A new paper proposes an experimental setup that could test the classic Daisyworld model — a hypothesis of a self-regulating planetary ecosystem — in the lab via two synthetic bacterial strains. Credit: Victor Maull/Image Designer
During the 1970s, inventor/environmentalist James Lovelock and evolutionary biologist Lynn Margulis proposed the Gaia Hypothesis. This theory posits that Earth is a single, self-regulating system where the atmosphere, hydrosphere, all life, and their inorganic surroundings work together to maintain the conditions for life on the planet. This theory was largely inspired by Lovelock’s work with NASA during the 1960s, where the skilled inventor designed instruments for modeling the climate of Mars and other planets in the Solar System.
According to this theory, planets like Earth would slowly grow warmer and their oceans more acidic without a biosphere that regulates temperature and ensures climate stability. While the theory was readily accepted among environmentalists and climatologists, many in the scientific community have remained skeptical since it was proposed. Until now, it has been impossible to test this theory because it involves forces that work on a planetary scale. But in a recent paper, a team of Spanish scientists proposed an experimental system incorporating synthetic biology that could test the theory on a small scale.
This artist's illustration shows what an icy exo-Earth might look like. A new study says liquid water could persist under ice sheets on planets outside of their habitable zones. Image Credit: NASA
When astronomers discover a new exoplanet, one of the first considerations is if the planet is in the habitable zone, or outside of it. That label largely depends on whether or not the temperature of the planet allows liquid water. But of course it’s not that simple. A new study suggests that frozen, icy worlds with completely frozen oceans could actually have livable land areas that remain habitable.
Artist's impression of a system of exoplanets orbiting a low mass, red dwarf star. Credit: NASA/JPL
It turns out that the TRAPPIST-1 star may be a terrible host for the TRAPPIST planets announced in February.
The TRAPPIST-1 star, a Red Dwarf, and its 7 planets caused a big stir in February when it was discovered that 3 of the rocky planets are in the habitable zone. But now more data is coming which suggests that the TRAPPIST-1 star is much too volatile for life to exist on its planets.
Red Dwarfs are much dimmer than our Sun, but they also last much longer. Their lifetimes are measured in trillions of years, not billions. Their long lives make them intriguing targets in the search for habitable worlds. But some types of Red Dwarf stars can be quite unstable when it comes to their magnetism and their flaring.
Our own Sun produces flares, but we are protected by our magnetosphere, and by the distance from the Sun to Earth. Credit: NASA/ Solar Dynamics Observatory,
A new study analyzed the photometric data on TRAPPIST-1 that was obtained by the K2 mission. The study, which is from the Konkoly Observatory and was led by astronomer Krisztián Vida, suggests that TRAPPIST-1 flares too frequently and too powerfully to allow life to form on its planets.
The study identified 42 strong flaring events in 80 days of observation, of which 5 were multi-peaked. The average time between flares was only 28 hours. These flares are caused by stellar magnetism, which causes the star to suddenly release a lot of energy. This energy is mostly in the X-ray or UV range, though the strongest can be seen in white light.
While it’s true that our Sun can flare, things are much different in the TRAPPIST system. The planets in that system are closer to their star than Earth is to the Sun. The most powerful flare observed in this data correlates to the most powerful flare observed on our Sun: the so-called Carrington Event.The Carrington Event happened in 1859. It was an enormously powerful solar storm, in which a coronal mass ejection struck Earth’s magnetosphere, causing auroras as far south as the Caribbean. It caused chaos in telegraph systems around the world, and some telegraph operators received electric shocks.
Earth survived the Carrington Event, but things would be much different on the TRAPPIST worlds. Those planets are much closer to their Sun, and the authors of this study conclude that storms like the Carrington Event are not isolated incidents on TRAPPIST-1. They occur so frequently that they would destroy any stability in the atmosphere, making it extremely difficult for life to develop. In fact, the study suggests that the TRAPPIST-1 storms could be hundreds or thousands of times more powerful than the storms that hit Earth.
A study from 2016 shows that these flares would cause great disturbances in the chemical composition of the atmosphere of the planets subjected to them. The models in that study suggest that it could take 30,000 years for an atmosphere to recover from one of these powerful flares. But with flares happening every 28 hours on TRAPPIST-1, the habitable planets may be doomed.
The Earth’s magnetic field helps protects us from the Sun’s outbursts, but it’s doubtful that the TRAPPIST planets have the same protection. This study suggests that planets like those in the TRAPPIST system would need magnetospheres of tens to hundreds of Gauss, whereas Earth’s magnetosphere is only about 0.5 Gauss. How could the TRAPPIST planets produce a magnetosphere powerful enough to protect their atmosphere?
It’s not looking good for the TRAPPIST planets. The solar storms that hit these worlds are likely just too powerful. Even without these storms, there are other things that may make these planets uninhabitable. They’re still an intriguing target for further study. The James Webb Space Telescope should be able to characterize the atmosphere, if any, around these planets.
Just don’t be disappointed if the James Webb confirms what this study tells us: the TRAPPIST system is a dead, lifeless, grouping of planets around a star that can’t stop flaring.
We’ve found hundreds of exoplanets in the galaxy. But only a few of them have just the right combination of factors to hold life like Earth’s.
The weather in your hometown is downright uninhabitable. There’s scorching heatwaves, annual tyhpoonic deluges, and snow deep enough to bury a corn silo.
The bad news is planet Earth is the only habitable place we know of in the entire Universe. Also, are the Niburians suffering from Niburian made climate change? Only Niburian Al Gore can answer that question.
We as a species are interested in habitability for an assortment of reasons, political, financial, humanitarian and scientific. We want to understand how our own climate is changing. How we’ll live in the climate of the future and what we can do to stem the tide of what our carbon consumption causes.
There could be agendas to push for cleaner energy sources, or driving politicians towards climate change denial to maintain nefarious financial gain.
We also might need a new lilypad to jump to, assuming we can sort out the travel obstacles. The thing that interests me personally the most is, when can I see an alien?
The habitable zone, also known as the “Goldilocks Zone”, is the region around a star where the average temperature on a planet allows for liquid water with which to make porridge. It’s that liquid water that we hunt for not only for our future uses, but as an indicator of where alien life could be in the Universe.
Problems outside this range are pretty obvious. Too hot, it’s a perpetual steam bath, or it produces separate piles of hydrogen and oxygen. Then your oxygen combines with carbon to form carbon dioxide, and then hydrogen just buggers off into space.
This is what happened with Venus. If the planet’s too cold, then bodies of water are solid skating rinks. There could be pockets of liquid water deep beneath the icy surface, but overall, they’re bad places to live.
We’ve got this on Mars and the moons of Jupiter and Saturn. The habitable zone is a rough measurement. It’s a place where liquid water might exist.
“The Chemistry of the Solar System” by Compound Interest’s Andy Brunning
Unfortunately, it’s not just a simple equation of the distance to the star versus the amount of energy output. The atmosphere of the planet matters a lot. In fact, both Venus and Mars are considered to be within the Solar System’s habitable zone.
Venusian atmosphere is so thick with carbon dioxide that it traps energy from the Sun and creates an inhospitable oven of heat that would quickboil any life faster than you can say “pass the garlic butter”.
It’s the opposite on Mars. The thin atmosphere won’t trap any heat at all, so the planet is bun-chillingly cold. Upgrade the atmospheres of either planet and you could get worlds which would be perfectly reasonable to live on. Maybe if we could bash them together and we could spill the atmosphere of one onto the other? Tell Blackbolt to ring up Franklin Richards, I have an idea!
When we look at other worlds in the Milky Way and wonder if they have life, it’s not enough to just check to see if they’re in the habitable zone. We need to know what shape their atmosphere is in.
Astronomers have actually discovered planets located in the habitable zones around other stars, but from what we can tell, they’re probably not places you’d want to live. They’re all orbiting red dwarf stars.
Artists impression of Gliese 581g. Credit: Lynette Cook/NSF
It doesn’t sound too bad to live in a red tinted landscape, provided it came with an Angelo Badalamenti soundtrack, red dwarf stars are extremely violent in their youth. They blast out enormous solar flares and coronal mass ejections. These would scour the surface of any planets caught orbiting them close enough for liquid water to be present.
There is some hope. After a few hundred million years of high activity, these red dwarf stars settle down and sip away at their fuel reserves of hydrogen for potentially trillions of years. If life can hold on long enough to get through the early stages, it might have a long existence ahead of it.
When you’re thinking about a new home among the stars, or trying to seek out new life in the Universe, look for planets in the habitable zone.
As we’ve seen, it’s only a rough guideline. You probably want to check out the place first and make sure it’s truly liveable before you commit to a timeshare condo around Gliese 581.
Do you think habitable planets are common in the Milky Way? Tell us what your perfect planet environment might be in the comments below.
Rock Target ‘Knorr’ Near Curiosity. Scientists used Curiosity's Mast Camera (Mastcam) to study spectral characteristics of the rock target called Knorr in the Yellowknife Bay area and determined that it possessed veins of hydrated minerals, including hydrated calcium sulfate. This self-portrait is a mosaic of images taken by Curiosity's Mars Hand Lens Imager (MAHLI) camera during Sol 177 (Feb. 3, 2013). Credit: NASA/JPL-Caltech/MSSS
The science team guiding NASA’s Curiosity Mars Science Lab (MSL) rover have demonstrated a new capability that significantly enhances the robots capability to scan her surroundings for signs of life giving water – from a distance. And the rover appears to have found that evidence for water at the Gale Crater landing site is also more widespread than prior indications.
The powerful Mastcam cameras peering from the rovers head can now also be used as a mineral-detecting and hydration-detecting tool to search 360 degrees around every spot she explores for the ingredients required for habitability and precursors to life.
Researchers announced the new findings today (March 18) at a news briefing at the Lunar and Planetary Science Conference in The Woodlands, Texas.
“Some iron-bearing rocks and minerals can be detected and mapped using the Mastcam’s near-infrared filters,” says Prof. Jim Bell, Mastcam co-investigator of Arizona State University, Tempe.
Bell explained that scientists used the filter wheels on the Mastcam cameras to run an experiment by taking measurements in different wavelength’s on a rock target called ‘Knorr’ in the Yellowknife Bay area were Curiosity is now exploring. The rover recently drilled into the John Klein outcrop of mudstone that is crisscrossed with bright veins.
Curiosity accomplished Historic 1st drilling into Martian rock at John Klein outcrop on Feb 8, 2013 (Sol 182), shown in this context mosaic view of the Yellowknife Bay basin taken on Jan. 26 (Sol 169) where the robot is currently working. The robotic arm is pressing down on the surface at John Klein outcrop of veined hydrated minerals – dramatically back dropped with her ultimate destination; Mount Sharp. Credit: NASA/JPL-Caltech/Ken Kremer (kenkremer.com)/Marco Di Lorenzo
Researchers found that near-infrared wavelengths on Mastcam can be used as a new analytical technique to detect the presence of some but not all types of hydrated minerals.
“Mastcam has some capability to search for hydrated minerals,” said Melissa Rice of the California Institute of Technology, Pasadena.
“The first use of the Mastcam 34 mm camera to find water was at the rock target called “Knorr.”
“With Mastcam, we see elevated hydration signals in the narrow veins that cut many of the rocks in this area. These bright veins contain hydrated minerals that are different from the clay minerals in the surrounding rock matrix.”
Mastcam thus serves as an early detective for water without having to drive up to every spot of interest, saving precious time and effort.
Hydration in Veins and Nodules at ‘Knorr’ rock in Yellowknife bay. At different locations on the surface of the same rock, scientists can use the Mast Camera (Mastcam) on Curiosity to measure the amount of reflected light at a series of different wavelengths to obtain spectral information about composition. The inset photograph shows two locations on a rock target called “Knorr,” where Mastcam spectral measurements were made: A light-toned vein and part of the host rock. The main graph shows the spectra recorded at those two points, with increasing wavelengths of visible light and near-infrared light from left to right, and with increasing intensity of reflectance from bottom to top. The bright vein shows greater reflectance through the range of wavelengths assessed. The shapes of the two curves also differ, especially where the vein spectrum dips in the near-infrared wavelengths. The range of wavelengths included in box-outlined portion of the vein spectrum is shown at the top of the group of reference spectra to the right. These reference spectra show how the dip in reflectance at those wavelengths in the vein material corresponds to dips in those wavelengths in several types of hydrated minerals — minerals that have molecules of water bound into their crystalline structure, including hydrated calcium-sulfates. Mastcam is not sensitive to all hydrated minerals, however, including many phyllosilicates. Credit: NASA/JPL-Caltech/MSSS/ASU
But Mastcam has some limits. “It is not sensitive to the hydrated phyllosilicates found in the drilling sample at John Klein” Rice explained.
“Mastcam can use the hydration mapping technique to look for targets related to water that correspond to hydrated minerals,” Rice added. “It’s a bonus in searching for water!”
The key finding of Curiosity thus far is that the fine-grained, sedimentary mudstone rock at the Yellowknife Bay basin possesses a significant amount of phyllosilicate clay minerals; indicating an environment where Martian microbes could once have thrived in the distant past.
“We have found a habitable environment which is so benign and supportive of life that probably if this water was around, and you had been on the planet, you would have been able to drink it,” said John Grotzinger, the chief scientist for the Curiosity Mars Science Laboratory mission at the California Institute of Technology in Pasadena, Calif.
Hydration Map, Based on Mastcam Spectra for ‘Knorr’ rock target shows coded map of the amount of mineral hydration indicated by a ratio of near-infrared reflectance intensities measured by Curiosity. The color scale on the right shows the assignment of colors for relative strength of the calculated signal for hydration. The map shows that the stronger signals for hydration are associated with pale veins and light-toned nodules in the rock. The Mastcam observations were conducted during Sol 133 (Dec. 20, 2012). The width of the area shown in the image is about 10 inches (25 centimeters). Credit: NASA/JPL-Caltech/MSSS/ASU
Impact cratering and erosion combine to reveal the composition of the Martian underground by exposing materials from the subsurface. Image credit: NASA/JPL-Caltech/JHUAPL
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Mars’ surface was probably not ever warm and wet long enough to support life, a new study published today in Nature concludes. But underground on the Red Planet might be a different story. By taking a look at several years of data from orbiting spacecraft and examining more than 350 sites on Mars, a team of researchers determined that Martian environments with abundant liquid water on the surface existed only in short episodes. But liquid and likely warm water more likely lasted for longer periods of time below the surface, and this would have been occurring at about the same time that life was developing on Earth.
“If surface habitats were short-term, that doesn’t mean we should be glum about prospects for life on Mars, but it says something about what type of environment we might want to look in,” said Bethany Ehlmann from Caltech and JPL, who is the lead author of the study. “The most stable Mars habitats over long durations appear to have been in the subsurface. On Earth, underground geothermal environments have active ecosystems.”
And so, the best place to look for signs of past life on Mars may be underground.
The researchers’ findings seem to indicate that Mars’ surface was almost always cold and dry, and any appearances of water – and the salts they left behind – occurred during geologically brief periods. This is certainly not the first time research has suggested brief periods of water flowing on Mars, or that underground water may have persisted, but the news study does help to provide a better picture of the history of water on Mars and even if it could possibly be there today.
Clays are crucial to understanding past water on Mars, as they form only when water is around long enough to change the chemical structure of rocks into clay, and different types of clay minerals result from different types of wet conditions.
Signs of deep water, deep life? Erosion has exposed clays (light blue) that subterranean waters favorable to life may have formed eons ago in the Nili Fossae region of Mars. Credit: NASA/JPL/JHUAPL/University of Arizona/Brown University
In 2005, clay minerals were discovered in many regions of Mars by the OMEGA spectrometer on the ESA’s Mars Express. This finding seemed to indicate the planet was once warm and wet. But there’s a problem with Mars’ atmosphere – it is not thick enough now for water to be retained on Mars’ surface, and there is not scientific consensus that it was ever thick enough in the past to have allowed water to remain on the surface.
But this new study supports an alternative hypothesis that warm water persisted under Mars surface and many erosional features seen by the orbiting spacecraft were carved during brief periods when liquid water was stable at the surface.
“The types of clay minerals that formed in the shallow subsurface are all over Mars,” said John Mustard, professor at Brown University in Providence, R.I. Mustard a co-author of the study. “The types that formed on the surface are found at very limited locations and are quite rare.”
During the past five years, researchers used OMEGA and NASA’s Compact Reconnaissance Imaging Spectrometer, or CRISM, instrument on the Mars Reconnaissance Orbiter to identify clay minerals at thousands of locations on Mars. Clay minerals that form with small amounts of water usually retain the same chemical elements as those found in the original volcanic rocks later altered by the water.
The study interprets this to be the case for most terrains on Mars with iron and magnesium clays. In contrast, surface environments with higher ratios of water to rock can alter rocks further. Soluble elements are carried off by water, and different aluminum-rich clays form.
Another clue is detection of a mineral called prehnite. It forms at temperatures above about 400 degrees Fahrenheit (about 200 degrees Celsius). These temperatures are typical of underground hydrothermal environments rather than surface waters.
Two upcoming missions will help decipher the water clues left behind on Mars. The Curiosity rover, or the Mars Science Laboratory will be heading towards Gale Crater, to investigate a large, layered hill that contain clay and sulfate minerals. Curiosity is scheduled to launch later this month.
These new findings also have implications for how Mars’ atmosphere may have evolved over time, and the Mars Atmosphere and Volatile Evolution Mission, or MAVEN, in development for a 2013 launch, may provide evidence for or against this new interpretation of the Red Planet’s environmental history. This new study predicts MAVEN findings will beconsistent with the atmosphere not having been thick enough to provide warm, wet surface conditions for a prolonged period.
This volcanic cone in the Nili Patera caldera on Mars has hydrothermal mineral deposits on the southern flanks and nearby terrains. Two of the largest deposits are marked by arrows, and the entire field of light-toned material on the left of the cone is hydrothermal deposits. Image Credit: NASA/JPL-Caltech/MSSS/JHU-APL/Brown Univ.
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Evidence of a past “hot spring” environment on Mars has shown up in images from the Mars Reconnaissance Orbiter. Scientists say light-colored mounds of hydrated silica on the side of a volcano are likely deposits from steam fumaroles, or hot springs, which may have provided a habitable environment on the Red Planet about three billion years ago. Concentrations of hydrated silica have been identified on Mars previously, including an ancient hot springs environment that the Spirit rover stumbled across in 2007.
“The heat and water required to create this deposit probably made this a habitable zone,” said J.R. Skok from Brown University, lead author of a paper about these findings published online today by Nature Geoscience. “If life did exist there, this would be a promising type of deposit to entomb evidence of it — a microbial mortuary.”
While it is not direct evidence of life on Mars, it adds to the mounting evidence of past habitable environments for at least microbial life on the planet, and is the most intact ancient hot springs region ever found. This specific spot in the Syrtis Major volcanic region on Mars would have been hospitable to life when most of Mars was already dry and cold.
Skok said, “You have spectacular context for this deposit. It’s right on the flank of a volcano. The setting remains essentially the same as it was when the silica was deposited.”
The small cone rises about 100 meters (100 yards) from the floor of a shallow volcanic caldera named Nili Patera and covers about 50 kilometers (30 miles) of Syrtis Major, which is near Mars equator. The collapse of an underground magma chamber from which lava had emanated created the bowl, and subsequent lave flows tell a story of how the cone formed.
“We can read a series of chapters in this history book and know that the cone grew from the last gasp of a giant volcanic system,” said John Mustard, Skok’s thesis advisor at Brown and a co-author of the paper. “The cooling and solidification of most of the magma concentrated its silica and water content.”
Orbital images revealed patches of bright deposits near the summit of the cone, fanning down its flank, and on flatter ground in the vicinity. The Brown researchers partnered with Scott Murchie of Johns Hopkins University Applied Physics Laboratory, Laurel, Md., to analyze the bright exposures with the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on the orbiter.
Silica can be dissolved, transported and concentrated by hot water or steam. Hydrated silica identified by the spectrometer in uphill locations — confirmed by stereo imaging — indicates that hot springs or fumaroles fed by underground heating created these deposits. Silica deposits around hydrothermal vents in Iceland are among the best parallels on Earth.
Murchie said, “The habitable zone would have been within and alongside the conduits carrying the heated water.” The volcanic activity that built the cone in Nili Patera appears to have happened more recently than the 3.7-billion-year or greater age of Mars’ potentially habitable early wet environments recorded in clay minerals identified from orbit.
