This simulated perspective oblique view shows Olympus Mons, the tallest volcano not only on Mars but in the entire solar system. The volcano measures some 600 km across. CREDIT Credit: ESA/DLR/FU Berlin (A. Valantinas)
It’s been known for years that there are large quantities of water ice locked up in the Martian poles. Around the equator however it is a barren dry wasteland devoid of any surface ice. Recent observations of Mars have discovered frost on the giant shield volcanoes but it only appears briefly after sunrise and soon evaporates. Estimates suggest that 150,000 tons of water cycle between the surface and atmosphere on a daily basis.
Artist's impression of the ExoMars Trace Gas orbiter spotting daylight green oxygen at Mars. Credit: ESA
On Earth, there is a phenomenon known as nightglow, where the atmosphere experiences faint light emissions that prevent the night sky from becoming completely dark. This is caused by various processes in the upper atmosphere, like the recombination of atoms, cosmic rays striking the atmosphere, or oxygen and nitrogen interacting with hydroxyl a few hundred kilometers from the surface. Thanks to data obtained by the ESA’s ExoMars Trace Gas Orbiter (TGO), the same phenomenon has been observed in the Martian atmosphere for the first time.
While scientists have long suspected that Mars also experiences this atmospheric phenomenon, this is the first time that effectively proves it. The revelation was made by an international team of scientists based on their analysis of data from the TGO’s Nadir and Occultation for MArs Discovery (NOMAD) spectrometer. When astronauts and rovers explore Mars’ polar regions in the near future, they will see a green glow whenever they look up at the sky and could even use the glow to navigate and find their way in the dark of night.
A Sign in Space is a worldwide artistic project that will inspire a conversation about the possibility of First Contact. Credit: SETI Institute
Someday, humanity might receive a message from space that will answer one of the greatest existential questions: is anybody out there? Regardless of the content, a message from an extraterrestrial civilization will be the single greatest event in human history. How would such an event happen, and how would it play out? What will be the repercussions of billions of people suddenly learning that we are NOT alone in the Universe? This question has inspired countless works of science fiction and scientific studies that have attempted to predict (and even quantify) our collective reaction.
This was the purpose behind A Sign in Space, a revolutionary art project designed to simulate a First Contact scenario. This project was the brainchild of Daniela de Paulis, a contemporary artist, and licensed radio operator currently serving as the Artist in Residence at the SETI Institute and the Green Bank Observatory. Together with a team of international experts, including SETI researchers, space scientists, and artists, de Paulis created this campaign to engage the global SETI community and the general public about the possibility of First Contact.
ExoMars Trace Gas Orbiter analyses the martian atmosphere. Credit: ESA/ATG medialab
At this very moment, eleven robotic missions are exploring Mars, a combination of orbiters, landers, rovers, and one aerial vehicle (the Ingenuity helicopter). Like their predecessors, these missions are studying Mars’ atmosphere, surface, and subsurface to learn more about its past and evolution, including how it went from a once warmer and wetter environment to the freezing, dusty, and extremely dry planet we see today. In addition, these missions are looking for evidence of past life on Mars and perhaps learning if and where it might still exist today.
One particularly interesting issue is how the atmosphere of Mars – primarily composed of carbon dioxide (CO2) – is relatively enriched with Carbon-13 (13C), aka. “heavy carbon.” For years, scientists have speculated that the ratio of this isotope to “light carbon” (12C) might be responsible for organics found on the surface (a sign of biological processes!). But after analyzing data from the ESA’s ExoMars Trace Gas Orbiter (TGO) mission, an international team led by The Open University determined that these organics may be “abiotic” in origin (i.e., not biological).
Artist's impression of the electricity generated by a Martian dust storm. Credit: NASA
Dust storms are a serious hazard on Mars. While smaller storms and dust devils happen regularly, larger ones happen every year (during summer in the southern hemisphere) and can cover continent-sized areas for weeks. Once every three Martian years (about five and a half Earth years), the storms can become large enough to encompass the entire planet and last up to two months. These storms play a major role in the dynamic processes that shape the surface of Mars and are sometimes visible from Earth (like the 2018 storm that ended the Opportunity rover’s mission).
When Martian storms become particularly strong, the friction between dust grains causes them to become electrified, transferring positive and negative charges through static electricity. According to research led by planetary scientist Alian Wang at Washington University in St. Louis, this electrical force could be the major driving force of the Martian chlorine cycle. Based on their analysis, Wang and her colleagues believe this process could account for the abundant perchlorates and other chemicals that robotic missions have detected in Martian soil.
Mosaic of the Valles Marineris hemisphere of Mars, similar to what one would see from orbital distance of 2500 km. Credit: NASA/JPL-Caltech
For generations, humans have dreamed of the day when we might set foot on Mars. For many others, the dream has been one of settling on Mars and creating an outpost of human civilization there. Today, it looks as though both of these dreams are getting closer to becoming a reality, as space agencies and the commercial space industry are deep into planning regular crewed missions to the Red Planet. And when planning for long-duration missions to destinations in deep space, a vital aspect is assessing the local environment.
For example, missions to Mars will need to be as self-sufficient as possible, which means using local resources to meet the needs of the mission and astronauts – a process known as in-situ resource utilization (ISRU). According to new data from the ESA-Roscomos ExoMars Trace Gas Orbiter (TGO), the massive equatorial canyon known as Valles Marineris (Valley of Mars) contains vast deposits of ice that have remained hidden to scientists until now.
NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft celebrated one Earth year in orbit around Mars on Sept. 21, 2015. MAVEN was launched to Mars on Nov. 18, 2013 from Cape Canaveral Air Force Station in Florida and successfully entered Mars’ orbit on Sept. 21, 2014. Credit: NASA
Despite decades of exploration and study, Mars still has its fair share of mysteries. In particular, scientists are still trying to ascertain what happened to the water that once flowed on Mars’ surface. Unfortunately, billions of years ago, the Martian atmosphere began to be stripped away by the solar wind, which also resulted in the loss of its surface water over time – although it was not entirely clear where it went and what mechanisms were involved.
To address this, a team of scientists recently consulted data obtained by three orbiter missions studying the Martian atmosphere. In the process, they found evidence that the smaller regional dust storms that happen almost annually on Mars are making the planet drier over time. These findings suggest that storms are a major driving force behind the evolution of Mars’ atmosphere and its transition to the freezing and desiccated place we know today.
In the course of studying Mars, scientists have come to identify some key similarities to Earth’s own. One notable example is the way our atmospheres interact with sunlight to produce dazzling displays of energy. On Earth, these include not just the aurorae near the polar regions (Aurora Borealis and Australis), but the constant green glow that is the result of oxygen molecules interacting with sunlight (aka. “airglow”).
On Earth, airglow can be seen “edge-on” from space, as exemplified by the many spectacular images that are taken by astronauts aboard the International Space Station (ISS). This phenomenon was recently observed around Mars for the first time by the ESA’s Trace Gas Orbiter (TGO), which arrived at Mars in 2016 a part of the ExoMars program. Like aurorae, this observation is yet another example of how Mars is “Earth’s Twin.”
This image from ESA’s Mars Express shows Korolev crater, an 82-kilometre-across feature found in the northern lowlands of Mars. Credit: ESA/DLR/FU Berlin
On June 2nd, 2003, the European Space Agency’s Mars Express mission left Earth to begin its journey to Mars. Six months later (on December 25th) the spacecraft fired its main engine and entered orbit around Mars. This Christmas will therefore mark the fifteenth anniversary of the orbiter’s arrival and all the observations it has made of the Red Planet since then.
Appropriately, the Mars Express mission was able to commemorate this occasion by capturing some beautiful photos of a Martian crater that remains filled with ice all year round. This feature is known as the Korolev crater, which measures 82 km (51 mi) in diameter and is located in the northern lowlands, just south of the northern polar ice cap.
On October 19th, 2016, the European Space Agency’s Exobiology on Mars (ExoMars) mission established orbit around Mars. Consisting of the ExoMars Trace Gas Orbiter (TGO) and the Schiaparelli lander, the purpose of this mission is to investigate Mars for past signs of life. And whereas the Schiaparelli unfortunately crashed during deployment, the TGO has managed to begin its mission ahead of schedule.
A few weeks ago, the satellite achieved a near circular orbit around Mars after performing a series of braking maneuvers. Since that time, the orbiter’s Color and Stereo Surface Imaging System (CaSSIS) took a stunning image of the surface. This picture was not only the TGO’s first image of Mars, it was also a test to see if the orbiter is ready to being its main mission on April 28th.
The image captured a 40 km- (25 mi) long segment of the Korolev Crater, which is located high in Mars’ northern hemisphere. The image was a composite of three images in different colors that were taken simultaneously on April 15th, 2018, which were then assembled to produce this color image. The bright material that appears at the edge of the crater is water ice.
The ExoMars Colour and Stereo Surface Imaging System, CaSSIS, captured this view of the rim of Korolev crater (73.3ºN/165.9ºE). Copyright ESA/Roscosmos/CaSSIS
As Antoine Pommerol, a member of the CaSSIS science team working on the calibration of the data, explained in a recent ESA press release:
“We were really pleased to see how good this picture was given the lighting conditions. It shows that CaSSIS can make a major contribution to studies of the carbon dioxide and water cycles on Mars.”
Prior to the test phase, the camera team transmitted new software to the TGO, and after a few minor issues, they determined that the instrument was ready to work. The camera is one of four instruments on the TGO, which also carries two spectrometer suites and a neutron detector. The spectrometers began their science mission on April 21st by taking the first sample of the atmosphere to see how its molecules absorb sunlight.
By doing this, the TGO hopes to determine the chemical composition of Mars atmosphere and find evidence of methane and other trace atmospheric gases that could be signatures of active biological or geological processes. Eventually, the camera will help characterize features on the surface that could be related to trace gas sources. Hence the importance of this recent test.
ExoMars’ Trace Gas Orbiter (TGO) and Schiaparelli lander seperating in orbit of Mars. Credit: ESA/ATG medialab
“We aim to fully automate the image production process,” said Nicolas Thomas, the camera’s principal investigator from the University of Bern. “Once we achieve this, we can distribute the data quickly to the science community for analysis.”
A lot of challenges lie ahead, which includes a long period of data collection to bring out the details of rare (or yet to be discovered) trace gases in Mars’ atmosphere. This is necessary since trace gases (as the name would suggest) are present in only very small amounts – i.e. less than 1% of the volume of the planet’s atmosphere. But as Håkan Svedhem – the ESA’s TGO project scientist – indicated, the test image was a good start.
“We are excited to finally be starting collecting data at Mars with this phenomenal spacecraft,” he said. “The test images we have seen so far certainly set the bar high.”
By 2020, the second part of the ExoMars mission is scheduled to launch. This will consist of a Russian surface platform and a European rover landing on the surface in support of a science mission that is expected to last into 2022 or longer. Alongside NASA’s proposed Mars 2020 rover, the Red Planet is due to have several more visitors in the coming years!
