Wouldn’t it be great if, when landing a robotic mission on another planet, the lander or rover could just scoop a sample, drop it into a chemical analyzer and get a “positive” or “negative” result for extraterrestrial life?
Well, this chemistry test isn’t so farfetched and scientists at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., are working on a method that is 10,000 times more sensitive than any other method currently employed by spacecraft.
Focused on the detection of specific types of amino acid tied to life, the researchers propose mixing a liquid sample collected from the surface of an alien world with a chemical known as a liquid reagent. Then, by shining a laser across the mixture, the molecules it contains can be observed moving at different speeds when exposed to an electric field. From this, the different molecules can be identified and the whole thing can be done autonomously, no humans required.
The method known as “capillary electrophoresis” can be used to detect many different types of amino acids simultaneously.
“Our method improves on previous attempts by increasing the number of amino acids that can be detected in a single run,” said researcher Jessica Creamer in a statement. “Additionally, it allows us to detect these amino acids at very low concentrations, even in highly salty samples, with a very simple ‘mix and analyze’ process.”
The team has already tested the method on water taken from Mono Lake in California — a mass of salty water with an extreme alkalinity — and simultaneously analyzed 17 different amino acids.
“Using our method, we are able to tell the difference between amino acids that come from non-living sources like meteorites versus amino acids that come from living organisms,” said Peter Willis, the project’s principal investigator also at JPL.
Molecules like amino acids come in two different “chiralties” that are mirror images of one another. Non-organic sources contain roughly equal “left-” and “right-handed” chirality amino acids, whereas amino acids from living organisms are predominantly left-handed — for life on Earth in any case. This differentiation can be detected by capillary electrophoresis.
This method is exceedingly powerful for several reasons. Currently, NASA is putting great efforts into looking for habitable environments on Mars. We know that the Red Planet used to be a very wet place and there’s evidence that suggests very briny sources of liquid water exists to this day. If life has ever taken hold on Mars, and if a future mission can directly sample this salty, toxic water, it’s sensitive chemical analyses such as this that will likely track it down.
Also, in the future, it is hoped that a mission may be sent to Jupiter’s moon Europa, which is known to possess an extensive subsurface ocean. Many components for life as we know it exists on Europa, so if a robotic mission can be sent to the moon’s ice-encrusted surface, or even dropped into the ocean itself, finding out whether there’s life elsewhere in the solar system could be one simple chemistry test away.
The Milky Way is littered with a vast diversity of planets: giants that blur the line between planet and failed-star brown dwarf; tiny worlds similar in size to Earth’s moon; planets that take 100,000 years to orbit their suns or whip around in hours; lava worlds; ice worlds; and planets that circle multiple suns or whirling pulsars.
Scientists find them by watching stars that wobble, change gravity, vary in color or dip slightly in brightness. (This last strategy is employed by the most prolific planet hunter of all time, NASA’s Kepler space telescope.) And someone needs to keep track of them all.
Rachel Akeson, deputy director at the NASA Exoplanet Science Institute, leads the space agency’s Exoplanet Archive, which is tasked with cataloging the ever-growing horde of planets known to exist outside the solar system.
“In 2011, there were about 700 [confirmed exoplanets]; now we’re over 3,400,” Akeson told Space.com. “In the next five years, there’s going to be tens of thousands.”
Those newly discovered exoplanets will come courtesy of various space observatories that are operating now or will come online soon. For example, the European Space Agency’s Gaia mission is precisely measuring the positions of 1 billion Milky Way stars, and the work should allow astronomers to notice movements caused by the pull of many orbiting planets.
And NASA’s Transiting Exoplanet Survey Satellite (TESS) is scheduled to launch to 2018 to search for planets all over the sky circling stars relatively close to the sun, using the same method as Kepler.
NASA’s Exoplanet Archive will house them all; the database, which was made publicly accessible in 2013, lets researchers and enthusiasts understand the distribution and properties of planets found thus far as they come in, as well as data about the stars they orbit and planet “candidates” that have yet to be confirmed. The archive also generates graphs from the latest information to show exoplanet trends.
Right now, a big part of the Exoplanet Archive takes the shape of a large interactive table of confirmed planets, which have been checked and double-checked by the authors to make sure they’re not flukes in the data. Most of the planets aren’t directly imaged but rather detected via their effects on their parent stars, and confirmations can come from observation by various methods or by a strong pattern of “transits” across their stars.
The archive also hosts data about the stars’ light curves when they’re available, showing their brightening and dimming, as well as Kepler data that has not been confirmed as a planet’s signature. It keeps a list of false positives, too, and the list is always in flux; additions and changes in status are implemented continuously.
“Things can go in and then come back out,” Akeson said. “And I think in one case, something went in, came out and has gone back in. There’s this series of papers in the literature — basically two groups arguing with each other via the papers — whether or not this is the planet signature versus another kind of signature.”
An exoplanet’s data is officially added only once it appears in a peer-reviewed publication.
As more and more planets come in, researchers can use the archive to begin to understand the galaxy’s overall distribution of planets. Different methods of detection find different kinds of planets. For instance, transit measurements from Kepler or TESS are more likely to find planets that orbit close to their stars, and Gaia should generally find planets that orbit farther away, Akeson said. With current technology, systems like Earth’s would still be hard to find, and so researchers don’t know how common they are.
“We have no system that looks like the solar system yet, where you have these small, rocky planets on the inside and then several gas giants on the outside,” Akeson said. “We’re now getting to the point where we’re starting to see things that are true Jupiter analogues, but the Earth analogues are very hard to find still.”
Going forward, a thorough survey could help researchers understand how planetary systems evolve and why our solar system is the way it is, instead of featuring mini-Neptune and super-Earth planets like researchers have found in other star systems.
As scientists continue to discover exoplanets, the catalogue will keep growing. The archive’s researchers are talking to groups of users to determine the most helpful way to display the information, and planning the best ways to wrangle and verify the new waves of planets, Akeson said.
“We are going to have to keep up,” she said.
This planet, known as Wolf 1061c, resides in the “habitable zone” of its host star, that just-right range of distances where liquid water could theoretically exist on a world’s surface. But it’s far from clear if Wolf 1061c could actually support life as we know it, study team members said.
For starters, Wolf 1061c — which circles a star located just 14 light-years from Earth’s sun — lies at the inner edge of the habitable zone, similar to where Venus is in Earth’s solar system. Venus has a hellish environment today, with surface temperatures reaching nearly 900 degrees Fahrenheit (480 degrees Celsius). [Gallery: The Strangest Alien Planets]
Venus likely had oceans on its surface in the past, but was so close to the sun that the heat made all the oceans evaporate. The water vapor assisted in trapping heat, contributing to Venus’ runaway greenhouse effect.
Something similar may have happened on Wolf 1061c, said the new study’s lead author, Stephen Kane, of San Francisco State University.
Wolf 1061c is “close enough to the star where it’s looking suspiciously like a runaway greenhouse,” Kane said in a statement.
Kane and colleagues studied Wolf 1061c’s parent star in detail using the Center for High Angular Resolution Astronomy array, which is located at the Mount Wilson Observatory in California. The researchers’ detailed measurements allowed them to better characterize the star’s habitable zone and the conditions that planets in the system likely experience. (Wolf 1061c is one of three worlds known to circle the star; all are “super-Earths,” planets slightly larger than Earth.)
“The Wolf 1061 system is important because it is so close [to Earth], and that gives other opportunities to do follow-up studies to see if it does indeed have life,” Kane said.
The team found that Wolf 1061c’s orbit varies at a faster rate than that of Earth, and this likely leads to greater climatic variations than Earth experiences
“It could cause the frequency of the planet freezing over or heating up to be quite severe,” Kane said.
So it’s unknown whether or not Wolf 1061c actually is habitable, study team members said. Getting to the bottom of this question may require more-advanced telescopes than are currently in operation, the researchers added.
One future instrument that should help is NASA’s $8.8 billion James Webb Space Telescope, which is scheduled to launch in late 2018 and succeed the Hubble Space Telescope, Kane said. Webb is expected to reveal the composition of nearby exoplanet atmospheres in detail.
Findings from the new study will appear in the next issue of the Astrophysical Journal. A preprint version is available now on the website arXiv.
Nearly two years after its historic encounter with the dwarf planet Pluto, NASA’s New Horizons spacecraft is getting ready for its next big adventure in the icy outskirts of the solar system.
Now, the spacecraft is on its way to a small, ancient object located about 1 billion miles (1.6 billion kilometers) beyond Pluto in the Kuiper Belt. This distant region surrounds the solar system and is filled with trillions of icy rocks that have yet to be explored. The new target was discovered by the Hubble Space Telescope in June 2014, and it was dubbed 2014 MU69.
Pluto, which officially lost its planetary status shortly after New Horizons launched in 2006, is also a Kuiper Belt object (KBO), and the largest of its kind. New Horizons became the first spacecraft to visit the Pluto system when the probe flew by the dwarf planet and its moons on July 14, 2015. [
It took the spacecraft about 16 months to beam back all of its data from the Pluto flyby, and planetary scientists have had a ball with that data.
The New Horizons flyby of the Pluto system was completely successful, and now we’ve got all the data on the ground and we’re putting a bow around it,” Alan Stern, the New Horizons principal investigator at Southwest Research Institute, said in a Facebook Live event on Thursday (Jan. 19).
Thanks to New Horizons, scientists now have a global map of Pluto and the most detailed images yet of the dwarf planet’s bizarre, mountainous landscape and icy volcanoes. Tall mountain ranges seen on Pluto also suggest recent geological activity on the dwarf planet’s surface.
New Horizons additionally beamed back a gorgeous photo of a huge, heart-shaped basin (unofficially called “Tombaugh Regio”) that quickly became Pluto’s most famous feature, taking the internet by storm and gracing the front page of hundreds of newspapers worldwide. The New Horizons science team has said Pluto’s “heart” seems to indicate the presence of a subsurface ocean.
The Pluto flyby also provided an opportunity to study Pluto’s moons, particularly Charon. Researchers discovered that Charon and Pluto are both tidally locked, meaning the same side of the moon always faces the dwarf planet and vice-versa. As a result, Pluto’s heart is always facing Charon. A giant red spot discovered on Charon’s surface revealed that the moon is taking some of its atmosphere from Pluto.
“One thing that we discovered is that small planets can be just as complex as big planets, and that really blew away our expectations,” Stern said, adding that all the new findings from Pluto “wet our appetite for future exploration of the Kuiper Belt.”
While the team continues to analyze the plethora of data — something that could go on for decades — it’s also busy planning for the next big stage of the mission, the flyby of 2014 MU69. That will occur in January 2019.
Pluto is the largest object known to exist in the Kuiper Belt, but MU69 is much smaller and more representative of the trillions of other KBOs, Kelsi Singer of the New Horizons science team told Space.com. Pluto is comparable to the size of North America at 1,475 miles (2,370 km) in diameter, while MU69 is less than 30 miles (about 45 km) across.
But MU69 isn’t just any old KBO. Singer said that the object “has a special kind of orbit that makes it possibly a type of object that is primordial and left over from early solar system formation. So we think that we’ll be able to look at what the building blocks of the solar system were like by going to this special object that has a special orbit.”
Part of the rationale for choosing MU69 as the next target was that it had a good location given the amount of fuel left on the New Horizons spacecraft.
“MU69 turned out to be really interesting, but we also had limited options,” Singer said. Using the Hubble Space Telescope, “we were searching the area of space where we had enough fuel left in the spacecraft to get to any objects that were there,” she said. Three good potential targets were located, but the other two “were just on the edge of where [the spacecraft] had enough fuel to get to.”
New Horizons runs on a radioactive plutonium power supply that could keep the spacecraft going through the mid-2030s, Glen Fountain, the New Horizons encounter project manager at Johns Hopkins University’s Applied Physics Laboratory, said during the Facebook Live event.
But after the 2019 flyby of MU69, the spacecraft probably won’t have much fuel left for special maneuvers, Singer said. “We won’t be able to switch directions, but we’ll still keep going out. It’s possible that we’ll be able to observe some other objects, but we haven’t identified any of them yet. So we’re going to keep an eye out to see what we can find.”
For now, the team will remain focused on planning the MU69 flyby and sifting through data from Pluto. The researchers need to plan the spacecraft’s every move far ahead of time; because of a 6-hour delay in communications with the distant spacecraft, they won’t be able to tell the probe what to do in real time. Instead, the team must program New Horizons at least several months in advance to do every observation and data transmission.
The spacecraft will take photos of MU69 along the way, starting out with pictures of a single-pixel speck from afar, Singer said. During the flyby, New Horizons will be able to get even closer to MU69 than it did with Pluto, because the small object has much less gravity. This means that the photos of MU69 will have a higher resolution than the photos of Pluto. Singer said that’s something she and the team look forward to seeing.
In April, New Horizons will be halfway to MU69 from Pluto, with 21 months of spaceflight left to go.
Microbes that rank among the simplest and most ancient organisms on Earth could survive the extremely thin air of Mars, a new study finds.
The Martian surface is presently cold and dry, but there is plenty of evidence suggesting that rivers, lakes and seas covered the Red Planet billions of years ago. Since there is life virtually wherever there is liquid water on Earth, scientists have suggested that life might have evolved on Mars when it was wet, and life could be there even now.
“In all the environments we find here on Earth, there is some sort of microorganism in almost all of them,” said Rebecca Mickol, an astrobiologist at the Arkansas Center for Space and Planetary Sciences at the University of Arkansas in Fayetteville, and the lead author of the study. “It’s hard to believe there aren’t other organisms out there on other planets or moons as well.”
Mickol and her team detailed their findings in the paper “Low Pressure Tolerance by Methanogens in an Aqueous Environment: Implications for Subsurface Life on Mars,” which was published in the journal Origins of Life and Evolution of Biospheres.
Previous research detected methane, the simplest organic molecule, in the Martian atmosphere. While there are abiotic ways to produce methane — such as volcanic activity — much of this colorless, odorless, flammable gas in Earth’s atmosphere is produced by life, such as cattle digesting food.
“One of the exciting moments for me was the detection of methane in the Martian atmosphere,” Mickol said. “On Earth, most methane is produced biologically by past or present organisms. The same could possibly be true for Mars. Of course, there are a lot of possible alternatives to the methane on Mars and it is still considered controversial. But that just adds to the excitement.”
On Earth, microbes known as methanogens produce methane, also known as natural gas. Methanogens typically live in swamps and marshes, but can also be found in the guts of cattle, termites and other herbivores, as well as in dead and decaying organic matter.
Methanogens are among the simplest and most ancient organisms on Earth. These microorganisms are anaerobes, meaning they do not require oxygen. Instead, they often rely on hydrogen for energy, and carbon dioxide is the main source of carbon atoms they use in creating organic molecules.
Methanogens contained in these test tubes, which also contained growth nutrients, sand and water, survived when subjected to Martian freeze-thaw cycles.
The fact that methanogens neither require oxygen nor photosynthesis means they could live just beneath the Martian surface, shielded from harsh levels of ultraviolet radiation on the Red Planet. This could make them ideal candidates for life on Mars.
However, the area just below the surface of Mars is exposed to extremely low atmospheric pressures, normally considered inhospitable to life. The surface pressure on Mars on average ranges from one-hundredth to one-thousandth that of the surface pressure of Earth over the course of the Martian year, too low for liquid water to last on the surface. In such thin air, water easily boils. (In contrast, the pressure at the highest point on Earth’s surface, the top of Mount Everest, is about one-third that of Earth’s surface pressure at sea level.)
To see if methanogens might survive such extremely thin air, Mickol and Timothy Kral, the senior author of the study and an astrobiologist at the University of Arkansas at Fayetteville, experimented with four species of methanogens. They included: Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, and Methanococcus maripaludis. Previous experiments on these four species over the course of more than 20 years generated a lot of data on these organisms and their rates of survival in simulated Martian conditions.
The more recent set of experiments, which took about a year, involved growing the microbes in test tubes within liquids as a proxy for the fluids potentially flowing through underground Martian aquifers. The microbes were fed hydrogen gas, and the liquids were covered with cotton swabs, which in turn were covered with dirt simulating what might be found on the Martian surface. The insides of each test tube were then subjected to low pressures.
Oxygen kills these methanogens, and maintaining a low-pressure, oxygen-free environment “was a difficult task,” Mickol said. Moreover, water evaporates quickly at low pressure, which can limit how long the experiments can last and can also clog the vacuum system with water.
Despite these problems, the researchers found that these methanogens all survived exposure of lengths varying from 3 to 21 days at pressures down to roughly six-thousandths of Earth’s surface pressure. “These experiments show that for some species, low pressure may not really have any effect on the survival of the organism,” Mickol said.
The scientists are also measuring methane to see whether methanogens are actively growing at low pressure and producing methane.
“The next step is to also include temperature,” Mickol said. “Mars is very, very cold, often getting down to -100ºC (-212ºF) at night, and sometimes, on the warmest day of the year, at noon, the temperature can rise above freezing. We’d run our experiments just above freezing, but the cold temperature would limit evaporation of the liquid media and it would create a more Mars-like environment.”
Mickol stressed that these experiments do not prove life exists on other planets. “That being said, with the abundance of life on Earth, in all the different extremes of environments found here, it’s quite possible there exists life — bacteria or tiny microorganisms — somewhere else in the Universe,” she said. “We’re just trying to explore that idea.”
This research was supported by the Exobiology & Evolutionary Biology element of the NASA Astrobiology Program.
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.