As NASA’s Mars rover Curiosity makes its way up the central peak of Gale Crater, it has been gathering evidence from ancient lake beds and long ago groundwater environments that are promising for life.
Scientists in charge of the mission gave an update of their findings Dec. 13 at the American Geophysical Union’s annual fall meeting in San Francisco, saying the landing site at Gale Crater had exceeded their expectations. They said they have “hit a jackpot” of exposed mineral layers as the rover moves up Mount Sharp, offering a glimpse into the geologic history of the site and how global environmental conditions might have changed on Mars over the course of millions of years.
“We see all of the properties in place that we really like to associate with habitability,” said mission team member John Grotzinger, a geologist at the California Institute of Technology in Pasadena. “There’s nothing extreme here. This is all good for habitability over time.”
Gale Crater is the lowest point within thousands of kilometers in all directions, and scientists believe water once pooled there into a lake and also seeped underground. They believe the groundwater may have persisted even after the surface water dried up, offering a prolonged period for life to persist. So far, there’s been no evidence of life, microbial or otherwise, but if Mars did once support living organisms, this would have been one of the most likely spots on the Red Planet.
After traveling 9 miles (15 kilometers) from its landing site, Curiosity has now entered a critical part of its mission, boring into the exposed mudstone every 82 feet (25 meters) as it goes uphill to progressively younger layers and analyzing the contents of the fractured rock.
“You might think mudstones would be boring, but they’re definitely not,” said Curiosity deputy project scientist Joy Crisp, of NASA’s Jet Propulsion Laboratory in Pasadena.
One clue to the changing conditions is the type of iron oxide present in the rocks. The lower, more ancient layers appear to be dominated by the mineral magnetite, indicating less weathering in the environment. Meanwhile, the upper rock layers show a greater amount of oxidizing hematite, a sign of chemical reactivity that would indicate a more acidic environment, though not extremely so.
“It’s acidic, but never super-acidic. It’s totally the kind of environment where an acidophilic organism could enjoy it,” said Grotzinger.
Curiosity has also detected the element boron for the first time on Mars, and it’s appearing within mineral veins that are mainly comprised of calcium sulfate. On Earth, boron — or rather, a certain form of it — is a component in the formation of RNA, usually found in arid sites with much-evaporated water like in Death Valley National Park in California.
“The only problem with this is, we don’t know what form of boron it is,” said Patrick Gasda, of Los Alamos National Laboratory in New Mexico. If the kind of boron present on Mars is found to be similar to what we see on Earth, that would be a strong sign that the ancient groundwater that formed these veins would have been between 32 degrees and 140 degrees Fahrenheit (0 to 60 degrees Celsius) and a neutral-to-alkaline pH, making the location entirely plausible for life, researchers said
The boron was identified by Curiosity’s ChemCam instrument, a laser-shooting device that vaporizes materials and then uses a spectrograph to analyze the elemental composition of the resulting plasma of super-heated ions and electrons. The scientists propose that the boron was deposited there by moving water, suggesting a dynamic system in which minerals and elements interacted with groundwater and surface water as it moved through the landscape.
“We are seeing chemical complexity indicating a long, interactive history with the water,” said Grotzinger. “The more complicated the chemistry is, the better it is for habitability. The boron, hematite and clay minerals underline the mobility of elements and electrons, and that is good for life.”
The scientists also gave a brief update on how Curiosity is faring. The rover continues to operate, although it has faced some recent malfunctions, including a break in the motor of the drill feed, a piece responsible for moving the drill up and down during rock sampling. Mission scientists are currently troubleshooting that problem with the hope of keeping the Curiosity drill going, though the rover has already well exceeded its nominal two-year mission that began in 2012.
Mars may appear red when viewed from Earth, but NASA’s Curiosity rover has captured an up-close photo of the planet’s mountainous landscape, with purple-colored rocks littered across the foreground.
This remarkable new photo was captured near the base of Mars’ Mount Sharp. The image’s three frames were taken by Curiosity’s Mast Camera (Mastcam)on Nov. 10.
“Variations in color of the rocks hint at the diversity of their composition on lower Mount Sharp. The purple tone of the foreground rocks has been seen in other rocks where Curiosity’s Chemical and Mineralogy (CheMin) instrument has detected hematite,” or a type of iron-oxide mineral, NASA officials said in a statement. “Winds and windblown sand in this part of Curiosity’s traverse and in this season tend to keep rocks relatively free of dust, which otherwise can cloak rocks’ color.”
Mount Sharp rises 3 miles (5 kilometers) from the center of Mars’ 96-mile-wide (154 km) Gale Crater. After arriving at the crater in 2012, Curiosity found evidence that suggested that the area could have supported microbial life in the ancient past.
In addition to the purple rocks in the foreground, the images from Curiosity capture higher layers of Mount Sharp. The rover will continue to traverse these slopes throughout the rest of its mission.
This uphill trek began in October at the orange-colored rocks of the Murray formation, near the base of Mount Sharp. Next the rover will climb upward to the Hematite Unit, followed by the Clay Unit and the rounded hills of the Sulfate Unit — which is Curiosity’s highest planned destination. Studying the composition of these different rock layers can help scientists learn more about Mars’ past.
The images have a white-balanced color adjustment that resembles how rocks and sand would appear under daytime lighting conditions on Earth. This helps geologists who study the rocks recognize color patterns that they are familiar with on Earth, NASA officials said in the statement.
Ellen Stofan, current NASA chief scientist, said sending humans to Mars would be a powerful step in the search for life beyond Earth.
“I am someone who believes it is going to take humans on the surface [of Mars] … to really get at the question of not just did life evolve on Mars, but what is the nature of that life,” Stofan said at a scientific workshop in Irvine, California, hosted by the National Academy of Sciences. “To me, we’re going to go Mars because Mars holds the answers to such fundamental scientific questions that we’re trying to ask.”
The workshop, titled “Searching for Life Across Space and Time,” drew together leading scientists who are, through various avenues, working to find signs of alien life in Earth’s solar system and beyond. Stofan has argued before for the scientific benefits of a human mission to the Red Planet.
Stofan said she believes strongly in sending humans to Mars to search for signs of life because humans can perform tasks that would be difficult for a rover. Humans can operate drills that could go deeper than the few inches plumbed by the Curiosity rover, or even beyond a depth of 6.5 feet (2 meters), which is the expected limit for the ExoMars rover, a joint mission between the European Space Agency and Russia’s Roscosmos. Humans could potentially explore more locations than a rover could and perform deeper scientific analysis than what is possible using a remote, robotic scientific laboratory, she said.
“We now know water was stable for long periods of time on the surface [of Mars], and Mars’ potential for habitability, I think, is huge,” Stofan said. “I do believe that we need … brave people to spend time on Mars, to have a scientific laboratory on Mars, to do the work that we need to do to truly understand what life on Mars tells us about life beyond Earth.”
Multiple sessions at the meeting focused on the search for signs of ancient life or even present-day life on Mars. Today, the surface of the Red Planet appears to be inhospitable to the kind of life that exists on Earth, mainly because liquid water exists only in very small amounts, and is extremely salty. Other factors would also make life hard on the Red Planet, including high doses of space radiation (because Mars lacks the protective atmosphere and magnetic field that Earth has),and wildly oscillating surface temperatures: During the Martian summer months, the surface of the planet might be 70 degrees Fahrenheit (21 degrees Celsius) during the day, but plummet to minus 100 F (minus 73 C) at night.
There are examples of extreme life-forms on Earth that can survive in some of those conditions, including frigid temperatures and exposure to high doses of radiation. However, liquid water is a necessity for all known Earth-based life-forms. But based on the discovery of brines on the surface of Mars, some people think it’s possible that life exists on the Red Planet today. With that in mind, some people are concerned that sending rovers and humans to Mars could risk contaminating the planet with Earth-based microbes.
Right now, NASA has plans that could allow scientists to bring rock samples back to Earth from Mars, Stofan said. An in-depth analysis of a Martian rock might help the scientific community make a more informed decision about whether life likely exists on Mars today, and thus what steps would be needed to prevent biological contamination from a human visit to the Red Planet, Stofan said.
“I think these are questions that should be in the hands of the science community via the [NAS],” she said.
Stofan briefly addressed concerns about whether NASA could actually pull off its plan to send humans into orbit around Mars by the early 2030s and onto the planet’s surface by the late 2030s, saying that she is an “incredible optimist on this
The scientist added that she has also heard people say that there is “no real reason” to send humans to the surface of Mars (as opposed to robotic missions), and she called on members of the science community to “speak up” if they disagree.
The scientific interest in Mars extends beyond NASA. The European, Indian and Chinese space agencies are all sending probes or rovers to Mars. Private companies (primarily Elon Musk’s SpaceX) are also working on plans related to Mars. Someone in the audience asked Stofan if she thought the global scientific community is engaged in a sort of “soft space race” to Mars.
“I really don’t see it as a soft race. I see it as this amazing confluence of interests,” Stofan said. “I think Mars has incredible public appeal. …. It engages the public in a way that very few other things do, which is great.
“I think this is a great opportunity to sort of explore Mars with humans in a very different way than we went to the moon with humans, where it really was a race. [Mars], I think, is going to be motivated by cooperation and collaboration. That’s how we’re going to move forward, rather than competition.”
There’s water, water everywhere on the dwarf planet Ceres according to new research. New observations have provided direct evidence that in water ice is ubiquitous in the surface and shallow subsurface of this massive asteroid.
Ceres is the largest object in the asteroid belt that lies between Mars and Jupiter, and has long been suspected of containing significant amounts of water — estimates projected up to 30 percent of its total mass. Evidence has pointed to water ice being mixed with the rock on Ceres’ surface, and in a few rare cases, more concentrated patches of exposed ice have been found. Ceres has even belched up plumes of water vapor.
The new results come from a global map of Ceres showing the distribution of hydrogen, which can then be used to infer the presence of water. The data supports the theory that Ceres’ water content separated from the rock content, and formed an ice-rich crust on the dwarf planet. The fact that so much water is still present on Ceres “confirms predictions that water ice can lie for billions of years within a meter of the surface,” the authors write in the new paper detailing the findings
The global map was created using an instrument on NASA’s Dawn probe, which is currently orbiting the dwarf planet, called the Gamma Ray and Neutron Detector (GRaND). This instrument detects two kinds of particles: neutrons, one of the particles that make up atoms, and gamma rays, very high-energy light. When cosmic rays (very high-energy particles from space) crash into the surface of the dwarf planet, the collision can create a spray of debris particles, including neutrons and gamma rays. But the debris isn’t random; the characteristics of some of those gamma rays and neutrons can provide information about the chemical composition of the surface of Ceres and to certain depths below the surface. So scientists looking at data from GRaND can learn about the abundance of elements, including potassium, iron and hydrogen on the surface of Ceres, and to a depth of about 3 feet (1 meter).
The instrument cannot directly detect water molecules, but that can be inferred from the data, according to the authors. One way this is done is with computer models, which can recreate the evolution of Ceres, producing various possible outcomes that show how those elements (and water) would be distributed today.
Comparing the models with the new map shows that water ice on Ceres is concentrated near the poles: At high latitudes (past about 40 degrees in both hemispheres), water ice on the surface of Ceres and in the layers just under the surface may compose up to 27 percent of Ceres’ mass, according to the new research. Near the equator, the water ice concentration is much lower.
They researchers also compared the map of Ceres with a map of Vesta, another body in the asteroid belt. The data from those global maps show that Ceres has over 100 times more hydrogen than Vesta, and that the hydrogen is distributed more evenly over the surface. That indicates some kind of global process, which implies that water was (and still is) a large component of Ceres’ composition, according to the lead author of the new research, Thomas Prettyman, principal investigator for GRaND. Prettyman spoke at a news conference today (Dec. 15) at the annual meeting of the American Geophysical Union in San Francisco.
Prettyman also noted that Ceres’ composition has been compared with a family of meteorites called carbonaceous chondrites. These rocks, like most asteroids in the asteroid belt, have evolved very little since the early days of the solar system. But the new map (which also shows the distribution of iron and potassium on Ceres) shows some key differences between Ceres and these meteorites.
“If you look at the elemental composition of Ceres, it bears some resemblance to the carbonaceous contrite meteorites,” Prettyman said. “But there are differences that support the idea that ice and rock that came together and formed Ceres actually separated in the interior and were redistributed by processes like convection.”
It is possible that Ceres harbors a liquid ocean deep below its surface, but if that is the case, the ocean is likely composed of a very salty chemical mixture, with little or no water, according to Carol Raymond, deputy principal investigator of the Dawn mission, who also spoke at the news conference. Instead, the new results indicate Ceres’ water is largely stored in ice deposits near the surface.
A separate study appearing in the journal Nature and also released today revealed the presence of a concentrated patch of surface ice on Ceres, located in a regions cloaked in permanent shadow. But this and other patches of surface ice deposits are “rare,” according to the paper’s authors, and don’t add up to anywhere near the total amount of ice now thought to lie buried just under Ceres’ surface.
The Dawn probe entered into orbit around Ceres in March 2015. The spacecraft completed its primary mission in June, and continues to study Ceres as part of its extended mission.
New analysis from NASA’s Mars Curiosity rover shows that the red planet is likely flush with organics.
“I am convinced that organics are all over Mars,” said Jennifer Eigenbrode, a biogeochemist and geologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
“They’re all over the surface and they’re probably through the rock record. What that means is something we’ll have to talk about,” Eigenbrode said last week during a National Academy of Sciences workshop about the search for life beyond Earth.
Scientists on Tuesday will present additional findings from Curiosity, which four years ago landed on Mars, the planet most like Earth in the solar system, to explore a mountain of sediments rising from the center of a 96-mile wide impact crater.
The rover quickly accomplished the primary goal of its mission, which was to determine if Mars ever had the chemical ingredients and suitable environments to support microbial life.
With strong evidence that Mars indeed was habitable at some point in its past — and may still be so today — scientists began using the rover to learn more about possible niches for life and how evidence of it might be preserved.
A key part of the search focused on organics, a quest that has led to the surprising discovery that organic matter may be widely distributed on Mars.
“To me this is the biggest take-home message. Four years ago, we would never have said this,” Eigenbrode said.
Scientists don’t know the source of the organics, nor how the material has managed to survive in the harsh radioactive environment on Mars. It was found in samples drilled out from rocks and chemically analyzed.
Whether biological or geologic in origin, a rich supply of organics has implications not only in the search for past life, but also in supporting future endeavors, such as farming.
“That organic matter could be really important,” Eigenbrode said. “The door is really open here to an expanded habitability potential.”
In related research, California Institute of Technology geologist John Grotzinger, said Curiosity, which has been slowly making its way up Mount Sharp, has found multiple examples of primary igneous minerals being altered.
“What this is telling us is that that sedimentary basin is a chemical reactor, that those primary igneous minerals are being converted under different chemical circumstances into different minerals,” Grotzinger said during the National Academy of Sciences workshop. “We’re not sure what all this means, but it’s pretty exciting for habitability.”
The Curiosity team also has made progress on locating potential types of rocks that could preserve evidence of past life. The most promising find, according to Grotzinger, has been a silica-rich rock which is chemically similar to early rocks on Earth that have been found to contain fossil cells.
“Silica is the great material on Earth that survives everything,” Grotzinger said. “If you have it precipitate early on, it is capable of preserving the things you’re most interested in and apparently Mars is making this stuff.”
As Curiosity has climbed Mount Sharp, it also has discovered increasingly enriched concentrations of boron inside rock fractures. On Earth, boron is tied to the formation of ribose, a key component of RNA.
“We haven’t found any boron-bearing minerals yet, so we need to be a cautious on that one, but it’s pretty tantalizing,” Grotzinger said.
Scientists plan to present new results from the Curiosity mission at the American Geophysical Union conference, being held this week in San Francisco.
Mercury is the closest planet to the sun. But although it boasts the most widely varying temperatures in the solar system, it is not the hottest planet How is this possible?
Orbiting between 28 and 43 million miles (46 and 70 million kilometers) from the sun, Mercury, also the smallest planet, feels the brunt of the solar rays. According to NASA, the tiny world suffers the most extreme temperature range of any other planet in the solar system. The day side of the planet reaches temperatures of up to 800 degrees Fahrenheit (427 degrees Celsius). In contrast, the chilly night side can get as cold as minus 290 F (minus 180 C). The planet has an average temperature of 332 F (167 C).
These variations are relatively long-lived. Scientists once thought that Mercury kept a single side perpetually facing the sun, in a condition known as tidal locking. Because the planet lies so close to the sun, it could only be studied when it showed the same rocky, cratered face toward Earth, though at different points in its orbit. However, further studies revealed that the planet spins very slowly — only three times every two Mercury years, or once every 60 Earth days.
Mercury’s low mass and proximity to the sun keep it from having anything but the thinnest of atmospheres, and this is the reason it must pass on being the hottest planet. An atmosphere helps to cloak a planet, keeping heat from leaking into space. Without an atmosphere, Mercury loses a great deal of heat into space, rather than sharing with its night side.
The hottest planet, incidentally, is Venus, the second body from the sun. Venus has a thick atmosphere that blankets the planet, keeping its temperature at an average of 864 F (462 C).
On Earth, seasonal temperature shifts are caused by the tilt of the planet’s axis. If the Southern Hemisphere is closer to the sun than its northern counterpart, it experiences spring and summer instead of autumn and winter. But on Mercury, the planet has essentially no tilt, which means that the hemispheres experience no significant difference in temperature from one another.
That allows Mercury, the closest planet to the sun, to hang onto ice at its surface. Parts of the poles never see sunlight, leading scientists to hypothesize that ice could survive on the world. Observations made from Earth in 1991 identified unusually bright patches that corresponded with craters mapped by Mariner 10 in the 1970s. When NASA’s MESSENGER spacecraft studied the north pole in 2011, it confirmed that radar-bright features at the poles were consistent with shadowed regions. In 2012, MESSENGER used a technique known as neutron spectroscopy to measure the average hydrogen concentrations in the radar-bright regions, strengthening the case for water.
“The neutron data indicates that Mercury’s radar-bright polar deposits contain, on average, a hydrogen-rich layer more than tens of centimeters thick beneath a surficial layer 10 to 20 centimeters thick that is less rich in hydrogen,” said MESSENGER participating scientist David Lawrence at the Johns Hopkins University Applied Physics Laboratory. “The buried layer has a hydrogen content consistent with nearly pure water ice.”
After the discovery, MESSENGER continued to study the polar ice deposits over its extended mission. By refining the imaging, MESSENGER captured images of the deposits on the surface.
“There is a lot to be learned by seeing the deposits,” Nancy Chabot, instrument scientist for MESSENGER’s Mercury Dual Imaging System, said in a statement.
However, Mercury has the least circular, most eccentric orbit of all the planets. The huge range in its distance from the sun means that the planet does feel some variation in temperature based on where it travels over the course of its 88 Earth-day year.
During its wheeled treks on the Red Planet, NASA’s Spirit rover may have encountered a potential signature of past life on Mars, report scientists at Arizona State University (ASU).
To help make their case, the researchers have contrasted Spirit’s study of “Home Plate” — a plateau of layered rocks that the robot explored during the early part of its third year on Mars — with features found within active hot spring/geyser discharge channels at a site in northern Chile called El Tatio.
The work has resulted in a provocative paper: “Silica deposits on Mars with features resembling hot spring biosignatures at El Tatio in Chile.”
As reported online last week in the journal Nature Communications, field work in Chile by the ASU team — Steven Ruff and Jack Farmer of the university’s School of Earth and Space Exploration — shows that the nodular and digitate silica structures at El Tatio that most closely resemble those on Mars include complex sedimentary structures produced by a combination of biotic and abiotic processes.
“Although fully abiotic processes are not ruled out for the Martian silica structures, they satisfy an a priori definition of potential biosignatures,” the researchers wrote in the study.
Spiritlanded on Mars in January 2004, a few weeks before its twin, Opportunity, touched down in a different part of the Red Planet. Both golf-cart-size rovers were tasked with looking for signs of past water activity during their missions, which were originally planned to last three months.
Spirit encountered outcrops and regolith composed of opaline silica (amorphous SiO2nH2O) in an ancient volcanic hydrothermal setting in Gusev crater.
An origin via either fumarole-related acid-sulfate leaching or precipitation from hot spring fluids was considered possible. “However, the potential significance of the characteristic nodular and [millimeter]-scale digitate opaline silica structures was not recognized,” Ruff and Farmer noted in the new study.
Spirit imagery shows opaline silica nodular outcrops adjacent to Home Plate showing typical stratiform expression. White outline highlights nodular silica outcrop. Rover wheel tracks are roughly 1 meter apart. Rolling wheels did not deform the roughly 6-inch-high high outcrop (lighter tracks) compared with the inoperative dragging wheel in a later traverse (darker track).
Credit: ASU/Ruff & Farmer
El Tatio: Mars-like conditions
The physical environment of El Tatio offers a rare combination of high elevation, low precipitation rate, high mean annual evaporation rate, common diurnal freeze-thaw and extremely high ultraviolet irradiance.
“Such conditions provide a better environmental analog for Mars than those of Yellowstone National Park (USA) and other well-known geothermal sites on Earth,” suggested Ruff and Farmer. “Our results demonstrate that the more Mars-like conditions of El Tatio produce unique deposits, including biomediated silica structures, with characteristics that compare favorably with the Home Plate silica outcrops. The similarities raise the possibility that the Martian silica structures formed in a comparable manner.”
Previously, a NASA science team defined a potential biosignature as “an object, substance and/or pattern that might have a biological origin and thus compels investigators to gather more data before reaching a conclusion as to the presence or absence of life.”
“Because we can neither prove nor disprove a biological origin for the microstromatolite-like digitate silica structures at Home Plate, they constitute a potential biosignature according to this definition,” Ruff and Farmer wrote.
Spirit bogged down on Mars in May 2009, becoming stuck in soft soil.
In late January 2010, after months of attempts to free the rover, NASA dubbed the wheeled robot a stationary research platform. The lack of mobility and the harsh climes of Mars conspired to seal Spirit’s fate, with attempts to regain contact with the robot ending in May 2011. Subsequently, NASA announced the end of contact efforts and the completion of Spirit’s mission. (Opportunity is still going strong today.)
The ASU researchers suggested that a future and specially instrumented rover mission could perhaps provide a more definitive assessment of possible biogenicity of Home Plate silica structures.
“However, because of the challenges in obtaining unambiguous evidence in situ, coordinated microscopic and compositional analyses of samples returned to laboratories on Earth may be required to reach a robust conclusion as to the presence or absence of past Martian life in these rocks,” Ruff and Farmer stated.
The new study can be viewed here: http://www.nature.com/articles/ncomms13554
Leonard David is author of “Mars: Our Future on the Red Planet.” The book is a companion to the National Geographic Channel six-part series airing in November. A longtime writer for Space.com, David has been reporting on the space industry for more than five decades. Follow us @Spacedotcom, Facebookor Google+. Story published on Space.com.
Poor little Mercury is getting even smaller.
Astronomers have discovered a large valley on Mercury that provides further evidence for the planet’s shrinkage — an odd phenomenon that has been the topic of debate for decades.
This newfound feature is about 620 miles long, 250 miles wide and 2 miles deep (1,000 by 400 by 3.2 kilometers), making it larger than Arizona’s famous Grand Canyon and deeper than the Great Rift Valley in East Africa, scientists said.
Unlike Earth’s Great Rift Valley, Mercury’s great valley is not caused by the pulling apart of lithospheric plates due to plate tectonics; it is the result of the global contraction of a shrinking one-plate planet,” Tom Watters, a senior scientist at the Smithsonian National Air and Space Museum in Washington, D.C., said in a statement.
Using colorized topography, Mercury’s “great valley” (dark blue) and Rembrandt impact basin (purple, upper right) are revealed in this high-resolution digital elevation model merged with an image mosaic obtained by NASA’s MESSENGER spacecraft.
Watters is lead author of a study published in Geophysical Research Letters that describes Mercury’s great valley. He and his colleagues spotted the feature in images captured by NASA’s MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) spacecraft, which orbited the planet from March 2011 through April 2015.
Mercury is 3,032 miles (4,880 km) wide, and the vast majority of the planet’s volume is taken up by its metallic core, which is estimated to be about 2,500 (4,000 km) wide. That core has been cooling slowly since Mercury (and the other planets) formed nearly 4.6 billion years ago, and the little world has been shrinking as a result.
The aforementioned debate involves the extent of that shrinkage. Observations by NASA’s Mariner 10 spacecraft, which flew by Mercury three times in the mid-1970s, suggested that the planet has contracted by 1.2 to 2.5 miles (2 to 4 km) since its formation — significantly less than researchers’ models had predicted.
But MESSENGER got a better look at Mercury, and its meticulous work allowed scientists to up the shrinkage estimate to 8.7 miles (14 km) or so. This higher number reconciled theory with observation
As Watters noted, Mercury’s crust is composed of a single plate (unlike Earth’s, which consists primarily of seven large, interlocking plates). As Mercury has cooled, the rocks in this plate have been pushed together, thrusting some of them upward in cliff-like formations called scarps.
Two large, parallel scarps bound Mercury’s great valley. But the valley’s floor lies below the surrounding terrain, suggesting that the valley also formed via another process called “long-wavelength buckling,” NASA officials said. Basically, the valley floor sagged downward as nearby rocks were pushed up.
“There are similar examples of this on Earth involving both oceanic and continental plates, but this may be the first evidence of this geological process on Mercury,” Watters said.
The Parkes dish becomes the third telescope to be employed by Breakthrough Listen, joining the Green Bank Telescope in West Virginia and the Automated Planet Finder at Lick Observatory in Northern California.
“The addition of Parkes is an important milestone,” billionaire entrepreneur Yuri Milner, founder of the Breakthrough Initiatives, which include Breakthrough Listen, said in a statement. “These major instruments are the ears of planet Earth, and now they are listening for signs of other civilizations.”
The first Breakthrough Listen observations for the Parkes dish came Monday, when scientists turned the telescope toward the Proxima Centauri star system to look for possible signals from alien civilizations
Proxima Centauri is the closest star to the sun, lying just 4.2 light-years away from Earth’s star. This past August, astronomers announced the discovery of an Earth-size planet orbiting in Proxima Centauri’s “habitable zone,” the just-right range of distances where liquid water could exist on a world’s surface.
It’s therefore possible that the planet, known as Proxima b, may be capable of supporting life as we know it, scientists have said.
“The chances of any particular planet hosting intelligent life-forms are probably minuscule,” Andrew Siemion, director of the University of California, Berkeley’s SETI (Search for Extraterrestrial Intelligence) Research Center, said in the same statement.
“But once we knew there was a planet right next door, we had to ask the question, and it was a fitting first observation for Parkes,” Siemion added. “To find a civilization just 4.2 light-years away would change everything.”
Proxima Centauri is also the target of Breakthrough Starshot, a Breakthrough Initiatives effort that aims to blast tiny, sail-equipped “nanoprobes” toward the system at 20 percent the speed of light using powerful lasers.
Milner and a group of researchers, including famed cosmologist Stephen Hawking, announced Breakthrough Listen in July 2015. Over the next 10 years, the $100 million endeavor aims to search the 1 million stars closest to the sun, as well as the 100 nearest galaxies to the Milky Way, for possible SETI signals.
The 210-foot-wide (64 meters) Parkes dish, which is operated by Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO), lies near the town of Parkes, in the state of New South Wales. The radio telescope famously helped relay live video of the Apollo 11 moon landing back to Earth in July 1969, a role featured in the 2000 film “The Dish.”
Breakthrough Listen representatives also announced last month that the project would be teaming up with China’s new Five-hundred-meter Aperture Spherical radio Telescope (FAST) — the world’s largest radio telescope — to coordinate SETI observations.
Single-celled microbes are considered a living example of the kind of life that might exist elsewhere in the universe, as they are able to survive some of the extreme conditions that exist on other worlds.
New research on the bacterium Tepidibacillus decaturensis shows that it could be a model organism for what might live on Mars, should any creature inhabit the Red Planet. This microorganism, found in water more than a mile underground in the Illinois Basin in a formation known as Mount Simon Sandstone, has been shown to be moderately tolerant of heat and salt and able to persist in an anoxic environment. Mars itself is believed to harbor similarly briny surface water without the presence of oxygen.
A paper based on this research, entitled “Tepidibacillus decaturensissp. nov.: a microaerophilic, moderately thermophilic iron-reducing bacterium isolated from a depth of 1.7 km in the Illinois Basin, USA,” was published in the International Journal of Systematic and Evolutionary Microbiology. [The Life on Mars Search: Photo Timeline]
The research was led by Yiran Dong, a research scientist at the Carl R. Woese Institute of Genomic Biology, Robert Sanford, a geomicrobiologist and research associate professor at the University of Illinois, Urbana-Champaign, and Bruce W. Fouke, a professor at the University of Illinois, Urbana-Champaign and was co-funded by the NASA Astrobiology Institute and the National Energy Technology Laboratory.
The research team piggybacked on drilling activity completed by the Midwest Geological Sequestration Consortium (MGSC), which includes the Illinois State Geological Survey (ISGS) and Archer Daniels Midland (ADM). Supported by the Department of Energy, this project is evaluating locations for storing carbon underground to sequester the enormous volume of CO2 emissions being produced by ADM industrial food production, Sanford explained.
The research team participated in two drill sessions that were completed on the grounds of the ADM facility in Decatur, Illinois. Both wells are within 1,000 feet of one another and clean deep, subsurface groundwater was collected at a variety of depths. The target lithology of the Mount Simon sandstone in this central portion of the Illinois Basin ranges from 1.5 kilometers (0.93 miles) to 2.2 kilometers (1.4 miles) in burial depth. This habitat also happens to have iron oxide minerals coating the sandstone grains, which is also true of much of the surface of Mars.
“There have been some iron-reducers [bacteria] found at deep subsurface environments,” Sanford said. “These organisms have respiratory functions for reducing iron; they are reducing iron like we use oxygen. They use ferric iron to breathe.”
The bacterium they were studying, however, is a fermentative organism. Another example of this kind of organism is yeast, a fungus that converts sugar to alcohol through enzymes. Tepidibacillus decaturensis does not use iron to breathe, but it uses iron to sustain its metabolism in a very similar fashion to how yeast produce ethanol to sustain theirs.
The team is analyzing the genomic composition of Tepidibacillus decaturensis. Luckily, they have found another, separate iron-reducing bacterium from the same geological formation called Orenia metallireducens, the first known bacterial species in genus Orenia that reduces ferric to ferrous iron. (A study based on this finding was recently accepted in the journal Applied and Environmental Microbiology.)
The combination of these two iron-reducing bacteria will allow the scientists to conduct comparative studies of their metabolisms and ecology, permitting them to further explore these novel metal-reducing mechanisms. Two iron-dependent organisms in a similar environment provide valuable comparisons to understand how life behaves in these deep, hostile environments.
In previous work published in the journal Genome Announcements earlier in 2016, the team presented the first sequenced genome of Tepidibacillus decaturensis. They found nearly 3,000 protein-coding genes and 52 transfer RNA (tRNA) genes; tRNA is used to decode messenger RNA sequences into proteins.
“We are trying to see whether there are some new [gene] features to set up experiments to test them, and thus explore for the first time the deep evolutionary history of these organisms on Earth and potentially Mars,” Dong said of the ongoing work.
As with everything in life, too much of a good thing can be bad — and that logic now seems to apply to alien life, too.
Since Proxima Centauri b (or just Proxima b) was discovered in August, countless imaginings as to what the small, Earth-sized planet would look like up-close have captivated the media. Is the planet truly Earth-like with mountains, oceans, lush green continents and an atmosphere in just the right proportions to support extraterrestrial life? Or is it actually a dry, barren hellhole being constantly irradiated by its star? It could go either way.
As Proxima b was only detected by its gravitational influence on Proxima Centauri — the small exoplanet’s orbit causes the tiny star to wobble — we only know its mass and orbital period. But these two characteristics are exciting. Not only is Proxima b of approximate Earth-mass, it also orbits within the star’s habitable zone, the region surrounding a star that is neither too hot or too cold for liquid water to exist on the surface.
On Earth, where there’s liquid water, there’s life. So if Proxima b has water on its surface, it might also be in a liquid state, so there’s certainly some excitement surrounding the possibility that the world may also play host to life. But so far, we have absolutely zero evidence that water is even there, so its life-giving potential is purely speculative.
Now, in new research by astrophysicists at the University of Bern, they’ve tackled this problem with planetary evolution models and found that red dwarf stars may preferentially host small, rocky worlds. Not only that, these worlds would likely contain large quantities of water.
“Our models succeed in reproducing planets that are similar in terms of mass and period to the ones observed recently,” said Yann Alibert, of the Center of Space and Habitability (CSH) at the University of Bern, in a statement. “Interestingly, we find that planets in close-in orbits around these type of stars are of small sizes. Typically, they range between 0.5 and 1.5 Earth radii with a peak at about 1.0 Earth radius. Future discoveries will tell if we are correct!”
From this study, which has been accepted for publication in the journal Astronomy & Astrophysics, these small alien worlds also evolved with huge quantities of water. For 90 percent of the exoplanets simulated, their total mass consisted of over 10 percent water. Considering Earth is only 0.02 percent water, the simulated red dwarf exoplanets are veritable ocean planets!
At first glance, this might seem like an incredible opportunity for advanced life forms to evolve on planets in red dwarf systems. After all, red dwarfs are among the most ancient of stars in our galaxy and have a predicted lifespan of longer than the age of the universe (14 billion years). Life on Earth only sprung into being 3 billion years ago when our sun was young; life on red dwarf worlds could evolve over epic timescales by comparison.
And now it seems that, according to established planetary formation theories, these ancient worlds could have a plentiful supply of water? Well, the mind boggles.
But a huge supply of water on small exoplanets orbiting red dwarfs may not necessarily be a good thing. “While liquid water is generally thought to be an essential ingredient, too much of a good thing may be bad,” said study co-author Willy Benz.
In previous studies, water-dominated worlds were found to have unstable climates that may work against the evolution of life, perhaps stymieing these planets’ potential for producing complex life forms. If this is the case, super-advanced alien civilizations stand little chance of becoming a reality. Add this to the fact that any habitable zone exoplanets around red dwarfs will be so close to their stars that they are constantly bathed in huge doses of radiation. Perhaps the only possible life on these worlds will be basic aquatic life and have to exist deep under protective layers of icy crust.
“Habitable or not, the study of planets orbiting very low mass stars will likely bring exciting new results, improving our knowledge of planet formation, evolution, and potential habitability,” said Benz.
The upshot is that although we have plenty of ideas as to what form Proxima b will take, red dwarfs are the most common type of star in our galaxy. And if they have a preference for forming small, rocky worlds of a similar mass as Earth, statistically-speaking, there should be millions of “Earth 2.0″s out there in our galaxy with just the right quantities of water.
But do any of these worlds host life? For now, we can only speculate.
Researchers know little about the distant, icy planet Uranus compared to other planets in the solar system. Only one spacecraft has flown by it, Voyager 2 in 1986, and scientists have pieced together the rest of their observations through views from Earth-based and orbiting telescopes. The planet has rings — narrower and much darker in color than most of Saturn’s, with uneven widths and strange, sharp edges — and is tilted dramatically on its side, giving rise to decades-long seasons and extreme weather patterns.
Uranus has a crowded consortium of at least 27 moons named for literary figures, some orbiting in tight, unstable-looking formations. And now, new analysis of data from the Voyager 2 flyby suggests that two more tiny moons lurk even closer to the planet than those already known. [Photos of Uranus: A Strange, Tilted Planet]
Robert Chancia, a graduate student at University of Idaho, Moscow, investigated the patterns created when Voyager 2 beamed radio waves through the planet’s rings toward Earth. Based on how much light makes it through the rings, researchers can discern how much ring material there is at a particular spot, Chancia told Space.com.
And he found something unexpected around two thin inner rings, called alpha and beta: “At the edges of the rings … it’s almost like the amount of stuff is going up and down in a periodic fashion that looks kind of like a wave, with crests and troughs,” Chancia said. “It seems consistent with something disturbing the rings there,” he added.
The waves’ composition seem to reflect the rippling wake of a passing moon, Chancia said. Plugging the data into a model used to discover one of Saturn’s moons, the group found that the waves could be caused by small moonlets orbiting just outside each of the rings.
Although the moons would have moved on from their exact positions 30 years ago, the waves reveal their approximate masses and radial locations, which likely still apply today, Chancia said. To try and verify the new moons’ existence, Chancia combined Voyager 2 images of the planet in which the moons should have been visible. While other known moons were highlighted using this method, the potential new moonlets did not materialize.
“Based on the amplitude of this wave pattern and that distance from the ring … and our attempts to find the moon in images, it basically points toward if they exist, they’re pretty tiny,” Chancia said. That means the moons are likely smaller than 3 miles (5 kilometers) in radius, which would make them smaller and closer in than any of Uranus’ known moons. “The most likely scenario is that it’s a small object that’s right at the level of the noise in the images
Understanding Uranus’ rings, and the moons interacting with them, can help reveal more about the planet’s gravity and interior structure. Eight of Uranus’ nine main rings are very thin, less than 10 km (6 miles) thick, Chancia said. Researchers aren’t sure how the rings stay narrow over time when the particle collisions should cause them to spread out, or how long they’ve existed around the planet, but the actions of “shepherd moons” orbiting along with the rings may be keeping some of them in line. The moons Cordelia and Ophelia appear to keep Uranus’ outermost, widest ring relatively confined between around 20 and 100 km (12 and 62 miles) in width, for instance, and a similar setup may corral one of Saturn’s rings.
“Finding a small moon like this that could be helping to keep the alpha and beta rings confined and shed some light on that story could help — or just confuse things more,” Chancia said.
Mark Showalter, a researcher at SETI Institute in California, told New Scientist that the moons’ presence is “certainly a very plausible possibility.” Chancia said that Showalter and others can investigate data about Uranus from the Hubble Space Telescope to try to scope out traces of the two new moons. A lot of what scientists know about Uranus came from similar telescope observations, and this data offers the best opportunity to verify the moons’ existence, Chancia said — at least until some future mission approaches the ice giant once again.
The new work has been accepted to The Astronomical Journal, and is available online at the preprint site arXiv.
Humanity should be wary of seeking out contact with alien civilizations, Stephen Hawking has warned once again.
In 2010, the famed astrophysicist said that intelligent aliens may be rapacious marauders, roaming the cosmos in search of resources to plunder and planets to conquer and colonize. He reiterates that basic concern in “Stephen Hawking’s Favorite Places,” a new documentary streaming now on the CuriosityStream video service.
“One day, we might receive a signal from a planet like this,” Hawking says in the documentary, referring to a potentially habitable alien world known as Gliese 832c. “But we should be wary of answering back. Meeting an advanced civilization could be like Native Americans encountering Columbus. That didn’t turn out so well.”
For what it’s worth, some other astronomers believe Hawking’s caution is unwarranted. Any alien civilization advanced enough to come to Earth would surely already know of humans’ existence via the radio and TV signals that humanity has been sending out into space since 1900 or so, this line of thinking goes.
The alien musings are just a small part of “Stephen Hawking’s Favorite Places.” The 26-minute documentary shows the scientist zooming through the cosmos on a souped-up CGI spaceship called the “S.S. Hawking,” making five separate stops.
Hawking observes the Big Bang that created the universe, visits the monster black hole at the center of the Milky Way, journeys to Gliese 832c and tours Saturn in Earth’s own solar system. Then, he makes a final stop in Santa Barbara, California, which Hawking calls “my home away from home.”
“In 1974, Caltech [the California Institute of Technology] offered me a job in California,” the Englishman Hawking says in the documentary. “I jumped at the opportunity. In the sun with my young family, it was a world away from the gray skies of Cambridge, [England]. I’ve traveled the globe, but I’ve never found anywhere quite like this.”
You can watch a preview of “Stephen Hawking’s Favorite Places,” and learn how to subscribe to CuriosityStream, at the video service’s website: www.curiositystream.com.
The two objects straddle the dividing line between gas giants and odd “failed stars” known as brown dwarfs in terms of mass, researchers said. The newfound bodies are also similar to each other in size and age.
“They’re probably brother and sister,” Daniella Gagliuffi told Space.com. Gagliuffi, a graduate student at the University of California, San Diego, found the objects amid a cloud of stars about 65 light-years from Earth.
“It’s a little incestuous,” said Gagliuffi, who presented her research at the American Astronomical Society’s summer meeting in San Diego in June.
The pair lie within a dense cluster of stars that would normally be expected to strip objects away from one another. However, observations suggest that the two objects are so close that interactions with other stars would instead push them closer together, Gagliuffi said.
Planets or failed stars?
Galaxies are filled with stars, but they also include faint drifting objects with characteristics that make their status debatable. Such objects can be classified either as planets or as failed stars, given a blurry dividing line between the two.
That’s the case for the two objects Gagliuffi identified in a search for failed stars known as brown dwarfs. Gagliuffi sought brown dwarfs that could help her probe the lower boundary of what makes a star.
Unlike stars, brown dwarfs fail to fuse “normal” hydrogen in their interior. But these odd objects are apparently capable of fusing deuterium,
The newfound pair weigh in at roughly 15 and 14 times the mass of Jupiter. But the error bars associated with those estimates are wide enough that they may actually be in the planetary range.
“Their mass is straddling the deuterium-burning limit,” Gagliuffi said.
So, the twins could be a pair of planets dancing around a central point of mass (in which case they would be the history-making exoplanet binary), but they could also be a pair of brown dwarfs, or a brown dwarf hosting a massive gas giant planet.
To complicate the matter, both brown dwarfs and young gas giants produce light so weak that it is difficult to study their composition or differentiate them from one another.
And massive young planets produce heat from within, slowly cooling over their lifetimes. Gagliuffi’s studies show the pair are between 200 million and 300 million years old — young enough to confuse the issue.
Pairs of brown dwarfs are abundant throughout the Milky Way galaxy, but young binaries are not so common, Gagliuffi said. If the siblings turn out to be failed stars, they could provide intriguing insights into their family’s formation history.
Binary worlds also are thought to be rare. Our solar system is considered by some to host one pair of planets. The dwarf planet Pluto and its largest moon Charon orbit a point of mass outside the boundaries of each, making Pluto-Charon a binary system. No other binary planets are known outside of the sun’s orbit.
The newfound twin worlds drift through what Gagliuffi calls “a whole zoo of different stars,” only about 926 million miles (1.49 trillion kilometers) apart. While that sounds like an enormous distance — it is 10 times the distance between the Earth and the sun, after all— it’s actually extremely close for worlds from two different systems. She and her colleagues think it’s unlikely that the pair are just drifting close to one another by chance.
Given that they’re so close, it’s extremely likely that they’re bound,” Gagliuffi said.
It’s possible that the pair is connected to a third, more distant star that they orbit together. No such star has been identified, but many binary systems are actually triples, and Gagliuffi will look for a parent star as she continues this work.
Of course, the pair may also be drifting alone without adult supervision.
Is anyone else out there? Humans have asked this question ever since we could look up at the stars, but hundreds of thousands of years later, we still don’t have a satisfactory answer. Logic would seem to dictate that there’s other intelligent life out there, and yet it also suggests that if there is, it may have found us by now. While we may not have an answer for another few decades — if ever — we are slowly but surely getting closer.
A panel called “First Contact: Looking for Life in the Universe” at “Star Trek”: Mission New York Sept. 4 gave the audience a look at the current state of humanity’s search for extraterrestrial intelligence (SETI). The “Star Trek” mythos came up surprisingly few times for a panel calling itself a “Trek Talk,” but the subject matter was still appropriate, given the abundance of alien life on “Star Trek,” both familiar and bizarre. Dan Werthimer, the SETI chief scientist at the University of California, Berkeley, and Bobak Ferdowski from the NASA Jet Propulsion Laboratory oversaw the discussion, which covered the basics of astrobiology.
The two panelists spent a lot of time discussing the potential of finding life on Europa, an icy moon of Jupiter. Scientists have theorized that Europa has a liquid ocean buried beneath 30 miles of surface ice, and liquid water is potentially one of the most conducive environments for life to evolve, the panelists said. [13 Ways to Hunt for Intelligent Alien Life]
If we were to find life on Europa, Ferdowski and Werthimer explained, it would most likely be primitive. Humans may appear to be the dominant species on Earth, after all, but our overall biomass is pretty small when compared to wildly successful organisms such as bacteria, or even insects.
“Europa [may be] completely covered in water,” Werthimer explained. “That’s great for primitive life, but if you want technology, you’ve got to have some land surfaces as well.” Organisms on Earth, he said, have evolved to fill even the most extreme niches, “but it won’t necessarily evolve into something more complex than single-celled life … What are the pressures that make you want to go from ‘I can feed’ to standing and talking
In fact, the relative likelihood of finding primitive versus sapient life was one of the recurring themes of the talk. Werthimer believes that humanity may confirm the existence of primitive extraterrestrial life within the next 20 to 30 years, especially if scientists can get missions to Europa, but technological life is harder to pinpoint, as we don’t know how often it occurs.
Another potentially limiting factor is that intelligent life does not necessarily equate to technological life. Ferdowski and Werthimer pointed out that intelligent life (with varying degrees of what scientists would call “intelligence”) has evolved many times on Earth. Humans are the most obvious example, but dolphins, octopi and crows are all fairly clever creatures, to say nothing of the other great apes, which share a lineage with humans.
Even if there’s another technological civilization somewhere nearby, scientists are not exactly sure how to contact them. Radio signals seem like a safe bet; indeed, nearby stars have already seen “The Simpsons” and “I Love Lucy” from Earth’s TV broadcasts. On the other hand, while radio signals travel at the speed of light, that won’t do much good for an exoplanet that could be tens of thousands of light-years away.
On the flip side, given how fast life can (theoretically) arise and evolve on a planet, other civilizations could be millions or even billions of years ahead of Earth. We would have no idea how to monitor their communications, and they might not even be interested in ours.
Ferdowski and Werthimer contrasted the Drake Equation, which suggests that sapient life in the universe should be at least somewhat common, and the Fermi Paradox, which questions why alien life is not observable if the universe teems with it. One potential answer to the Fermi Paradox includes an alien version of the “Star Trek” Prime Directive, which prohibits interference with less advanced cultures. Another suggests that not all technological civilizations are necessarily driven by exploration, and may have directed their efforts inward to cultural matters instead.
Assuming that scientists can find life, however, there is (at least) one very important question to answer: Does it resemble humanity on a genetic level?
“Did it have a different biogenesis?” Ferdowski asked. “If it’s exactly the same as us, that probably doesn’t mean there were two independent origins of life.” In other words, if scientists find alien life that follows the basic biological dogma, such as translating DNA to RNA to proteins, it’s very likely that all life in the solar system originated from a common precursor
This theory, known as panspermia, suggests that extraordinarily simple, hardy life (or proto-life) could travel between planets aboard asteroids or other interplanetary debris. While this is harder to do once you get outside of a given solar system, it’s entirely possible that life on Earth and, say, Europa could have originated from the same predecessor, the researchers said.
While Ferdowski and Werthimer did not come to any hard conclusions as to whether or not humanity can expect to find life, they did say that the question has far-reaching consequences, regardless of the outcome.
“It’s a profound question either way,” Werthimer said. “If we find the universe is teeming with life, we can learn a lot. If we find out that we are alone, that somehow life is incredibly rare out of the trillion planets, that’s very profound also.
“If we find out we’re alone,” he added, “that means we’d better take incredibly good care of the precious life here on Earth.”