This mosaic taken by NASA's Mars Curiosity rover looks uphill at Mount Sharp, which Curiosity has been climbing since 2014. Highlighted in white is an area with clay-bearing rocks that scientists are eager to explore; it could shed additional light on the role of water in creating Mount Sharp. Credit: NASA/JPL-Caltech/MSSS
Since it landed on Mars in 2012, the Curiosity rover has made some rather startling scientific discoveries. These include the discovery of methane and organic molecules, evidence of how it lost its ancient atmosphere, and confirming that Mars once had flowing water and lakes on its surface. In addition, the rover has passed a number of impressive milestones along the way.
In fact, back in January of 2018, the rover had spent a total of 2,000 Earth days on Mars. And as of March 22nd, 2018, NASA’s Mars Curiosity rover had reached its two-thousandth Martian day (Sol) on the Red Planet! To mark the occasion, NASA released a mosaic photo that previews what the rover will be investigating next (hint: it could shed further light on whether or not Mars was habitable in the past).
The image (shown at top and below) was assembled from dozens of images taken by Curiosity‘s Mast Camera (Mastcam) on Sol 1931 (back in January). To the right, looming in the background, is Mount Sharp, the central peak in the Gale Crater (where Curiosity landed back in 2012). Since September of 2014, the rover has been climbing this feature and collecting drill samples to get a better understanding of Mars’ geological history.
Image of the mosaic taken by NASA’s Mars Curiosity rover in January of 2018 (Sol 1931). Click to enlarge. Credit: NASA/JPL-Caltech/MSSS
In the center of the image is the rover’s next destination and scientific target. This area, which scientists have been studying from orbit, is rich in clay minerals, which indicates that water once existed there. In the past, the Curiosity rover found evidence of clay minerals on the floor of the Gale Crater. This confirmed that the crater was a lake bed between 3.3 and 3.8 billion years ago.
Mount Sharp, meanwhile, is believed to have formed from sedimentary material that was deposited over a period of about 2 billion years. By examining patches of clay minerals that extend up the mountain’s side, scientists hope to gain insight into the history of Mars since then. These include how long water may have persisted on its surface and how the planet made the transition to the cold and desiccated place it is today.
The Curiosity science team is eager to analyze rock samples pulled from the clay-bearing rocks seen in the center of the image, and not just because of the results they could provide. Recently, the science team developed a new drilling technique to compensate for the failure of a faulty motor (which allows the drill to extend and retract). When the rover begins to drill again, it will be the first time since December 2016.
All told, the rover has spent a total of about 2055 Earth days (5 years and 230 days), which means Curiosity now ranks third behind the Opportunity (5170 days; 5031 sols) and the Spirit rovers (2269 days; 2208 sols) in terms of total time spent on Mars. Since it arrived on Mars in 2012, Curiosity has also traveled a total distance of 18.7 km (11.6 mi) and studied more than 180 meters (600 feet) vertical feet of rock.
But above all, Curiosity‘s greatest achievement has been the discovery that Mars once had all the necessary conditions and chemical ingredients to support microbial life. Based on their findings, Curiosity‘s international science team has concluded that habitable conditions must have lasted for at least millions of years before Mars’ atmosphere was stripped away.
Finding the evidence of this, and how the transition occurred, will not only advance our understanding of the history of Mars, but of the Solar System itself. It also might provide clues as to how Mars could be made into a warmer, wetter environment again someday!
Mosaic image of the Curiosity rover on Mars, which recently turned up more evidence that supports the idea that the planet was once habitability. Credit: NASA/JPL-Caltech/MSSS.
On August 5th, 2012, after spending over 8 months in space, NASA’s Curiosity rover landed on Mars. As part of the NASA Mars Science Laboratory (MSL) mission, and the latest in a series of rovers deployed to the Martian surface, Curiosity had some rather ambitious research goals. In addition to investigating Mars’ climate and geology, the rover was also tasked with revealing more about Mars’ past and determining if it ever supported microbial life.
And recently, the Curiosity rover hit another major milestone in its exploration of the Red Planet. As of January 26th, 2018 the rover has spent a total of 2,000 days on Mars, which works out to 5 years, 5 months and 21 days – or 1947 Martian days (sols). That’s especially impressive when you consider that the mission was only meant to last 687 days (668 sols), or just little under 2 years.
In all that time, the Curiosity rover has accomplished some major feats and has the scars to prove it! Some of it’s wheels have become teared, holed and cracked and its drill has been pushed almost to the point of breaking. And yet, Curiosity is still hard at work pushing itself up a mountain – both literally and figuratively! The rover has also managed to exceed everyone’s expectations.
MRO image of Gale Crater illustrating the landing location and trek of the Rover Curiosity. Credits: NASA/JPL, illustration, T.Reyes
As Ashwin Vasavada, the MSL Project Scientist, told Universe Today via email:
“In terms of challenges, the first 2000 days of Curiosity’s mission went better than I could have hoped. For much of the time, the rover remained as capable as the day it landed. We had a scare in the first year when a memory fault triggered additional problems and nearly resulted in the loss of the mission. We famously wore down our wheels pretty early, as well, but since then we’ve kept that under control. In the last year, we’ve had a major problem with our drill. That’s the only major issue currently, but we believe we’ll be back to drilling in a month or so. If that works out, we’ll amazingly be back to having all systems ready for science!”
As of the penning of this article, the rover is climbing Mount Sharp in order to collect further samples from Mars’ past. Also known as Aeolis Mons, this mountain resides in the center of the Gale Crater where Curiosity landed in 2012 and has been central to Curiosity’s mission. Standing 5,500 meters (18,000 ft) above the valley floor, Mount Sharp is believed to have formed from sediment that was slowly deposited by flowing water over billions of years.
This is all in keeping with current theories about how Mars once had a denser atmosphere and was able to sustain liquid water on its surface. But between 4.2 and 3.7 billion years ago, this atmosphere was slowly stripped away by solar wind, thus turning Mars into the cold and desiccated place that we know today. As a result, the study of Mount Sharp was always expected to reveal a great deal about Mars’ geological evolution.
Image of Mount Sharp taken by the Curiosity rover on Aug. 23rd, 2012. The layers at the base of Mt. Sharp show the geological history of Mars. Credit: NASA/JPL-Caltech/MSSS.
In it’s first year, Curiosity achieved a major milestone when the rover obtained drill samples from low-lying areas that indicated that lakes and streams existed in the Gale Crater between 3.3 to 3.8 billion years ago. In addition, the rover has also obtained ample evidence that the crater once had all the chemical elements and even a chemical source of energy needed for microbial life to exist.
“NASA’s charge to our mission was to determine whether Mars ever had conditions suitable for life,” said Vasavada. “Success was not a foregone conclusion. Would we arrive safely? Would the scientific instruments work? Would the area we chose for the landing site hold the clues we were looking for? For me, meeting each of these objectives are the highlights of the mission. I’ll never forget witnessing the launch, or nervously waiting for a safe touchdown. Discovering an ancient, freshwater lake environment at Gale crater was profound scientifically, but also was the moment that I knew that our team had delivered what we promised to NASA.”
Basically, by scaling Mount Sharp and examining the layers that were deposited over the course of billions of years, Curiosity is able to examine a living geological record of how the planet has evolved since then. Essentially, the lower layers of the mountain are believed to have been deposited 3.5 billion years ago when the Gale Crater was still a lakebed, as evidenced by the fact that they are rich in clay minerals.
The upper layers, meanwhile, are believed to have been deposited over the ensuing millions of years, during which time the lake in the Gale Crater appears to have grown, shrunk, disappeared and then reappeared. Basically, by scaling the mountain and obtaining samples, Curiosity will be able to illustrate how Mars underwent the transition from being a warmer, wetter place to a frozen and dry one.
Image taken of drill sample obtained at the ‘Lubango’ outcrop target on Sol 1320, Apr. 23, 2016. Lubango is located in the Stimson unit on the lower slopes of Mount Sharp inside Gale Crater. Credit: NASA/JPL/MSSS/Ken Kremer/kenkremer.com/Marco Di Lorenzo
As Vasavada explained, this exploration is also key to answering a number of foundational questions about the search for life beyond Earth:
“Curiosity established that Mars was once a suitable home for life; it had liquid water, key chemical building blocks, and energy sources required by life in the lake and groundwater environment within Gale crater. Curiosity also has detected organic molecules in ancient rocks, in spite of all the degradation that could have occurred in three billion years. While Curiosity cannot detect life itself, knowing that Mars can preserve organic molecules bodes well for missions that will explore ancient rocks, looking for signs of past life.”
At this juncture, its not clear how much longer Curiosity will last. Considering that it has already lasted over twice as long as originally intended, it is possible the rover will remain in operation for years to come. However, unlike the Opportunity rover – who’s mission was intended to last for 90 days, but has remained in operation for 5121 days (4984 sols) – Curiosity has a shelf life.
Whereas Opportunity is powered by solar cells, Curiosity is dependent on its Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). Eventually, this slow-fission reactor will exhaust its supply of nuclear fuel and the rover will be forced to come to a halt. And considering how the rover has been put through its paces in the past 5 years, there’s also the chance that it will suffer a mechanical failure.
But in the meantime, there’s plenty of work to be done and lots of opportunities for vital research. As Vasavada put it:
“Curiosity won’t last forever, but in the years we have left, I hope we can complete our traverse through the lowermost strata on Mount Sharp. We’re well over halfway through. There are changes in the composition of the rocks ahead that might tell us how the climate of Mars changed over time, perhaps ending the era of habitability. Every day on Mars still counts, perhaps even more than before. Now every new discovery adds a piece to a puzzle that’s more than halfway done; it reveals more given all the other pieces already around it.”
And be sure to check out this retrospective of the Curiosity rover’s mission, courtesy of NASA:
Researchers from Lomonosov MSU, Faculty of Soil Science, have studied the resistance microorganisms have against gamma radiation in very low temperatures. Credit: YONHAP/EPA
Mars is not exactly a friendly place for life as we know it. While temperatures at the equator can reach as high as a balmy 35 °C (95 °F) in the summer at midday, the average temperature on the surface is -63 °C (-82 °F), and can reach as low as -143 °C (-226 °F) during winter in the polar regions. Its atmospheric pressure is about one-half of one percent of Earth’s, and the surface is exposed to a considerable amount of radiation.
Until now, no one was certain if microorganisms could survive in this extreme environment. But thanks to a new study by a team of researchers from the Lomonosov Moscow State University (LMSU), we may now be able to place constraints on what kinds of conditions microorganisms can withstand. This study could therefore have significant implications in the hunt for life elsewhere in the Solar System, and maybe even beyond!
Image taken by the Viking 1 orbiter in June 1976, showing Mars thin atmosphere and dusty, red surface. Credits: NASA/Viking 1
For the sake of their study, the research team hypothesized that temperature and pressure conditions would not be the mitigating factors, but rather radiation. As such, they conducted tests where microbial communities contained within simulated Martian regolith were then irradiated. The simulated regolith consisted of sedimentary rocks that contained permafrost, which were then subjected to low temperature and low pressure conditions.
As Vladimir S. Cheptsov, a post-graduate student at the Lomonosov MSU Department of Soil Biology and a co-author on the paper, explained in a LMSU press statement:
“We have studied the joint impact of a number of physical factors (gamma radiation, low pressure, low temperature) on the microbial communities within ancient Arctic permafrost. We also studied a unique nature-made object—the ancient permafrost that has not melted for about 2 million years. In a nutshell, we have conducted a simulation experiment that covered the conditions of cryo-conservation in Martian regolith. It is also important that in this paper, we studied the effect of high doses (100 kGy) of gamma radiation on prokaryotes’ vitality, while in previous studies no living prokaryotes were ever found after doses higher than 80 kGy.”
To simulate Martian conditions, the team used an original constant climate chamber, which maintained the low temperature and atmospheric pressure. They then exposed the microorganisms to varying levels of gamma radiation. What they found was that the microbial communities showed high resistance to the temperature and pressure conditions in the simulated Martian environment.
Image of Martian soils, where the Spirit mission embedded itself. Credit: NASA/JPL
However, after they began irradiating the microbes, they noticed several differences between the irradiated sample and the control sample. Whereas the total count of prokaryotic cells and the number of metabolically active bacterial cells remained consistent with control levels, the number of irradiated bacteria decreased by two orders of magnitude while the number of metabolically active cells of archaea also decreased threefold.
The team also noticed that within the exposed sample of permafrost, there was a high biodiversity of bacteria, and this bacteria underwent a significant structural change after it was irradiated. For instance, populations of actinobacteria like Arthrobacter – a common genus found in soil – were not present in the control samples, but became predominant in the bacterial communities that were exposed.
In short, these results indicated that microorganisms on Mars are more survivable than previously thought. In addition to being able to survive the cold temperatures and low atmospheric pressure, they are also capable of surviving the kinds of radiation conditions that are common on the surface. As Cheptsov explained:
“The results of the study indicate the possibility of prolonged cryo-conservation of viable microorganisms in the Martian regolith. The intensity of ionizing radiation on the surface of Mars is 0.05-0.076 Gy/year and decreases with depth. Taking into account the intensity of radiation in the Mars regolith, the data obtained makes it possible to assume that hypothetical Mars ecosystems could be conserved in an anabiotic state in the surface layer of regolith (protected from UV rays) for at least 1.3 million years, at a depth of two meters for no less than 3.3 million years, and at a depth of five meters for at least 20 million years. The data obtained can also be applied to assess the possibility of detecting viable microorganisms on other objects of the solar system and within small bodies in outer space.”
Future missions could determine the presence of past life on Mars by looking for signs of extreme bacteria. Credit: NASA.
This study was significant for multiple reasons. On the one hand, the authors were able to prove for the first time that prokaryote bacteria can survive radiation does in excess of 80 kGy – something which was previously thought to be impossible. They also demonstrated that despite its tough conditions, microorganisms could still be alive on Mars today, preserved in its permafrost and soil.
The study also demonstrates the importance of considering both extraterrestrial and cosmic factors when considering where and under what conditions living organisms can survive. Last, but not least, this study has done something no previous study has, which is define the limits of radiation resistance for microorganisms on Mars – specifically within regolith and at various depths.
This information will be invaluable for future missions to Mars and other locations in the Solar System, and perhaps even with the study of exoplanets. Knowing the kind of conditions in which life will thrive will help us to determine where to look for signs of it. And when preparing missions to other words, it will also let scientists know what locations to avoid so that contamination of indigenous ecosystems can be prevented.
Future missions could determine the presence of past life on Mars by looking for signs of extreme metal-metabolizing bacteria. Credit: NASA.
Today, there are multiple lines of evidence that indicate that during the Noachian period (ca. 4.1 to 3.7 billion years ago), microorganisms could have existed on the surface of Mars. These include evidence of past water flows, rivers and lakebeds, as well as atmospheric models that indicate that Mars once had a denser atmosphere. All of this adds up to Mars having once been a warmer and wetter place than it is today.
However, to date, no evidence has been found that life ever existed on Mars. As a result, scientists have been trying to determine how and where they should look for signs of past life. According to a new study by a team of European researchers, extreme lifeforms that are capable of metabolizing metals could have existed on Mars in the past. The “fingerprints” of their existence could be found by looking at samples of Mars’ red sands.
For the sake of their study, which recently appeared in the scientific journal Frontiers of Microbiology, the team created a “Mars Farm” to see how a form of extreme bacteria might fare in an ancient Martian environment. This environment was characterized by a comparatively thin atmosphere composed of mainly of carbon dioxide, as well as simulated samples of Martian regolith.
Metallosphaera sedula grown on synthetic Martian Regolith. The microbes are specifically stained by Fluorescence-In-Situ-Hybridization (FISH). Credit: Tetyana Milojevic
They then introduced a strain of bacteria known as Metallosphaera sedula, which thrives in hot, acidic environments. In fact, the bacteria’s optimal conditions are those where temperatures reach 347.1 K (74 °C; 165 °F) and pH levels are 2.0 (between lemon juice and vinegar). Such bacteria are classified as chemolithotrophs, which means that they are able to metabolize inogranic metals – like iron, sulfur and even uranium.
These stains of bacteria were then added to the samples of regolith that were designed to mimic conditions in different locations and historical periods on Mars. First, there was sample MRS07/22, which consisted of a highly-porous type of rock that is rich in silicates and iron compounds. This sample simulated the kinds of sediments found on the surface of Mars.
Then there was P-MRS, a sample that was rich in hydrated minerals, and the sulfate-rich S-MRS sample, which mimic Martian regolith that was created under acidic conditions. Lastly, there was the sample of JSC 1A, which was largely composed of the volcanic rock known as palagonite. With these samples, the team was able to see exactly how the presence of extreme bacteria would leave biosignatures that could be found today.
As Tetyana Milojevic – an Elise Richter Fellow with the Extremophiles Group at the University of Vienna and a co-author on the paper – explained in a University of Vienna press release:
“We were able to show that due to its metal oxidizing metabolic activity, when given an access to these Martian regolith simulants, M. sedula actively colonizes them, releases soluble metal ions into the leachate solution and alters their mineral surface leaving behind specific signatures of life, a ‘fingerprint’, so to say.”
Microspheroids containing mostly aluminium and chlorine overgrow the mineral surface of synthetic Mars regolith. These microspheroids can only be observed after cultivation of Metallosphaera sedula Credit: Tetyana Milojevic
The team then examined the samples of regolith to see if they had undergone any bioprocessing, which was possible thanks to the assistance of Veronika Somoza – a chemist from the University of Vienna’s Department of Physiological Chemistry and a co-author on the study. Using an electron microscope, combined with analytical spectroscopy technique, the team sought to determine if metals with the samples had been consumed.
In the end, the sets of microbiological and mineralogical data they obtained showed signs of free soluble metals, which indicated that the bacteria had effectively colonized the regolith samples and metabolized some of the metallic minerals within. As Milojevic indicated:
“The obtained results expand our knowledge of biogeochemical processes of possible life beyond Earth, and provide specific indications for detection of biosignatures on extraterrestrial material – a step further to prove potential extra-terrestrial life.”
In effect, this means that extreme bacteria could have existed on Mars billions of years ago. And thanks to the state of Mars today – with its thin atmosphere and lack of precipitation – the biosignatures they left behind (i.e. traces of free soluble metals) could be preserved within Martian regolith. These biosignatures could therefore be detected by upcoming sample-return missions, such as the Mars 2020 rover.
In addition to pointing the way towards possible indications of past life on Mars, this study is also significant as far as the hunt for life on other planets and star systems is concerned. In the future, when we are able to study extra-solar planets directly, scientists will likely be looking for signs of biominerals. Among other things, these “fingerprints” would be a powerful indicator of the existence of extra-terrestrial life (past or present).
Studies of extreme lifeforms and the role they play in the geological history of Mars and other planets is also helpful in advancing our understanding of how life emerged in the early Solar System. On Earth too, extreme bacteria played an important role in turning the primordial Earth into a habitable environment, and play an important role in geological processes today.
Last, but not least, studies of this nature could also pave the way for biomining, a technique where strains of bacteria extract metals from ores. Such a process could be used for the sake of space exploration and resource exploitation, where colonies of bacteria are sent out to mine asteroids, meteors and other celestial bodies.
Future missions could determine the presence of past life on Mars by looking for signs of extreme metal-metabolizing bacteria. Credit: NASA.
Over the past few decades, our ongoing studies of Mars have revealed some very fascinating things about the planet. In the 1960s and early 70s, the Mariner probes revealed that Mars was a dry, frigid planet that was most likely devoid of life. But as our understanding of the planet has deepened, it has come to be known that Mars once had a warmer, wetter environment that could have supported life.
This in turn has inspired multiple missions whose purpose it has been to find evidence of this past life. The key questions in this search, however, are where to look and what to look for? In a new study led by researchers from the University of Kansas, a team of international scientists recommended that future missions should look for vanadium. This rare element, they claim, could point the way towards fossilized evidence of life.
The microphone for the upcoming Mars mission will be attached to the SuperCam, seen here in this illustration zapping a rock with its laser. Credit: NASA/JPL-Caltech
To be clear, finding signs of life on a planet like Mars is no easy task. As Craig Marshall indicated in a University of Kansas press release:
“You’ve got your work cut out if you’re looking at ancient sedimentary rock for microfossils here on Earth – and even more so on Mars. On Earth, the rocks have been here for 3.5 billion years, and tectonic collisions and realignments have put a lot of stress and pressure on rocks. Also, these rocks can get buried, and temperature increases with depth.”
In their paper, Marshall and his colleagues recommend that missions like NASA’s Mars 2020 rover, the ESA’s ExoMars 2020 rover, and other proposed surface missions could combine Raman spectroscopy with the search for vanadium to find evidence of fossilized life. On Earth, this element has been found in crude oils, asphalts, and black shales that have been formed by the slow decay of biological organic material.
In addition, paleontologists and astrobiologists have used Raman spectroscopy – a technique that reveals the cellular compositions of samples – on Mars for some time to search for signs of life. In this respect, the addition of vanadium would provide material that would act as a biosignature to confirm the existence of organic life in samples under study. As Marshall explained:
“People say, ‘If it looks like life and has a Raman signal of carbon, then we have life. But, of course, we know there can be carbonaceous materials made in other processes — like in hydrothermal vents — consistent with looking like microfossils that also have some carbon signal. People also make wonderful carbon structures artificially that look like microfossils — exactly the same. So, we’re at a juncture now where it’s really hard to tell if there’s life only based on morphology and Raman spectroscopy.”
Artist’s impression of the Mars 2020 with its sky crane landing system deployed. Credit: NASA/JPL
This is not the first time that Marshall and his co-authors have advocated using vanadium to search for signs of life. Such was the subject of a presentation they made at the Astrobiology Science Conference in 2015. What’s more, Marshall and his team emphasize that it would be possible to perform this technique using instruments that are already part of NASA’s Mars 2020 mission.
Their proposed method also involves new technique known as X-ray fluorescence microscopy, which looks at elemental composition. To test this technique, the team examined thermally altered organic-walled microfossils which were once organic materials )called acritarchs). From their data, they confirmed that traces of vanadium are present within microfossils that were indisputably organic in origin.
“We tested acritarchs to do a proof-of-concept on a microfossil where there’s no shadow of a doubt that we’re looking at preserved ancient biology,” Marshall said. “The age of this microfossil we think is Devonian. These guys are aquatic microorganisms — they’re thought to be microalgae, a eukaryotic cell, more advanced than bacterial. We found the vanadium content you’d expect in cyanobacterial material.”
These microfossilized bit of life, they argue, are probably not very distinct from the kinds of life that could have existed on Mars billions of years ago. Other scientific research has also indicated that vanadium is the result of organic compounds (like chlorophyll) from living organisms undergoing a transformation process caused by heat and pressure (i.e. diagenetic alteration).
Artist’s impression of ESA’s ExoMars rover (foreground) and Russia’s stationary surface science platform (background) on the surface of Mars. Credit: ESA/ATG medialab
In other words, after living creatures die and become buried in sediment, vanadium forms in their remains as a result of being buried under more and more layers of rock – i.e. fossilization. Or, as Marshall explained it:
“Vanadium gets complexed in the chlorophyll molecule. Chlorophylls typically have magnesium at the center — under burial, vanadium replaces the magnesium. The chlorophyll molecule gets entangled within the carbonaceous material, thus preserving the vanadium. It’s like if you have a rope stored in your garage and before you put it away you wrap it so you can unravel it the next time you need it. But over time on the garage floor it becomes tangled, things get caught in it. Even when you shake that rope hard, things don’t come out. It’s a tangled mess. Similarly, if you look at carbonaceous material there’s a tangled mess of sheets of carbon and you’ve got the vanadium mixed in.”
The work was supported by an ARC International Research Grant (IREX) – which sponsors research that seeks to find biosignatures for extracellular life – with additional support from the Australian Synchrotron and the Advanced Photon Source at the Argonne National Laboratory. Looking forward, Marshall and his colleagues hope to conduct further research that will involve using Raman spectroscopy to study carbonaceous materials.
At present, their research appears to have attracted the interesting of the European Space Agency. Howell Edwards, who also conducts research using Raman spectroscopy (and who’s work has been supported by an ARC grant), is part of the ESA’s Mars Explorer team, where he is responsible for instrumentation on the ExoMars 2020 rover. But, as Marshall indicated, the team also hopes that NASA will consider their study:
“Hopefully someone at NASA reads the paper. Interestingly enough, the scientist who is lead primary investigator for the X-ray spectrometer for the space probe, they call it the PIXL, was his first graduate student from Macquarie University, before his KU times. I think I’ll email her the paper and say, ‘This might be of interest.’”
The next decade is expected to be a very auspicious time for exploration missions to Mars. Multiple rovers will be exploring the surface, hoping to find the elusive evidence of life. These missions will also help pave the way for NASA’s crewed mission to Mars by the 2030s, which will see astronauts landing on the surface of the Red Planet for the first time in history.
If, in fact, these missions find evidence of life, it will have a profound effect on all future mission to Mars. It will also have an immeasurable impact on humanity’s perception of itself, knowing at long last that billions of years ago, life did not emerge on Earth alone!
Mosaic image of the Curiosity rover on Mars, which recently turned up more evidence that supports the idea that the planet was once habitability. Credit: NASA/JPL-Caltech/MSSS.
It has become a well-known scientific fact that billions of years ago, Mars once had a thicker atmosphere and liquid water on its surface. Scientists have also discovered that it was the gradual loss of this atmosphere, between 4.2 and 3.7 billion years ago, that caused Mars to go from being a warmer, wetter environment to the dry, freezing environment it is today.
Despite the existence of both a thicker atmosphere and water, questions remain as to whether or not Mars was truly habitable in the past. According to a new study from a team of researchers from the Los Alamos National Laboratory (LANL), the discovery of a specific mineral (boron) has added weight to the argument that Mars was once a potentially life-bearing world.
The study, titled “In situ detection of boron by ChemCam on Mars“, was recently published in the scientific journal Geophysical Research Letters. For the sake of this study, the LANL research team consulted data collected by the Chemistry and Camera (ChemCam) instrument aboard the Curiosity rover, which showed evidence of boron on the surface of Mars.
Mars, as it may have looked 4.2 billion years ago (left) and today (right). Credit: Kevin Gill
Boron, an element which is created by cosmic rays and is relatively rare in the Solar System, is necessary for the creation of ribonucleic acid – which is present in all forms of modern life. Essentially, RNA requires a key ingredient to form, which is a sugar called ribose. Like all sugars, ribose is highly unstable and decomposes quickly in water. As such, it needs another element to stabilize it, which is where boron comes into play.
As Patrick Gasda, a postdoctoral researcher at the Los Alamos National Laboratory and lead author on the paper, explained in a LANL press statement:
“Because borates may play an important role in making RNA – one of the building blocks of life – finding boron on Mars further opens the possibility that life could have once arisen on the planet. Borates are one possible bridge from simple organic molecules to RNA. Without RNA, you have no life. The presence of boron tells us that, if organics were present on Mars, these chemical reactions could have occurred.”
When boron is dissolved in water (which, as noted, Mars once had in abundance) it becomes borate. This compound (when combined with ribose) would act as a stabilizing agent, keeping the sugar together long enough so that RNA can form. As Gasda explained, “We detected borates in a crater on Mars that’s 3.8 billion years old, younger than the likely formation of life on Earth.”
Artist rendition of how the “lake” at Gale Crater on Mars may have looked millions of years ago. Credit and copyright: Kevin Gill.
The boron was detected by Curiosity’s laser-shooting ChemCam instrument, which was developed by the LANL in conjunction with France’s space agency, the National Center of Space Studies (CNES). It detected the element in veins of calcium sulfate minerals located in the Gale Crater, which means that boron was present in Mars’ groundwater and was preserved with other minerals when the water dissolved, leaving behind rich mineral veins.
This provides further evidence that the lake that is now known to have once filled the Gale Crater could have had life in it. During the time period in question, this lake would have experienced temperatures ranging from from 0 to 60 ° C (32 to 140 °F) and had a pH level that would have been neutral-to-alkaline. It also means that on ancient Mars, the conditions necessary for life would have existed, and independent of Earth to boot.
This is just one of many findings Curiosity has made related to the composition of Martian rocks. Since it touched down in the Gale Crater in 2012, the rover has been gathering chemical evidence of the ancient lake that once existed there, as well as geological evidence that has been preserved by sedimentary deposits. As the rover began to scale the slope of Mount Sharp, the composition of the surface began to change.
Whereas samples taken from the crater floor tended to contain more in the way of clays, samples collected higher up Mount Sharp contained more boron. These and other chemical traces are indications of how conditions under which sediments were deposited changed over time. Analysis conducted of the mountain’s layers has also showed how the movement of groundwater through these layers of sediment altered and transported elements (like boron).
MRO image of Gale Crater illustrating the landing location and trek of the Rover Curiosity. Credits: NASA/JPL, illustration, T.Reyes
All of this is providing a picture of how Mars’ environment changed over the course of billions of years and affected the planet’s potential favorability for microbial life. And while scientists have a general picture of how Mars underwent a very significant transition billions of years ago, whether or not Martian life ever existed remains unknown.
The main goal of the Curiosity mission was to determine whether the area ever offered a habitable environment. Thanks to evidence of past water and the discovery of minerals like boron, this has been confirmed. In the coming years, the deployment of the Mars 2020 rover is expected to follow-up on these findings and shed more light on Mars’ case for past habitability.
Once it reaches the surface, the Mars 2020 rover – which relies on much of the same technology as Curiosity – will use an instrument called the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals (SHERLOC). Also developed by the LANL, this “SuperCam” instrument will use spectrometers, a laser and a camera to search for organics and minerals that could indicate the existence of past microbial life.
If there is still preserved evidence of life to be found on Mars or – fingers crossed! – microbial life still exists there today, we can expect to find it before long. If that should be the case, human beings will finally know with certainty that life evolved on a planet other than Earth, and perhaps independent of it!
The valleys of Coprates Chasma in the east of Valles Marineris. This perspective view was created using stereo image data from DLR’s HRSC (High Resolution Stereo Camera) camera on board ESA’s Mars Express spacecraft Credit: ESA/DLR/FU Berlin
For decades, Mars has been the focal point of intense research. Beginning in the 1960s, literally dozens of robotic spacecraft, orbiters and rovers have explored Mars’ atmosphere and surface, looking for clues to the planet’s past. From this, scientists now know that billions of years ago, Mars was a warmer, wetter place. Not only did liquid water exist on its surface, but it is possible life existed there in some form as well.
Granted, some recent findings have cast some doubt in this, indicating that Mars’ surface may have been hostile to microbes. But a new study from an international team of scientists indicates that evidence life could be found in volcanic deposits. Specifically, they argue that within the massive geological structure known as Valles Marineris, there may be ancient volcanoes that have preserved ancient microbes.
The study, titled “Amazonian Volcanism Inside Valles Marineris on Mars“, recently appeared in the journal Earth and Planetary Science Letters. Led by Petr Brož of the Institute of Geophysics at the Czech Academy of Sciences (AVCR), the team examined Mars’ famous Valles Marineris region – a canyon system stretching for 4000 km (2485.5 mi) – for signs of recent geological activity, which opens up the possibility of there also being fossilized life there.
Valles Marineris, part of NASA World Wind map of Mars. Credit: NASA
The team began by examining the Coprates Chasma canyon, one of the lowest points in Valles Marineris, which is home to over 130 volcanoes and solidified lava flows. This consisted of analyzing high-resolution images of the region that were taken by NASA’s Mars Reconnaissance Orbiter (MRO), which revealed cones of basaltic lava (aka. scoria) and ash that measured around 400-meters (1300 ft) high.
After examining the cones’ surface patterns and morphological details, they confirmed that these were indeed the remains of lava volcanoes (and not mud volcanoes, which was another possibility). In addition, they also noted similarities between these cone and others on Mars where mud volcanism is not possible – as well as similarities with volcanic cones here on Earth.
“The spatial distribution of the cones also suggests their volcanic origin. They appear to occur more frequently along tectonic fractures that formed the trough in the surface and whose fracture interfaces continue into the subsurface, creating pathways for the magma to ascend.”
Even more surprising was the apparent age of the volcanoes, which was very young. On Mars, the main period of volcanic activity ended during Mars’ Hesperian Period – which ran from 3.7 to approximately 3.0 billion years ago. And while images acquired by the Mars Express mission have shown indications of younger volcanoes (occurring 500 million years ago), these tend to be located in volcanic provinces.
A colorized image of the surface of Mars taken by the Mars Reconnaissance Orbiter. The line of three volcanoes is the Tharsis Montes, with Olympus Mons to the northwest. Valles Marineris is to the east. Image: NASA/JPL-Caltech/ Arizona State University
A good example of this is the Tharsis Bulge, which is located several thousand km from the Coprates Chasma canyon. It is here that the Tharses Montes mountain chain is located, which consists of the shield volcanoes of Ascraeus Mons, Pavonis Mons and Arsia Mons. Olympus Mons, the tallest mountain in the Solar System (with an elevation of 22 km or 13.6 mi), is located at the edge of this region.
In contrast, the volcanic cones spotted in the Coprates Chasma canyon were estimates to be between 200 and 400 million years of age, placing them in the most recent geological period known as the Amazonian (3.0 billion years ago to the present day). This effectively demonstrates that these volcanoes formed late in Mars’ history and far away from volcanic areas like Tharsis and Elysium.
It also demonstrates that these volcanoes were not part of the original formation of Valles Marineris, which is believed to be related to the formation of the Tharsis Bulge. This all took place between the Noachian to Late Hesperian periods of Mars (ca. 3.5 billion years ago), which was the last time Mars experienced widespread geological activity.
Last, but not least, the team used the Compact Reconnaissance Imaging Spectrometer (CRISM) aboard the MRO to learn more about the mineral compositions of the region’s lava and volcanic cones. Once again, their findings proved to be surprising, and could indicate that the Coprates Chasma region is a suitable location to search for evidence of ancient life on Mars.
Image of young volcanoes at the base of Coprates Chasma on Mars, obtained by the Mars Reconnaissance Orbiter. Credit: NASA/JPL/University of Arizona
Essentially, the CRISM data indicated the presence of high-silica content minerals in the volcanic rock, which included opaline-like substances at one of the peaks. Opaline silicates, it should be noted, are water-bearing materials that are often produced by hydrothermal processes – where silicate structures form from supersaturated, hot solutions of minerals that cool to become solid.
On Earth, microorganisms are often found within opal deposits since they form in energy and mineral-rich environments, where microbial lifeforms thrive. The presence of these minerals in the Coprates Chasma region could therefore mean that ancient microorganisms once thrived there. Moreover, such organisms could also be fossilized within the mineral-rich lava rock, making it a tempting target for future research.
As Hauber indicated, the appeal of Coprates Chasma doesn’t end there, and future mission will surely want to make exploring this region a priority:
“Coprates Chasma is not just interesting with regard to the question of previous life on Mars. The region would also be an excellent landing site for future Mars Rovers. Here we could investigate many scientifically important and interesting topics. Analyzing samples for their elemental isotopic fractions would allow us to determine with far greater precision when the volcanoes were actually active.
“On the towering, steep walls, the geologic evolution of the Valles Marineris is presented to us almost like a history book – gypsum strata and layers of old, crustal rocks can be observed, as well as indications for liquid water trickling down the slopes even today during the warm season. That is as much Mars geology as you can get!”
Scientists were able to gauge the rate of water loss on Mars by measuring the ratio of water and HDO from today and 4.3 billion years ago. Credit: Kevin Gill
In other words, this low-lying region could be central to future studies that attempt to unlock the history and geological evolution of the Red Planet. The payoffs of studying this region not only include determining if Mars had life in the past, but when and how it went from being a warmer, wetter environment to the cold, dessicated landscape we know today.
In the future, NASA, the ESA, the China National Space Agency (CNSA) and Roscosmos all hope to mount additional robotic missions to Mars. In addition, NASA and even SpaceX hope to send crewed missions to the planet in the hopes of learning more about its past – and possibly future – habitability. Between its geological history, greater atmospheric pressure, and the possibility of fossilized life, one or more of these missions may be headed to Valles Marineris to have a look around.
Image taken by the Viking 1 orbiter in June 1976, showing Mars thin atmosphere and dusty, red surface. Credits: NASA/Viking 1
One of the most significant finds to come from our ongoing exploration and research efforts of Mars is the fact that the planet once had a warmer, wetter environment. Between 4.2 and 3.7 billion years ago, the planet had a thicker atmosphere and was able to maintain liquid water on its surface. As such, it has been ventured that life could have once existed there, and might still exist there in some form.
However, according to some recent lab tests by a pair of researchers from the UK Center for Astrobiology at the University of Edinburgh, Mars may be more hostile to life than previously thought. Not only does this not bode well for those currently engaged in the hunt for life on Mars (sorry Curiosity!), it could also be bad news for anyone hoping to one day grow things on the surface (sorry Mark Watney!).
Their study, titled “Perchlorates on Mars Enhance the Bacteriocidal Effects of UV Light“, was recently published in the journal Science Reports. Performed by Jennifer Wadsworth and Charles Cockell – a postgraduate student and a professor of astrobiology at the UK Center for Astrobiology, respectively – the purpose of this study was to see how perchlorates (a chemical compound that is common to Mars) behaved under Mars-like conditions.
An artist’s impression of what Mars might have looked like with water, when any potential Martian microbes would have evolved. Credit: ESO/M. Kornmesser
Basically, perchlorates are a negative ion of chlorine and oxygen that are found on Earth. When the Pheonix lander touched down on Mars in 2008, it found that this chemical was also found on the Red Planet. While stable at room temperature, perchlorates become active when exposed to high levels of heat energy. And under the kinds of conditions associated with Mars, they become rather toxic.
Interestingly enough, the presence of perchlorates on the surface of Mars was presented in 2015 as evidence of there being liquid water there in the past. This was due to the fact that these compounds were found both in-situ and as part of what are known as “brine sweeps”. In other words, some of the discovered perchlorates took the form of streaky lines that were thought to have been the result of water evaporating.
Water, as we all know, is also an essential ingredient to life as we know it, and it’s discovery of Mars was seen as evidence that life could have once existed there. Hence, as Jennifer Wadsworth (the study’s lead author) told Universe Today via email, she and Dr. Cockell were interested to see how such compounds would behave under conditions that are particular to Mars:
“There is a relatively large amount of perchlorate on Mars (0.6 weight percent) and it was confirmed to be a component of a Martian brine by NASA in 2015. It has been speculated that these brines may be habitable. There has been previous work done showing that perchlorates can be ‘activated’ by ionizing radiation which leads them to chlorinate amino acids and degrade organics. We wanted to test whether perchlorate could be activated by UV under Martian environmental conditions to directly kill bacteria. We thought it would be interesting to investigate in light of the discussions of brine habitability.”
Scientists were able to gauge the rate of water loss on Mars by measuring the ratio of water
After recreating the temperature conditions that are common to the Martian surface, Wadsworth and Cockell began exposing the samples to ultra-violet light – which the surface of Mars gets plenty of exposure to. What they found was that under cold conditions, the samples became activated when exposed to UV radiation. And As Wadsworth explained, the results were less than encouraging:
“The main results were that perchlorate, that is usually only activated at high temperatures, can be activated by only using UV light. This is interesting because this compound is abundant on Mars (where it’s very cold), so we might have previously thought it wouldn’t be possible to activate it under Martian conditions. We also found the bactericidal effect increased when bacteria were irradiated with perchlorate and other Martian compounds (iron oxide and hydrogen peroxide). This is important because it is lethal to bacteria when activated. So, if we want to find life on Mars, we have to take this into consideration.”
Iron oxide – aka. rust – and hydrogen peroxide are two compounds that are also found in abundance on the surface of Mars. In fact, it is the prevalence of iron oxide in the soil that gives Mars its distinct, reddish appearance. When Wadsworth and Cockell added these compounds to the perchlorates, the result was nothing less than a 10.8-fold increase in the death of bacterial cells, when compared to perchlorates alone.
While the surface of Mars has long been suspected of having toxic effects, this study shows that it could actually be very hostile to living cells. Thanks to the toxic combination that is created when these three chemical compounds come together and are activated by UV light, the most basic of life forms may be unable to survive there. For those researchers attempting to determine if Mars could in fact be habitable, this is not good news!
Sorry, Mark Watney. Turns out, your potatoes are growing in dirt that is toxic to lifeforms. Credit: Twentieth Century Fox Film Corporation
It is also bad news as far as the existence of liquid water is concerned. While the presence of liquid water in Mars’ past was seen as compelling evidence for past habitability, this water would not have been particularly supportive for life as we know it. Not if these compounds were present in Mars’ surface water, which this study would seem to suggest. Luckily, this research does present a few silver linings.
On the one hand, the fact that perchlorates became hostile to B. subtilis in the presence of UV does not necessarily mean that the Martian surface is hostile to all life. Second, the presence of these bacteria-killing compounds means that contaminants left behind by robotic explorers are not likely to survive long. So the risk of contaminating Mars’ environment (always a going concern for any mission) is very low.
As Wadsworth explained, there are unanswered questions, and more research is necessary:
“We don’t know exactly how far reaching the effect of UV and perchlorate would penetrate the surface layers, as the precise mechanism isn’t understood. If it’s the case of altered forms of perchlorate (such as chlorite or hypochlorite) diffusing through the environment, that might extend the uninhabitable zone. If you’re looking for life you have to additionally keep the ionizing radiation in mind that can penetrate the top layers of soil, so I’d suggest digging at least a few meters into the ground to ensure the levels of radiation would be relatively low. At those depths, it’s possible Martian life may survive.”
As for all the potential Mark Watney’s out there (the protoganist from The Martian), there might be some good news as well. “Perchlorate can be dangerous to humans so we’d just have to make sure we keep it out of the austronauts’ living quarters,” said Wadsworth. “We could potentially use it in sterilization processes. I think the more immediate threat to Martian colonies would be the amount of radiation reaching the surface.”
So maybe we don’t need to cancel our tickets to Mars just yet! However, as the day draws nearer to where people like Elon Musk and Bas Lansdorp are able to make commercial trips to the Red Planet a reality, we will need to know precisely how terrestrial organisms will fare on the planet – and that includes us! And if the prospects don’t look good, we better make certain we have some decent counter-measures in place.
Did you know that it’s been almost 45 years since humans walked on the surface of the Moon? Of course you do. Anyone who loves space exploration obsesses about the last Apollo landings, and counts the passing years of sadness.
Sure, SpaceX, Blue Origins and the new NASA Space Launch Systems rocket offer a tantalizing future in space. But 45 years. Ouch, so much lost time.
What would happen if we could go back in time? What amazing and insane plans did NASA have to continue exploring the Solar System? What alternative future could we have now, 45 years later?
In order to answer this question, I’ve teamed up with my space historian friend, Amy Shira Teitel, who runs the Vintage Space blog and YouTube Channel. We’ve decided to look at two groups of missions that never happened.
In her part, Amy talks about the Apollo Applications Program; NASA’s original plans before the human exploration of the Moon was shut down. More Apollo missions, the beginnings of a lunar base, and even a human flyby of Venus.
In my half of the series, I look at Werner Von Braun’s insanely ambitious plans to send a human mission to Mars. Put it together with Amy’s episode and you can imagine a space exploration future with all the ambition of the Kerbal Space Program.
Keep mind here that we’re not going to constrain ourselves with the pesky laws of physics, and the reality of finances. These ideas were cool, and considered by NASA engineers, but they weren’t necessarily the best ideas, or even feasible.
So, 2 parts, tackle them in any order you like. My part begins right now.
Werner Von Braun, of course, was the architect for NASA’s human spaceflight efforts during the space race. It was under Von Braun’s guidance that NASA developed the various flight hardware for the Mercury, Gemini and Apollo missions including the massive Saturn V rocket, which eventually put a human crew of astronauts on the Moon and safely returned them back to Earth.
Wernher von Braun. Credit: NASA/Marshall Space Flight Center
Von Braun was originally a German rocket scientist, pivotal to the Nazi “rocket team”, which developed the ballistic V-2 rockets. These unmanned rockets could carry a 1-tonne payload 800 kilometers away. They were developed in 1942, and by 1944 they were being used in war against Allied targets.
By the end of the war, Von Braun coordinated his surrender to the Allies as well as 500 of his engineers, including their equipment and plans for future rockets. In “Operation Paperclip”, the German scientists were captured and transferred to the White Sands Proving Ground in New Mexico, where they would begin working on the US rocket efforts.
Von Braun and others standing in front a V-2 rocket engine at White Sands. Credit: U.S. Army/ Ordway Collection/Space Rocket Center
Before the work really took off, though, Von Braun had a couple of years of relative downtime, and in 1947 and 1948, he wrote a science fiction novel about the human exploration of Mars.
The novel itself was never published, because it was terrible, but it also contained a detailed appendix containing all the calculations, mission parameters, hardware designs to carry out this mission to Mars.
The Mars Project
In 1952, this appendix was published in Germany as “Das Marsproject”, or “The Mars Project”. And an English version was published a few years later. Collier’s Weekly Magazine did an 8-part special on the Mars Project in 1952, captivating the world’s imagination.
Here’s the plan: In the Mars Project, Von Braun envisioned a vast armada of spaceships that would make the journey from Earth to Mars. They would send a total of 10 giant spaceships, each of which would weigh about 4,000 tonnes.
Just for comparison, a fully loaded Saturn V rocket could carry about 140 tonnes of payload into Low Earth Orbit. In other words, they’d need a LOT of rockets. Von Braun estimated that 950 three-stage rockets should be enough to get everything into orbit.
Ships being assembled in orbit. Credit: Collier’s
All the ships would be assembled in orbit, and 70 crewmembers would take to their stations for an epic journey. They’d blast their rockets and carry out a Mars Hohmann transfer, which would take them 8 months to make the journey from Earth to Mars.
The flotilla consisted of 7 orbiters, huge spheres that would travel to Mars, go into orbit and then return back to Earth. It also consisted of 3 glider landers, which would enter the Martian atmosphere and stay on Mars.
Once they reached the Red Planet, they would use powerful telescopes to scan the Martian landscape and search for safe and scientifically interesting landing spots. The first landing would happen at one of the planet’s polar caps, which Von Braun figured was the only guaranteed flat surface for a landing.
A rocket-powered glider descending towards Mars. Credit: Collier’s
At this point, it’s important to note that Von Braun assumed that the Martian atmosphere was about as thick as Earth’s. He figured you could use huge winged gliders to aerobrake into the atmosphere and land safely on the surface.
He was wrong. The atmosphere on Mars is actually only 1% as thick as Earth’s, and these gliders would never work. Newer missions, like SpaceX’s Red Dragon and Interplanetary Transport Ship will use rockets to make a powered landing.
I think if Von Braun knew this, he could have modified his plans to still make the whole thing work.
Landed at the polar cap. Credit: Collier’s
Once the first expedition landed at one of the polar caps, they’d make a 6,400 kilometer journey across the harsh Martian landscape to the first base camp location, and build a landing strip. Then two more gliders would detach from the flotilla and bring the majority of the explorers to the base camp. A skeleton crew would remain in orbit.
Once again, I think it’s important to note that Von Braun didn’t truly understand how awful the surface of Mars really is. The almost non-existent atmosphere and extreme cold would require much more sophisticated gear than he had planned for. But still, you’ve got to admire his ambition.
Preparing the gliders for rocket-powered ascent. Credit: Collier’s
With the Mars explorer team on the ground, their first task was to turn their glider-landers into rockets again. They would stand them up and get them prepped to blast off from the surface of Mars when their mission was over.
The Martian explorers would set up an inflatable habitat, and then spend the next 400 days surveying the area. Geologists would investigate the landscape, studying the composition of the rocks. Botanists would study the hardy Martian plant life, and seeing what kinds of Earth plants would grow.
Zoologists would study the local animals, and help figure out what was dangerous and what was safe to eat. Archeologists would search the region for evidence of ancient Martian civilizations, and study the vast canal network seen from Earth by astronomers. Perhaps they’d even meet the hardy Martians that built those canals, struggling to survive to this day.
Once again, in the 1940s, we thought Mars would be like the Earth, just more of a desert. There’d be plants and animals, and maybe even people adapted to the hardy environment. With our modern knowledge, this sounds quaint today. The most brutal desert on Earth is a paradise compared to the nicest place on Mars. Von Braun did the best he could with the best science of the time.
Finally, at the end of their 400 days on Mars, the astronauts would blast off from the surface of Mars, meet up with the orbiting crew, and the entire flotilla would make the return journey to Earth using the minimum-fuel Mars-Earth transfer trajectory.
The planned trajectories to and from Mars. Credit: Collier’s
Although Von Braun got a lot of things wrong about his Martian mission plan, such as the thickness of the atmosphere and habitability of Mars, he got a lot of things right.
He anticipated a mission plan that required the least amount of fuel, by assembling pieces in orbit, using the Hohmann transfer trajectory, exploring Mars for 400 days to match up Earth and Mars orbits. He developed the concept of using orbiters, detachable landing craft and ascent vehicles, used by the Apollo Moon missions.
The missions never happened, obviously, but Von Braun’s ideas served as the backbone for all future human Mars mission plans.
I’d like to give a massive thanks to the space historian David S.F. Portree. He wrote an amazing book called Humans to Mars, which details 50 years of NASA plans to send humans to the Red Planet, including a fantastic synopsis of the Mars Project.
I asked David about how Von Braun’s ideas influenced human spaceflight, he said it was his…
“… reliance on a conjunction-class long-stay mission lasting 400 days. That was gutsy – in the 1960s, NASA and contractor planners generally stuck with opposition-class short-stay missions. In recent years we’ve seen more emphasis on the conjunction-class mission mode, sometimes with a relatively short period on Mars but lots of time in orbit, other times with almost the whole mission spent on the surface.”
An interdisciplinary team from MIT (with support from NASA) is seeking to create an instrument that can performing in-situ test for life. Credit: setg.mit.edu
In 2015, then-NASA Chief Scientist Ellen Stofan stated that, “I believe we are going to have strong indications of life beyond Earth in the next decade and definite evidence in the next 10 to 20 years.” With multiple missions scheduled to search foe evidence of life (past and present) on Mars and in the outer Solar System, this hardly seems like an unrealistic appraisal.
But of course, finding evidence of life is no easy task. In addition to concerns over contamination, there is also the and the hazards the comes with operating in extreme environments – which looking for life in the Solar System will certainly involve. All of these concerns were raised at a new FISO conference titled “Towards In-Situ Sequencing for Life Detection“, hosted by Christopher Carr of MIT.
Carr is a research scientist with MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS) and a Research Fellow with the Department of Molecular Biology at Massachusetts General Hospital. For almost 20 years, he has dedicated himself to the study of life and the search for it on other planets. Hence why he is also the science principal investigator (PI) of the Search for Extra-Terrestrial Genomes (SETG) instrument.
This artist’s rendering shows NASA’s Europa mission spacecraft, which will search for life on Europa beginning sometime in the 2020s. Credit: NASA/JPL-Caltech
Led by Dr. Maria T. Zuber – the E. A. Griswold Professor of Geophysics at MIT and the head of EAPS – the inter-disciplinary group behind SETG includes researchers and scientists from MIT, Caltech, Brown University, arvard, and Claremont Biosolutions. With support from NASA, the SETG team has been working towards the development of a system that can test for life in-situ.
Introducing the search for extra-terrestrial life, Carr described the basic approach as follows:
“We could look for life as we don’t know it. But I think it’s important to start from life as we know it – to extract both properties of life and features of life, and consider whether we should be looking for life as we know it as well, in the context of searching for life beyond Earth.”
Towards this end, the SETG team seeks to leverage recent developments in in-situ biological testing to create an instrument that can be used by robotic missions. These developments include the creation of portable DNA/RNA testing devices like the MinION, as well as the Biomolecule Sequencer investigation. Performed by astronaut Kate Rubin in 2016, this was first-ever DNA sequencing to take place aboard the International Space Station.
Building on these, and the upcoming Genes in Space program – which will allow ISS crews to sequence and research DNA samples on site – the SETG team is looking to create an instrument that can isolate, detect, and classify any DNA or RNA-based organisms in extra-terrestrial environments. In the process, it will allow scientists to test the hypothesis that life on Mars and other locations in the Solar System (if it exists) is related to life on Earth.
The theory of Lithopanspermia states that life can be shared between planets within a planetary system. Credit: NASA
To break this hypothesis down, it is a widely accepted theory that the synthesis of complex organics – which includes nucleobases and ribose precursors – occurred early in the history of the Solar System and took place within the Solar nebula from which the planets all formed. These organics may have then been delivered by comets and meteorites to multiple potentially-habitable zones during the Late Heavy Bombardment period.
Known as lithopansermia, this theory is a slight twist on the idea that life is distributed throughout the cosmos by comets, asteroids and planetoids (aka. panspermia). In the case of Earth and Mars, evidence that life might be related is based in part on meteorite samples that are known to have come to Earth from the Red Planet. These were themselves the product of asteroids striking Mars and kicking up ejecta that was eventually captured by Earth.
By investigating locations like Mars, Europa and Enceladus, scientists will also be able to engage in a more direct approach when it comes to searching for life. As Carr explained:
“There’s a couple main approaches. We can take an indirect approach, looking at some of the recently identified exoplanets. And the hope is that with the James Webb Space Telescope and other ground-based telescopes and space-based telescopes, that we will be in a position to begin imaging the atmospheres of exoplanets in much greater detail than characterization of those exoplanets has [allowed for] to date. And that will give us high-end, it will give the ability to look at many different potential worlds. But it’s not going to allow us to go there. And we will only have indirect evidence through, for example, atmospheric spectra.”
Enceladus in all its glory. NASA has announced that Enceladus, Saturn’s icy moon, has hydrogen in its oceans. Image: NASA/JPL/Space Science Institute
Mars, Europa and Enceladus present a direct opportunity to find life since all have demonstrated conditions that are (or were) conducive to life. Whereas there is ample evidence that Mars once had liquid water on its surface, Europa and Enceladus both have subsurface oceans and have shown evidence of being geologically active. Hence, any mission to these worlds would be tasked with looking in the right locations to spot evidence of life.
On Mars, Carr notes, this will come down to looking in places there there is a water-cycle, and will likely involve some a little spelunking:
“I think our best bet is to access the subsurface. And this is very hard. We need to drill, or otherwise access regions below the reach of space radiation which could destroy organic materiel. And one possibility is to go to fresh impact craters. These impact craters could expose material that wasn’t radiation-processed. And maybe a region where we might want to go would be somewhere where a fresh impact crater could connect to a deeper subsurface network – where we could get access to material perhaps coming out of the subsurface. I think that is probably our best bet for finding life on Mars today at the moment. And one place we could look would be within caves; for example, a lava tube or some other kind of cave system that could offer UV-radiation shielding and maybe also provide some access to deeper regions within the Martian surface.”
As for “ocean worlds” like Enceladus, looking for signs of life would likely involve exploring around its southern polar region where tall plumes of water have been observed and studied in the past. On Europa, it would likely involve seeking out “chaos regions”, the spots where there may be interactions between the surface ice and the interior ocean.
Exploring Europa’s “chaos terrain”, where the is interaction between the interior ocean and the surface ice, could yield evidence of biological organisms. Credit: NASA/JPL-Caltech
Exploring these environments naturally presents some serious engineering challenges. For starters, it would require the extensive planetary protections to ensure that contamination was prevented. These protections would also be necessary to ensure that false positives were avoided. Nothing worse than discovering a strain of DNA on another astronomical body, only to realize that it was actually a skin flake that fell into the scanner before launch!
And then there are the difficulties posed by operating a robotic mission in an extreme environment. On Mars, there is always the issue of solar radiation and dust storms. But on Europa, there is the added danger posed by Jupiter’s intense magnetic environment. Exploring water plumes coming from Enceladus is also very challenging for an orbiter that would most likely be speeding past the planet at the time.
But given the potential for scientific breakthroughs, such a mission it is well worth the aches and pains. Not only would it allow astronomers to test theories about the evolution and distribution of life in our Solar System, it could also facilitate the development of crucial space exploration technologies, and result in some serious commercial applications.
Looking to the future, advances in synthetic biology are expected to lead to new treatments for diseases and the ability to 3-D print biological tissues (aka. “bioprinting”). It will also help ensure human health in space by addressing bone density loss, muscle atrophy, and diminished organ and immune-function. And then there’s the ability to grow organisms specially-designed for life on other planets (can you say terraforming?)
Is life in our Solar System, and the Universe for that matter, universal in nature? Credit: NASA/Jenny Mottor
On top of all that, the ability to conduct in-situ searches for life on other Solar planets also presents scientists with the opportunity to answer a burning question, one which they’ve struggled with for decades. In short, is carbon-based life universal? So far, any and all attempts to answer this question have been largely theoretical and have involved the “low hanging fruit variety” – where we have looked for signs of life as we know it, using mainly indirect methods.
By finding examples that come from environments other than Earth, we would be taking some crucial steps towards preparing ourselves for the kinds of “close encounters” that could be happening down the road.
