mars. These are far more sparse than Earth's, and appear dominated by magnesium-bearing carbonates in contrast to Earth's calcium carbonates [main component of limestone and marine coral skeletons on Earth].
Much of the crustal rocks on Mars are rich in high-mass elements, particularly Fe [iron], with many of the volcanic eruptions after the first major eon, the Noachian, producing lava flows that would remind any US geologist of the Hawaiian islands.
Gale Crater is also the first to reveal the presence of sedimentary rocks that usually form in river-bed settings on Earth. These martian conglomerates contain the pebble-to-sand mixtures that would fit well in any terrestrial paleo-river bed. The roundness of the pebbles suggested transport over kilometer scale distances.
Only four landing sites (Gale Crater by Curiosity, the "Northern Wastelands" called Vastitas Borealis by Phoenix, Meridiani Plains by Opportunity, and Gusev Crater by Spirit) have been explored during the digital age of our civilization. Given how Mars has a radius nearly half that of Earth, we have only as much, perhaps even less, ground-truth on Mars as Chinese explorers from ~200 CE had of western Eurasia! Mars2020 will allow the structural analysis of rock layers with ground penetrating radar, a first on Mars.