Trace Gas Orbiter, Schiaparelli and the ExoMars rover at Mars. Credit: ESA/ATG medialab
Next year, the European Space Agency (ESA) will be sending the ExoMars 2020 mission to the Red Planet. This mission consists of an ESA-built rover (Rosalind Franklin) and a Russian-led surface science platform (Kazachok) that will study the Martian environment in order to characterize its surface, atmosphere, and determine whether or not life could have once existed on the planet.
In preparation for this mission, engineers are putting the rover and lander through their paces. This includes the ongoing development of the mission’s parachute system, which is currently in troubleshooting after a failed deployment test earlier this month. These efforts are taking place at the Swedish Space Corporation testing site in Esrange, and involve the largest parachute ever used by a mission to Mars.
This image illustrates possible ways methane might get into Mars’ atmosphere and also be removed from it: microbes (left) under the surface that release the gas into the atmosphere, weathering of rock (right) and stored methane ice called a clathrate. Ultraviolet light can work on surface materials to produce methane as well as break it apart into other molecules (formaldehyde and methanol) to produce carbon dioxide. Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan
For centuries, scientists have speculated about the existence of life on Mars. But it was only within the past 15 years that the search for life (past and present) really began to heat up. It was at this time that methane, an organic molecule that is associated with many forms of life here on Earth (i.e. a “biosignature”) was detected in Mars’ atmosphere.
Since that time, attempts to study Mars’ atmospheric methane have produced varying results. In some cases, methane has been found that was several times its normal concentrations; in others, it was absent. Seeking to answer this mystery, an interdisciplinary team from Aarhus Universityrecently conducted a study where they investigated a possible mechanism for the removal of methane from Mars’ atmosphere.
This artist's concept depicts NASA's Mars 2020 rover exploring Mars. Credit: NASA
A little over a year from now, NASA’s Mars 2020 rover will launch for Cape Canaveral and begin its journey to the Red Planet. When it arrives, in February 2021, it will begin exploring the Jezero Crater to learn more about Mars’ past and search for evidence of past and present life. But before that happens, this robotic explorer still needs a proper name.
Like its predecessors, Spirit, Opportunity, and Curiosity, the Mars 2020 rover will get its official name with the help of a nationwide contest. Towards this end, NASA recently announced that it has partnered with two organizations to give K-12 students all across the US a chance to name the rover that will continue in the search for life and pave the way for humans to begin exploring Mars.
This low-angle self-portrait of NASA's Curiosity Mars rover shows the vehicle at the site from which it reached down to drill into a rock target called "Buckskin" on lower Mount Sharp. Credits: NASA/JPL-Caltech/MSSS
Since it landed on Mars in 2012, one of the main scientific objectives of the Curiosity rover has been finding evidence of past (or even present) life on the Red Planet. In 2014, the rover may have accomplished this very thing when it detected a tenfold increase in atmospheric methane in its vicinity and found traces of complex organic molecules in drill samples while poking around in the Gale Crater.
About a year ago, Curiosity struck pay dirt again when it found organic molecules in three-billion-year-old sedimentary rocks located near the surface of lower Mount Sharp. But last week, the Curiosity rover made an even more profound discovery when it detected the largest amount of methane ever measured on the surface of Mars – about 21 parts per billion units by volume (ppbv).
Spring System at Yellowstone. Photo by Bruce Fouke.
According to a new NASA-funded study that appeared in Astrobiology, the next missions to Mars should be on the lookout for rocks that look like “fettuccine”. The reason for this, according to the research team, is that the formation of these types of rocks is controlled by a form of ancient and hardy bacteria here on Earth that are able to thrive in conditions similar to what Mars experiences today.
One solution could be to have the Mars 2020 rover drive from one potential landing site toward another favorite. Credit: NASA/JPL-Caltech
In the summer of 2020, NASA’s Mars 2020rover will launch from Cape Canaveral and commence its journey towards the Red Planet. Once it arrives on the Martian surface, the rover will begin building on the foundation established by the Opportunity and Curiosityrovers. This will include collecting samples of Martian soil to learn more about the planet’s past and determine if life ever existed there (and still does).
Up until now, though, NASA has been uncertain as to where the rover will be landing. For the past few years, the choice has been narrowed down to three approved sites, with a fourth added earlier this year for good measure. And after three days of intense debate at the recent fourth Landing Site Workshop, scientists from NASA’s Mars Exploration Program held a non-binding vote that has brought them closer to selecting a landing site.
Artist's impression of water under the Martian surface. Credit: ESA/Medialab
The possibility that life could exist on Mars has captured the imagination of researchers, scientists and writers for over a century. Ever since Giovanni Schiaparelli (and later, Percival Lowell) spotted what they believed were “Martian Canals” in the 19th century, humans have dreamed of one day sending emissaries to the Red Planet in the hopes of finding a civilization and meeting the native Martians.
While the Mariner and Viking programs of the 1960s and 70s shattered the notion of a Martian civilization, multiple lines of evidence have since emerged that indicate how life could have once existed on Mars. Thanks to a new study, which indicates that Mars may have enough oxygen gas locked away beneath its surface to support aerobic organisms, the theory that life could still exist there has been given another boost.
NASA image of the Martian surface, showing a rock formation that was the result of interactions with water. Credit: NASA.
For some time, scientists have known that Mars was once a much warmer and wetter environment than it is today. However, between 4.2 and 3.7 billion years ago, its atmosphere was slowly stripped away, which turned the surface into the cold and desiccated place we know today. Even after multiple missions have confirmed the presence of ancient lake beds and rivers, there are still unanswered questions about how much water Mars once had.
One of the most important unanswered questions is whether or not large seas or an ocean ever existed in the northern lowlands. According to a new study by an international team of scientists, the Hypanis Valles ancient river system is actually the remains of a river delta. The presence of this geological feature is an indication that this river system once emptied into an ancient Martian sea in Mars’ northern hemisphere.
Mosaic image of "Wdowiak Ridge", taken by NASA's Mars Exploration Rover Opportunity on Sept. 17th, 2014. Credit: NASA/JPL
For generations, many have dreamed about the day when it would be possible to set foot on Mars – aka. “Earth’s Twin” planet. And in the past few years, multiple orbiters, landers and rovers have revealed evidence of past water on Mars, not to mention the possibility that water still exists underground. These findings have fueled the desire to send crewed missions to Mars, not to mention proposals to establish a colony there.
However, this enthusiasm may seem a little misguided when you consider all the challenges the Martian environment presents. In addition to it being very cold and subject to a lot of radiation, the surface of Mars today is also extremely dry. According to a new study led by researchers from NASA’s Ames Research Center, Martian soil is roughly 1000 times drier than some of the driest regions on Earth.
The Atacama Desert in northern Chile. Credit: NASA/Frank Tavares
For the sake of their study, the research team sought to determine if microorganisms can survive under the types of conditions present on Mars. To answer this question, the team traveled to the the Atacama Desert in Chile, a 1000 km (620 mi) strip of land on South America’s west coast. With an average rainfall of just 1 to 3 mm (0.04 to 0.12 in) a year, the Atacama desert is known as the driest nonpolar place in the world.
However, the Atacama desert is not uniformly dry, and experiences different levels of precipitation depending on the latitude. From the southern end to the northern end, annual precipitation shifts from a few millimeters of rain per year to only a few millimeters of rain per decade. This environment provides an opportunity to search for life at decreasing levels of precipitation, thus allowing researchers to place constraints on microorganism survivability.
It is at the northern end of the desert (in what is known as the Antofagasta region) where conditions become most Mars-like. Here, the average annual rainfall is just 1 mm a year, which has made it a popular destination for scientists looking to simulate a Martian environment. In addition to seeing if microbes could survive in these dry conditions, the team also sought to determine if they were capable of growth and reproduction.
As Mary Beth Wilhelm – an astrobiologist at the Georgia Institute of Technology, NASA’s Ames Research Center, and lead author of the new study – explained in a recent NASA press release:
“On Earth, we find evidence of microbial life everywhere. However, in extreme environments, it’s important to know whether a microbe is dormant and just barely surviving, or really alive and well… By learning if and how microbes stay alive in extremely dry regions on Earth, we hope to better understand if Mars once had microbial life and whether it could have survived until today.”
Researchers collect samples from the surface of the Atacama Desert in Chile, going a few centimeters into the ground. Credits: NASA Ames Research Center
After collecting soil samples from across the Atacama Desert and brought them back to their lab at Ames, the research team began performing tests to see if their microorganism samples showed any indication of stress markers. These are a key way in which life can be shown to be growing, since organisms in a dormant state (i.e. that are just surviving) show no signs of stress markers.
Specifically, they looked for changes in the lipid structure of the cells outer membranes, which typically become more rigid in response to stress. What they found was that in the less dry parts of the Atacama Desert, this stress marker was present; but strangely, these same markers were missing in the driest regions of the desert where microbes would be more stressed.
Based on these and other results, the team concluded that there is a transition line for microorganisms in environments like the Atacama Desert. On one side of this line, the presence of minute amounts of water is enough for organisms to still be able to grow. On the other side, the environment is so dry that organisms can survive but will not grow and reproduce.
The team was also able to find evidence of microbes that had been dead in the Atacama soil samples for at least 10,000 years. They were able to determine this by examining the amino acids of the microbes, which are the building blocks of proteins, and examining the rate at which their structure changed. This find was rather surprising, seeing as how it is extremely rare that the remnant of ancient life be found on the surface of Earth.
This artist’s concept depicts NASA’s Mars 2020 rover exploring Mars. Credit: NASA
Given that Mars is 1,000 times drier than even the driest parts of Atacama, these results were not encouraging news for those hoping that microbial life will still be found there. However, the fact that the remnants of past microbial life were found in the driest areas of Chile’s desert – which would have existed when conditions were wetter and were well-preserved – is very good news when it comes to the search for past life on Mars.
Essentially, if microbial life did exist on Mars back when it was a warmer, wetter environment, traces of that ancient life might still exist. As Wilhelm explained:
“Before we go to Mars, we can use the Atacama like a natural laboratory and, based on our results, adjust our expectations for what we might find when we get there. Knowing the surface of Mars today might be too dry for life to grow, but that traces of microbes can last for thousands of years helps us design better instruments to not only search for life on and under the planet’s surface, but to try and unlock the secrets of its distant past.”
In the future, missions like NASA’s Mars 2020 rover will be seeking to procure samples of Martian soil. If NASA’s proposed “Journey to Mars” takes place by the 2030s as planned, these samples could then be returned to Earth for analysis. With luck, these soil samples will reveal evidence of past life and prove that Mars was once a habitable planet!
Mars’ south polar ice cap. Credit: ESA / DLR / FU Berlin /
According to evidence gathered by multiple robotic orbiters, rovers, and landers over the course of several decades, scientists understand that Mars was once a warmer, watery place. But between 4.2 and 3.7 billion years ago, this began to change. As Mars magnetic field disappeared, the atmosphere slowly began to be stripped away by solar wind, leaving the surface the cold and dry and making it impossible for water to exist in liquid form.
While much of the planet’s water is now concentrated in the polar ice caps, scientists have speculated some of Mars’ past water could still be located underground. Thanks to a new study by a team of Italian scientists, it has now been confirmed that liquid water still exists beneath Mars’ southern polar region. This discovery has put an end to a fifteen-year mystery and bolstered the potential for future missions to Mars.
Radar detection of water under the south pole of Mars. Credit: ESA/NASA/JPL/ASI/Univ. Rome
So far, robotic missions have revealed considerable evidence of past water on Mars. These include dried-out river valleys and gigantic outflow channels discovered by orbiters, and evidence of mineral-rich soils that can only form in the presence of liquid water by rovers and landers. Early evidence from the ESA’s Mars Express probe has also showed that water-ice exists at the planet’s poles and is buried in the layers interspersed with dust.
However, scientists have long suspected that liquid water could exist beneath the polar ice caps, much in the same way that liquid water is believed to underlie glaciers here on Earth. In addition, the presence of salts on Mars could further reduce the melting point of subsurface water and keep it in a liquid state, despite the sub-zero temperatures present on both the surface and underground.
For many years, data from the Mars Express’Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument – which has been used to study the southern polar region – has remained inconclusive. Like all ground-penetrating radar, this instrument relies on radar pulses to map surface topography and determine the properties of the materials that lie beneath the surface.
Luckily, after considerable analysis, the study team was able to develop new techniques that allowed them to collect enough high-resolution data to confirm the presence of liquid water beneath the southern ice cap. As Andrea Cicchetti, the MARSIS operations manager and a co-author on the new paper, indicated:
“We’d seen hints of interesting subsurface features for years but we couldn’t reproduce the result from orbit to orbit, because the sampling rates and resolution of our data was previously too low. We had to come up with a new operating mode to bypass some onboard processing and trigger a higher sampling rate and thus improve the resolution of the footprint of our dataset: now we see things that simply were not possible before.”
Water detection under the south pole of Mars. Credit: Context map: NASA/Viking; THEMIS background: NASA/JPL-Caltech/Arizona State University; MARSIS data: ESA/NASA/JPL/ASI/Univ. Rome; R. Orosei et al 2018
What they found was that the southern polar region is made of many layers of ice and dust down to a depth of about 1.5 km over a 200 km-wide area, and featured an anomalous area measuring 20-km wide. As Roberto Orosei, the principal investigator of the MARSIS experiment and lead author of the paper, explained in a recent ESA press release:
“This subsurface anomaly on Mars has radar properties matching water or water-rich sediments. This is just one small study area; it is an exciting prospect to think there could be more of these underground pockets of water elsewhere, yet to be discovered.”
After analyzing the properties of the reflected radar signals and taking into account the composition of the layered deposits and expected temperature profiles below the surface, the scientists concluded that the 20-km wide feature is an interface between the ice and a stable body of liquid water. For MARSIS to be able to detect such a patch of water, it would need to be at least several tens of centimeters thick.
These findings also raise the possibility of there being life on Mars, both now and in the past. This is based on research that found microbial life in Lake Vostok, which is located some 4 km (2.5 mi) below the ice in Antarctica. If life can thrive in salty, subglacial environments on Earth, then it is possible that they could survive on Mars as well. Determining if this is the case will be the purpose of existing and future missions to Mars.
The MARSIS instrument on the Mars Express is a ground penetrating radar sounder used to look for subsurface water and ice. Credit: ESA
As Dmitri Titov, one of the Mars Express project scientist, explained:
“The long duration of Mars Express, and the exhausting effort made by the radar team to overcome many analytical challenges, enabled this much-awaited result, demonstrating that the mission and its payload still have a great science potential. This thrilling discovery is a highlight for planetary science and will contribute to our understanding of the evolution of Mars, the history of water on our neighbour planet and its habitability.”
The Mars Express launched on June 2nd, 2003, and will celebrate 15 years in orbit of Mars by December 25th this year. In the coming years, it will be joined by the ESA’s ExoMars 2020 mission, NASA’s Mars 2020 Rover, and a number of other scientific experiments. These missions will pave the way for a potential crewed mission, which NASA is planning to mount by the 2030s.
If there is indeed liquid water to be found on Mars, it will go a long way towards facilitating future research and even an ongoing human presence on the surface. And if there is still life on Mars, the careful research of its ecosystems will help address the all-important question of how and when life emerged in the Solar System.
