NASA scientists have determined that a primitive ocean on Mars held more water than Earth's Arctic Ocean and that the Red Planet has lost 87 percent of that water to space. Credit: NASA/GSFC
It’s hard to believe it now looking at Mars’ dusty, dessicated landscape that it once possessed a vast ocean. A recent NASA study of the Red Planet using the world’s most powerful infrared telescopes clearly indicate a planet that sustained a body of water larger than the Earth’s Arctic Ocean.
If spread evenly across the Martian globe, it would have covered the entire surface to a depth of about 450 feet (137 meters). More likely, the water pooled into the low-lying plains that cover much of Mars’ northern hemisphere. In some places, it would have been nearly a mile (1.6 km) deep.
Three of the best infrared observatories in the world were used to study normal to heavy water abundances in Mars atmosphere, especially the polar caps, to create a global map of the planet’s water content and infer an ancient ocean. Credit: NASA/ GSFC
Now here’s the good part. Before taking flight molecule-by-molecule into space, waves lapped the desert shores for more than 1.5 billion years – longer than the time life needed to develop on Earth. By implication, life had enough time to get kickstarted on Mars, too.
A hydrogen atom is made up of one proton and one electron, but its heavy form, called deuterium, also contains a neutron. HDO or heavy water is rare compared to normal drinking water, but being heavier, more likely to stick around when the lighter form vaporizes into space. Credit: NASA/GFSC
Using the three most powerful infrared telescopes on Earth – the W. M. Keck Observatory in Hawaii, the ESO’s Very Large Telescope and NASA’s Infrared Telescope Facility – scientists at NASA’s Goddard Space Flight Center studied water molecules in the Martian atmosphere. The maps they created show the distribution and amount of two types of water – the normal H2O version we use in our coffee and HDO or heavy water, rare on Earth but not so much on Mars as it turns out.
Maps showing the distribution of H20 and HDO (heavy water) across the planet made with the trio of infrared telescopes. Credit: NASA/GSFC
In heavy water, one of the hydrogen atoms contains a neutron in addition to its lone proton, forming an isotope of hydrogen called deuterium. Because deuterium is more massive than regular hydrogen, heavy water really is heavier than normal water just as its name implies. The new “water maps” showed how the ratio of normal to heavy water varied across the planet according to location and season. Remarkably, the new data show the polar caps, where much of Mars’ current-day water is concentrated, are highly enriched in deuterium.
It’s thought that the decay of Mars’ once-global magnetic field, the solar wind stripped away much of the planet’s early, thicker atmosphere, allowing solar UV light to break water molecules apart. Lighter hydrogen exited into space, concentrating the heavier form. Some of the hydrogen may also departed due to the planet’s weak gravity. Credit: NASA/GSFC
On Earth, the ratio of deuterium to normal hydrogen in water is 1 to 3,200, but at the Mars polar caps it’s 1 to 400. Normal, lighter hydrogen is slowly lost to space once a small planet has lost its protective atmosphere envelope, concentrating the heavier form of hydrogen. Once scientists knew the deuterium to normal hydrogen ratio, they could directly determine how much water Mars must have had when it was young. The answer is A LOT!
Goddard scientists estimate that only 13% of Mars’ original water reserves are still around today, concentrated in the icy polar caps. The rest took off for space. Credit: NASA/GSFC
Only 13% of the original water remains on the planet, locked up primarily in the polar regions, while 87% of the original ocean has been lost to space. The most likely place for the ocean would have been the northern plains, a vast, low-elevation region ideal for cupping huge quantities of water. Mars would have been a much more earth-like planet back then with a thicker atmosphere, providing the necessary pressure, and warmer climate to sustain the ocean below.
Mars at the present time has little to no liquid water on its cold, desert-like surface. Long ago, the Sun almost certainly saw its reflection from wave-rippled lakes and a northern ocean. Credit: NASA/GSFC
What’s most exciting about the findings is that Mars would have stayed wet much longer than originally thought. We know from measurements made by the Curiosity Rover that water flowed on the planet for 1.5 billion years after its formation. But the new study shows that the Mars sloshed with the stuff much longer. Given that the first evidence for life on Earth goes back to 3.5 billion years ago – just a billion years after the planet’s formation – Mars may have had time enough for the evolution of life.
So while we might bemoan the loss of so wonderful a thing as an ocean, we’re left with the tantalizing possibility that it was around long enough to give rise to that most precious of the universe’s creations – life.
To quote Charles Darwin: “… from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.
Illustration showing Mars evolving from a wet world to the present-day where liquid water can’t pond on its surface without vaporizing directly into the planet’s thin air. As Mars lost its atmosphere over billions of years, the remaining water, cooled and condensed to form the north and south polar caps. Credit: NASA/GSFC
The dinosaur on Mars, the Face in Cydonia, the rat, the human skull, the Smiley face, the prehistoric vertebrae and the conglomerate rock. Something is amiss in this montage and shouldn't be included. (Photo Credits: NASA/JPL)
What is up with the fossils on Mars? Found – a dinosaur skull on Mars? Discovered – a rat, squirrel or gerbil on Mars? In background of images from Curiosity, vertebrae from some extinct Martian species? And the human skull, half buried in photos from Opportunity Rover. All the images are made of stone from the ancient past and this is also what is called Pareidolia. They are figments of our imaginations, and driven by our interest to be there – on Mars – and to know that we are not alone. Altogether, they make a multitude of web pages and threads across the internet.
Rock-hounds and Martian paleontologists, if only amateur or retired, have found a bounty of fascinating rocks nestled among the rocks on Mars. There are impressive web sites dedicated to each’s eureka moment, dissemination among enthusiasts and presentation for discussion.
NASA scientists have sent the most advanced robotic vehicles to the surface of Mars, to the most fascinating and diverse areas that are presently reachable with our technology and landing skills. The results have been astounding scientifially but also in terms of mysteries and fascination with the strange, alien formations. Some clearly not unlike our own and others that must be fossil remnants from a bygone era – so it seems.
Be sure to explore, through the hyperlinks, many NASA, NASA affiliates’ and third party websites – embedded throughout this article. Also, links to specific websites are listed at the end of the article.
The Dinosaur skull on Mars is actually dated from Martian Sol 297 (June 7, 2013). The imager used to return this was the MASTCAM and an historic array of landscapes, close-ups and selfies has been produced by the Mars Hand Lens Imager (MAHLI). Other MSL Curiosity cameras are the NAVCAM, cameras for navigation, HAZCAM and MARDI camera. The array of images is historic and overwhelming raising more questions than answers including speculative and imaginative “discoveries.” (Photo Credit: NASA/JPL)
The centerpiece of recent interest is the dinosaur skull protruding from the Martian regolith, teeth still embedded, sparkling efferdent white. There are no sockets for these teeth. Dinosaur dentures gave this senior citizen a few extra good years. The jaw line of the skull has no joint or connection point with the skull. So our minds make up the deficits, fill in the blanks and we agree with others and convince ourselves that this is a fossilized skull. Who knows how this animal could have evolved differently.
But evolve it did – within our minds. Referencing online dictionaries [ref], “Pareidolia is the imagined perception of a pattern (or meaning) where it does not actually exist, as in considering the moon to have human features.” I must admit that I do not seek out these “discoveries” on Mars but I enjoy looking at them and there are many scientists at JPL that have the same bent. Mars never fails to deliver and caters to everyone, but when skulls and fossils are seen, it is actually us catering to the everyday images and wishes we hold in our minds.
No one is left out of the imagery returned from the array of NASA’s Martian assets in orbit. Mars exhibits an incredible display of wind swept sand dunes (center photo). (Photo Credits: NASA, Paramount Pictures)
The “Rat on Mars” (main figure, top center) is actually quite anatomically complete and hunkered down, having taken its final gasps of air, eons ago, as some cataclysmic event tore the final vestiges of Earth-like atmosphere off the surface. It died where it once roamed and foraged for … nuts and berries? Surprisingly, no nuts have been found. Blueberries – yes – they are plentiful on Mars and could have been an excellent nutritional source for rats; high in iron and possibly like their Earthly counterpart, high in anti-oxidants.
The Blueberries of Mars are actually concretions of iron rich minerals from water – ground or standing pools – created over thousands of years during periodic epochs of wet climates on Mars. (Photo Credits: NASA/JPL/Cornell)
The blueberries were popularized by Dr. Steve Squyres, the project scientist of the Mars Exploration Rover (MER) mission. Discovered in Eagle crater and across Meridiani Planum, “Blueberries” are spherules of concretions of iron rich minerals from water. It is a prime chapter in the follow-the-water story of Mars. And not far from the definition of Pareidolia, Eagle Crater refers to the incredible set of landing bounces that sent “Oppy” inside its capsule, surrounded by airbags on a hole-in-one landing into that little crater.
When the global dust storm cleared, Mariner 9’s first landfall was the tip of Olympus Mons, 90,000 feet above its base. Two decades later, Mars Global Surveyors laser altimeter data was used to computer generate this image(NASA Solar System Exploration page). At left are sand dunes near the north pole photographed in 2008 (APOD) by the Mars Reconnaissance Orbiter HiRISE camera. The sand dunes challenge scientists’ understanding of Mars’ geology and meterology while fueling speculation that such features are plants or trees on Mars. (Photo Credit: NASA/JPL)
Next, is the face of Mars of the Cydonia region (Images of Cydonia, Mars, NSSDC). As seen in the morphed images, above, the lower resolution Viking orbiter images presented Mars-o-philes clear evidence of a lost civilization. Then, Washington handed NASA several years of scant funding for planetary science, and not until Mars Global Surveyor, was the Face of Cydonia photographed again. The Mars Orbiter Camera from the University of Arizona delivered high resolution images that dismissed the notion of a mountain-sized carving. Nonetheless, this region of Mars is truly fascinating geologically and does not disappoint those in search of past civilizations.
At left, drawings by Italian astronomer Giovanni Schiaparelli coinciding with Mars’ close opposition with Earth in 1877. At right, the drawings of Percival Lowell who built the fine observatory in Flagstaff to support his interest in Mars and the search for a ninth planet. H.G. Wells published his book “War of the Worlds” in 1897. (Image Credits: Wikipedia)
And long before the face on Mars in Cydonia, there were the canals of Mars. Spotted by the Mars observer Schiaparelli, the astronomer described them as “channels” in his native language of Italian. The translation of the word turned to “Canals” in English which led the World to imagine that an advanced civilization existed on Mars. Imagine if you can for a moment, this world without Internet or TV or radio and even seldom a newspaper to read. When news arrived, people took it verbatim. Canals, civilizations – imagine how imaginations could run with this and all that actually came from it. It turns out that the canals or channels of Mars as seen with the naked eye were optical illusions and a form of Pareidolia.
So, as our imagery from Mars continues to return in ever greater detail and depth, scenes of pareidolia will fall to reason and we are left with understanding. It might seem sterile and clinical but its not. We can continue to enjoy these fascinating rocks – dinosaurs, rats, skulls, human figures – just as we enjoy a good episode of Saturday Night Live. And neither the science or the pareidolia should rob us of our ability to see the shear beauty of Mars, the fourth rock from the Sun.
Having supported Mars Phoenix software development including the final reviews of the EDL command sequence, I was keen to watch images arrive from the lander. The image was on an office wall entertaining the appearance of a not-so-tasty junk food item on Mars. (Photo Credit: NASA/JPL/Univ. Arizona, Illustration – T.Reyes)
In the article’s main image, what should not be included is the conglomerate rock on Mars. NASA/JPL scientists and geologists quickly recognized this as another remnant of Martian hydrologics – the flow of water and specifically, the bottom of a stream bed (NASA Rover Finds Old Streambed on Martian Surface). Truly a remarkable discovery and so similar to conglomerate rocks on Earth.
In December, 2014 researchers in the Mars Science Laboratory Project announced that they had made the first definitive detection of organic materials on the surface of Mars. The sample was taken on May 19, 2013 from a rock that mission controllers named “Cumberland”. The Curiosity Mars rover drilled a hole 1.6 cm wide and 6.6 cm deep in the Martian rock. Powered rock from the hole was delivered to the rover’s Sample Analysis at Mars (SAM) instrument for analysis. The scientists drew their conclusions only after months of careful analysis. The identity and complexity of the organic substances remains uncertain, because they may have been altered by perchlorates that were also present in the rock, when the material was heated for analysis. The Viking Mars landers of 1976 had earlier failed to detect organic materials on Mars.
Credits: NASA/Jet Propulsion Laboratory, Caltech
How can astrobiologists find extraterrestrial life? In everyday life, we usually don’t have any problem telling that a dog or a rosebush is a living thing and a rock isn’t. In the climatic scene of the movie ‘Europa Report’ we can tell at a glance that the multi-tentacled creature discovered swimming in the ocean of Jupiter’s moon Europa is alive, complicated, and quite possibly intelligent.
But unless something swims, walks, crawls, or slithers past the cameras of a watching spacecraft, astrobiologists face a much tougher job. They need to devise tests that will allow them to infer the presence of alien microbial life from spacecraft data. They need to be able to recognize fossil traces of past alien life. They need to be able to determine whether the atmospheres of distant planets circling other stars contain the tell-tale traces of unfamiliar forms of life. They need ways to infer the presence of life from knowledge of its properties. A definition of life would tell them what those properties are, and how to look for them. This is the first of a two part series exploring how our concept of life influences the search for extraterrestrial life.
What is it that sets living things apart? For centuries, philosophers and scientists have sought an answer. The philosopher Aristotle (384-322 BC) devoted a great deal of effort to dissecting animals and studying living things. He supposed that they had distinctive special capacities that set them apart from things that aren’t alive. Inspired by the mechanical inventions of his times, the Renaissance philosopher Rene Descartes (1596-1650) believed that living things were like clockwork machines, their special capacities deriving from the way their parts were organized.
In 1944, the physicist Erwin Schrödinger (1887-1961) wrote What is Life? In it, he proposed that the fundamental phenomena of life, including even how parents pass on their traits to their offspring, could be understood by studying the physics and chemistry of living things. Schrödinger’s book was an inspiration to the science of molecular biology.
Living organisms are made of large complicated molecules with backbones of linked carbon atoms. Molecular biologists were able to explain many of the functions of life in terms of these organic molecules and the chemical reactions they undergo when dissolved in liquid water. In 1955 James Watson and Francis Crick discovered the structure of deoxyribonucleic acid (DNA) and showed how it could be the storehouse of hereditary information passed from parent to offspring.
While all this research and theorizing has vastly increased our understanding of life, it hasn’t produced a satisfactory definition of life; a definition that would allow us to reliably distinguish things that are alive from things that aren’t. In 2012 the philosopher Edouard Mahery argued that coming up with a single definition of life was both impossible and pointless. Astrobiologists get by as best they can with definitions that are partial, and that have exceptions. Their search is conditioned by our knowledge of the specific features of life on Earth; the only life we currently know.
Here on Earth, living things are distinctive in their chemical composition. Besides carbon, the elements hydrogen, nitrogen, oxygen, phosphorus, and sulfur are particularly important to the large organic molecules that make up terrestrial life. Water is a necessary solvent. Since we don’t know for sure what else might be possible, the search for extraterrestrial life typically assumes its chemical composition will be similar to that of life on Earth.
Making use of that assumption, astrobiologists assign a high priority to the search for water on other celestial bodies. Spacecraft evidence has proven that Mars once had bodies of liquid water on its surface. Determining the history and extent of this water is a central goal of Mars exploration. Astrobiologists are excited by evidence of subsurface oceans of water on Jupiter’s moon Europa, Saturn’s moon Enceladus, and perhaps on other moons or dwarf planets. But while the presence of liquid water implies conditions appropriate for Earth-like life, it doesn’t prove that such life exists or has ever existed. Jupiter’s icy moon Europa appears to host liquid water, an essential condition for life as we know it on Earth. Its surface is covered with a crust of water ice. The Voyager and Galileo spacecraft have provided evidence that under this icy crust, there is an ocean of saltwater, containing more liquid water than all the oceans of Earth. Europa’s interior is heated by gravitational tidal forces exerted by giant Jupiter. This heat energy may drive volcanism, hydrothermal vents, and the production of chemical energy sources that living things could make use of. Interaction between materials from Europa’s surface and the ocean environment beneath could make available carbon and other chemical elements essential for Earth-like life. Credits: NASA/Jet Propulsion Laboratory, SETI Institute
Organic chemicals are necessary for Earth-like life, but, as for water, their presence doesn’t prove that life exists, because organic materials can also be formed by non-biological processes. In 1976, NASA’s two Viking landers were the first spacecraft to make fully successful landings on Mars. They carried an instrument; called the gas chromatograph-mass spectrometer, that tested the soil for organic molecules.
Even without life, scientists expected to find some organic materials in the Martian soil. Organic materials formed by non-biological processes are found in carbonaceous meteorites, and some of these meteorites should have fallen on Mars. They were surprised to find nothing at all. At the time, the failure to find organic molecules was considered a major blow to the possibility of life on Mars.
In 2008, NASA’s Phoenix lander discovered an explanation of why Viking didn’t detect organic molecules. If found that the Martian soil contains perchlorates. Containing oxygen and chlorine, perchlorates are oxidizing agents that can break down organic material. While perchlorates and organic molecules could coexist in Martian soil, scientists determined that heating the soil for the Viking analysis would have caused the perchlorates to destroy any organic material it contained. Martian soil might contain organic materials, after all.
At a news briefing in December 2014, NASA announced that an instrument carried on board the Curiosity Mars rover had succeeded in detected simple organic molecules on Mars for the first time. Researchers believe it is possible that the molecules detected may be breakdown products of more complex organic molecules that were broken down by perchlorates during the process of analysis. In 1996 a team of scientists lead by Dr. David McKay of NASA’s Johnson Space Center announced possible evidence of life on Mars. The evidence came from their studies of a Martian meteorite found in Antarctica, called Alan Hills 84001. The researchers found chemical and physical traces of possible life including carbonate globules that resemble terrestrial nanobacteria (electron micrograph shown) and polycyclic aromatic hydrocarbons. In terrestrial rock, the chemical traces would be considered breakdown products of bacterial life. The findings became the subject of controversy as non-biological explanations for the findings were found. Today, they are no longer regarded as definitive evidence of Martian life. Credits: NASA Johnson Space Center
The chemical make-up of terrestrial life has also guided the search for traces of life in Martian meteorites. In 1996 a team of investigators lead by David McKay of the Johnson Space Center in Houston reported evidence that a Martian meteorite found at Alan Hills in Antarctica in 1984 contained chemical and physical evidence of past Martian life.
There have since been similar claims about other Martian meteorites. But, non-biological explanations for many of the findings have been proposed, and the whole subject has remained embroiled in controversy. Meteorites have not so far yielded the kind of evidence needed to prove the existence of extraterrestrial life beyond reasonable doubt.
Following Aristotle, most scientists prefer to define life in terms of its capacities rather than its composition. In the second installment, we will explore how our understanding of life’s capacities has influenced the search for extraterrestrial life.
S. Tirard, M. Morange, and A. Lazcano, (2010), The definition of life: A brief history of an elusive scientific endeavor, Astrobiology, 10(10):1003-1009.
A raw shot from the front hazcam of NASA's Opportunity rover taken on Sol 3757, on Aug. 19, 2014. Credit: NASA/JPL-Caltech
Feel like visiting a dwarf planet today? How about a comet or the planet Mars? Luckily for us, there are sentinels across the Solar System bringing us incredible images, allowing us to browse the photos and follow in the footsteps of these machines. And yes, there are even a few lucky humans taking pictures above Earth as well.
Below — not necessarily in any order — are some of the best space photos of 2014. You’ll catch glimpses of Pluto and Ceres (big destinations of 2015) and of course Comet 67P/Churyumov–Gerasimenko (for a mission that began close-up operations in 2014 and will continue next year.) Enjoy!
The Philae that could! The lander photographed during its descent by Rosetta. Credit: ESA/Rosetta/MPS for Rosetta Team/The Aurora Borealis seen from the International Space Station on June 28, 2014, taken by astronaut Reid Wiseman. Credit: Reid Wiseman/NASA.NASA’s Mars Curiosity Rover captures a selfie to mark a full Martian year — 687 Earth days — spent exploring the Red Planet. Curiosity Self-Portrait was taken at the ‘Windjana’ Drilling Site in April and May 2014 using the Mars Hand Lens Imager (MAHLI) camera at the end of the roboic arm. Credit: NASA/JPL-Caltech/MSSSThis global map of Dione, a moon of Saturn, shows dark red in the trailing hemisphere, which is due to radiation and charged particles from Saturn’s intense magnetic environment. Credit: NASA/JPL/Space Science InstituteComet Siding Spring shines in ultraviolet in this image obtained by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. Credit: Laboratory for Atmospheric and Space Physics/University of Colorado; NASAThis “movie” of Pluto and its largest moon, Charon b yNASA’s New Horizons spacecraft taken in July 2014 clearly shows that the barycenter -center of mass of the two bodies – resides outside (between) both bodies. The 12 images that make up the movie were taken by the spacecraft’s best telescopic camera – the Long Range Reconnaissance Imager (LORRI) – at distances ranging from about 267 million to 262 million miles (429 million to 422 million kilometers). Charon is orbiting approximately 11,200 miles (about 18,000 kilometers) above Pluto’s surface. (Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)The Mars Reconnaissance Orbiter took this image of a “circular feature” estimated to be 1.2 miles (2 kilometers) in diameter. Picture released in December 2014. Credit: NASA/JPL-Caltech/University of ArizonaJets of gas and dust are seen escaping comet 67P/C-G on September 26 in this four-image mosaic. Click to enlarge. Credit: ESA/Rosetta/NAVCAMCeres as seen from the Earth-based Hubble Space Telescope in 2004 (left) and with the Dawn spacecraft in 2014 as it approached the dwarf planet. Hubble Credit: NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), L. McFadden (University of Maryland, College Park), and M. Mutchler and Z. Levay (STScI). Dawn Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA. Photo Combination: Elizabeth Howell
For those following all the habitability results from the Curiosity rover lately, here’s a special treat — the Discovery Channel will air a behind-the-scenes documentary on the mission tonight (Dec. 18) at 10 p.m. Eastern.
After a 20 month trek across Mars and careful analysis of data, NASA scientists have announced two separate detection of organics - in the surface and the air of Mars. (Photo Credit: NASA/JPL, Illustration - T. Reyes)
On Tuesday, December 16, 2014, NASA scientists attending the American Geophysical Union Fall Meeting in San Francisco announced the detection of organic compounds on Mars. The announcement represents the discovery of the missing “ingredient” that is necessary for the existence – past or present – of life on Mars.
Indeed, the extraordinary claim required extraordinary evidence – the famous assertion of Dr. Carl Sagan. The scientists, members of the Mars Science Lab – Curiosity Rover – mission, worked over a period of 20 months to sample and analyze Martian atmospheric and surface samples to arrive at their conclusions. The announcement stems from two separate detections of organics: 1) ten-fold spikes in atmospheric Methane levels, and 2) drill samples from a rock called Cumberland which included complex organic compounds.
The Tunable Laser Spectrometer, one of the tools within the Sample Analysis at Mars (SAM) laboratory on NASA’s Curiosity Mars rover. By measuring absorption of light at specific wavelengths, it measures concentrations of methane, carbon dioxide and water vapor in Mars’ atmosphere. (Image Credit: NASA/JPL-Caltech)
Methane, of the simplest organic compounds, was detected using the Sample Analysis at Mars instrument (SAM). This is one of two compact laboratory instruments embedded inside the compact car-sized rover, Curiosity. Very soon after landing on Mars, the scientists began to use SAM to periodically measure the chemical content of the Martian atmosphere. Over many samples, the level of Methane was very low, ~0.9 parts per billion. However, that suddenly changed and, as scientists stated in the press conference, it was a “wow” moment that took them aback. Brief daily spikes in Methane levels averaging 7 parts per billion were detected.
The detection of methane at Mars has been claimed for decades, but more recently, in 2003 and 2004, independent research teams using sensitive spectrometers on Earth detected methane in the atmosphere of Mars. One group led by Vladimir Krasnopolsky of Catholic University, and another led by Dr. Michael Mumma from NASA Goddard Space Flight Center, detected broad regional and temporal levels of Methane as high as 30 parts per billion. Those announcements met with considerable skepticism from the scientific community. And the first atmospheric measurements by Curiosity were negative. However, neither group backed down from their claims.
Regions where methane appears notably localized in Northern Summer (A, B1, B2), and their relationship to mineralogical and geo-morphological domains. (A.) Observations of methane near the Syrtis Major volcanic district. (B.) Geologic map of Greeley and Guest (41) superimposed on the topographic shaded-relief from MOLA (42). The most ancient terrain (Npld, Nple) is Noachian in age (~3.6 – 4.5 billion years old, when Mars was wet), and is overlain by volcanic deposits from Syrtis Major of Hesperian (Hs) age (~3.1 – 3.6 billion yrs old). (Credit: Mumma, et al., 2009, Figure 3)
The sudden detection of ten-fold spikes in methane levels in Gale crater is not inconsistent with the earlier remote measurements from Earth. The high seasonal concentrations were in regions that do not include Gale Crater, and it remains possible that the Curiosity measurements are of a similar nature but due to some less active process than exists at the regions identified by Dr. Mumma’s team.
This graphic shows tenfold spiking in the abundance of methane in the Martian atmosphere surrounding NASA’s Curiosity Mars rover, as detected by a series of measurements made with the Tunable Laser Spectrometer instrument in the rover’s Sample Analysis at Mars laboratory suite. (Image Credit: NASA/JPL-Caltech)
The NASA scientists at AGU led by MSL project scientist Dr. John Grotzinger emphasized that they do not yet know how the methane is being generated. The process could be biological or not. There are abiotic chemical processes that could produce methane. However, the MSL SAM detections were daily spikes and represent an active real on-going process on the red planet. This alone is a very exciting aspect of the detection.
The team presented slides to describe how methane could be generated. With the known low background levels of methane at ~ 1 part per billion, an external cosmic source, for example micro-meteoroids entering the atmosphere and releasing organics which is then reduced by sunlight to methane, could be ruled out. The methane source must be of local origin.
This image illustrates possible ways methane might be added to Mars’ atmosphere (sources) and removed from the atmosphere (sinks). NASA’s Curiosity Mars rover has detected fluctuations in methane concentration in the atmosphere, implying both types of activity occur on modern Mars. A longer caption discusses which are sources and which are sinks. (Image Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan)
The scientists illustrated two means of production. In both instances, there is some daily – or at least periodic – activity that is releasing methane from the subsurface of Mars. The source could be biological which is accumulated in subsurface rocks then suddenly released. Or an abiotic chemistry, such as a reaction between the mineral olivine and water, could be the generator.
The subsurface storage mechanism of methane proposed and illustrated is called clathrate storage. Clathrate storage involves lattice compounds that can trap molecules such as methane which can subsequently be released by physical changes in the clathrate, such as solar heating or mechanical stresses. Through press Q&A, the NASA scientists stated that such clathrates could be preserved for millions and billions of years underground.
The second discovery of organics involved more complex compounds in surface materials. Also since arriving at Mars, Curiosity has utilized a drilling tool to probe the interiors of rocks. Grotzinger emphasized how material immediately at the surface of Mars has experienced the effects of radiation and the ubiquitous soil compound perchlorate reducing and destroying organics both now and over millions of years. The detection of no organics in loose and exposed surface material had not diminished NASA scientists’ hopes of detecting organics in the rocks of Mars.
Comparisons between the amount of an organic chemical named chlorobenzene detected in the “Cumberland” rock sample and amounts of it in samples from three other Martian surface targets analyzed by NASA’s Curiosity Mars rover. (Image Credit: NASA/JPL-Caltech)
Drilling was performed on several selected rocks and it was finally a mud rock called Cumberland that revealed the presence of organic compounds more complex than simple methane. The scientists did emphasize that what exactly these organic compounds are remains a mystery because of the confounding presence of the active chemical perchlorate which can quickly breakdown organics to simpler forms.
Examples from the Sample Analysis at Mars (SAM) laboratory’s detection of Martian organics in a sample of powder that the drill on NASA’s Curiosity Mars rover collected from a rock target called “Cumberland.” (Image Credit: NASA/JPL-Caltech)
The detection of organics in the mud rock Cumberland required the drilling tool and also the scoop on the multifaceted robotic arm to deliver the sample into the SAM laboratory for analysis. To detect methane, SAM has an intake valve to receive atmospheric samples.
Dr. Grotzinger described how Cumberland was chosen as a sample source. The rock is called a mud stone which has undergone a process called digenesis – the metamorphosis of sediment to rock. Grotzinger emphasized that fluids will move through such rock during digenesis and perchlorate can destroy organics in the process. Such might be the case for many metamorphic rocks on the Martian surface. The panel of scientists showed a comparison between rock samples measured by SAM. Two in particular – from the rock “John Klein” and the Cumberland rock — were compared. The former showed no organics as well as other rocks that were sampled; but Cumberland’s drill sample from its interior did reveal organics.
Illustration of some of the reasons why finding organic chemicals on Mars is challenging. Whatever organic chemicals may be produced on Mars or delivered to Mars face several possible modes of being transformed or destroyed. (Image Credit: NASA/JPL-Caltech)
The analysis of the work was painstaking – harking back to the Sagan statement. The importance of discovering organics on Mars could not be understated by the panel of scientists and Grotzinger called these two discoveries as the lasting legacy of the Mars Curiosity Rover. Furthermore, he stated that the discovery and analysis methods will go far to guide the choice of instruments and their use during the Mars 2020 rover mission.
The discovery of organics completes the necessary set of “ingredients” for past or present life on Mars: 1) an energy source, 2) water, and 3) organics. These are the basic requirements for the existence of life as we know it. The search for life on Mars is still just beginning and the new discoveries of organics is still not a clear sign that life existed or is present today. Nevertheless, Dr. Jim Green, introducing the panel of scientists, and Dr. Grotzinger both emphasized the magnitude of these discoveries and how they are tied into the objectives of the NASA Mars program — particularly now with the emphasis on sending humans to Mars. For the Mars Curiosity rover, the journey up the slopes of Mount Sharp continues and now with greater earnestness and a continued search for rocks similar to Cumberland.
Artist rendition of how the "lake" at Gale Crater on Mars may have looked millions of years ago. Credit and copyright: Kevin Gill.
What is now a mountain, was once a lake. That’s the conclusion of the Curiosity Mars rover science team after studying data and imagery from the rover, which indicates that the mountain the rover is now climbing in Gale Crater – Aeolis Mons, or Mount Sharp — was built by sediments deposited in a large lake bed over tens of millions of years.
“Gale Crater had a large lake at the bottom — perhaps even a series of lakes,” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program during a press briefing on Monday, “that may have been big enough to last millions of years.”
This evenly layered rock photographed by the Mast Camera (Mastcam) on NASA’s Curiosity Mars Rover on Aug. 7, 2014, shows a pattern typical of a lake-floor sedimentary deposit not far from where flowing water entered a lake. Credit: NASA/JPL-Caltech/MSSS.
This isn’t the first time that the Mars Science Laboratory team has made the conclusion that a lake once existed in Gale Crater, or even that the water was long-lived. A year ago, the team said that an ancient fresh water lake at the Yellowknife Bay area near Curiosity’s landing site once existed for periods spanning perhaps millions to tens of millions of years in length – before eventually evaporating completely after Mars lost its thicker atmosphere.
But now, the team has garnered a bigger picture of Gale Crater, and they suggest that water could have covered nearly the entirety of the 154-kilometer-wide crater around 3.5 billion years ago, and that the 5-kilometer-high mountain that now towers over the crater could have been formed by repeated cycles of sediment buildup and erosion.
“If our hypothesis for Mount Sharp holds up, it challenges the notion that warm and wet conditions were transient, local, or only underground on Mars,” said Ashwin Vasavada, Curiosity deputy project scientist. “A more radical explanation is that Mars’ ancient, thicker atmosphere raised temperatures above freezing globally, but so far we don’t know how the atmosphere did that.”
By continuing the study of this crater, Vasavada said, the team is “more sure than ever that we’re going to learn about the early history of Mars, it’s changing climate, and the potential for Mars to support life.”
A few months ago, when Curiosity was still a few kilometers away from the base of Aeolis Mons, the science team started noticing distinct patterns on the rocks from images taken by the rover. There were tilted beds of sandstone all facing south in the direction of the mountain. The planetary geologists concluded that these tilted beds of sandstone formed where streams emptied into standing bodies of water, probably lakes.
This diagram depicts rivers feeding into a lake. Where the river enters the water body, the water’s flow decelerates, sediments drop out, and a delta forms, depositing a prism of sediment that tapers out toward the lake’s interior. Progressive build-out of the delta through time leads to formation of sediments that are inclined in the direction toward the lake body. Credit: NASA/JPL-Caltech/MSSS/Imperial College.
Sediments carried by flowing water sink when they enter a body of water, forming a sloped wall that slowly advances forward as sediment continues to fall.
In September of this year, when Curiosity arrived at the rocks that form the base of Aeolis Mons at a region the team calls “Kimberley,” they saw a new type of rock, one that forms when tiny particles of sediment slowly settle out within a lake, forming mud at the lake bottom. These ‘mudstones’ are very finely layered, suggesting that the river and lake system was going through cycles of change.
“Layered sandstone or pebble beds at the Kimberley record a build-out or accretion of sediment from north to south,” said Curiosity science team member Sanjeev Gupta, “ and that build-out of inclined beds strongly suggests rivers depositing sediment into a standing body of water.”
This image from Curiosity’s Mastcam shows inclined beds of sandstone interpreted as the deposits of small deltas fed by rivers flowing down from the Gale Crater rim and building out into a lake where Mount Sharp is now. It was taken March 13, 2014, just north of the “Kimberley” waypoint. Credit: NASA/JPL-Caltech/MSSS
Over a span of perhaps millions of years, water flowed from the northern rim of Gale Crater toward the center, bringing sediment that slowly formed the lower layers of Mount Sharp.
After the crater filled to a height of at least a few hundred yards and the sediments hardened into rock, the accumulated layers of sediment were sculpted over time into a mountainous shape by wind erosion that carved away the material between the crater perimeter and what is now the edge of the mountain.
While this is definitely not the first time that evidence of water has been discovered on Mars — evidence from several Mars missions point to wet environments on ancient Mars – scientist have yet to put together a model of Mars’ ancient climate that could have produced long periods warm enough for stable water on the surface.
This illustration depicts a lake of water partially filling Mars’ Gale Crater, receiving runoff from snow melting on the crater’s northern rim. Image Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS
But this latest finding suggests Mars may have maintained a climate that could have produced long-lasting lakes at many locations on the Red Planet, which leads to potentially long-lasting habitable environments.
To learn more about this intriguing region on Mars, over the next few months the Curiosity rover will continue to climb up the lower layers of Aeolis Mons to see if the hypothesis for how it formed holds up. The team will also look at the chemistry of the rocks to see if the water that was once present would’ve been of the kind that could support microbial life.
“With only 30 vertical feet of the mountain behind us, we’re sure there’s a lot more to discover,” said Vasavada.
The moon appears above NASA's Orion EFT-1 spacecraft in the Kennedy Space Center area as its set to soar to space atop a Delta 4 Heavy Booster at Space Launch Complex 37 (SLC-37) at Cape Canaveral Air Force Station in Florida ahead of launch set for Dec. 4, 2014. Credit: Ken Kremer - kenkremer.com
KENNEDY SPACE CENTER, FL – This week’s appearance of the Moon over the Kennedy Space Center marks the perfect backdrop heralding the start of NASA’s determined push to send Humans to Mars by the 2030s via the agency’s new Orion crew capsule set to soar to space on its maiden test flight in less than two days.
Orion is the first human rated vehicle that can carry astronauts beyond low Earth orbit on voyages to deep space in more than 40 years.
Top managers from NASA, United Launch Alliance (ULA), and Lockheed Martin met on Tuesday, Dec. 2, and gave the “GO” to proceed toward launch after a thorough review of all systems related to the Orion capsule, rocket, and ground operation systems at the launch pad at the Launch Readiness Review (LRR), said Mark Geyer at a NASA media briefing on Dec. 2.
A new countdown display has been constructed in the place of the former analog countdown clock at the Press Site at NASA’s Kennedy Space Center in Florida for Orion’s first launch slated for Dec. 4, 2014. The display is a modern, digital LED display akin to stadium monitors. It allows television images to be shown along with numbers. Note former shuttle launch pad 39A in the background above clock. Credit: Ken Kremer – kenkremer.com
Orion is slated to lift off on a United Launch Alliance Delta IV Heavy rocket on its inaugural test flight to space on the uncrewed Exploration Flight Test-1 (EFT-1) mission at 7:05 a.m. EST on December 4, 2014, from Space Launch Complex 37 (SLC-37) at Cape Canaveral Air Force Station in Florida.
America’s astronauts flying aboard Orion will venture farther into deep space than ever before – beyond the Moon to Asteroids, Mars, and other destinations in our Solar System starting around 2020 or 2021 on Orion’s first crewed flight atop NASA’s new monster rocket – the SLS – concurrently under development.
NASA Administrator Charles Bolden officially unveils world’s largest welder to start construction of core stage of NASA’s Space Launch System (SLS) rocket at NASA Michoud Assembly Facility, New Orleans, on Sept. 12, 2014. SLS will be the world’s most powerful rocket ever built. Credit: Ken Kremer – kenkremer.com
The current weather forecast states the launch is 60 percent “GO” for favorable weather condition at the scheduled liftoff time of at 7:05 a.m. on Dec. 4, 2014.
The launch window extends for 2 hours and 39 minutes.
The two-orbit, four and a half hour Orion EFT-1 flight around Earth will lift the Orion spacecraft and its attached second stage to an orbital altitude of 3,600 miles, about 15 times higher than the International Space Station (ISS) – and farther than any human spacecraft has journeyed in 40 years.
EFT-1 will test the rocket, second stage, and jettison mechanisms, as well as avionics, attitude control, computers, and electronic systems inside the Orion spacecraft.
Orion atop Delta 4 Heavy Booster. Credit: NASA/Kim Shiflett
Then the spacecraft will carry out a high speed re-entry through the atmosphere at speeds approaching 20,000 mph and scorching temperatures near 4,000 degrees Fahrenheit to test the heat shield, before splashing down for a parachute assisted landing in the Pacific Ocean.
NASA TV will provide several hours of live Orion EFT-1 launch coverage with the new countdown clock – starting at 4:30 a.m. on Dec. 4.
Orion’s move to Launch Complex-37. Credit: Mike Killian
Watch for Ken’s ongoing Orion coverage and he’ll be onsite at KSC in the days leading up to the historic launch on Dec. 4.
Stay tuned here for Ken’s continuing Orion and Earth and planetary science and human spaceflight news.
Ken Kremer
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Learn more about Orion, SpaceX, Antares, NASA missions, and more at Ken’s upcoming outreach events:
Dec 1-5: “Orion EFT-1, SpaceX CRS-5, Antares Orb-3 launch, Curiosity Explores Mars,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
Side view shows trio of Common Booster Cores (CBCs) with RS-68 engines powering the Delta IV Heavy rocket resting horizontally in ULA’s HIF processing facility at Cape Canaveral that will launch NASA’s maiden Orion on the EFT-1 mission in December 2014 from Launch Complex 37. Credit: Ken Kremer/kenkremer.com
It's not much, but it's the clearest view taken by NASA's Curiosity Rover of C/2013 A1 Siding Spring as it passed near Mars on October 19th. The comet is the fuzzy streak moving from right to left. Click for a full-sized view. Credit: NASA/JPL-Caltech/MSSS/TAMU
NASA’s Curiosity Rover spends most of its time staring at the ground, but like humans, it looks up once in a while too. As reported earlier, NASA ground controllers pointed the rover’s Mast Camera (mastcam) skyward to shoot a series of photos of Comet Siding Spring when it passed closest to the Red Planet on October 19th. Until recently, noise-speckled pictures available on the raw image site confounded interpretation. Was the comet there or wasn’t it? In these recently released versions, the fuzzy intruder is plain to see, tracking from right to left across the field of view.
Remember the monster sunspot group on bold display during last month’s partial solar eclipse? It was the largest group of the current solar cycle and largest recorded in 24 years. Here it is again (lower left) – returning for a second time – as seen by Curiosity on November 10th. Click for raw version. Credit: NASA/JPL-Caltech
Ten exposures of 25 seconds each were taken between 4:33 p.m. and 5:54 p.m. CDT on October 19th to create the animation. The few specks you see are electronic noise, but the sharp, bright streaks are stars that trailed during the time exposure. Curiosity’s Mastcam camera system has dual lenses – a 100mm f/10 lens with a 5.1° square field of view and a 34mm, f/8 lens with a 15° square field of view. NASA didn’t include the information about which camera was used to make the photos, but if I had to guess, the faster, wide-angle view would be my choice. Siding Spring was moving relatively quickly across the Martian sky at closest approach.
Sunspot region 2192 (lower left) has returned for an encore in this photo taken by NASA’s Solar Dynamics Observatory. The same group is visible in images taken 4 days earlier from Mars. Credit: NASA/SDO
Prowling through the Curiosity raw image files, I came across this photo of the Sun on November 10th. Three dark spots at the left are immediately obvious and a dead-ringer for Active Region 2192, now re-named 2209 as it rounds the Sun for Act II. You’ll recall this was the sunspot group that nearly stole the show during the October 23rd partial solar eclipse. From Mars’ perspective, which currently allows Curiosity to see further around the solar “backside”, AR 2209 showed up a few days before it was visible from Earth.
Because of Mars’ position relative to the Sun, Curiosity saw the return of sunspot group 2192 before it was visible from Earth. The Sun had to rotate about another 4 days to carry the group into Earth’s line of sight. Source: Solarsystemscope with additions by the author
Although it’s slimmed down in size, the region is still large enough to view with the naked eye through a safe solar filter. More importantly, it possesses a complex beta-gamma-delta magnetic field where magnetic north and south poles are in close proximity and ripe for reconnection and production of M-class and X-class flares. Already, the region’s crackled with three moderate M-class flares over the past two days. In no mood to take a back seat, AR 2209 continues to dominate solar activity even during round two.
Phobos is very small but orbits close enough for someone on the surface to see its shape with the naked eye, especially when it’s high in the sky and closest to the observer. Phobos is about 1/3 the size of our Moon. This photo was taken by Curiosity on October 20th and shows the moon’s largest crater, Stickney, at top. Credit: NASA/JPL-Caltech with toning by the author to bring out details
Mars possesses two small moons, Deimos and Phobos. Curiosity has photographed them both before including an occultation Deimos (9 miles/15 km) by the larger Phobos (13.5 miles/22 km). Phobos orbits closer to Mars than any other moon does to its primary in the Solar System, just 3,700 miles (6,000 km). As a result, it moves too fast for Mars’ rotation to overtake it the way Earth’s rotation overtakes the slower-moving Moon, causing it to set in the west overnight. Contrarian Phobos rises in the western sky and sets in the east just 4 hours 15 minutes later. When nearest the horizon and farthest from an observer, it’s apparent size is just 0.14º. At the zenith it grows to 0.20º of 1/3 the diameter of the Moon.
Phobos occults Deimos in real time photographed by the Curiosity Rover on August 1, 2013. Credit: NASA/JPL-Caltech
One longish observing session on the planet would cover a complete rise-set cycle during which Phobos would first appear as a crescent and finish up a full moon a few hours later. All this talk about Phobos is only meant to direct you to the picture above taken by Curiosity on October 20, 2014 when the moon was a thick crescent. As on Earth, where Earthshine fills out the remainder of the crescent Moon, so too does Mars-shine provide enough illumination to see the full outline of Phobos.
Four-wheel drive only! Curiosity took this photo showing a sea of dark dunes from the Pahrump Hills outcrop on November 13th. Credit: NASA/JPL-Caltech
Curiosity has also photographed Earth, sunsets and transits of Phobos across the Sun while rambling across the dusty red landscape since August 2012. Before we depart, it seems only fair to aim our gaze Mars-ward again to see what’s up. Or down. The rover’s been doing a geological “Walkabout” in the Pahrump Hills outcrop at the base of Mt. Sharp in Gale Crater since September. Earlier this fall it drilled and sampled rock there containing more hematite than at any of its previous stops. Hematite is an iron oxide that’s often associated with water.
The mission may spend weeks or months at the outcrop looking for and drilling new target rocks before moving further up the geological layer cake better known as Mt. Sharp.
A mock-up of a future Chinese Martian rover was displayed at the International Industry Fair in Shanghai (Credit: South China Morning Post)
For many space-faring nations, ambitions for Mars run broad and deep. Now, add China to the list of countries with Mars in their sights. News reports from China disclosed that country is considering a future Mars rover mission, with a potential 2020 launch date. Additionally came other hints that China may be looking to develop a next-generation heavy-lift launch system.
This new project, while early in development, reveals how Chinese aspirations are growing rapidly. Human space flight successes have been followed by recent lunar mission successes of the Yutu lunar rover and the Chang’e-5 T1 test of a sample return mission. The Chinese Mars missions could influence future plans of ESA, India and NASA or more simply raise the urgency to execute missions in concept or early development without hesitation.
China View reporter Lai Yuchen is seen describing and pointing out the future Sino-Mars rover with plans for a 2020 launch coinciding with the NASA/JPL Mars 2020 rover mission . (Click still image for video Link) (Photo/Video Credit: China View)
The Mars rover mock-up display was presented at the aerospace show by China Aerospace Science and Technology Corporation (CASC). The design appears similar to the Yutu rover which landed successfully on the Moon late in 2013. While Yutu’s mobility system failed prematurely, many mission milestones were achieved.
The Mars rover design is significantly larger than Yutu but includes changes that can be attributed to the challenges of roving Mars at tens of millions of kilometers distance and under more gravitational force. The wheels are beefed up, since it must withstand more force and rugged martian terrain (gravity on Mars is 37% of the Earth’s in strength but 2.25 times the strength of gravity on the Moon’s surface.) The the solar panels are larger due to 1.) less sunlight at Mars – 35% to 50% of Earth’s, and 2.) more electrically demanding instruments.
The goals of the Chinese Mars rover will be to search for life and water. The NASA missions searching for indicators of habitable environments and for water has cost billions of dollars but the Chinese space program is operating on a fraction of what NASA’s annual budget is. Whereas the Chinese Mars program will be competing with the lunar program for government funds, it remains to be seen how quickly they can make progress and actually meet milestones for a 2020 launch date.
Besides video of the China View reporter presenting and discussing the Mars rover (link to photo above), the video also includes a simulation of the Chinese lunar sample return spacecraft, which is underdevelopment and was tested early this month during a the Chang’e-5 T1 circum-lunar mission that proved a small re-entry vehicle.
The future Chinese rover would be nearly as large as the MER rovers. Full scale models of all three NASA/JPL Mars rovers are shown here – Mars Pathfinder, MER and MSL in a JPL Mars yard with engineers. (Photo Credit: NASA/JPL)
The actual dimensions of this rover were not reported but an estimate of the size can be determined by the size of the high-gain directional antenna. Assuming it is an X-Band dish, like the one on the MER Rovers and Curiosity, then this Sino-rover would be near the same size as the MER rovers – Spirit and Opportunity. The Sino-rover shares a six wheel design like MER and MSL rovers.
Other reports from the China Daily indicated that industry leaders in China are urging China’s space agency to develop a more powerful heavy-lift launch system. It could be used for the nation’s human spaceflight goals to send a space station in to orbit, as well as send missions to Mars and beyond.
“It is a must for us to develop a more powerful heavy-lift rocket if we want to reach and explore deep space,” Zhang Zhi, a senior rocket researcher at the China Academy of Launch Vehicle Technology the aerospace exhibition.
Plans also call for an orbiter to likely function as a communication relay as MGS, Mars Odyssey and MRO have done for the American rovers. Whether this would involve a single spacecraft such as the NASA Vikings or dual crafts such as the present American rovers with supporting orbiters is unknown. Given the successful landing of the Yutu rover encapsuled in a soft-lander, one might expect the same for the Chinese Mars rover rather than an airbag landing used by MER. Either way, they will be challenged by the seven minutes of terror just like the American rovers. They will have to solve for themselves the entry, descent and landing of a rover. Only American-made rovers have successfully landed on Mars; all Russian attempts have ended in failure.
The Chinese Lunar Sample Return mission is show in simulation in the China View video. This mission would pave the way for a Chinese Mars sample return by 2030. (Photo Credit: China View)
The presentation also stated future plans for a sample-return mission by 2030. If the first Chineses Mars rover lands successfully in 2020, it will join up to four active rovers on the surface. Curiosity, ExoMars (ESA/NASA), Mars Rover 2020 and MER Opportunity. Six years seems like a long time but MER’s Oppy is a proven trooper having lasted over ten years. Curiosity, barring the unexpected, might last beyond 2020. ExoMars and NASA’s 2020 rover are still in development phases. Using ExoMars or 2020, NASA has plans to recover collected samples from rovers and return them to Earth in the 2020s and possibly as soon as 2022.
